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Sample records for al-si tipo a319

  1. Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

    Science.gov (United States)

    Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

    2017-03-01

    The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating coating coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

  2. Al-Si/B{sub 4}C composite coatings on Al-Si substrate by plasma spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Sarikaya, Ozkan [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Anik, Selahaddin [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Aslanlar, Salim [Sakarya University, Faculty of Technical Education, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Cem Okumus, S. [Sakarya University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Celik, Erdal [Dokuz Eylul University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Buca, Izmir 35160 (Turkey)]. E-mail: erdal.celik@deu.edu.tr

    2007-07-01

    Plasma-sprayed coatings of Al-Si/B{sub 4}C have been prepared on Al-Si piston alloys for diesel engine motors. The Al-Si/B{sub 4}C composite powders including 5-25 wt% B{sub 4}C were prepared by mixing and ball-milling processes. These powders were deposited on Al-Si substrate using an atmospheric plasma spray technique. The coatings have been characterised with respect to phase composition, microstructure, microhardness, bond strength and thermal expansion. It was found that Al, Si, B{sub 4}C and Al{sub 2}O{sub 3} phases were determined in the coatings with approximately 600 {mu}m thick by using X-ray diffraction analysis. Scanning electron microscope observation revealed that boron carbide particles were uniformly distributed in composite coatings and B{sub 4}C particles were fully wetted by Al-Si alloy. Also, no reaction products were observed in Al-Si/B{sub 4}C composite coatings. It was found that surface roughness, porosity, bond strength and thermal expansion coefficient of composite coatings decreased with increasing fraction of the boron carbide particle. It was demonstrated that the higher the B{sub 4}C content, the higher the hardness of coatings because the hardness of B{sub 4}C is higher than that of Al-Si.

  3. Defining and comparing vibration attributes of AlSi10 foam and CFRP coated AlSi10 foam materials

    Science.gov (United States)

    Çolak, O.; Yünlü, L.

    2017-06-01

    Now, Aluminum materials have begun being manufactured as porous structures and being used with additive composite materials through emerging manufacturing technologies. These materials those porous structures have also begun being used in many areas such as automotive and aerospace due to light-weighted structures. In addition to examining mechanical behavior of porous metallic structures, examining vibration behavior is important for defining characteristic specifications. In this study, vibration attributes belong to %80 porous AlSi10 foam and CFRP coated %80 porous AlSi10 foam are determined with modal analysis. Modal parameters such as natural frequencies and damping coefficient from frequency response functions at the end of hammer impact tests. It is found that natural frequency of CFRP coated AlSi10 foam’s is 1,14 times bigger than AlSi10 foam and damping coefficient of CFRP coated AlSi10 foam is 5 times bigger than AlSi10 foam’s with tests. Dynamic response of materials in various conditions is simulated by evaluating modal parameters with FEM. According to results of the study, CFRP coating on AlSi10 foam effect vibration damping and resonance avoidance ability positively.

  4. U-Mo/Al-Si interaction: Influence of Si concentration

    International Nuclear Information System (INIS)

    Allenou, J.; Palancher, H.; Iltis, X.; Cornen, M.; Tougait, O.; Tucoulou, R.; Welcomme, E.; Martin, Ph.; Valot, C.; Charollais, F.; Anselmet, M.C.; Lemoine, P.

    2010-01-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 deg. C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 , when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6 Mo 4 Al 43 . For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3 (Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 . On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

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

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    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.

  6. Relationships Between Solidification Parameters in A319 Aluminum Alloy

    Science.gov (United States)

    Vandersluis, E.; Ravindran, C.

    2018-03-01

    The design of high-performance materials depends on a comprehensive understanding of the alloy-specific relationships between solidification and properties. However, the inconsistent use of a particular solidification parameter for presenting materials characterization in the literature impedes inter-study comparability and the interpretation of findings. Therefore, there is a need for accurate expressions relating the solidification parameters for each alloy. In this study, A319 aluminum alloy castings were produced in a permanent mold with various preheating temperatures in order to control metal cooling. Analysis of the cooling curve for each casting enabled the identification of its liquidus, Al-Si eutectic, and solidus temperatures and times. These values led to the calculation of the primary solidification rate, total solidification rate, primary solidification time, and local solidification time for each casting, which were related to each other as well as to the average casting SDAS and material hardness. Expressions for each of their correlations have been presented with high coefficients of determination, which will aid in microstructural prediction and casting design.

  7. Gerichtete Erstarrung von Al-Si und Al-Si-Mn Legierungen unter dem Einfluss von magnetischen Wechselfeldern

    OpenAIRE

    Orth, Andreas

    2013-01-01

    In this work, samples of two alloys, Al-Si7 and Al-Si7-Mn1, are directionally solidified and their structure microscopically analysed. Thereby, the combined influence of induced current flow and intermetallic precipitates is of particular interest. A newly modified "Artemis" setup at the institute of material physics at the DLR in Cologne allows controlled solidification velocities of 30 to 240 micron/s under a constant temperature gradient of 3 K/mm. In using silica aerogels as part of the c...

  8. 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.

  9. Elimination of Iron Based Particles in Al-Si Alloy

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    Bolibruchová D.

    2015-03-01

    Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.

  10. 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

  11. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

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    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

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

    Energy Technology Data Exchange (ETDEWEB)

    Genau, Amber Lynn [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    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.

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

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    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.

  14. Fabrication of Spherical AlSi10Mg Powders by Radio Frequency Plasma Spheroidization

    Science.gov (United States)

    Wang, Linzhi; Liu, Ying; Chang, Sen

    2016-05-01

    Spherical AlSi10Mg powders were prepared by radio frequency plasma spheroidization from commercial AlSi10Mg powders. The fabrication process parameters and powder characteristics were investigated. Field emission scanning electron microscope, X-ray diffraction, laser particle size analyzer, powder rheometer, and UV/visible/infrared spectrophotometer were used for analyses and measurements of micrographs, phases, granulometric parameters, flowability, and laser absorption properties of the powders, respectively. The results show that the obtained spherical powders exhibit good sphericity, smooth surfaces, favorable dispersity, and excellent fluidity under appropriate feeding rate and flow rate of carrier gas. Further, acicular microstructures of the spherical AlSi10Mg powders are composed of α-Al, Si, and a small amount of Mg2Si phase. In addition, laser absorption values of the spherical AlSi10Mg powders increase obviously compared with raw material, and different spectra have obvious absorption peaks at a wavelength of about 826 nm.

  15. Comparative study of anisotropic superconductivity in CaAlSi and CaGaSi

    International Nuclear Information System (INIS)

    Tamegai, T.; Uozato, K.; Kasahara, S.; Nakagawa, T.; Tokunaga, M.

    2005-01-01

    In order to get some insight into the origin of the anomalous angular dependence of H c2 in a layered intermetallic compound CaAlSi, electronic, superconducting, and structural properties are compared between CaAlSi and CaGaSi. The angular dependence of H c2 in CaGaSi is well described by the anisotropic GL model. Parallel to this finding, the pronounced lattice modulation accompanying the superstructure along the c-axis in CaAlSi is absent in CaGaSi. A relatively large specific heat jump at the superconducting transition in CaAlSi compared with CaGaSi indicates the presence of strong electron-phonon coupling in CaAlSi, which may cause the superstructure and the anomalous angular dependence of H c2

  16. Coupling of experimental measurements to study the influence of microscopic defects on the fatigue damage in A319 Al-Si alloy

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    Wang Long

    2014-06-01

    Full Text Available An experimental protocol based on the coupling of kinematic field measurements on the surface and in volume at the microstructure scale has been set up in order to study the influence of the casting microstructure upon the initiation and propagation of cracks in low cycle fatigue. Preliminary applications of this protocol on tensile tests were successful as it allowed tracking the development and localization of plastic deformation and identifying the initiation sites of microcracks during tests in relation with the observed surface and volume microstructures. Application of the proposed protocol to low cycle fatigue is an on-going work.

  17. Effect of Heat Treatment on Commercial AlSi12Cu1(Fe) and AlSi12(b) Aluminum Alloy Die Castings

    Science.gov (United States)

    Battaglia, E.; Bonollo, F.; Ferro, P.; Fabrizi, A.

    2018-03-01

    High-pressure die castings (HPDCs) cannot normally be heat-treated at a high temperature because of the presence of inner air/gas- or shrinkage-porosity that may lead to the formation of undesired surface blisters. In this paper, an unconventional heat treatment is proposed. Two secondary Al-Si alloys, AlSi12(b) and AlSi12Cu1(Fe), were stabilization heat-treated at 624 K (350 °C) with soaking times ranging from 1 to 8 hours. Enhancement of both static and dynamic mechanical properties was found to be related to the fragmentation of interconnected eutectic Si particles and the smoothing of coarser crystals. Increased ductility after heat treatment was correlated with a decrease in hardness and Si particle roundness. The formation of Si precipitates within the α-Al matrix was also observed.

  18. Cell adhesion to cathodic arc plasma deposited CrAlSiN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Kyu, E-mail: skim@ulsan.ac.kr [School of Materials Science and Engineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Pham, Vuong-Hung [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Chong-Hyun [Department of Food Science, Cornell University, Ithaca, NY 14853 (United States)

    2012-07-01

    Osteoblast cell response (cell adhesion, actin cytoskeleton and focal contact adhesion as well as cell proliferation) to CrN, CrAlSiN and Ti thin films was evaluated in vitro. Cell adhesion and actin stress fibers organization depended on the film composition significantly. Immunofluorescent staining of vinculin in osteoblast cells showed good focal contact adhesion on the CrAlSiN and Ti thin films but not on the CrN thin films. Cell proliferation was significantly greater on the CrAlSiN thin films as well as on Ti thin films than on the CrN thin films.

  19. Study of polarization curves from AlSi12, AlSi5Mg and AlMg5 alloys due to corrosion problems in telecomunication equipment

    International Nuclear Information System (INIS)

    Silva, J.R.A. da

    1984-01-01

    The corrosion behaviour of three aluminium based alloys (AlSi 12, AlMg5 and AlSi 5Mg) when exposed to aqueous media containing chloride is investigated; these alloys are used in the manufacturing of telecomunication equipment. Accelerated corrosion testing and salt spray tests were carried out. The results include polarization curves obtained with three kinds of aqueous solutions (the first containing only 3% NaCl and the others, 3% NaCl and small amounts of Fe 3+ and Cu 2+ ions). (C.L.B.) [pt

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

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    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.

  1. Influence of Iron in AlSi10MgMn Alloy

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    Žihalová M.

    2014-12-01

    Full Text Available Presence of iron in Al-Si cast alloys is common problem mainly in secondary (recycled aluminium alloys. Better understanding of iron influence in this kind of alloys can lead to reduction of final castings cost. Presented article deals with examination of detrimental iron effect in AlSi10MgMn cast alloy. Microstructural analysis and ultimate tensile strength testing were used to consider influence of iron to microstructure and mechanical properties of selected alloy.

  2. Ion beam mixing to produce disordered AlSi superconducting alloys

    International Nuclear Information System (INIS)

    Xi Xiaoxing; Ran Qize; Liu Jiarui; Guan Weiyan

    1987-01-01

    Multilayered Al/Si films were bombarded with Ar ions at LHe temperature and superconducting transition temperature Tsub(c) was measured in situ. The highest Tsub(c) thus obtained was 7.53 K. The systematic studies on samples with different compositions suggest that ion induced disorder might be the main reason for Tsub(c) enhancement in these AlSi alloys. (author)

  3. The Evaluation of the Corrosion Resistance of the Al-Si Alloys Antimony Alloyed

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    Svobodova J.

    2014-06-01

    Full Text Available This paper deals with the evaluation of the corrosion resistance of the Al-Si alloys alloyed with the different amount of antimony. Specifically it goes about the alloy AlSi7Mg0,3 which is antimony alloyed in the concentrations 0; 0,001; 0,005; 0,01 a 0,05 wt. % of antimony. The introduction of the paper is dedicated to the theory of the aluminium alloys corrosion resistance, testing and evaluation of the corrosion resistance. The influence of the antimony to the Al-Si alloys properties is described further in the introduction. The experimental part describes the experimental samples which were prepared for the experiment and further they were exposed to the loading in the atmospheric conditions for a period of the 3 months. The experimental samples were evaluated macroscopically and microscopically. The results of the experiment were documented and the conclusions in terms of the antimony impact to the corrosion resistance of the Al-Si alloy were concluded. There was compared the corrosion resistance of the Al-Si alloy antimony alloyed (with the different antimony content with the results of the Al-Si alloy without the alloying after the corrosion load in the atmospheric conditions in the experiment.

  4. Thermodynamic aspects of grain refinement of Al-Si alloys using Ti and B

    Energy Technology Data Exchange (ETDEWEB)

    Groebner, Joachim [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Mirkovic, Djordje [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, Rainer [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

    2005-03-25

    A thermodynamic assessment of ternary Al-Si-Ti phases was performed. Published datasets for the other subsystems were checked and adapted. Based on that, a consistent thermodynamic description of quaternary Al-Si-Ti-B alloys was generated. This was applied in a calculation of Al-Si-Ti-B phase diagram sections for practically relevant temperatures and compositions of Al-Si alloys from Al-rich to typical Al-Si foundry alloys. These stable and metastable phase diagrams could be correlated to many detailed aspects of possible reactions observed or suggested in experimental studies of grain refining. Understanding the mechanisms of grain refining of Al wrought alloys and Al-Si foundry alloys using titanium and boron requires a fundamental knowledge of both thermodynamic and kinetic aspects of this complex process. This work focuses exclusively on the thermodynamic aspects and the phase diagrams, which were not available for the quaternary alloys and partly incomplete and inconsistent for the ternary subsystems.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Graphical abstract: - Highlights: • The demand for high performance nanostructured coatings has been increasing. • AlSiTiN and AlSiCrN nanocomposite coatings were deposited by PVD technique. • Coatings were analyzed in terms of structure, hardness and adhesion. • Tribological properties under dry and lubricated conditions were studied. • The effects of surface and bulk properties on friction evolution were assessed. - Abstract: 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.

  6. Low silicon U(Al,Si)3 stabilization by Zr addition

    International Nuclear Information System (INIS)

    Pizarro, L.M.; Alonso, P.R.; Rubiolo, G.H.

    2009-01-01

    Previous knowledge states that (U,Zr)Al 3 and U(Al,Si) 3 phases with Zr and Si content higher than 6 at.% (7.7 wt%) and 4 at.% (1.4 wt%), respectively, does not partially transform to UAl 4 at 600 o C. In this work, four alloys within the quaternary system U-Al-Si-Zr were made with a fixed nominal 0.18 at.% (0.1 wt%) Si content in order to assess the synergetic effect of both Zr and Si alloying elements to the thermodynamic stability of the (U,Zr)(Al,Si) 3 phase. Heat treatments at 600 deg. C were undertaken and samples were analyzed by means of XRD, EPMA and EDS techniques. A remarkable conclusion is that addition of 0.3 at.% Si in the (U,Zr)(Al,Si) 3 phase reduces in 2.7 at.% the necessary Zr content to inhibit its transformation to U(Al,Si) 4 .

  7. Assessment of circumferential cracks in hypereutectic Al-Si clutch housings

    Directory of Open Access Journals (Sweden)

    M. Haghshenas

    2017-04-01

    Full Text Available As in situ natural composites with silicon phase acting as the reinforcing phase, Al-Si alloys are among most commonly used aluminum alloys in automotive applications (i.e. engine component. Silicon contributes to the strength of Al-Si alloys through load transfer from the Al matrix to the hard (rigid Si phase in the microstructure (load-carrying capacity. Casting parameters (i.e. solidification rate, elemental segregation, secondary dendrite spacing… as well as the size and distribution of the microstructural constituents in Al-Si alloys (i.e. morphology of Si particles, intermetallic compounds, secondary dendrite spacing contribute directly to the mechanical response and failure (or fracture behavior of the alloy within the service. In hyper-eutectic Al-Si alloys (i.e. B390.0, distribution of coarse pre-eutectic Si particle mainly contribute to stress concentration, crack initiation and propagation during the actual service condition. In the present paper, the parameters contribution to the formation of the circumferential cracks in clutch housings made of die cast hyper-eutectics B390.0 Al-Si alloys are assessed through optical microscopy and scanning electron microscopy. Casting variable, cooling rate, their effect on the cracks as well some of the possible causes are also discussed in detail.

  8. 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

  9. Selective laser melting of carbon/AlSi10Mg composites: Microstructure, mechanical and electronical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiao; Song, Bo, E-mail: bosong@hust.edu.cn; Fan, Wenrui; Zhang, Yuanjie; Shi, Yusheng

    2016-04-25

    Carbon nanotubes/AlSi10Mg composites has drawn lots of attention in structural engineering and functional device applications due to its extraordinary high elastic modulus and mechanical strength as well as excellent electrical and thermal conductivities. In this study, the CNTs/AlSi10Mg composites was firstly prepared and then processed by selective laser melting. The powder preparation, SLM process, and microstructure evolution, properties were clarified. The results showed that CNTs were decomposed due to the direct interaction with the laser beam. The SLMed composites displayed a similar microstructure to that of SLMed AlSi10Mg. The common brittleness phase Al{sub 4}C{sub 3} didn't form, and the carbon dispersion strengthening was observed. The electrical resistivity of the composites was reduced significantly and the hardness was improved. - Highlights: • Carbon nanotubes/AlSi10Mg powder were prepared by slurry ball milling process. • Carbon nanotubes/AlSi10Mg composites were firstly prepared by SLM. • The electrical resistivity of the composites was significantly reduced and hardness was improved.

  10. 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.

  11. 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

  12. State diagram of U-Al-Si as a basis for analysis of the processes in nuclear fuel compositions based on U(Al, Si)3 and U3Si compounds

    International Nuclear Information System (INIS)

    Chebotarev, N.T.; Konovalov, L.N.; Zhmak, V.A.; Chebotarev, Ya.N.

    1996-01-01

    Results of studies into the Al-UAl 3 -USi 3 -Si of the U-Al-Si ternary system are presented. It is established that phase equilibrium between the intermetallic compound U(Al, Si) 3 and the aluminium-silicon alloys may be presented in form of conodes on the isothermal cross-section of the state diagram. It is shown that the U(Al, Si) 3 intermetallic compound, containing up to 6.5 at.% silicon, interacts both with liquid and solid aluminium with the U(Al, Si) 4 phase formation [ru

  13. Creep behaviour of a casting titanium carbide reinforced AlSi12CuNiMg piston alloy at elevated temperatures; Hochtemperaturkriechverhalten der schmelzmetallurgisch hergestellten dispersionsverstaerkten Kolbenlegierung AlSi12CuNiMg

    Energy Technology Data Exchange (ETDEWEB)

    Michel, S.; Scholz, A. [Zentrum fuer Konstruktionswerkstoffe, TU Darmstadt (Germany); Tonn, B. [Institut fuer Metallurgie, TU Clausthal (Germany); Zak, H.

    2012-03-15

    This paper deals with the creep behaviour of the titanium carbide reinforced AlSi12CuNiMg piston alloy at 350 C and its comparison to the conventional AlSi12Cu4Ni2MgTiZr piston alloy. With only 0,02 vol-% TiC reinforcement the creep strength and creep rupture strength of the AlSi12CuNiMg piston alloy are significantly improved and reach the level of the expensive AlSi12Cu4Ni2MgTiZr alloy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Effect of high power ultrasound on mechanical properties of Al-Si alloys

    Science.gov (United States)

    Srivastava, N.; Gupta, R.; Chaudhari, G. P.

    2018-03-01

    Effect of high power ultrasonic treatment on the solidification microstructures of Al-Si alloys containing varying content of solute Si (1, 2, 3 and 5 wt %) is investigated. Large variation in microstructures is seen and refinement of primary α-Al grains is observed. It is observed that increasing the weight percentage of solute along with ultrasonic treatment resulted in finer primary phase. By increasing the solute content from 1% to 5 wt.% in Al-Si alloys, hardness increased by about 38% without and 48% with ultrasonic treatment. Tensile strength of the alloys with ultrasonic treatment is higher as compared to those without ultrasonic treated.

  15. Modeling and optimization of cylindrical grinding of Al/SiC composites using genetic algorithms

    OpenAIRE

    Thiagarajan, C.; Sivaramakrishnan, R.; Somasundaram, S.

    2012-01-01

    The Al/SiC composites have received more commercial attention than other kinds of Metal Matrix Composites (MMCs) due to their high performance. However, a continuing problem with MMCs is that they are difficult to machine, due to the hardness and abrasive nature of the SiC particles. Grinding is often the method of choice for machining Al/SiC composites to acquire high dimensional accuracy and surface finish in large scale production. Based on the full factorial design (3(4)), a total of 81 e...

  16. 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 ...

  17. Effect of load and reciprocating velocity on the transition from mild to severe wear behavior of Al-Si-SiCp composites in reciprocating conditions

    International Nuclear Information System (INIS)

    Rajeev, V.R.; Dwivedi, D.K.; Jain, S.C.

    2010-01-01

    In the present paper, the effect of normal load and reciprocating velocity on transition from mild to severe wear of A319/15%SiC p , A336/15%SiC p , and A390/15%SiC p composites have been reported. Composites were produced through liquid metal metallurgy route. Adhesive wear behavior of composites was studied under dry reciprocating conditions using indigenously developed reciprocating friction wear test rig conforming to ASTM Standard G133-05. It was found that increase in normal load increases wear rate and depending upon the reciprocating velocity and type of composites, mode of wear changes from mild oxidative to severe metallic wear was noticed. The load corresponding to the transition from mild to severe wear usually termed as transition load was found to decrease with increase in reciprocating velocity and reduction in silicon content in the alloys used for the development of Al-Si-SiC p composites. At 1 m/s reciprocating velocity, the transition load for A319/15%SiC p , A336/15%SiC p and A390/15%SiC p composites were found to be in the range of 60-90 N, 60-105 N and 60-120 N respectively. Scanning electron microscope (SEM) study of wear surface and wear debris were conducted to analyze the mode of wear and operating wear mechanism. Severe wear was characterized by massive plastic deformation and gross material removal while the mild wear was found to be associated with delamination and scoring as main wear mechanisms responsible for material loss. Wear mechanism maps for different Al-(6-18)%Si-15%SiC p composites were proposed in reciprocating contacts.

  18. Modeling of Eutectic Formation in Al-Si Alloy Using A Phase-Field Method

    Directory of Open Access Journals (Sweden)

    Ebrahimi Z.

    2017-12-01

    Full Text Available We have utilized a phase-field model to investigate the evolution of eutectic silicon in Al-Si alloy. The interfacial fluctuations are included into a phase-field model of two-phase solidification, as stochastic noise terms and their dominant role in eutectic silicon formation is discussed. We have observed that silicon spherical particles nucleate on the foundation of primary aluminum phase and their nucleation continues on concentric rings, through the Al matrix. The nucleation of silicon particles is attributed to the inclusion of fluctuations into the phase-field equations. The simulation results have shown needle-like, fish-bone like and flakes of silicon phase by adjusting the noise coefficients to larger values. Moreover, the role of primary Al phase on nucleation of silicon particles in Al-Si alloy is elaborated. We have found that the addition of fluctuations plays the role of modifiers in our simulations and is essential for phase-field modeling of eutectic growth in Al-Si system. The simulated finger-like Al phases and spherical Si particles are very similar to those of experimental eutectic growth in modified Al-Si alloy.

  19. Weld microstructure in cast AlSi9/SiC(p metal matrix composites

    Directory of Open Access Journals (Sweden)

    J. Wysocki

    2009-04-01

    Full Text Available Welded joint in cast AlSi9/SiC/20(p metal matrix composite by manual TIG arc welding using AlMg5 filler metal has been described inhis paper. Cooling curves have been stated, and the influence in distribution of reinforced particles on crystallization and weldmicrostructure. Welded joint mechanical properties have been determined: hardness and tensile.

  20. 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...

  1. 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

  2. In Situ Synthesis of Al-Si-Cu Alloy During Brazing Process and Mechanical Property of Brazing Joint

    Directory of Open Access Journals (Sweden)

    LONG Wei-min

    2016-06-01

    Full Text Available The Al-Si-Cu alloy system is considered to be a promising choice of filler metal for aluminium alloys brazing due to its high strength and low melting point. The greatest obstacle is its lack of plastic forming ability and being difficult to be processed by conventional methods. This disadvantage is ascribed to the considerable amount of brittle CuAl2 intermetallic compound which forms when alloy composition is around the ternary eutectic point. In order to overcome this deficiency, authors of this article proposed to synthesize Al-Si-Cu filler metal by using in situ synthesis method, and the structure and properties of brazing joints were studied. The results show that AlSi alloy is used as the wrap layer, and CuAl alloy is used as the powder core in the composite brazing wire, the two alloys have similar melting points. The machinability of the composite brazing wire is much superior to the traditional Al-Si-Cu filler metal. During the induction brazing of 3A21 alloy, when using AlSi-CuAl composite filler wire, AlSi and CuAl alloys melt almost simultaneously, then after short time holding, Al-Si-Cu braze filler is obtained, the brazing seam has uniform composition and good bonding interface, also, the shearing strength of the brazing joints is higher than the joint brazed by conventional Al-Si-Cu filler metal.

  3. Improving the characteristics of foundry alloys AlSiCuMg during manufacturing

    Science.gov (United States)

    Fragoso, Bruno Filipe Marques

    As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de

  4. Microstructure and mechanical properties of thixoformed A319 aluminium alloy

    International Nuclear Information System (INIS)

    Salleh, M.S.; Omar, M.Z.; Syarif, J.; Alhawari, K.S.; Mohammed, M.N.

    2014-01-01

    Highlights: • A319 was successfully thixoformed at 50% liquid, i.e. at 571 °C. • T6 heat treatment has increased the strength and hardness of the thixoformed alloy. • The elongation after T6 heat treatment is even significantly improved. • The iron-rich intermetallic phase reduces the strength of the thixoformed alloy. - Abstract: Thixoforming is a viable technology for forming alloys in a semisolid state into near net-shaped products. In the present study, the effect of a thixoforming process on the microstructure and mechanical properties of A319 aluminium alloy was investigated. The ingots obtained from the cooling slope were thixoformed in a press after they remained at 571 °C for 5 min, yielding a microstructure predominantly composed of α-Al globules and inter-globular Si particles. Some of the thixoformed samples were treated with an ageing process (T6) and then, hardness and tensile samples were prepared from the as-cast, as-thixoformed and thixoformed T6. All the thixoformed samples were characterised using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) as well as hardness measurements and tensile tests. The results indicate that the mechanical properties of the thixoformed A319 alloy increased after the T6 heat treatment (hardness of 124.2 ± 3.2 HV, tensile strength of 298 ± 3.0 MPa, yield strength of 201 ± 2.6 MPa and elongation to fracture of 4.5 ± 0.3%). The fracture samples from the tensile test were analysed, revealing that the iron-rich intermetallic observed in the samples reduced the tensile strength and ductility of the thixoformed A319 alloys

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

    International Nuclear Information System (INIS)

    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 dynamic properties. High fatigue properties coupled with high modulus, good high temperature behaviour and low thermal expansion, allow their use for applications in the automotive industry. In opposition to MMC's, these materials present the advantage of easy recycling and easy machinability as it is the case for the conventional AlSi alloys. The low oxygen content allows quality joining with conventional arc welding techniques. (orig.)

  6. Microstructure and properties of TiAlSiN coatings prepared by hybrid PVD technology

    International Nuclear Information System (INIS)

    Yu Donghai; Wang Chengyong; Cheng Xiaoling; Zhang Fenglin

    2009-01-01

    TiAlSiN coatings with different Si content were prepared by hollow cathode discharge (HCD) and mid-frequency magnetron sputtering (MFMS) hybrid coating deposition technology. The chemical composition, microstructure, mechanical properties of these coatings were systematically investigated by means of energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation measurement, scratch and high speed milling hardened steel tests. The coatings prepared by this method showed the structure of crystalline phase was corresponding to that of TiAlN, however, different preferred orientation with addition of Si. Proper content of Si into TiAlN led to increase of microhardness and adhesion. TiAlSiN coated end mill with Si content of 4.78 at.% had the least flank wear, which was improved about 20% milling distance than TiAlN coated end mill.

  7. Microstructure and properties of TiAlSiN coatings prepared by hybrid PVD technology

    Energy Technology Data Exchange (ETDEWEB)

    Yu Donghai [Faculty of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Wang Chengyong, E-mail: cywang@gdut.edu.c [Faculty of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Cheng Xiaoling; Zhang Fenglin [Faculty of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2009-07-01

    TiAlSiN coatings with different Si content were prepared by hollow cathode discharge (HCD) and mid-frequency magnetron sputtering (MFMS) hybrid coating deposition technology. The chemical composition, microstructure, mechanical properties of these coatings were systematically investigated by means of energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation measurement, scratch and high speed milling hardened steel tests. The coatings prepared by this method showed the structure of crystalline phase was corresponding to that of TiAlN, however, different preferred orientation with addition of Si. Proper content of Si into TiAlN led to increase of microhardness and adhesion. TiAlSiN coated end mill with Si content of 4.78 at.% had the least flank wear, which was improved about 20% milling distance than TiAlN coated end mill.

  8. Crack resistance behaviour of an intermetallic Ti-Al-Si-Nb alloy at room temperature

    International Nuclear Information System (INIS)

    Wittkowsky, B.U.; Pfuff, M.J.

    1996-01-01

    The room temperature crack growth behaviour of a Ti-Al-Si-Nb alloy consisting of the two intermetallic phases (Ti, Nb) 3 (Al, Si) and (Ti, Nb) 5 (Si, Al) 3 is investigated in the present paper. The material exhibits a heterogeneous disordered microstructure and fails in a brittle manner. Crack growth is associated with a pronounced crack resistance behaviour. For a sample of nominally identical specimens the R-curves scatter around a mean curve with a standard deviation which remains roughly constant as the crack grows. A natural extension of the bundle model introduced in a previous paper is used to simulate R-curves and their scatter is in reasonably good agreement with the experimental findings. (orig.)

  9. Morphology of intermetallic phases in Al-Si cast alloys and their fracture behaviour

    Directory of Open Access Journals (Sweden)

    Lenka Hurtalová

    2015-03-01

    Full Text Available Applications of Al-Si cast alloys in recent years have increased especially in the automotive industry (dynamic exposed cast, en-gine parts, cylinder heads, pistons and so on. Controlling the microstructure of secondary aluminium cast alloys is very important, because these alloys contain more additional elements that form various intermetallic phases in the structure. Therefore, the contribution is dealing with the valuation type of intermetallic phases and their identification with using optical and scanning microscopy. Some of the intermetallic phases could be identified on the basis of morphology but some of them must be identified according EDX analysis. The properties of alu-minium alloy are affected by morphology of intermetallic phases and therefore it is necessary to study morphology and its fracture behav-iour. The present work shows morphology and typical fracture behaviour as the most common intermetallic phases forming in Al-Si alloys.

  10. 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.

  11. 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

  12. Effects of grain refinement on the rheological behaviors of semisolid hypoeutectic Al-Si alloys

    International Nuclear Information System (INIS)

    Yan, M.; Luo, W.

    2007-01-01

    The paper experimentally investigated the effects of grain refinement on the rheological response of Al and hypoeutectic Al-Si alloys. Selected refiners included K 2 TiF 6 , K 2 TiF 6 plus graphite and Al-5Ti-B. The apparent viscosity of semisolid Al alloys was measured during solidification. Samples at different solid fractions were quenched to observe the microstructure. It was found that grain refinement drastically lowered the apparent viscosity of Al-Si alloys. Among selected refiners, the effect of Al-5Ti-B was the best. The effect of K 2 TiF 6 plus graphite was better than that of K 2 TiF 6 . Silicon contents in Al alloys affected the apparent viscosity. With increasing silicon content the apparent viscosity decreased, resulted from promotion of silicon to both refining effects of titanium and boron

  13. 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.

  14. EFFECT OF SILICON CONTENT ON MACHINABILITY OF Al-Si ALLOYS

    Directory of Open Access Journals (Sweden)

    Birol Akyüz

    2016-09-01

    Full Text Available In this study the effect of the change in the amount of Silicon (Si occuring in Al-Si alloys on mechanical and machinability properties of the alloy was investigated. The change in mechanical properties and microstructure, which depends on the increase in Si percentage, and the effects of this change on Flank Build-up (FBU, wear on the cutting edge, surface roughness, and machinability were also studied. Alloys in different ratios of Si (i.e. 2 to 12 wt %, were employed in the study. The specimens for tests were obtained by casting into metal moulds. The results obtained from experimental studies indicate improved mechanical properties and machinability, depending on the rise in Si percentage in Al-Si alloys. It is also observed that the increase in Si percentage enhanced surface quality.

  15. Vanadium Influence on Iron Based Intermetallic Phases in AlSi6Cu4 Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2014-10-01

    Full Text Available Negative effect of iron in Al-Si alloys mostly refers with iron based intermetallic phases, especially Al5FeSi phases. These phases are present in platelet-like forms, which sharp edges are considered as main cracks initiators and also as contributors of porosity formation. In recent times, addition of some elements, for example Mn, Co, Cr, Ni, V, is used to reduce influence of iron. Influence of vanadium in aluminium AlSi6Cu4 alloy with intentionally increased iron content is presented in this article. Vanadium amount has been graduated and chemical composition of alloy has been analysed by spectral analysis. Vanadium influence on microstructural changes was evaluated by microstructural analysis and some of intermetallic particles were reviewed by EDX analysis.

  16. Primary Structure and Mechanical Properties of AlSi2 Alloy Continuous Ingots

    Directory of Open Access Journals (Sweden)

    Wróbel T.

    2017-06-01

    Full Text Available The paper presents the research results of horizontal continuous casting of ingots of aluminium alloy containing 2% wt. silicon (AlSi2. Together with the casting velocity (velocity of ingot movement we considered the influence of electromagnetic stirring in the area of the continuous casting mould on refinement of the ingot’s primary structure and their selected mechanical properties, i.e. tensile strength, yield strength, hardness and elongation. The effect of primary structure refinement and mechanical properties obtained by electromagnetic stirring was compared with refinement obtained by using traditional inoculation, which consists in introducing additives, i.e. Ti, B and Sr, to the metal bath. On the basis of the obtained results we confirmed that inoculation done by electromagnetic stirring in the range of the continuous casting mould guarantees improved mechanical properties and also decreases the negative influence of casting velocity, thus increasing the structure of AlSi2 continuous ingots.

  17. Study on characteristics of U-Mo/Al-Si interaction layers of dispersion fuel plates

    International Nuclear Information System (INIS)

    Liu Lijian; Yin Changgeng; Chen Jiangang; Sun Changlong; Liu Yunming

    2014-01-01

    In this paper, we analyzed the characteristics of U-Mo/Al-Si interaction layers of dispersion fuel plates. The results show that the interaction layers (IL) are with irregular morphology and uneven thickness, and are mainly formed in the internal micro cracks of the dispersion fuel particles or at the interface between the particles and the substrates. The diffusion mechanism of U-Mo/Al-Si is the vacancy diffusion, Al and Si are migrating elements, and the diffusion reaction is that Al and Si diffuse to U-Mo alloy. Inside the interaction layers, the Al content keeps constant basically, but the Si content gradually increases with the substrate-fuel direction, and the maximum content of Si appears interaction layers near the U-Mo side. Adding about 5 wt% Si into Al matrix can restrain the diffusion reaction, and improve the performance of dispersion fuel plates finally. (authors)

  18. Selective laser melting of hypereutectic Al-Si40-powder using ultra-short laser pulses

    Science.gov (United States)

    Ullsperger, T.; Matthäus, G.; Kaden, L.; Engelhardt, H.; Rettenmayr, M.; Risse, S.; Tünnermann, A.; Nolte, S.

    2017-12-01

    We investigate the use of ultra-short laser pulses for the selective melting of Al-Si40-powder to fabricate complex light-weight structures with wall sizes below 100 μ {m} combined with higher tensile strength and lower thermal expansion coefficient in comparison to standard Al-Si alloys. During the cooling process using conventional techniques, large primary silicon particles are formed which impairs the mechanical and thermal properties. We demonstrate that these limitations can be overcome using ultra-short laser pulses enabling the rapid heating and cooling in a non-thermal equilibrium process. We analyze the morphology characteristics and micro-structures of single tracks and thin-walled structures depending on pulse energy, repetition rate and scanning velocity utilizing pulses with a duration of 500 {fs} at a wavelength of 1030 {nm}. The possibility to specifically change and optimize the microstructure is shown.

  19. Optimization of Squeeze Parameters and Modification of AlSi7Mg Alloy

    Directory of Open Access Journals (Sweden)

    Zyska A.

    2013-06-01

    Full Text Available The paper present the examination results concerning mechanical properties of castings made of AlSi7MG alloy in correlation both with the most significant squeeze casting parameters and with the modification treatment. Experiments were planned and held according to the 23 factorial design. The regression equations describing the influence of the squeeze pressure, the mould temperature, and the quantity of strontium modifier on the strength and elongation of the examined alloy were obtained. It was found that the main factor controlling the strength increase is the squeeze pressure, while the plasticity (A5 of the alloy is affected most advantageously by modification. The application of modification treatment in squeeze casting technology enables for production of the slab-type castings made of AlSi7Mg alloy exhibiting strength at the level of 230 MPa and elongation exceeding 14%.

  20. 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.

  1. 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...

  2. Investigation of the brittle fracture behavior of intermetallic Ti-Al-Si-Nd-alloys

    International Nuclear Information System (INIS)

    Wittkowsky, B.U.

    1995-01-01

    The object of this paper is the fracture behaviour of three Ti-Al-Si-Nb alloys. Fracture mechanical data are experimentally determined and their statistical properties are investigated. To describe the fracture process of disordered heterogeneous brittle materials a statistical model was developed, based on damage mechanics. With the aid of this model it was possible to attribute the fracture behaviour, the fracture mechanical data and their statistical properties to the microstructure of the materials studied. (orig.) [de

  3. 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.

  4. Structure evaluation of cast dispersive AlSi-CrxCy composites

    OpenAIRE

    M. Cholewa

    2008-01-01

    In this work author showed the diversification of structure for cast dispersive AlSi-CrxCy composites. Wide possibilities of properties control and optimization were described, through microstructure of the matrix and the transition zone shaping. Utility castings were prepared with use of traditional casting techniques, ceramic and metal moulds. The influence of technological conditions and cooling rate ion the composite structure was studied. The main factor of structural changes was the dif...

  5. Influence of refining process on the porosity of high pressure die casting alloy Al-Si

    Directory of Open Access Journals (Sweden)

    A.W. Orlowicz

    2009-04-01

    Full Text Available This study presents research results of the influence that refining and transfer of AlSi12S alloy on the porosity of high pressure diecastings.Tests were conducted under production conditions of Die-casting Foundry META-ZEL Sp z o.o. The operation of refining was conducted in a melting furnace, with the use of an FDU Mini Degasser. Decay of the refining effect was assessed by evaluating the porosity content and metallographic examination.

  6. 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 ?-Al2O3 also undesired TiO2. However, when

  7. Marbled texture of sputtered Al/Si alloy thin film on Si

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, M.G. [Physics Department and NIS Interdepartmental Center, University of Torino, via P. Giuria 1, 10125 Torino (Italy); Vishay Intertechnology, Diodes Division, Via Liguria 49, 10071 Borgaro Torinese, Turin (Italy); Muñoz-Tabares, J.A.; Chiodoni, A. [Istituto Italiano di Tecnologia, Center for Space Human Robotics, Corso Trento 21, 10129 Torino (Italy); Sgorlon, C. [Vishay Intertechnology, Diodes Division, Via Liguria 49, 10071 Borgaro Torinese, Turin (Italy); Para, I. [Department of Applied Science and Technology (DISAT), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Carta, R.; Richieri, G. [Vishay Intertechnology, Diodes Division, Via Liguria 49, 10071 Borgaro Torinese, Turin (Italy); Bejtka, K. [Istituto Italiano di Tecnologia, Center for Space Human Robotics, Corso Trento 21, 10129 Torino (Italy); Merlin, L. [Vishay Intertechnology, Diodes Division, Via Liguria 49, 10071 Borgaro Torinese, Turin (Italy); Vittone, E. [Physics Department and NIS Interdepartmental Center, University of Torino, via P. Giuria 1, 10125 Torino (Italy)

    2016-08-01

    DC magnetron sputtering is a commonly used technique for the fabrication of silicon based electronic devices, since it provides high deposition rates and uniform large area metallization. However, in addition to the thickness uniformity, coating optical uniformity is a crucial need for semiconductor industrial processes, due to the wide use of optical recognition tools. In the silicon-based technology, aluminum is one of the most used materials for the metal contact. Both the pre-deposition substrate cleaning and the sputtering conditions determine the quality and the crystalline properties of the final Al deposited film. In this paper is shown that not all the mentioned conditions lead to good quality and uniform Al films. In particular, it is shown that under certain standard process conditions, Al/Si alloy (1% Si) metallization on a [100] Si presents a non-uniform reflectivity, with a marbled texture caused by flakes with milky appearance. This optical inhomogeneity is found to be caused by the coexistence of randomly orient Al/Si crystal, with heteroepitaxial Al/Si crystals, both grown on Si substrate. Based on the microstructural analysis, some strategies to mitigate or suppress this marbled texture of the Al thin film are proposed and discussed. - Highlights: • Sputtered Al/Si layers deposited on Si present evident optical non-uniformity • It could be an issue for optical recognition tools used in semiconductor industries • Optical non-uniformity is due to randomly oriented growth of Al grains. • Substrate misorientation and process temperature can mitigate the problem.

  8. Structural transformation in mechanosynthesized bcc Fe-Al-Si(Ge) solid solutions during heating

    International Nuclear Information System (INIS)

    Kubalova, L.M.; Sviridov, I.A.; Vasilyeva, O.Ya.; Fadeeva, V.I.

    2007-01-01

    X-ray diffractometry and Moessbauer spectroscopy study of Fe 50 Al 25 Si 25 and Fe 50 Al 25 Ge 25 alloys obtained by mechanical alloying (MA) of elementary powders was carried out. Phase transformation during heating of synthesized products was studied using differential scanning calorimetry (DSC). After 2.5 h of MA monophase alloys containing bcc Fe(Al, Ge) solid solutions Fe(Al, Si) are formed. Fe(Al, Si) is partially ordered B2 type and Fe(Al, Ge) is completely disordered. DSC curves of synthesized alloys displayed the presence of exothermal peaks caused by phase transformation. The metastable Fe(Al, Si) solid solution transformed into FeAl 1-x Si x (B2) and FeSi 1-x Al x (B20) equilibrium phases. The Fe(Al, Ge) solid solution transformed into equilibrium phases through intermediate stage of Fe 6 Ge 3 Al 2 metastable phase formation. The Fe 6 Ge 3 Al 2 phase dissociated into three equilibrium phases: FeAl 1-x Ge x (B2), χ-Fe 6 Ge 5 and η-Fe 13 (Ge, Al) 8 (B8 2 ). The structure of Fe 6 Ge 3 Al 2 was calculated by Rietveld method, the distribution of Al and Ge in the elementary cell and its parameters were calculated. Moessbauer study showed that Fe(Al, Si) and Fe(Al, Ge) solid solutions are paramagnetic. In the equilibrium state the alloy containing Si is also paramagnetic while the alloy with Ge showed ferromagnetic properties

  9. Radiation Resistance of the U(Al, Si)(3) Alloy: Ion-Induced Disordering

    Czech Academy of Sciences Publication Activity Database

    Meshi, L.; Yaniv, G.; Horák, Pavel; Vacík, Jiří; Mykytenko, N.; Rafailov, G.; Dahan, I.; Fuks, D.; Kiv, A.

    2018-01-01

    Roč. 11, č. 2 (2018), č. článku 228. ISSN 1996-1944 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 Keywords : U-Al-Si * ion-irradiation * transmission electron microscopy * structural defects * disordering Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 2.654, year: 2016

  10. Microstructure and mechanical properties of AC AlSi9CuX alloys

    OpenAIRE

    L.A. Dobrzański; R. Maniara; M. Krupiński; J.H. Sokołowski

    2007-01-01

    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 ...

  11. First discovery and structural characterization of a new compound in Al-Si-O-C system

    International Nuclear Information System (INIS)

    Iwata, Tomoyuki; Kaga, Motoaki; Nakano, Hiromi; Fukuda, Koichiro

    2009-01-01

    A quaternary oxycarbide, [Al 16.77(5) Si 1.23(5) ] Σ 18 [O 3.04(9) C 10.96(9) ] Σ 14 , has been for the first time discovered in the Al-Si-O-C system. The crystal structure was characterized by X-ray powder diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The atom ratios [Al:Si] were determined by EDX, and the initial structural model was derived by the direct methods. The structural parameters as well as the atom ratios [O:C] were determined by the Rietveld method. The crystal is monoclinic (space group C2/m, Z=1) with lattice dimensions a=0.57404(1) nm, b=0.331435(5) nm, c=1.92410(2) nm, β=90.036(1) o and V=0.366076(9) nm 3 . The final structural model showed the positional disordering of Al/Si sites. The validity of the split-atom model was verified by the three-dimensional electron density distribution, the structural bias of which was reduced as much as possible using the maximum-entropy methods-based pattern fitting (MPF). The reliability indices calculated from the MPF were R wp =4.20% (S=1.14), R p =3.09%, R B =0.92% and R F =1.05%. The crystal was an inversion twin with nearly the same twin fraction. - Graphical abstract: A quaternary oxycarbide firstly discovered in the Al-Si-O-C system. The crystal is an inversion twin, and hence the structure is represented by a split-atom model. The three-dimensional electron density distribution is determined by the maximum-entropy methods-based pattern fitting, being consistent with the disordered structural model.

  12. Oxidation resistance of quintuple Ti-Al-Si-C-N coatings and associated mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Wu Guizhi; Ma Shengli; Xu Kewei; Ji, Vincent; Chu, Paul K. [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); ICMMO/LEMHE, Universite Paris-Sud 11, 91405 Orsay Cedex (France); Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon (Hong Kong)

    2012-07-15

    The oxidation behavior of Ti-Al-Si-C-N hard coatings with different Al contents deposited on high-speed steel and Si substrates by hybrid arc-enhanced magnetron sputtering is investigated in the temperature range of 500 Degree-Sign C-1000 Degree-Sign C. The coating hardness is maintained at around 35 GPa, and the parabolic oxidation rate constant K{sub p} at 1000 Degree-Sign C decreases to 3.36 Multiplication-Sign 10{sup -10} kg{sup 2} m{sup -4} s{sup -1} when the Al concentration is increased to 30 at. %, indicating that Ti-Al-Si-C-N coatings with larger Al concentrations have better oxidation resistance. X-ray diffraction, cross-sectional scanning electron microscopy, and x-ray photoelectron spectroscopy reveal a protective surface layer consisting of Al{sub 2}O{sub 3}, TiO{sub 2}, and SiO{sub 2} that retards inward oxygen diffusion. A mechanism is proposed to elucidate the oxide formation. As a consequence of the good oxidation resistance, the Ti-Al-Si-C-N coatings have a large potential in high-speed dry cutting as well as other high temperature applications.

  13. Iron Intermetallic Phases in the Alloy Based on Al-Si-Mg by Applying Manganese

    Directory of Open Access Journals (Sweden)

    Podprocká R.

    2017-09-01

    Full Text Available Manganese is an effective element used for the modification of needle intermetallic phases in Al-Si alloy. These particles seriously degrade mechanical characteristics of the alloy and promote the formation of porosity. By adding manganese the particles are being excluded in more compact shape of “Chinese script” or skeletal form, which are less initiative to cracks as Al5FeSi phase. In the present article, AlSi7Mg0.3 aluminium foundry alloy with several manganese content were studied. The alloy was controlled pollution for achieve higher iron content (about 0.7 wt. % Fe. The manganese were added in amount of 0.2 wt. %, 0.6 wt. %, 1.0 wt. % and 1.4 wt. %. The influence of the alloying element on the process of crystallization of intermetallic phases were compared to microstructural observations. The results indicate that increasing manganese content (> 0.2 wt. % Mn lead to increase the temperature of solidification iron rich phase (TAl5FeSi and reduction this particles. The temperature of nucleation Al-Si eutectic increase with higher manganese content also. At adding 1.4 wt. % Mn grain refinement and skeleton particles were observed.

  14. Effect of Cold Forging on Microstructure and MechanicalProperties of Al/SiC Composites

    Science.gov (United States)

    Hanamantraygouda, M. B.; Shivakumar, B. P., Dr; Siddappa, P. N.; Sampathkumar, L.; Prashanth, L.

    2018-02-01

    The objective of this work was to investigate the effect of cold forging on mechanical properties and microstructural study of Al MMCs, at different wt% of SiC and forging cycle. The Al-SiC composite material was fabricated by stir casting method at different weight percentage of SiC such as 2.5, 5, 7.5 and 10%. Further, the deformation characteristics during open-die forging of Al-SiC composite at cold conditions was investigated. Cast and forged composite material was subjected to hardness test, tensile test and impact test. The grain size, microstructure behaviour was investigated using optical microscope. The results show that hardness and strength of Al-SiC composite increases and ductility decreases as compared to Al alloy in both as-cast and forged conditions. Optical microscope images showed that the distribution of SiC in Al matrix was more homogeneous in a forged composite as compared to cast one and reduction of porosity was found. Further, it showed that due to forging cycle the grain size was reduced by 30% to 35% from initial size.

  15. Effect of Carbon in Fabrication Al-SiC Nanocomposites for Tribological Application

    Directory of Open Access Journals (Sweden)

    Bartosz Hekner

    2017-06-01

    Full Text Available Aluminium-based hybrid composites are a new class of advanced materials with the potential of satisfying the demands in engineering applications. This paper describes the effects of carbon addition on the formation and properties of AMC with SiC nanoparticles reinforcement. The composites were produced via mechanical alloying followed by hot pressing. Three forms of carbon, graphite (GR, multiwalled carbon nanotubes (CNTs, and, for the first time, glassy carbon (GC, were used for the hybrid composites manufacturing and compared with tribological properties of Al-SiC composite without carbon addition. GC and CNTs enhanced formation of Al-SiC composite particles and resulted in a homogeneous distribution of reinforcing particles. On the other hand, GR addition altered mechanochemical alloying and did not lead to a proper distribution of nanoparticulate SiC reinforcement. Hot pressing technique led to the reaction between Al and carbon as well as SiC particles and caused the formation of Al4C3 and γ-Al2O3. The subsistence of carbon particles in the composites altered the predominant wear mechanisms since the wear reduction and the stabilization of the friction coefficient were observed. GC with simultaneous γ-Al2O3 formation in the hybrid Al-SiC(n-C composites turned out to be the most effective additive in terms of their tribological behaviour.

  16. Characterization and properties Ti-Al-Si-N nanocomposite coatings prepared by middle frequency magnetron sputtering

    Science.gov (United States)

    Zou, C. W.; Zhang, J.; Xie, W.; Shao, L. X.; Guo, L. P.; Fu, D. J.

    2011-10-01

    TiN-containing amorphous Ti-Al-Si-N (nc-TiN/a-Si 3N 4 or a-AlN) nanocomposite coatings were deposited by using a modified closed field twin unbalanced magnetron sputtering system which is arc assisted and consists of two circles of targets, at a substrate temperature of 300 °C. XRD, XPS and High-resolution TEM experiments showed that the coatings contain TiN nanocrystals embedded in the amorphous Si 3N 4 or AlN matrix. The coatings exhibit good mechanical properties that are greatly influenced by the Si contents. The hardness of the Ti-Al-Si-N coatings deposited at Si targets currents of 5, 8, 10, and 12 A were 45, 47, 54 and 46 GPa, respectively. The high hardness of the deposited Ti-Al-Si-N coatings may be own to the plastic distortion and dislocation blocking by the nanocrystalline structure. On the other hand, the friction coefficient decreases monotonously with increasing Si contents. This result would be caused by tribo-chemical reactions, which often take place in many ceramics, e.g. Si 3N 4 reacts with H 2O to produce SiO 2 or Si(OH) 2 tribolay-layer.

  17. 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.

  18. Percolative ionic conduction in the LiAlSiO4 glass-ceramic system

    International Nuclear Information System (INIS)

    Biefeld, R.M.; Pike, G.E.; Johnson, R.T. Jr.

    1977-01-01

    The effect f crystallinity on the lithium ion conductivity in LiAlSiO 4 glass and glass-ceramic solid electrolytes has been determined. The ionic conductivity is thermally activated with an activation energy and pre-exponential factor that change in a marked and nonsimple manner as the volume fraction of crystallinity changes. These results are explained by using a continuum percolation model (effective-medium approximation) which assumes that ionic conduction in the glass-ceramic is almost entirely within the glass phase until the crystalline volume fraction rises above approx. 55%. The LiAlSiO 4 system would seem to be nearly ideal for application of percolation theory since the crystalline phase, β eucryptite, has nearly the same composition as the glass phase. Hence, as the crystallite volume fraction increases in the glass ceramic, the residual glass composition and conductivity remain the same. This is the first application of percolation theory to ionic transport in glass-ceramics and excellent agreement is obtained between theory and experiment for the LiAlSiO 4 system

  19. Experiencias de calorimetría diferencial de barrido en aleaciones Al-Si

    Directory of Open Access Journals (Sweden)

    Carolina López-Eckerdt

    2016-01-01

    Full Text Available La observación de agujas características de una transformación displaciva en aleaciones U-Al-Si en el entorno del compuesto U3Si5 evidencia la necesidad de analizar las distintas transformaciones que ocurren durante el enfriamiento utilizando una técnica dinámica de identificación de transformaciones (calorimetría diferencial de barrido. Para evaluar la versatilidad de esta técnica, se estudiaron aleaciones Al-Si con concentraciones de Si entre 0,6% y 7,1% en peso. Se determinaron las temperaturas liquidus y eutéctica de cada aleación y se estimó la entalpía de formación de los precipitados de Si y de la reacción eutéctica. Los resultados reproducen las temperaturas de ambas reacciones según el diagrama de equilibrio del sistema binario Al-Si. Para el cálculo de las entalpías de transformación resulta indispensable obtener el porcentaje de fase transformada por otras técnicas de caracterización una vez finalizado el ensayo.

  20. Experimental Research on Selective Laser Melting AlSi10Mg Alloys: Process, Densification and Performance

    Science.gov (United States)

    Chen, Zhen; Wei, Zhengying; Wei, Pei; Chen, Shenggui; Lu, Bingheng; Du, Jun; Li, Junfeng; Zhang, Shuzhe

    2017-12-01

    In this work, a set of experiments was designed to investigate the effect of process parameters on the relative density of the AlSi10Mg parts manufactured by SLM. The influence of laser scan speed v, laser power P and hatch space H, which were considered as the dominant parameters, on the powder melting and densification behavior was also studied experimentally. In addition, the laser energy density was introduced to evaluate the combined effect of the above dominant parameters, so as to control the SLM process integrally. As a result, a high relative density (> 97%) was obtained by SLM at an optimized laser energy density of 3.5-5.5 J/mm2. Moreover, a parameter-densification map was established to visually select the optimum process parameters for the SLM-processed AlSi10Mg parts with elevated density and required mechanical properties. The results provide an important experimental guidance for obtaining AlSi10Mg components with full density and gradient functional porosity by SLM.

  1. 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.

  2. 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.

  3. Evolution of Primary Fe-Rich Compounds in Secondary Al-Si-Cu Alloys

    Science.gov (United States)

    Fabrizi, Alberto; Capuzzi, Stefano; Timelli, Giulio

    Although iron is usually added in die cast Al-Si foundry alloys to prevent die soldering, primary Fe-rich particles are generally considered as "hardspot" inclusions which compromise the mechanical properties of the alloy, namely ductility and toughness. As there is no economical methods to remove the Fe excess in secondary Al-Si alloys at this time, the control of solidification process and chemical composition of the alloy is a common industrial practice to overcome the negative effects connected with the presence of Fe-rich particles. In this work, the size and morphology as well as the nucleation density of primary Fe-rich particles have been studied as function of cooling rate and alloy chemical composition for secondary Al-Si-Cu alloys. The solidification experiments were carried out using differential scanning calorimetry whereas morphology investigations were conducted using optical and scanning electron microscopy. Mcrosegregations and chemical composition of primary Fe-rich particles were examined by energy dispersive spectroscopy.

  4. Wear behaviour of plasma-sprayed AlSi/B4C composite coatings

    International Nuclear Information System (INIS)

    Sarikaya, Ozkan; Anik, Selahaddin; Celik, Erdal; Okumus, S. Cem; Aslanlar, Salim

    2007-01-01

    This paper describes the wear behaviour of AlSi/B 4 C composite coatings with 0-25 wt% B 4 C particles for diesel engine motors. These coatings were successfully fabricated on AlSi substrates using an atmospheric plasma spray technique. The produced samples were characterized by means of an optical microscope, scanning electron microscope and microhardness tester. The obtained results pointed out that an increase of B 4 C particles in AlSi coatings was caused on the rising of the microhardness values and the decrease of the thermal expansion coefficient of the coatings. The friction and wear experiments were performed under dry conditions using a ball-on-dics configuration against WC/Co counter material for different loads. It was concluded that wear resistance of the coatings produced using B 4 C powders is greatly improved compared with the substrate material. The highest wear resistance of the coatings were also determined in the 20% B 4 C coating

  5. Osteoblast Adhesion on Cathodic Arc Plasma Deposited Nano-Multilayered TiCrAlSiN Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Kyu [University of Ulsan, Ulsan (Korea, Republic of); Pham, Vuong Hung [Hanoi University of Science and Technology (HUST), Hanoi (Viet Nam)

    2014-03-15

    Adhesion of osteoblast cells to TiCrAlSiN thin films was evaluated in vitro. Ti and TiCrAlSiN thin films were deposited on glass substrates by cathodic arc deposition. Surface roughness and chemistry of the TiCrAlSiN thin films was characterized by AFM and EPMA, respectively. Ti and TiCrAlSiN thin films and glass coverslips were cultured with human osteoblast cells (hFOB 1.19). The cell cytoskeleton was analyzed by observing the organization of actin stress fibers and microtubules. Cell proliferation was investigated by MTT assay and visualization. Focal contact adhesion was studied by observing the vinculin density. The results indicated that the TiCrAlSiN coating significantly influenced the actin cytoskeleton and microtubule organization. Human osteoblasts hFOB attached and proliferated better on TiCrAlSiN thin films with more focal contact adhesions than on Ti thin films or glass surfaces. These results suggest that TiCrAlSiN thin films can be an implantable material where the maximum cell adhesion is required.

  6. 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.)

  7. 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.)

  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. Effect of Copper on Corrosion of Forged AlSi1MgMn Automotive Suspension Components

    Science.gov (United States)

    Koktas, Serhan; Gokcil, Emre; Akdi, Seracettin; Birol, Yucel

    2017-09-01

    Recently, modifications in the alloy composition and the manufacturing process cycle were proposed to achieve a more uniform structure with no evidence of coarse grains across the section of the AlSi1MgMn alloys. Cu was added to the AlSi1MgMn alloy to improve its age hardening capacity without a separate solution heat treatment. However, Cu addition degrades the corrosion resistance of this alloy due to the formation of Al-Cu precipitates along the grain boundaries that are cathodic with respect to the aluminum matrix and thus encourage intergranular corrosion. The present work was undertaken to identify the impact of Cu addition on the corrosion properties of AlSi1MgMn alloys with different Cu contents. A series of AlSi1MgMn alloys with 0.06-0.89 wt.% Cu were tested in order to identify an optimum level of Cu addition.

  10. Effect of electric pulse modification on mircostructure and properties of Ni-rich Al-Si piston alloy

    Directory of Open Access Journals (Sweden)

    Bing Wang

    2016-03-01

    Full Text Available In order to improve the properties of Ni-rich (2.5wt.% Al-Si piston alloy, electric pulse modification was applied in fabricating the Ni-rich Al-Si piston alloy in this study. The effect of electric pulse modification on the mechanical properties of the Ni-rich Al-Si piston alloy was studied using optical microscope (OM, scanning electron microscope (SEM, X-ray diffraction (XRD, microhardness measurement and tensile strength testing. The results showed that the microstructures of Ni-rich Al-Si piston alloy treated by electric pulse modification were refined, the solid solubility of Cu, Ni, Si, etc. in α-Al matrix was improved, and furthermore, the microhardness and high-temperature tensile strength were increased by 9.41% and 17.5%, respectively. The distribution of second phases was also more uniform compared with that of a non-modified sample.

  11. Effects of Eutectic Si and Secondary Dendrite Arm Spacing on the Mechanical Properties of Al-Si-Cu Cast Alloys

    International Nuclear Information System (INIS)

    Lee, Kyungmin; Kim, Yumi; Kim, Youngman; Hong, Sungkil; Choi, Seweon; Kim, Youngchan; Kang, Changseok

    2014-01-01

    The present study aims at investigating the effects of eutectic Si and Secondary dendrite arm spacing (SDAS) on mechanical properties of Al-Si-Cu alloy. Heat treatment and controlling of solidification rate affect to microstructure of Al-Si-Cu alloy. Al-Si-Cu alloy was dissolved in an electric furnace. The alloy cast in STD61 mold which had been pre-heated to 95 ℃ and 200 ℃. Eutectic Si and SDAS were finer as cooling rate increased. Image analysis technique has been utilized to examine the microstructure. Microstructure observation results showed that T6 heat treatment has a strong influence eutectic Si particle morphology. The mechanical properties, such as tensile strength, yield strength, elongation, were improved by ASTM E8 standard. Tensile properties of the Al-Si-Cu alloys prepared by different cooling rates were the same as each other by T6 heat treatment.

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

    International Nuclear Information System (INIS)

    Markoli, B.; Spaic, S.; Zupanic, F.

    2001-01-01

    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 (α Al , β Si , Al 3 Sm, Al 2 Si 2 Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L → α Al + β Si + Al 2 Si 2 Sm, and two liquidus transition reactions, i. e., L + Al 3 Sm → α Al + AlSiSm, and L + AlSiSm → α Al + Al 2 Si 2 Sm. 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. The constitution of alloys in the Al-rich corner of the Al-Si-Sm ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Markoli, B.; Spaic, S. [Ljubljana Univ. (Slovenia). Faculty of Natural Science and Engineering; Zupanic, F. [Maribor Univ. (Slovenia). Faculty of Mechanical Engineering

    2001-09-01

    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 ({alpha}{sub Al}, {beta}{sub Si}, Al{sub 3}Sm, Al{sub 2}Si{sub 2}Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L {yields} {alpha}{sub Al} + {beta}{sub Si} + Al{sub 2}Si{sub 2}Sm, and two liquidus transition reactions, i. e., L + Al{sub 3}Sm {yields} {alpha}{sub Al} + AlSiSm, and L + AlSiSm {yields} {alpha}{sub Al} + Al{sub 2}Si{sub 2}Sm. 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.)

  14. Effect of alumina on grain refinement of Al-Si hypereutectic alloys

    Science.gov (United States)

    Majhi, J.; Sahoo, S. K.; Patnaik, S. C.; Sarangi, B.; Sachan, N. K.

    2018-03-01

    The size, volume fraction and distribution of primary as well as eutectic silicon affect the mechanical properties of the Al-Si hypereutectic alloys. It is very difficult for the simultaneous refinement and modification of primary and secondary Si particles in hypereutectic Al-Si alloys through traditional processes. This paper explores the role of γ-Al2O3 nanoparticles on Si particles in the course of solidification in hypereutectic Al-Si alloys at particular pouring temperature. The present study involves incorporation of varying contents dispersed γ-Al2O3 nanoparticles into a molten base metal during stir casting and followed by solidification. It has been reported that the synthesized composites having good interfacial bonding (wetting) between the dispersed phase and the liquid matrix was achieved in order to provide improved mechanical properties of the composite. The cast product of hypereutectic Al-16Si alloy with the reinforcement of nanoparticles, illustrated a significant improvement in both wear behaviour and hardness. The dry sliding wear test has been performed on a group of specimens with varying parameters (different loads and sliding velocities) in a pin on disc wear testing machine. Moreover, the wear rate and specific wear rate also affected in different load and different sliding velocities. However in XRD analysis of the samples, the enhancement of wear resistance as well as hardness was due to the formation of brittle phases like SiO2, Al2O3 and Al-rich intermetallic compounds. The hardness value of the materials increases nearly 6% in addition to increase in the density of only 0.8%. As per literature, the large plate eutectic Si particles were modified in to the fine core particles and it acquires enough potential for various applications.

  15. 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.

  16. Polarizabilities and hyperpolarizabilities for the atoms Al, Si, P, S, Cl, and Ar: Coupled cluster calculations.

    Science.gov (United States)

    Lupinetti, Concetta; Thakkar, Ajit J

    2005-01-22

    Accurate static dipole polarizabilities and hyperpolarizabilities are calculated for the ground states of the Al, Si, P, S, Cl, and Ar atoms. The finite-field computations use energies obtained with various ab initio methods including Moller-Plesset perturbation theory and the coupled cluster approach. Excellent agreement with experiment is found for argon. The experimental alpha for Al is likely to be in error. Only limited comparisons are possible for the other atoms because hyperpolarizabilities have not been reported previously for most of these atoms. Our recommended values of the mean dipole polarizability (in the order Al-Ar) are alpha/e(2)a(0) (2)E(h) (-1)=57.74, 37.17, 24.93, 19.37, 14.57, and 11.085 with an error estimate of +/-0.5%. The recommended values of the mean second dipole hyperpolarizability (in the order Al-Ar) are gamma/e(4)a(0) (4)E(h) (-3)=2.02 x 10(5), 4.31 x 10(4), 1.14 x 10(4), 6.51 x 10(3), 2.73 x 10(3), and 1.18 x 10(3) with an error estimate of +/-2%. Our recommended polarizability anisotropy values are Deltaalpha/e(2)a(0) (2)E(h) (-1)=-25.60, 8.41, -3.63, and 1.71 for Al, Si, S, and Cl respectively, with an error estimate of +/-1%. The recommended hyperpolarizability anisotropies are Deltagamma/e(4)a(0) (4)E(h) (-3)=-3.88 x 10(5), 4.16 x 10(4), -7.00 x 10(3), and 1.65 x 10(3) for Al, Si, S, and Cl, respectively, with an error estimate of +/-4%. (c) 2005 American Institute of Physics.

  17. 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.

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

    International Nuclear Information System (INIS)

    Arico, S F; Mirandou, M I; Balart, S N; Fabro, J O

    2012-01-01

    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)

  19. 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.

  20. Structure evaluation of cast dispersive AlSi-CrxCy composites

    Directory of Open Access Journals (Sweden)

    M. Cholewa

    2008-08-01

    Full Text Available In this work author showed the diversification of structure for cast dispersive AlSi-CrxCy composites. Wide possibilities of properties control and optimization were described, through microstructure of the matrix and the transition zone shaping. Utility castings were prepared with use of traditional casting techniques, ceramic and metal moulds. The influence of technological conditions and cooling rate ion the composite structure was studied. The main factor of structural changes was the diffusion at matrix – reinforcement interface. Divers structure was observed in particle close neighborhood. Possibilities of diffusion control were indicated through application of factors assisting the crystallization.

  1. Changes in Structural Characteristics of Hypoeutectic Al-Si Cast Alloy after Age Hardening

    OpenAIRE

    Lenka HURTALOVÁ; Juraj BELAN; Eva TILLOVÁ; Mária CHALUPOVÁ

    2012-01-01

    The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness) and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled) AlSi9Cu3 cast alloy. A combination of different an...

  2. Influence exothermical mixtures contents Na or B on elongation and hardness AlSi12 alloy

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2008-04-01

    Full Text Available The experiments were conducted on alloy AlSi12, following a factor design 23 for 3 independent variables. Mixtures composed of NaNO3, Na2B4O7, and Mg were used for alloy treatment. The amount of a reducing agent (Mg necessary to carry out the process was calculated on the basis of chemical reactions. The mass fraction (weight in weight concentration of individual variables is presented in Table 1. Results of study present by graphical forms. Figures 2-8 present until elongation (A5 and Brinell hardness (HB for each variable, at extreme (lower or higher levels of the other two.

  3. K-capture by Al-Si based Additives in an Entrained Flow Reactor

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao

    2016-01-01

    A water slurry, consisting of KCl and Al-Si based additives (kaolin and coal fly ash) was fed into an entrained flow reactor (EFR) to study the K-capturing reaction of the additives at suspension-fired conditions. Solid products collected from the reactor were analysed with respect to total...... of KCl to K-aluminosilicate decreased. When reaction temperature increased from 1100 °C to 1450 °C, the conversion of KCl does not change significantly, which differs from the trend observed in fixed-bed reactor....

  4. 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...

  5. Optimizing the milling characteristics of Al-SiC particulate composites

    Science.gov (United States)

    Karthikeyan, R.; Raghukandan, K.; Naagarazan, R. S.; Pai, B. C.

    2000-12-01

    The present investigation focuses on the face milling characteristics of LM25Al-SiC particulate composites produced through stir casting. Experiments were conducted according to an L27 orthogonal array and mathematical models were developed for such machining characteristics as flank wear, specific energy and surface roughness whose adequacy was checked. The insignificant effects present in the models were eliminated using a t-test. Goal programming was employed to optimize the cutting conditions by considering such primary objectives as maximizing the metal removal rate and minimizing tool wear, specific energy and surface roughness.

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

    International Nuclear Information System (INIS)

    Chacko, Melby; Nayak, Jagannath

    2015-01-01

    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. (paper)

  7. 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.

  8. Fabrication and structure of bulk nanocrystalline Al-Si-Ni-mishmetal alloys

    International Nuclear Information System (INIS)

    Latuch, Jerzy; Cieslak, Grzegorz; Kulik, Tadeusz

    2007-01-01

    Al-based alloys of structure consisting of nanosized Al crystals, embedded in an amorphous matrix, are interesting for their excellent mechanical properties, exceeding those of the commercial crystalline Al-based alloys. Recently discovered nanocrystalline Al alloys containing silicon (Si), rare earth metal (RE) and late transition metal (Ni), combine high tensile strength and good wear resistance. The aim of this work was to manufacture bulk nanocrystalline alloys from Al-Si-Ni-mishmetal (Mm) system. Bulk nanostructured Al 91-x Si x Ni 7 Mm 2 (x = 10, 11.6, 13 at.%) alloys were produced by ball milling of nanocrystalline ribbons followed by high pressure hot isostating compaction

  9. 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.

  10. 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)

  11. TEM analysis of a friction stir-welded butt joint of Al-Si-Mg alloys

    International Nuclear Information System (INIS)

    Cabibbo, M.; Meccia, E.; Evangelista, E.

    2003-01-01

    The microstructure evolution of a joint of Al-Si-Mg alloys A6056-T4 and A6056-T6 has been characterized by transmission electron microscopy (TEM). Metallurgical investigations, hardness and mechanical tests were also performed to correlate the TEM investigations to the mechanical properties of the produced friction stir-welded butt joint. After friction stir-welding thermal treatment has been carried out at 530 deg. C followed by ageing at 160 deg. C (T6). The base material (T4) and the heat-treated one (T6) were put in comparison showing a remarkable ductility reduction of the joint after T6 treatment

  12. Corrosion behaviour of the AlSi6Cu4 alloy and cast AlSi6Cu4-graphite particles composite

    Directory of Open Access Journals (Sweden)

    S. Holecek

    2009-04-01

    Full Text Available The corrosion behaviour of the AlSi6Cu4 alloy as a composite matrix and of composites with 8% vol. of graphite particles was investigated. The corrosion experiments were performed over a range of elevated temperatures and were carried out in sea water (3.5%NaCl solution. We have focused our attention to the determination of the mode of corrosion attack and to the determination of the rate ofcorrosion and other corrosion characteristics. Both as-cast and annealed matrix and composite specimens were tested, as well as the99.9% as-cast aluminium for comparison. Corrosion behaviour of the materials was assessed by the corrosion potential (Ec and bypotentiodynamic (polarization curves. As expected, composite is less corrosion resistant than the matrix alloy. In addition to pitting,a severe galvanic corrosion occurs as a result of galvanic couple aluminium/graphite formation. Corrosion potentials imply that examinedmaterials would be sufficiently resistant in non or slightly oxidizing solutions without dissolved oxygen. All studied materials corrode very slowly at potentials negative to corrosion potential, while at potentials positive to corrosion potential the corrosion rate goes up by 1 or 2 orders.

  13. Mechanical properties enhancement and microstructure study of Al-Si-TiB2 in situ composites

    Science.gov (United States)

    Sahoo, S. K.; Majhi, J.; Pattnaik, A. B.; Sahoo, J. K.; Das, Swagat

    2018-03-01

    Al–Si alloy-based composite is one of the most promising MMC materials owing to its outstanding mechanical properties, wear and corrosion resistance, low cost and ability to be synthesized via conventional casting routes. Challenges in achieving clean interface between reinforced particles and matrix alloy have been overcome by means of in-situ techniques of fabrication. Present investigation is concerned with synthesizing Al-Si-TiB2 in-situ composites through stir casting route using K2TiF6 and KBF4 halide salts for exothermic salt metal reaction. X-Ray diffraction analysis revealed the existence of TiB2 in the prepared samples. Effect of TiB2in-situ particles in the Al-Si base alloy has been investigated from the results obtained from optical microscopy as well as SEM study and wear analysis with a pin on disc wear testing apparatus. Improved hardness and wear properties were observed with addition of TiB2.

  14. The Effects of Pressure During the Crystallization on Properties of the AlSi12 Alloy

    Directory of Open Access Journals (Sweden)

    Pastirčák R.

    2017-09-01

    Full Text Available The paper deals with the impact of technological parameters on the mechanical properties and microstructure in AlSi12 alloy using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. From the experiments we can conclude that operating pressure of 100 MPa is sufficient to influence the structural characteristics of the alloy AlSi12. The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. At a pressure of 100 MPa was increased of tensile strength on average of 20%. At a pressure of 150 MPa was increased of tensile strength on average of 30%. During the experiment it was also observed, that increasing difference between the casting temperature and the mold temperature leads to increase of mechanical properties.

  15. Wear study of Al-SiC metal matrix composites processed through microwave energy

    Science.gov (United States)

    Honnaiah, C.; Srinath, M. S.; Prasad, S. L. Ajit

    2018-04-01

    Particulate reinforced metal matrix composites are finding wider acceptance in many industrial applications due to their isotropic properties and ease of manufacture. Uniform distribution of reinforcement particulates and good bonding between matrix and reinforcement phases are essential features in order to obtain metal matrix composites with improved properties. Conventional powder metallurgy technique can successfully overcome the limitation of stir casting techniques, but it is time consuming and not cost effective. Use of microwave technology for processing particulate reinforced metal matrix composites through powder metallurgy technique is being increasingly explored in recent times because of its cost effectiveness and speed of processing. The present work is an attempt to process Al-SiC metal matrix composites using microwaves irradiated at 2.45 GHz frequency and 900 W power for 10 minutes. Further, dry sliding wear studies were conducted at different loads at constant velocity of 2 m/s for various sliding distances using pin-on-disc equipment. Analysis of the obtained results show that the microwave processed Al-SiC composite material shows around 34 % of resistance to wear than the aluminium alloy.

  16. Radiation Resistance of the U(Al, Si)3 Alloy: Ion-Induced Disordering

    Science.gov (United States)

    Yaniv, Gili; Horak, Pavel; Vacik, Jiri; Mykytenko, Natalia; Rafailov, Gennady; Dahan, Itzchak; Fuks, David; Kiv, Arik

    2018-01-01

    During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current research, U(Al, Si)3 composition was studied as a potential constituent of an interaction layer. Phase content of the alloy of an interest was ordered U(Al, Si)3, structure of which was reported earlier, and pure Al (constituting less than 20 vol % of the alloy). This alloy was investigated prior and after the irradiation performed by Ar ions at 30 keV. The irradiation was performed on the transmission electron microscopy (TEM, JEOL, Japan) samples, characterized before and after the irradiation process. Irradiation induced disorder accompanied by stress relief. Furthermore, it was found that there is a dose threshold for disordering of the crystalline matter in the irradiated region. Irradiation at doses equal or higher than this threshold resulted in almost solely disordered phase. Using the program “Stopping and Range of Ions in Matter” (SRIM), the parameters of penetration of Ar ions into the irradiated samples were estimated. Based on these estimations, the dose threshold for ion-induced disordering of the studied material was assessed. PMID:29393870

  17. Manufacture of hypoeutectic Al-Si metal powders for dispersion matriz in nuclear fuels

    International Nuclear Information System (INIS)

    Raffaeli, H A; Harri, S; Acosta, M; Castillo Guerra, R; Rossi, G; Fabro, J O; Rubiolo, G H

    2012-01-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U.Mo/Al is the most promising option that has however to be optimized. Indeed at the U.Mo/Al interfaces between U.Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U.Mo/Al.Si protective layer around U.Mo particles appeared during fuel manufacturing. The present work deals with three techniques applied to produce metal powders of hypoeutectic Al-Si alloys: ball milling, centrifugal atomization and gas atomization. Size and microstructure of the particles are analyzed in the three techniques. The best result is found with the gas atomization system, flakes and rods morphology predominates in the produced powders, with particle sizes below 150 microns and the greater mass population (65%) is between 150 and 125 microns. The particle surface is smooth and the high solidification rate provides a good distribution of the α-Al primary and eutectic phase within each particle (author)

  18. Study of Bending Fatigue Properties of Al-Si Cast Alloy

    Directory of Open Access Journals (Sweden)

    Tillová E.

    2017-09-01

    Full Text Available Fatigue properties of casting Al-alloys are very sensitive to the microstructural features of the alloy (e.g. size and morphology of the eutectic Si, secondary dendrite arm spacing - SDAS, intermetallics, grain size and casting defects (porosity and oxides. Experimental study of bending fatigue properties of secondary cast alloys have shown that: fatigue tests up to 106-107cycles show mean fatigue limits of approx. 30-49 MPa (AlSi9Cu3 alloy - as cast state, approx. 65-76 MPa (AlSi9Cu3 alloy after solution treatment and 60-70 MPa (self-hardened AlZn10Si8Mg alloy in the tested casting condition; whenever large pore is present at or near the specimen’s surface, it will be the dominant cause of fatigue crack initiation; in the absence of large casting defects, the influence of microstructural features (Si morphology; Fe-rich phases on the fatigue performance becomes more pronounced.

  19. 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.

  20. Multiscale tomographic analysis of heterogeneous cast Al-Si-X alloys.

    Science.gov (United States)

    Asghar, Z; Requena, G; Sket, F

    2015-07-01

    The three-dimensional microstructure of cast AlSi12Ni and AlSi10Cu5Ni2 alloys is investigated by laboratory X-ray computed tomography, synchrotron X-ray computed microtomography, light optical tomography and synchrotron X-ray computed microtomography with submicrometre resolution. The results obtained with each technique are correlated with the size of the scanned volumes and resolved microstructural features. Laboratory X-ray computed tomography is sufficient to resolve highly absorbing aluminides but eutectic and primary Si remain unrevealed. Synchrotron X-ray computed microtomography at ID15/ESRF gives better spatial resolution and reveals primary Si in addition to aluminides. Synchrotron X-ray computed microtomography at ID19/ESRF reveals all the phases ≥ ∼1 μm in volumes about 80 times smaller than laboratory X-ray computed tomography. The volumes investigated by light optical tomography and submicrometre synchrotron X-ray computed microtomography are much smaller than laboratory X-ray computed tomography but both techniques provide local chemical information on the types of aluminides. The complementary techniques applied enable a full three-dimensional characterization of the microstructure of the alloys at length scales ranging over six orders of magnitude. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  1. Porosity formation in Al-Si casting alloys: role of Sr oxide

    International Nuclear Information System (INIS)

    Liu, L.; Samuel, A.M.; Samuel, F.H.; Doty, H.W.; Valtierra, S.

    2002-01-01

    The strength and quality of an Al-Si alloy casting are determined by its microstructure and the amount of porosity present in the casting. Modification is one of the processes used to improve the microstructural quality, where the addition of a modifying agent alters the shape of the eutectic Si from an acicular to a fibrous form that is extremely beneficial to the mechanical properties. Among various modifiers, strontium, although easy to handle and resistant to fading, also causes porosity formation in these alloys, attributed variously to an increase in the hydrogen level of the melt, feedability problems in the mushy zone, changes in the mode of eutectic nucleation, etc. The present study shows how the presence of oxides is responsible for the porosity formation, and that the difference in porosity characteristics with the addition of Sr depends on the amount of Sr oxides present the solidified structure. Both Sr and Al oxides are favourable sites for the nucleation of other microconstituents. A number of experimental (binary Al-Si) and industrial (319 and 356) alloys have been studied, to cover various alloy freezing ranges. Thermal analysis, optical microscopy, SEM/EDX and EPMA analyses were employed to obtain the results. (author)

  2. Ti-Al-Si-C-N hard coatings synthesized by hybrid arc enhanced magnetron sputtering

    International Nuclear Information System (INIS)

    Wu, Guizhi; Liu, Sitao; Ma, Shengli; Xu, Kewei; Vincent, Ji; Chu, Paul K.

    2010-01-01

    Ti-Al-Si-C-N coatings are deposited by hybrid arc-enhanced magnetic sputtering and characterized by various micro- and macro-tools. X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy reveal that the coatings are nanocomposites consisting of nanocrystallites and amorphous phases. They are generally in the form of nc-(Ti,Al)(C,N)/a-Si_3N_4/a-C depending on the composition of the coatings. With increasing Al concentrations, the X-ray diffraction peaks shift to a lower angle indicating compressive stress in the coatings. The measured hardness also diminishes implying reduced contributions from the self-organized stable nanostructure. The dry friction coefficients of the Ti-Al-Si-C-N coatings are found to be about 0.3 which is lower than that of conventional Ti-Si-N coatings. These coatings can find potential applications requiring high temperature with heavy contact loading. (author)

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

    Directory of Open Access Journals (Sweden)

    CHEN Xiang

    2005-11-01

    Full Text Available Most evaluations of modification level are done according to a specific scale based on an merican 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 ualitativeanalysis 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 hermal 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.

  4. Influence of Sc on microstructure and mechanical properties of Al-Si-Mg-Cu-Zr alloy

    Science.gov (United States)

    Li, Yukun; Du, Xiaodong; Zhang, Ya; Zhang, Zhen; Fu, Junwei; Zhou, Shi'ang; Wu, Yucheng

    2018-02-01

    In the present study, the effects of Mg, Cu, Sc and Zr combined additions on the microstructure and mechanical properties of hypoeutectic Al-Si cast alloy were systematically investigated. Characterization techniques such as optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron back-scatter diffraction (EBSD), atomic force microscopy (AFM), transmission electron microscope (TEM), Brinell hardness tester and universal testing machine were employed to analyze the microstructure and mechanical properties. The results showed that Sc served as modifier on the microstructure of Al-3Si-0.45Mg-0.45Cu-0.2Zr alloys, including modification of eutectic Si and grains. Extraordinarily, grain refinement was found to be related to the primary particles, which exhibited a close orientation to matrix. After T6 heat treatment, the grain structures were composed of nano-scaled secondary Al3(Sc, Zr) precipitates and spherical eutectic Si. Combined with T6 heat treatment, the highest hardness, yield strength, ultimate tensile strength and elongation were achieved in 0.56 wt.% Sc-modified alloy. Interestingly, the strength and ductility had a similar tendency. This paper demonstrated that combined additions of Mg, Cu, Sc and Zr could significantly improve the microstructure and performance of the hypoeutectic Al-Si cast alloy.

  5. A study of Al/Si interface by photoemission, Auger electron yield and Auger electron spectroscopies

    International Nuclear Information System (INIS)

    Kobayashi, K.L.I.; Barth, J.; Gerken, F.; Kunz, C.; Deutsches Elektronen-Synchrotron

    1980-06-01

    Photoemission, Auger electron yield and Auger electron spectra were observed for Al/Si(111) interfaces with various Al coverage prepared by successive deposition using a molecular beam source. The Al 3p derived states are introduced at around the top of the valence band by the Al coverage of less than one monolayer. The Al surface layer behaves as a 'metal' and the Fermi level is stabilized in the Al 3p derived states at about 0.3 eV above the top of the valence band of Si. The Schottky barrier height in this stage is about 0.8 eV and further increase in Al coverage does not change the barrier height. A covalent bonding model of the Al/Si interface based on the experimental results is proposed. The present result favors the on-top geometry of Al atoms on Si(111) surface among the geometries used in the pseudopotential calculation by Zhang and Schlueter. (orig.)

  6. Heat treatment of the EN AC-AlSi9Cu3(Fe alloy

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2010-04-01

    Full Text Available Silumins are widely used in automotive, aviation and shipbuilding industries; as having specific gravity nearly three times lower than specific gravity of cast iron the silumins can be characterized by high mechanical properties. Additionally, they feature good casting properties, good machinability and good thermal conductivity. i.e. properties as required for machinery components operating in high temperatures and at considerable loads. Mechanical properties of the silumins can be upgraded, implementing suitably selected heat treatment. In the paper is presented an effect of modification and heat treatment processes on mechanical properties of the EN AC-AlSi9Cu3(Fe alloy. Investigated alloy has undergone typical processes of modification and refining, and next heat treatment. Temperature range of the heat treatment operations was determined on base of curves from the ATD method. Obtained results concern registered melting and solidification curves from the ATD method and strength tests. On base of the performed tests one has determined range of the heat treatment parameters which would assure obtainment of the best possible mechanical properties of the EN AC-AlSi9Cu3(Fe alloy.

  7. 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.

  8. Experimental and computer thermodynamics evaluations of an Al-Si-Coating on a quenchable steel

    International Nuclear Information System (INIS)

    Trindade, Vicente Braz

    2017-01-01

    High-strength steels are commonly used in the automobile industry in order to reduce the weight of the vehicles. However, a technical difficulty appears due to the need of hot stamping of the components, which leads to oxidation. Therefore, the application of a coating on the substrate to avoid high-temperature oxidation is used. In this work, experimental analysis and computer thermodynamic calculation were used to describe the phase transformations within an Al-Si coating on a quenchable high strength steel. The Al-Si coating was deposited by hot dipping and its characterization was done using SEM and XRD techniques. Computer thermodynamics calculations were done using the commercial software FactSage using the Calphad methodology. It demonstrated a good relationship between the experimental results and the computer calculations of phase stabilities for the as-deposited condition and after diffusion experiment at 920 deg C for 7 minutes, which simulates the thermal cycle of hot stamping of the quenchable steel used. (author)

  9. Wear of tin coating and Al-Si alloy substrate against carburized steel under mixed lubrication

    Science.gov (United States)

    Wang, Q.; Cheng, H. S.; Fine, M. E.

    1994-04-01

    Tin coatings on Al-Si alloys are widely used in the automotive industries. The soft tin coating and the harder substrate alloy form a tribological system with the advantages of low friction and reasonably high load-bearing capacity. Wear tests of tin coated Al-Si Z332 alloy in conformal contact against carburized 1016 steel have been carried out under mixed lubrications with SAE 10W30 oil to study the wear mechanisms. Two major wear mechanisms, uniform wear of the tin coating due to micro-plowing and spall pitting related to the substrate are found to contribute to the bearing material loss when the fluid lubrication film is relatively thick (Lambda about 1.6). Under conditions of thinner films (Lambda approximately = 0.8), some local coating debonding occurs. The pitting and local coating debounding are closely related to fracture in the substrate. The bonding between silicon and tin seems to be weaker than between aluminum and tin. During wear, oxidation occurs.

  10. Experimental and computer thermodynamics evaluations of an Al-Si-Coating on a quenchable steel

    Energy Technology Data Exchange (ETDEWEB)

    Trindade, Vicente Braz, E-mail: vicentebraz@yahoo.com.b [Universidade Federal de Ouro Preto (UFOP), Ouro Preto, MG (Brazil). Escola de Minas. Departamento de Engenharia Metalurgica e de Materiais; Christ, Hans-Juergen, E-mail: christ@ifwt.mb.uni-siegen.de [University of Siegen (Germany)

    2017-01-15

    High-strength steels are commonly used in the automobile industry in order to reduce the weight of the vehicles. However, a technical difficulty appears due to the need of hot stamping of the components, which leads to oxidation. Therefore, the application of a coating on the substrate to avoid high-temperature oxidation is used. In this work, experimental analysis and computer thermodynamic calculation were used to describe the phase transformations within an Al-Si coating on a quenchable high strength steel. The Al-Si coating was deposited by hot dipping and its characterization was done using SEM and XRD techniques. Computer thermodynamics calculations were done using the commercial software FactSage using the Calphad methodology. It demonstrated a good relationship between the experimental results and the computer calculations of phase stabilities for the as-deposited condition and after diffusion experiment at 920 deg C for 7 minutes, which simulates the thermal cycle of hot stamping of the quenchable steel used. (author)

  11. Effect of grain refinement on the fluidity of two commercial Al-Si foundry alloys

    Science.gov (United States)

    Dahle, A. K.; Tøndel, P. A.; Paradies, C. J.; Arnberg, L.

    1996-08-01

    The effect of grain refinement on the fluidity of AlSi7Mg and AlSi11Mg has been investigated by spiral tests. Two different types of grain refiners have been evaluated. An AlTi5Bl master alloy was added to different Ti contents. Since the commercial alloys had a high initial content of titanium, model alloys were made to investigate the fluidity at low grain refiner additions. Commercial alloys grain refined only by boron additions have also been investigated. The results from the fluidity measurements have been verified by measuring the dendrite coherency point of the different cast alloys. Although different, the two methods show similar trends. The spirals from each fraction grain refiner cast were subsequently investigated metallographically at the tip of the spirals and at a reference point a distance behind, but no obvious difference in structure was observed. For both alloys, an increase in fluidity is observed as the content of grain refiner increases above 0.12 pct Ti, while the fluidity is impaired with increased grain refinement below 0.12 pct Ti. The alloys grain refined with ~0.015 pct B show the highest fraction solid at dendrite coherency, the smallest grain size, and the best fluidity.

  12. Microstructure and Properties of AlSi10Mg Powder for Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    TANG Pengjun

    2018-02-01

    Full Text Available The AlSi10Mg powder was prepared by supersonic gas atomization. After classified, the powder was fabricated into block by selective laser melting (SLM. The microstructure, phase, and evolutions of powder and block were investigated by optical microscope, scanning electron microscope and X-Ray Diffraction. The tensile properties of SLM block were tested by tensile experiments at room temperature. The results show that the size distribution of AlSi10Mg powder after classified can meet the requirements of SLM technology. The powder always is spherical and spherical-like. Meanwhile, the microstructure of powders is fine and uniform, which contain α(Al matrix and (α+Si eutectic. In addition, the melt pool boundaries of SLM block are legible. The microstructure is also uniform and densified, the relative density approaches to 99.5%. On the other hand, only α(Al and few Silicon phase are detected in this condition, due to the most alloying elements are dissolved in α(Al matrix. At room temperature, the ultimate tensile strength of SLM block reaches up to 442 MPa.

  13. Experimental and Theoretical Investigations of the Solidification of Eutectic Al-Si Alloy

    Science.gov (United States)

    Sen, S.; Catalina, A. V.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    The eutectic alloys have a wide spectrum of applications due to their good castability and physical and mechanical properties. The interphase spacing resulting during solidification is an important microstructural feature that significantly influences the mechanical behavior of the material. Thus, knowledge of the evolution of the interphase spacing during solidification is necessary in order to properly design the solidification process and optimize the material properties. While the growth of regular eutectics is rather well understood, the irregular eutectics such as Al-Si or Fe-graphite exhibit undercoolings and lamellar spacings much larger than those theoretically predicted. Despite of a considerable amount of experimental and theoretical work a clear understanding of the true mechanism underlying the spacing selection in irregular eutectics is yet to be achieved. A new experimental study of the solidification of the eutectic Al-Si alloy will be reported in this paper. The measured interface undercoolings and lamellar spacing will be compared to those found in the literature in order to get more general information regarding the growth mechanism of irregular eutectics. A modification of the present theory of the eutectic growth is also proposed. The results of the modified mathematical model, accounting for a non-isothermal solid/liquid interface, will be compared to the experimental measurements.

  14. Microstructure and mechanical properties of spray deposited hypoeutectic Al-Si alloy

    International Nuclear Information System (INIS)

    Ferrarini, C.F.; Bolfarini, C.; Kiminami, C.S.; Botta F, W.J.

    2004-01-01

    The microstructure and the tensile properties of an Al-8.9 wt.% Si-3.2 wt.% Cu-0.9 wt.% Fe-0.8% Zn alloy processed by spray forming was investigated. The alloy was gas atomized with argon and deposited onto a copper substrate. The microstructure was evaluated by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Small faceted dispersoids observed surrounding equiaxial α-Al matrix were identified by SEM-EDS as silicon particles. Sand cast samples with the same composition showed a columnar dendritic α-Al matrix, Al-Si eutectic, polyhedric α-AlFeSi and needle-like β-AlFeSi intermetallics. In the spray formed material the formation of the Al-Si eutetic was suppressed, and the formation of the α-AlFeSi and β-AlFeSi intermetallics was strongly reduced. The fine and homogeneous microstructure showed an aluminium matrix with grain size ranging from 30 to 40 μm, and particle size of the silicon dispersoids having a mean size of 12 μm. Room temperature tensile tests of the spray formed alloy showed relative increasing of strength and elongation when compared with the values observed for the conventionally cast counterparts. These results can be ascribed to the refined microstructure and the scarce presence of intermetallics of the spray formed material

  15. Precipitation and strengthening phenomena in Al-Si-Ge and Al-Cu-Si-Ge alloys

    International Nuclear Information System (INIS)

    Mitlin, D.; Morris, J.W.; Dahmen, U.; Radmilovic, V.

    2000-01-01

    The objective of this work was to determine whether Al rich Al-Si-Ge and 2000 type Al-Cu-Si-Ge alloys have sufficient hardness to be useful for structural applications. It is shown that in Al-Si-Ge it is not possible to achieve satisfactory hardness through a conventional heat treatment. This result is explained in terms of sluggish precipitation of the diamond-cubic Si-Ge phase coupled with particle coarsening. However, Al-Cu-Si-Ge displayed a uniquely fast aging response, a high peak hardness and a good stability during prolonged aging. The high hardness of the Cu containing alloy is due to the dense and uniform distribution of fine θ' precipitates (metastable Al 2 Cu) which are heterogeneously nucleated on the Si-Ge particles. High resolution TEM demonstrated that in both alloys all the Si-Ge precipitates start out, and remain multiply twinned throughout the aging treatment. Since the twinned section of the precipitate does not maintain a low index interface with the matrix, the Si-Ge precipitates are equiaxed in morphology. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  16. The structure-property relationships of powder processed Fe-Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prichard, Paul D. [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D84 < 32 μm). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 μm. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 μm to 104 μm. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase α + DO3 structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  17. Antimony Influence on Shape of Eutectic Silicium in Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2017-12-01

    Full Text Available Liquid AI-Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved properties. For many years, sodium additions to hypoeutectic and eutectic AI-Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic structure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI-Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non-fading refining ability. In this paper, the authors summarize work on antimony treatment of Al-Si based alloys.

  18. Study of Al-Si Alloy Oxygen Saturation on Its Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Arkady Finkelstein

    2017-07-01

    Full Text Available One of the main goals of modern materials research is obtaining different microstructures and studying their influence on the mechanical properties of metals; aluminum alloys are particularly of interest due to their advanced performance. Traditionally, their required properties are obtained by alloying process, modification, or physical influence during solidification. The present work describes a saturation of the overheated AlSi7Fe1 casting alloy by oxides using oxygen blowing approach in overheated alloy. Changes in metals’ microstructural and mechanical properties are also described in the work. An Al10SiFe intermetallic complex compound was obtained as a preferable component to Al2O3 precipitation on it, and its morphology was investigated by scanning electron microscopy. The mechanical properties of the alloy after the oxygen blowing treatment are discussed in this work.

  19. Influence of copper content on microstructure development of AlSi9Cu3 alloy

    Directory of Open Access Journals (Sweden)

    Brodarac Zovko Z.

    2014-01-01

    Full Text Available Microstructure development and possible interaction of present elements have been determined in charge material of EN AlSi9Cu3 quality. Literature review enables prediction of solidification sequence. Modelling of equilibrium phase diagram for examined chemical composition has been performed, which enables determination of equilibrium solidification sequence. Microstructural investigation indicated distribution and morphology of particular phase. Metallographic analysis tools enable exact determination of microstructural constituents: matrix αAl, eutectic αAl+βSi, iron base intermetallic phase - Al5FeSi, Alx(Fe,MnyCuuSiw and/or Alx(Fe,MnyMgzCuuSiw and copper base phases in ternary eutectic morphology Al-Al2Cu-Si and in complex intermetallic ramified morphology Alx(Fe,MnyMgzSiuCuw. Microstructure development examination reveals potential differences due to copper content which is prerequisite for high values of final mechanical, physical and technological properties of cast products.

  20. 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.

  1. Rapid solidification growth mode transitions in Al-Si alloys by dynamic transmission electron microscopy

    International Nuclear Information System (INIS)

    Roehling, John D.; Coughlin, Daniel R.; Gibbs, John W.; Baldwin, J. Kevin; Mertens, James C.E.; Campbell, Geoffrey H.; Clarke, Amy J.; McKeown, Joseph T.

    2017-01-01

    In situ dynamic transmission electron microscope (DTEM) imaging of Al-Si thin-film alloys was performed to investigate rapid solidification behavior. Solidification of alloys with compositions from 1 to 15 atomic percent Si was imaged during pulsed laser melting and subsequent solidification. Solely α-Al solidification was observed in Al-1Si and Al-3Si alloys, and solely kinetically modified eutectic growth was observed in Al-6Si and Al-9Si alloys. A transition in the solidification mode in eutectic and hypereutectic alloys (Al-12Si and Al-15Si) from nucleated α-Al dendrites at lower solidification velocities to planar eutectic growth at higher solidification velocities was observed, departing from trends previously seen in laser-track melting experiments. Comparisons of the growth modes and corresponding velocities are compared with previous solidification models, and implications regarding the models are discussed.

  2. 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.

  3. 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.

  4. The Study of Phase Transformations of AlSi9Cu3 Alloy by DSC Method

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2016-12-01

    Full Text Available With the use of differential scanning calorimetry (DSC, the characteristic temperatures and enthalpy of phase transformations were defined for commercial AlSi9Cu3 cast alloy (EN AC-46000 that is being used for example for pressurized castings for automotive industry. During the heating with the speed of 10°C·min−1 two endothermic effects has been observed. The first appears at the temperature between 495 °C and 534 °C, and the other between 555 °C and 631 °C. With these reactions the phase transformation enthalpy comes up as +6 J g−1 and +327 J g−1. During the cooling with the same speed, three endothermic reactions were observed at the temperatures between 584 °C and 471 °C. The total enthalpy of the transitions is – 348 J g−1.

  5. Comparison Study on Additive Manufacturing (AM) and Powder Metallurgy (PM) AlSi10Mg Alloys

    Science.gov (United States)

    Chen, B.; Moon, S. K.; Yao, X.; Bi, G.; Shen, J.; Umeda, J.; Kondoh, K.

    2018-02-01

    The microstructural and mechanical properties of AlSi10Mg alloys fabricated by additive manufacturing (AM) and powder metallurgy (PM) routes were investigated and compared. The microstructures were examined by scanning electron microscopy assisted with electron-dispersive spectroscopy. The crystalline features were studied by x-ray diffraction and electron backscatter diffraction. Room-temperature tensile tests and Vickers hardness measurements were performed to characterize the mechanical properties. It was found that the AM alloy had coarser Al grains but much finer Si precipitates compared with the PM alloy. Consequently, the AM alloy showed more than 100% increment in strength and hardness compared with the PM alloy due to the presence of ultrafine forms of Si, while exhibiting moderate ductility.

  6. Drainage effect in eutectic Al-Si foam using similar alporas process

    International Nuclear Information System (INIS)

    Filho, M.O.; Junior, A.C.S; Ferrandini, P.L.; Nakazato, A.Z.; Assis, W.L.S.

    2016-01-01

    Cellular materials have particular properties. This properties are very interesting in various type of industries, as construction, automobile and shipbuilding. Two reasons why metal foams are apply in more companies are difficult process control and high production costs. Therefore, this study aims to analyze the drainage effect in four samples produced with alloy Al-Si eutectic using CaCO 3 as foaming agent, since this is low cost than TiH 2 used normally in Alporas process and this foam have well pores uniform. For these samples has been used 700°C during all process, mixing time was 180 seconds, holding time was 150 seconds and 3,5 w.t% CaCO3. Therefore, these samples were cut transversally and analyzed what were the drainage effect on the apparent density, relative density and porosity. The free zone bubbles were noticed in all the samples. (author)

  7. 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.)

  8. Structure and Mechanical Properties of AlSiCuMg Alloy after Thermo Processing

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2015-03-01

    Full Text Available In the dissertation it has been shown, that so called „time-thermal treatment” (TTT of the alloy in liquid state, as overheating the metal with around 250°C above the Tliq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, Rm, R0,2. It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform arrangement of the Si primeval crystals in the warp, and α(Al solution type, supersaturated with alloying elements present in the base content (Cu, Mg assures not only increased durability in the ambient temperature, but also at elevated temperature (250°C, what is an advantage, especially due to the use in car industry.

  9. Anisotropic Responses of Mechanical and Thermal Processed Cast Al-Si-Mg-Cu Alloy

    Science.gov (United States)

    Adeosun, S. O.; Akpan, E. I.; Balogun, S. A.; Onoyemi, O. K.

    2015-05-01

    The effects of ambient directional rolling and heat treatments on ultimate tensile strength (UTS), hardness (HD), percent elongation (PE), and impact energy (IE) on Al-Si-Mg-Cu alloy casting with reference to inclination to rolling direction are discussed in this article. The results show that rolled and quenched (CQ) sample possess superior UTS and HD to as-cast and those of rolled and aged samples (CA). Improved IE resistance with ductility is shown by both CQ and CA samples. However, these mechanical properties are enhanced as changes in the test sample direction moved away from rolling direction for all heat-treated samples. The CQ samples displayed highest tensile strength (108 MPa) and PE (19.8%) in the 90° direction.

  10. Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

    Directory of Open Access Journals (Sweden)

    Kuchariková L.

    2017-03-01

    Full Text Available The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h, followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

  11. Influence of Ultrasound Treatment on Cavitation Erosion Resistance of AlSi7 Alloy

    Directory of Open Access Journals (Sweden)

    Annalisa Pola

    2017-03-01

    Full Text Available Ultrasound treatment of liquid aluminum alloys is known to improve mechanical properties of castings. Aluminum foundry alloys are frequently used for production of parts that undergo severe cavitation erosion phenomena during service. In this paper, the effect of the ultrasound treatment on cavitation erosion resistance of AlSi7 alloy was assessed and compared to that of conventionally cast samples. Cavitation erosion tests were performed according to ASTM G32 standard on as-cast and heat treated castings. The response of the alloy in each condition was investigated by measuring the mass loss as a function of cavitation time and by analyzing the damaged surfaces by means of optical and scanning electron microscope. It was pointed out that the ultrasound treatment increases the cavitation erosion resistance of the alloy, as a consequence of the higher chemical and microstructural homogeneity, the finer grains and primary particles and the refined structure of the eutectic induced by the treatment itself.

  12. Influence of Ultrasound Treatment on Cavitation Erosion Resistance of AlSi7 Alloy.

    Science.gov (United States)

    Pola, Annalisa; Montesano, Lorenzo; Tocci, Marialaura; La Vecchia, Giovina Marina

    2017-03-03

    Ultrasound treatment of liquid aluminum alloys is known to improve mechanical properties of castings. Aluminum foundry alloys are frequently used for production of parts that undergo severe cavitation erosion phenomena during service. In this paper, the effect of the ultrasound treatment on cavitation erosion resistance of AlSi7 alloy was assessed and compared to that of conventionally cast samples. Cavitation erosion tests were performed according to ASTM G32 standard on as-cast and heat treated castings. The response of the alloy in each condition was investigated by measuring the mass loss as a function of cavitation time and by analyzing the damaged surfaces by means of optical and scanning electron microscope. It was pointed out that the ultrasound treatment increases the cavitation erosion resistance of the alloy, as a consequence of the higher chemical and microstructural homogeneity, the finer grains and primary particles and the refined structure of the eutectic induced by the treatment itself.

  13. 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.

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

    International Nuclear Information System (INIS)

    Djurdjevic, M. B.; Vicario, I.

    2013-01-01

    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)

  15. Athermal metal optics made of nickel plated AlSi40

    Science.gov (United States)

    Gebhardt, Andreas; Kinast, Jan; Rohloff, Ralf-Rainer; Seifert, Walter; Beier, Matthias; Scheiding, Sebastian; Peschel, Thomas

    2017-11-01

    Metal optics is an inherent part of space instrumentation for years. Diamond turned aluminum (Al6061) mirrors are widely used for application in the mid- and near-infrared (mid-IR and NIR, respectively) spectral range. Aluminum mirrors plated with electroless nickel (NiP) expand the field of application towards multispectral operating instruments down to the ultraviolet wavelengths. Due to the significant mismatch in the coefficient of thermal expansion (CTE) between aluminum and NiP, however, this advantage occurs at the cost of bimetallic bending. Challenging requirements can be met by using bare beryllium or aluminum beryllium composites (AlBeMet) as a CTE tailored substrate material and amorphous NiP as polishable layer. For health reasons, the use of beryllium causes complications in the process chain. Thus, the beryllium approach is subjected to specific applications only. Metal optics has proven to be advantageous in respect of using conventional CNC and ultra-precision fabrication methods to realize complex and light-weighted instrument structures. Moreover, the mirror designs can be effectively optimized for a deterministic system assembly and optimization. Limitations in terms of dimensional stability over temperature and time are mainly given by the inherent material properties (figures of merit) of the substrate material in interaction with the polishing layer. To find an optimal compromise, a thermal matched aluminum-silicon alloy (silicon contents ≍ 40 wt%) plated with NiP (AlSi40/NiP ) was investigated in a joined project of the Max Planck Institute for Astronomy MPIA and the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. The main tasks of the project were the minimization of the bimetallic bending, the development of reliable stabilizing and aging procedures, and the establishment of a proven fabrication method. This paper describes fundamental results regarding the optimization of the athermal material combination

  16. The electrochemical properties of melt-spun Al-Si-Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Sun Zhanbo, E-mail: szb@mail.xjtu.edu.cn [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Song Xiaoping; Yang Sen; Wang Liqun [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2011-10-03

    Highlights: {yields} Non-equilibrium Al{sub 75-X}Si{sub 25}Cu{sub X} alloys exhibit high lithiation storages. {yields} The lithiation mechanism is different from melt-spun Al-Si-Mn system. {yields} The structural evolution is mitigated in the non-equilibrium alloys. {yields} Volume variation is alleviated due to the co-existence of Al{sub 2}Cu, {alpha}-Si and {alpha}-Al. - Abstract: Melt spinning was used to prepare Al{sub 75-X}Si{sub 25}Cu{sub X} (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, {alpha}-Si and Al{sub 2}Cu co-existed in the alloys. Nano-scaled {alpha}-Al grains, as the matrix, formed in the as-quenched ribbons. The Al{sub 74}Si{sub 25}Cu{sub 1} and Al{sub 71}Si{sub 25}Cu{sub 4} anodes exhibited initial discharge specific capacities of 1539 mAh g{sup -1}, 1324 mAh g{sup -1} and reversible capacities above 472 mAh g{sup -1}, 508 mAh g{sup -1} at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled {alpha}-Al, {alpha}-Si, and Al{sub 2}Cu for the present alloys.

  17. 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.

  18. The electrochemical properties of melt-spun Al-Si-Cu alloys

    International Nuclear Information System (INIS)

    Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing; Sun Zhanbo; Song Xiaoping; Yang Sen; Wang Liqun

    2011-01-01

    Highlights: → Non-equilibrium Al 75-X Si 25 Cu X alloys exhibit high lithiation storages. → The lithiation mechanism is different from melt-spun Al-Si-Mn system. → The structural evolution is mitigated in the non-equilibrium alloys. → Volume variation is alleviated due to the co-existence of Al 2 Cu, α-Si and α-Al. - Abstract: Melt spinning was used to prepare Al 75-X Si 25 Cu X (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, α-Si and Al 2 Cu co-existed in the alloys. Nano-scaled α-Al grains, as the matrix, formed in the as-quenched ribbons. The Al 74 Si 25 Cu 1 and Al 71 Si 25 Cu 4 anodes exhibited initial discharge specific capacities of 1539 mAh g -1 , 1324 mAh g -1 and reversible capacities above 472 mAh g -1 , 508 mAh g -1 at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled α-Al, α-Si, and Al 2 Cu for the present alloys.

  19. 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.

  20. The role of elevated temperature exposure on structural evolution and fatigue strength of eutectic AlSi12 alloys

    Czech Academy of Sciences Publication Activity Database

    Konečná, R.; Nicoletto, G.; Kunz, Ludvík; Riva, E.

    2016-01-01

    Roč. 83, č. 1 (2016), s. 24-35 ISSN 0142-1123 Institutional support: RVO:68081723 Keywords : Piston * Al-Si alloy * Elevated temperature * Fatigue strength Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.899, year: 2016

  1. Identification of intermetallic phases in a eutectic Al-Si casting alloy using electron backscatter diffraction pattern analysis

    International Nuclear Information System (INIS)

    Kral, M.V.; McIntyre, H.R.; Smillie, M.J.

    2004-01-01

    Intermetallic phases in sand cast eutectic Al-Si alloys were characterized using a combination of SEM, EDS and EBSD pattern analysis. Chinese script α-phase particles were consistent with cubic Al 19 (Fe,Mn) 5 Si 2 . Plate-shaped β-phase particles were consistent with tetragonal Al 3 (Fe,Mn)Si 2

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

    International Nuclear Information System (INIS)

    Liang, S M; Schmid-Fetzer, R

    2016-01-01

    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. (paper)

  3. 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.

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

    International Nuclear Information System (INIS)

    Susmikanti, Mike; Sulistyo, Jos

    2014-01-01

    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

  5. Determination of Mg, Al, Si, Cl and K in some medicinal plants by NAA and REA methods

    International Nuclear Information System (INIS)

    Mumba, N.K.; Csikai, J.; Petoe, G.

    1982-01-01

    Trace elements have been determined in biological samples including pepperwort, thyme, plantain, blessed thistle and common comfrey as well as cabbage leaves and milk powder. Concentrations of Al, Si, and Cl have been determined by fast neutron activation analysis while, in the case of Mo-, K, and Cl the X-ray fluorescence method was used. (author)

  6. Determination of Mg, Al, Si, Cl and K in some medicinal plants by NAA and REA methods

    Energy Technology Data Exchange (ETDEWEB)

    Mumba, N.K.; Csikai, J.; Petoe, G. (Kossuth Lajos Tudomanyegyetem, Debrecen (Hungary). Kiserleti Fizikai Intezet)

    1982-07-26

    Trace elements have been determined in biological samples including pepperwort, thyme, plantain, blessed thistle and common comfrey as well as cabbage leaves and milk powder. Concentrations of Al, Si, and Cl have been determined by fast neutron activation analysis while, in the case of Mg-, K, and Cl the X-ray fluorescence method was used.

  7. 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.

  8. 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

  9. On the fatigue behavior of friction stir welded AlSi 10 Mg alloy

    Directory of Open Access Journals (Sweden)

    Ramos, R. A.

    2005-04-01

    Full Text Available The high cycle fatigue behavior of friction stir welded AlSi10Mg samples was investigated for a stress ratio R = 0.1, ranging from 0.5 to 0.9 of the yield strength, in addition to tensile tests. The welds were produced with different tool rotation and travel speeds, and these welding parameters were correlated to residual stresses, measured by X-Ray diffraction (sen2 ψmethod. Moreover, the residual stresses were measured during the fatigue testing, at fixed cycle intervals, being reported. It was observed that the residual (compressive stresses within the nugget were smaller than in the interface regions (between the thermomechanically affected zone and the base metal and stabilized above 4x105 cycles. Fatigue crack morphology and microstructural changes were characterized by optical and electron microscopy and the observations are discussed along with the fatigue results.

    Se estudia el comportamiento a la fatiga de alto ciclo de muestras de AlSi10Mg soldadas por fricción lineal para relación de tensión R = 0,1 cubriendo el rango de 0,5 a 0,9 de la resistencia a tracción, además de los datos del ensayo de tracción. Las soldaduras ensayadas fueron producidas con diferentes velocidades de rotación y avance de la herramienta. Las variables de proceso han sido correlacionadas con el análisis de tensiones residuales por difracción de Rayos X (método sen2 ψ. Además, se midieron las tensiones residuales durante la deformación en fatiga a intervalos regulares de ciclos. Se observa que las tensiones residuales (de compresión dentro del nugget son más reducidas que en la interfase entre la región afectada térmica y mecánicamente y el material base, y se mantuvieron estables de manera progresiva a partir de los 4 x 10 5ciclos. Se ha empleado la microscopía óptica y de barrido para evaluar la morfología y microestructura de las grietas de fatiga. Estos resultados se analizan

  10. HPDL Remelting of Anodised Al-Si-Cu Cast Alloys Surfaces

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2012-12-01

    Full Text Available The results of the investigations of the laser remelting of the AlSi9Cu4 cast aluminium alloy with the anodised and non-anodised surfacelayer and hardness changes have been presented in this paper. The surface layer of the tested aluminium samples was remelted with thelaser of a continuous work. The power density was from 8,17•103 W/cm2 to 1,63•104 W/cm2. The metallographic tests were conducted inform of light microscope investigations of the received surface layer. The main goal of the investigation was to find the relation betweenthe laser beam power and its power density falling on a material, evaluating the shape and geometry of the remelted layers and theirhardness. As the substrate material two types of surfaces of the casted AlSi9Cu4 alloy were applied – the non–treated as cast surface aswell the anodized surface. As a device for this type of surface laser treatment the High Power Diode Laser was applied with a maximumpower of 2.2 kW and the dimensions of the laser beam focus of 1.8 x 6.8 mm. By mind of such treatment it is also possible to increasehardness as well eliminate porosity and develop metallurgical bonding at the coating-substrate interface. Suitable operating conditions forHPDL laser treatment were finally determined, ranging from 1.0 to 2.0 kW. Under such conditions, taking into account the absorptionvalue, the effects of laser remelting on the surface shape and roughness were studied. The results show that surface roughness is reducedwith increasing laser power by the remelting process only for the non-anodised samples, and high porosity can be found in the with highpower remelted areas. The laser influence increases with the heat input of the laser processing as well with the anodisation of the surface,because of the absorption enhancement ensured through the obtained alumina layer.

  11. Hydrogen release at metal-oxide interfaces: A first principle study of hydrogenated Al/SiO{sub 2} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jianqiu, E-mail: jianqiu@vt.edu [Department of Mechanical Engineering, Virginia Tech, Goodwin Hall, 635 Prices Fork Road - MC 0238, Blacksburg, VA 24061 (United States); Tea, Eric; Li, Guanchen [Department of Mechanical Engineering, Virginia Tech, Goodwin Hall, 635 Prices Fork Road - MC 0238, Blacksburg, VA 24061 (United States); Hin, Celine [Department of Mechanical Engineering, Virginia Tech, Goodwin Hall, 635 Prices Fork Road - MC 0238, Blacksburg, VA 24061 (United States); Department of Material Science and Engineering, Virginia Tech, Goodwin Hall, 635 Prices Fork Road-MC 0238, Blacksburg, VA 24061 (United States)

    2017-06-01

    Highlights: • Hydrogen release process at the Al/SiO{sub 2} metal-oxide interface has been investigated. • A mathematical model that estimates the hydrogen release potential has been proposed. • Al atoms, Al−O bonds, and Si−Al bonds are the major hydrogen traps at the Al/SiO{sub 2} interface. • Hydrogen atoms are primarily release from Al−H and O−H bonds at the Al/SiO{sub 2} metal-oxide interface. - Abstract: The Anode Hydrogen Release (AHR) mechanism at interfaces is responsible for the generation of defects, that traps charge carriers and can induce dielectric breakdown in Metal-Oxide-Semiconductor Field Effect Transistors. The AHR has been extensively studied at Si/SiO{sub 2} interfaces but its characteristics at metal-silica interfaces remain unclear. In this study, we performed Density Functional Theory (DFT) calculations to study the hydrogen release mechanism at the typical Al/SiO{sub 2} metal-oxide interface. We found that interstitial hydrogen atoms can break interfacial Al−Si bonds, passivating a Si sp{sup 3} orbital. Interstitial hydrogen atoms can also break interfacial Al−O bonds, or be adsorbed at the interface on aluminum, forming stable Al−H−Al bridges. We showed that hydrogenated O−H, Si−H and Al−H bonds at the Al/SiO{sub 2} interfaces are polarized. The resulting bond dipole weakens the O−H and Si−H bonds, but strengthens the Al−H bond under the application of a positive bias at the metal gate. Our calculations indicate that Al−H bonds and O−H bonds are more important than Si−H bonds for the hydrogen release process.

  12. Refraction of polarized neutrons on the boundary in thick magnetic film FeAlSi

    Energy Technology Data Exchange (ETDEWEB)

    Aksenov, V L; Kozhevnikov, S V; Nikitenko, Yu V [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Frank Lab. of Neutron Physics

    1999-07-01

    Complete text of publication follows. Refraction of polarized neutrons in multilayer structure FeAlSi(20 mkm)/Cr(0.05 mkm)/CaTiO{sub 3}(1000 mkm) has been investigated. An external magnetic field was applied under an angle to the sample surface. Refraction on themagnetic boundaries of two types has been investigated. First type is the boundary vacuum-magnetic film. Second type is magnetic film - non-magnetic substrate CaTiO{sub 3} (thin non-magnetic Cr layer doesn't refract the beam). On the boundary there are spin-flip and beam-splitting. Four spatial splitted beams were observed for different spin transitions on each type of the boundary: '+-', '++', '-+' and '--'. From the experimental values of the glancing angles of refracted beam the following parameters has been derives: the nuclear potentials of the magnetic film and the non-magnetic substrate, the magnitude and the direction of a magnetic induction in the magnetic film. It has been shown that the method of refractometry of polarized neutrons can be used for investigation of thick (about mkm) magnetic films. (author)

  13. Microstructural and thermal study of Al-Si-Mg/melon shell ash particulate composite

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    M. Abdulwahab

    Full Text Available The microstructural study via scanning electron microscope (SEM and thermal study via differential scanning calorimetric (DSC study of Al-7%Si-0.3Mg/melon shell ash particulate composite has been carried out. The melon shell ash was used in the production of MMC ranging from 5% to 20% at interval of 5% addition using stir casting method. The melon shell ash was characterized using X-ray fluorescent (XRF that reveal the presence of CaO, SiO2, Al2O3, MgO, and TiO2 as major compounds. The composite was machined and subjected to heat treatment. Microstructural analyses of the composite produced were done using scanning electron microscope (SEM. The microstructure obtained reveals a dark ceramic (reinforcer and white metallic phase. Equally, the 5 wt% DSC result gives better thermal conductivity than other proportions (10 wt%, 15 wt%, and 20 wt%. These results showed that an improved property of Al-Si-Mg alloy was achieved using melon shell ash particles as reinforcement up to a maximum of 20 wt% for microstructural and 5% wt DSC respectively. Keywords: Microstructural analysis, Melon shell ash, Stir casting, X-ray fluorescent, Reinforcement, Composite

  14. Microstructural characterisation of Al-Si cast alloys containing rare earth additions

    Science.gov (United States)

    Elgallad, E. M.; Ibrahim, M. F.; Doty, H. W.; Samuel, F. H.

    2018-05-01

    This paper presents a thorough study on the effect of rare earth elements, specifically La and Ce, on the microstructure characteristics of non-modified and Sr-modified A356 and A413 alloys. Several alloys were prepared by adding 1% La and 1% Ce either individually or in combination. Microstructural characterisation was carried out using optical microscopy, scanning electron microscopy and electron probe microanalysis as well as differential scanning calorimetry (DSC) analysis. The results showed that the individual and combined additions of La and Ce did not bring about any modification or even refinement in the eutectic Si structure. Moreover, these additions were found to negate the modification effect of Sr, particularly in the presence of La. The A356 and A413 alloys containing La and/or Ce displayed high phase volume fractions owing to the formation of Al-Si-La/Ce/(La,Ce) and Al-Ti-La/Ce intermetallic phases. DSC analysis revealed that the formation temperatures of these phases varied from 560 to 568 °C and 568 to 574 °C, respectively. This analysis also showed that the addition of La and Ce whether individually or in combination resulted in a depression in the eutectic temperature and a considerable increase in the solidification range, particularly for the A413 alloy.

  15. 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

  16. 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.

  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. Temperature and microstructure characteristics of silumin casting AlSi9 made with investment casting method

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2011-07-01

    Full Text Available This work presents the research result of the temperature distribution and the microstructure in certain parts of the field-glass body frame casting made from silumin AlSi9 using the investment casting method in the ceramic mould. It was proved that the highest temperature of the silumin appears in the sprue in which the silumin is in the liquid-solid state, though the process of silumin crystallization in the casting is finished. It was stated that in certain elements of the casting the side opposite to the runner crystallizes and cools fastest. The differences in the rate of crystalline growth and cooling of certain casting elements cause differ- ent microstructure in them which can also influence the mechanic properties.It is necessary to state that the temperature of the initial heating of the ceramic mold equal to 60oC guarantees obtaining of the castings without defects and of little porosity. Incomplete modification of the silumin with strontium causes silica precipitation to appear close to the spherical ones.

  19. Structure of new Al-Si based RQ systems with potentially enhanced stiffness

    International Nuclear Information System (INIS)

    Zigo, J.; Svec, P.; Janickovic, D.; Janotova, I.; Matko, I.; Svec, P. Sr.

    2014-01-01

    Amorphous and nanocrystalline metallic systems prepared by rapid quenching of melt are interesting for many unique properties. Mechanical properties are among the most important ones. Rapid quenching of metallic melt can enhance mechanical properties of material, compared to metal alloys prepared by conventional metallurgy. Aluminium as one of most accessible light-weight metals has wide range of applications as construction material. Alloying aluminium with another element can significantly improve mechanical properties. Reasonable choice for alloying element in terms of sustaining light-weight nature of the material is silicon. Dissolving silicon in aluminium can be achieved, even with the aid of rapid quenching, only up to few weight percent. Increasing the content of dissolved silicon is possible by adding other alloying components. Candidates with respect to low specific mass are transition elements of 4"t"h period (from scandium to zinc). In our experimental study, we have chosen alloying of Al-Si with transition elements (T) iron, cobalt and nickel. Composition of the investigated systems was Al_8_0_-_xT_xSi_2_0 where T = Fe, Co, Ni and x = 0, 5 and 10. (authors)

  20. First principles calculation of thermodynamic properties of NaAlSi ternary

    International Nuclear Information System (INIS)

    Qin Jining; Lu Weijie; Zhang Di; Fan Tongxiang

    2012-01-01

    PbFCl-type NaAlSi ternary is a corrosion compound found in aluminum, which is used as a sealing material in sodium sulfur battery. To understand and control the corrosion process, it is important to predict its quantitative properties. In this study, a first-principles calculation has been carried out to calculate its equilibrium lattice parameters, bulk modulus and pressure derivative of bulk modulus by both all-electron full-potential linear augmented plane wave scheme and pseudopotential plane wave scheme within the generalized gradient approximation. The theoretical results show good agreement with the available experimental data. The thermodynamic properties, including the specific heat capacity and entropy with pressure up to 9 GPa, have been investigated for the first time by coupling of density functional perturbation theory and quasiharmonic approximation. The volume and linear thermal expansion coefficients were estimated and the results show that the linear thermal expansion on c-axis is nearly twice as large as that on a-axis within the calculated temperature.

  1. Microstructure of Al-Si Slurry Coatings on Austenitic High-Temperature Creep Resisting Cast Steel

    Directory of Open Access Journals (Sweden)

    Agnieszka E. Kochmańska

    2018-01-01

    Full Text Available This paper presents the results of microstructural examinations on slurry aluminide coatings using scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. Aluminide coatings were produced in air atmosphere on austenitic high-temperature creep resisting cast steel. The function of aluminide coatings is the protection of the equipment components against the high-temperature corrosion in a carburising atmosphere under thermal shock conditions. The obtained coatings had a multilayered structure composed of intermetallic compounds. The composition of newly developed slurry was powders of aluminium and silicon; NaCl, KCl, and NaF halide salts; and a water solution of a soluble glass as an inorganic binder. The application of the inorganic binder in the slurry allowed to produce the coatings in one single step without additional annealing at an intermediate temperature as it is when applied organic binder. The coatings were formed on both: the ground surface and on the raw cast surface. The main technological parameters were temperature (732–1068°C and time of annealing (3.3–11.7 h and the Al/Si ratio (4–14 in the slurry. The rotatable design was used to evaluate the effect of the production parameters on the coatings thickness. The correlation between the technological parameters and the coating structure was determined.

  2. Microstructural observation on the composite Al-SiC-15p obtained by the compocasting process

    International Nuclear Information System (INIS)

    Manzano-Ramirez, A.; Ruiz, F.; Magallanes-Castaneda, A.

    1996-01-01

    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 (gamma=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 chemical facilities of SEM it was attempted to determine the composition of the second phase responsible of bonding between matric 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 (gamma>120 s''-1). In contrast, at low fs(<0.3) and low gamma (<27 s''-1) such effect is poor. In addition, cualitative 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 are needed. (Author) 22 refs

  3. Effect of negative bias on TiAlSiN coating deposited on nitrided Zircaloy-4

    Science.gov (United States)

    Jun, Zhou; Zhendong, Feng; Xiangfang, Fan; Yanhong, Liu; Huanlin, Li

    2018-01-01

    TiAlSiN coatings were deposited on the nitrided Zircaloy-4 by multi-arc ion plating at -100 V, -200 V and -300 V. In this study, the high temperature oxidation behavior of coatings was tested by a box-type resistance furnace in air for 3 h at 800 °C; the macro-morphology of coatings was observed and analyzed by a zoom-stereo microscope; the micro-morphology of coatings was analyzed by a scanning electron microscopy (SEM), and the chemical elements of samples were analyzed by an energy dispersive spectroscopy(EDS); the adhesion strength of the coating to the substrate was measured by an automatic scratch tester; and the phases of coatings were analyzed by an X-ray diffractometer(XRD). Results show that the coating deposited at -100 V shows better high temperature oxidation resistance behavior, at the same time, Al elements contained in the coating is of the highest amount, meanwhile, the adhesion strength of the coating to the substrate is the highest, which is 33N. As the bias increases, high temperature oxidation resistance behavior of the coating weakens first and then increases, the amount of large particles on the surface of the coating increases first and then decreases whereas the density of the coating decreases first and then increases, and adhesion strength of the coating to the substrate increases first and then weakens. The coating's quality is relatively poor when the bias is -200 V.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeon Soo, E-mail: yskim@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Park, Jong Man; Ryu, Ho Jin; Jung, Yang Hong [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong, Daejeon 305-353 (Korea, Republic of); Hofman, G.L. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2012-11-15

    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 {approx}50% burnup of initial 19.75% U-235 enrichment at {approx}200 Degree-Sign 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.

  5. Ostwald ripening of faceted Si particles in an Al-Si-Cu melt

    International Nuclear Information System (INIS)

    Shahani, A. J.; Xiao, X.; Skinner, K.; Peters, M.; Voorhees, P. W.

    2016-01-01

    The microstructural evolution of an Al-Si-Cu alloy during Ostwald ripening is imaged via synchrotron-based, four-dimensional (i.e., space and time resolved) X-ray tomography. Samples of composition Al-32 wt%Si-15 wt%Cu were annealed isothermally at 650 °C, in the two-phase solid-liquid regime, while tomographic projections were collected in situ over the course of five hours. Advances in experimental methods and computational approaches enable us to characterize the local interfacial curvatures and velocities during ripening. The sequence of three-dimensional reconstructions and interfacial shape distributions shows highly faceted Si particles in a copper-enriched liquid, that become increasingly isotropic or rounded over time. In addition, we find that the coarsening rate constant is approximately the same in the binary and ternary systems. By coupling these experimental measurements with CALPHAD modeling and ab initio molecular dynamics simulation, we assess the influence of Cu on the coarsening process. Lastly, we find the unusual “pinning” of microstructure at the junction between rough and smooth interfaces and suggest a mechanism for this behavior.

  6. Changes in Structural Characteristics of Hypoeutectic Al-Si Cast Alloy after Age Hardening

    Directory of Open Access Journals (Sweden)

    Lenka HURTALOVÁ

    2012-09-01

    Full Text Available The contribution describes influence of the age-hardening consist of solution treatment at 515 °C with holding time 4 hours, water quenching at 40 °C and artificial aging at different temperature 150 °C, 170 °C and 190 °C with different holding time 2, 4, 8, 16 and 32 hours on mechanical properties (tensile strength and Brinell hardness and changes in morphology of eutectic Si, Fe-rich and Cu-rich intermetallic phases in secondary (recycled AlSi9Cu3 cast alloy. A combination of different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM upon deep etching and energy dispersive X-ray analysis (EDX were therefore been used for the identification of the various phases. Quantitative study of changes in morphology of eutectic Si, Cu-rich and Fe-rich phases was carried out using Image Analyzer software NIS-Elements. Mechanical properties were measured in line with EN ISO. Age-hardening led to changes in microstructure include the spheroidization and coarsening of eutectic silicon, gradual disintegration, shortening and thinning of Fe- rich intermetallic phases, the dissolution of precipitates and the precipitation of finer hardening phase (Al2Cu further increase in the hardness and tensile strength in the alloy.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2430

  7. Material properties of Al-Si-Cu aluminium alloy produced by the rotational cast technology

    Directory of Open Access Journals (Sweden)

    Muhammad Syahid

    2017-03-01

    Full Text Available The aim of the present study is to explore microstructural and mechanical properties of cast Al-Si-Cu aluminum alloy (ADC12. To obtain excellent material properties, the cast Al alloys were produced by an originally developed mold rotational machine, namely liquid aluminum alloy is solidified during high speed rotating. The casting process was conducted under various casting conditions, in which the following factors were altered, e.g., melt temperature, metal mold temperature and different rotational speed. Microstructural characteristics were examined by direct observation using an optical microscope and a scanning electron microscope (SEM, and the secondary dendrite arm spacing of alpha-Al phase (SDAS and the size of Si eutectic phase were identified. Mechanical properties were investigated by micro-hardness and tensile tests. Rotation speed and melt temperature were directly attributed to the SDAS, and severe shear stress arising from the rotation made fine and complicated grain structure, leading to the high mechanical properties. The extent of the shear stress was altered depending on the area of the sample due to the different shear stress. Furthermore, high melt temperature and high rotational speed decrease the size of Si eutectic phases. The high mechanical properties were detected for the cast samples produced by the casting condition as follows: melt temperature 700oC, mold temperature 400oC and rotation speed 400 rpm

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

    International Nuclear Information System (INIS)

    Miranda, Carlos A.J.; Libardi, Rosani M.P.; Marcelino, Sergio; Boari, Zoroastro M.

    2013-01-01

    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)

  9. Effect of dispersion hardening process on machinability of EN AB-AlSi9Mg silumin

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2009-07-01

    Full Text Available Nowadays, aluminum and its alloys found their application in any type design structures, many’s the time being an alternative for a ferrous alloys due to their technological properties like low density, ductility, high strength and good corrosion resistance. Among different fabrication processes the machining stage has a significant importance considering fabrication costs and processing time. Therefore, optimization of the process parameters that affect machining stages such as, tool wear, alloy machinability, machining effort and cutting speed becomes an area of constant development and study. To the most important factors having impact on machining properties belong: initial condition of machined material, which depends on a method and conditions of material preparation. In the paper are presented initial tests of machining properties of the EN AB-AlSi9Mg silumin subjected to heat treatment. Machinability measurements of the investigated alloy were performed with use of reboring method with constant force of feed. It enabled determination of an effect of heat treatment on machining properties of the investigated alloy. A further investigation shall be connected with determination of optimal parameters of solutionizing and ageing treatments in aspects of improvement of both mechanical properties and its machinability.

  10. Evolution of a novel Si-18Mn-16Ti-11P alloy in Al-Si melt and its influence on microstructure and properties of high-Si Al-Si alloy

    Directory of Open Access Journals (Sweden)

    Xiao-Lu Zhou

    Full Text Available A novel Si-18Mn-16Ti-11P master alloy has been developed to refine primary Si to 14.7 ± 1.3 μm, distributed uniformly in Al-27Si alloy. Comparing with traditional Cu-14P and Al-3P, Si-18Mn-16Ti-11P provided a much better refining effect, with in-situ highly active AlP. The refined Al-27Si alloy exhibited a CTE of 16.25 × 10−6/K which is slightly higher than that of Sip/Al composites fabricated by spray deposition. The UTS and elongation of refined Al-27Si alloy were increased by 106% and 235% comparing with those of unrefined alloy. It indicates that the novel Si-18Mn-16Ti-11P alloy is more suitable for high-Si Al-Si alloys and may be a candidate for refining hypereutectic Al-Si alloy for electronic packaging applications. Moreover, studies showed that TiP is the only P-containing phase in Si-18Mn-16Ti-11P master alloy. A core-shell reaction model was established to reveal mechanism of the transformation of TiP to AlP in Al-Si melts. The transformation is a liquid-solid diffusion reaction driven by chemical potential difference and the reaction rate is controlled by diffusion. It means sufficient holding time is necessary for Si-18Mn-16Ti-11P master alloy to achieve better refining effect. Keywords: Hypereutectic Al-Si alloy, Primary Si, Refinement, AlP, Thermal expansion behavior, Si-18Mn-16Ti-11P master alloy

  11. Influence of Stored Strain on Fabricating of Al/SiC Nanocomposite by Friction Stir Processing

    Science.gov (United States)

    Khorrami, M. Sarkari; Kazeminezhad, M.; Kokabi, A. H.

    2015-05-01

    In this work, 1050 aluminum (Al) sheets were annealed and severely deformed by 1, 2, and 3 passes of constrained groove pressing process to obtain the various initial stored strain values of 0, 1.16, 2.32, and 3.48, respectively. Friction stir processing (FSP) was then applied using SiC nanoparticles to fabricate Al/SiC nanocomposite with approximately 1.5 vol pct reinforced particles. Microstructural examinations revealed that an increase in the initial stored strain of the base metal led to the formation of finer grain structure after 1 pass of FSP. The finer grain structure occurred in the stir zone where a sufficient amount of nanoparticles with a relatively proper distribution existed. However, the initial stored strain value had a contrary influence in the regions with low volume fraction of nanoparticles. In fact, more stored strain in the base metal provided more driving force for both nucleation and grain growth of newly recrystallized grains at the stir zone. Pinning effect of well-distributed nanoparticles could effectively retard grain growth leading to the formation of very fine grain structure. Also it was observed that the initial stored strain values did not have impressive rule in the microstructural evolutions at the stir zone during the second and third FSP passes signifying that all of the stored energy in the base metal would be released after 1 pass of FSP. The results obtained with microhardness measurement at the stir zone were fairly in agreement with those achieved by the microstructure assessments.

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

    Science.gov (United States)

    Ibrahim, Mohamed F; Elgallad, Emad M; Valtierra, Salvador; Doty, Herbert W; Samuel, Fawzy H

    2016-01-27

    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.

  13. 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.

  14. Electrochemical corrosion behaviour of Mg-Al alloys with thermal spray Al/SiCp composite coatings; Comportamiento a la corrosion electroquimica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyeccion termica

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, A.; Feliu Jr, S.; Merino, M. C.; Mohedano, M.; Casajus, P.; Arrabal, R.

    2010-07-01

    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 un reinforced thermal spray aluminium coatings. (Author) 31 refs.

  15. Die-cast of a hypo-eutectic AL-SI alloy: influence of injection temperature on microstructure and mechanical properties; Fundicao sob pressao das ligas de AL-SI: influencia da temperatura de injecao nas microestruturas e propriedades mecanicas

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Silvano Leal dos; Santos, Sydney Ferreira, E-mail: silvano_lleal@yahoo.com.br [Universidade Federal do ABC (UFABC), SP (Brazil)

    2014-07-01

    Die-casting is widely used for manufacturing light alloy components for automotive industry. Among others, hypo-eutectic Al-Si alloys are currently processed by die-casting. To obtain high quality die-cast components, a better understanding on the correlations between processing parameters, microstructures, and mechanical properties are of utmost importance. In this study, we investigate the effect of injection temperature of liquid metal on the microstructure and mechanical properties of Al-Si alloy EN AC 46000 (DIN designation). The injection temperatures were 579, 589, 643, and 709 deg C. As-cast components had their microstructures analyzed by X-ray diffraction, optical and scanning electron microscopy, and X-ray energy dispersive spectroscopy. The mechanical properties were examined by micro-hardness and tensile tests. It was observed that the ultimate tensile strength slightly increased with the increase of injection temperature. The same trend was observed for micro-hardness. The amount of porosity in the samples varies in a small amount for different injection temperatures. On the other hand, the microstructure of the alloys seems more refined for higher temperatures of injection. This refinement in microstructure might play a major role on the mechanical properties of the Al-Si die-cast alloy. (author)

  16. Inclusions, Porosity, and Fatigue of AlSi10Mg Parts Produced by Selective Laser Melting

    Science.gov (United States)

    Tang, Ming

    Additive manufacturing (AM) has experienced remarkable growth in the past decade with applications in both rapid prototyping and rapid manufacturing for functional end-usable parts. As one of the most promising AM processes, selective laser melting (SLM) can be used to fabricate metal products line by line and layer upon layer within a powder bed system. Such process allows the building of parts with customized shapes, which brings higher design flexibility than traditional casting and wrought manufacturing. In this work, AlSi10Mg powder is chosen as the raw material for producing parts by SLM, since aluminum alloys are widely used in automotive and aerospace industries thanks to an excellent combination of low density and competitive mechanical properties. However, there remain multiple drawbacks which limit further applications of aluminum parts produced by SLM: lack of prediction of solidification microstructure, few studies on fatigue properties, and cost and time caused by the limited production rate. All these issues were studied in this work and summarized as follows: Rapid movement of the melt pool (at a speed around 1 m/s) in SLM of metal powder directly implies rapid solidification. In this research, 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 alpha-aluminum. The dependence of the measured cell spacing on the 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

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

    International Nuclear Information System (INIS)

    Yan, Fei; Wang, Chun Ming; Wang, Ya Jun; Xu, Dao Rong; Wu, S.C.; Sun, Qin De

    2012-01-01

    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

  18. Possibilities of Fe-RICH phases elimination with using heat treatment in secondary Al-Si-Cu cast alloy

    Directory of Open Access Journals (Sweden)

    L. Hurtalová

    2015-01-01

    Full Text Available The mechanical properties of Al-Si-Cu cast alloy are strongly dependent upon the morphologies, type and distribution of the second phases. The skeleton like – Al15(FeMn 3Si2 and needles - Al5FeSi phases were observed in experimental material AlSi9Cu3. The Fe-rich phases morphology was affected with applying two types of heat treatment, T4 and T6, which caused positive changes of mechanical properties especially ultimate tensile strength, gives that for as cast state was Rm = 211 MPa, than at optimum T4 (515 °C/ 4 hours was Rm = 273 MPa and at optimum T6 (515 °C/ 4 hours with artificial aging 170 °C/ 16 hours was Rm = 311 MPa.

  19. Abrasive Wear of AlSi12-Al2O3 Composite Materials Manufactured by Pressure Infiltration

    Directory of Open Access Journals (Sweden)

    Kremzer M.

    2016-09-01

    Full Text Available The aim of this study is to investigate tribological properties of EN AC-AlSi12 alloy composite materials matrix manufactured by pressure infiltration of Al2O3 porous preforms. In the paper, a technique of manufacturing composite materials was described in detail as well as wear resistance made on pin on disc was tested. Metallographic observations of wear traces of tested materials using stereoscopic and confocal microscopy were made. Studies allow concluding that obtained composite materials have much better wear resistance than the matrix alloy AlSi12. It was further proved that the developed technology of their preparation consisting of pressure infiltration of porous ceramic preforms can find a practical application.

  20. The Influence of Selective Laser Melting Parameters on Density and Mechanical Properties of AlSi10Mg

    Directory of Open Access Journals (Sweden)

    Raus A. A.

    2016-01-01

    Full Text Available Selective Laser Melting (SLM is one of the most effective powder bed technique in the additive Manufacturing (AM which able to fabricate functional metal parts directly from 3D Computer Aided Design (CAD file data. In this paper, the influence of SLM parameters, such as laser power, scanning speed and hatching distance on the density of AlSi10Mg samples are investigated using one factor at a time (OFAT. Furthermore, the optimum results are used to fabricate samples for hardness, tensile strength, and impact toughness test. It is revealed that AlSi10Mg parts fabricated by SLM achieving the best density of 99.13% at the value of 350 watts laser power, 1650 mm/s scanning speed and hatching distance 0.13mm, whereby resulted comparable and even better mechanical properties to those of conventionally HDPC A360F and HDPC A360T6 alloys although without any comprehensive post processing methods.

  1. Experimental investigation on densification behavior and surface roughness of AlSi10Mg powders produced by selective laser melting

    Science.gov (United States)

    Wang, Lin-zhi; Wang, Sen; Wu, Jiao-jiao

    2017-11-01

    Effects of laser energy density (LED) on densities and surface roughness of AlSi10Mg samples processed by selective laser melting were studied. The densification behaviors of the SLM manufactured AlSi10Mg samples at different LEDs were characterized by a solid densitometer, an industrial X-ray and CT detection system. A field emission scanning electron microscope, an automatic optical measuring system, and a surface profiler were used for measurements of surface roughness. The results show that relatively high density can be obtained with the point distance of 80-105 μm and the exposure time of 140-160 μs. The LED has an important influence on the surface morphology of the forming part, too high LED may lead to balling effect, while too low LED tends to produce defects, such as porosity and microcrack, and then affect surface roughness and porosities of the parts finally.

  2. 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.

  3. High-Pressure Spark Plasma Sintering (HP SPS): A Promising and Reliable Method for Preparing Ti-Al-Si Alloys.

    Science.gov (United States)

    Knaislová, Anna; Novák, Pavel; Cygan, Sławomir; Jaworska, Lucyna; Cabibbo, Marcello

    2017-04-27

    Ti-Al-Si alloys are prospective material for high-temperature applications. Due to low density, good mechanical properties, and oxidation resistance, these intermetallic alloys can be used in the aerospace and automobile industries. Ti-Al-Si alloys were prepared by powder metallurgy using reactive sintering, milling, and spark plasma sintering. One of the novel SPS techniques is high-pressure spark plasma sintering (HP SPS), which was tested in this work and applied to a Ti-10Al-20Si intermetallic alloy using a pressure of 6 GPa and temperatures ranging from 1318 K (1045 °C) to 1597 K (1324 °C). The low-porosity consolidated samples consist of Ti₅Si₃ silicides in an aluminide (TiAl) matrix. The hardness varied between 720 and 892 HV 5.

  4. Tensile behaviour at room and high temperatures of novel metal matrix composites based on hyper eutectic Al-Si alloys

    International Nuclear Information System (INIS)

    Valer, J.; Rodriguez, J.M.; Urcola, J.J.

    1997-01-01

    This work shows the improvement obtained on tensile stress at room and high temperatures of hyper eutectic Al-Si alloys. These alloys are produced by a combination of spray-forming, extrusion 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. (Author) 20 refs

  5. Growth Structure and Properties of Gradient Nanocrystalline Coatings of the Ti-Al-Si-Cu-N System

    Science.gov (United States)

    Ovchinnikov, S. V.; Pinzhin, Yu. P.

    2016-10-01

    Methods of electron microprobe analysis, X-ray structure analysis and electron microscopy were used to study the element composition and features of the structure-phase, elastic stress state of nanocrystalline coatings of the Ti- Al- Si- Cu- N system with gradient of copper concentration across their thickness. The authors established the effects of element composition modification, non-monotonous behavior of the lattice constant of alloyed nitride and rise in the bending-torsion value of the crystalline lattice in individual nanocrystals to values of around 400 degrees/μm with increase in copper concentration, whereas the sizes of alloyed nitride crystals remained practically unchanged. Mechanical (hardness), adhesion and tribological properties of coatings were examined. Comparative analysis demonstrates higher values of adhesion characteristics in the case of gradient coatings of the Ti- Al- Si- Cu- N system than in the case of single-layer (with constant element concentration) analogues.

  6. Role of bismuth on solidification, microstructure and mechanical properties of a near eutectic Al-Si alloys

    Science.gov (United States)

    Farahany, Saeed; Ourdjini, Ali; Bakar, Tuty Asma Abu; Idris, Mohd Hasbullah

    2014-09-01

    Computer aided thermal analysis and microstructural observation showed that addition of bismuth (Bi) within the range of 0.25 and 2 wt% produced a greater effect on the Al-Si eutectic phase than on primary aluminium and Al2Cu phases. Results showed that with addition of 1 wt% Bi the eutectic silicon structure was refined from flake-like morphology into lamellar. Bi refines rather than modifies the Si structure and increases the Al-Si eutectic fraction solid and more significantly there was no fading even up to 180 min of melt holding. Transmission electron microscopy study showed that the Si twin spacing decreased from 160 to 75 nm which is likely attributed to the refining effect of Bi. It was also found that addition of 1 wt% Bi increased the tensile strength, elongation and the absorbed energy for fracture due to the refined eutectic silicon structure.

  7. Assessment of AlSi21CuNi Alloy’s Quality with Use of ATND Method

    Directory of Open Access Journals (Sweden)

    Pezda J.

    2013-12-01

    Full Text Available Majority of combustion engines is produced (poured from Al-Si alloys with low thermal expansion coefficient, so called piston silumins. Hypereutectic alloys normally contain coarse, primary angular Si particles together with eutectic Si phase. The structure and mechanical properties of these alloys are highly dependent upon cooling rate, composition, modification and heat-treatment operations. In the paper one depicts use of the ATND method (thermal-voltage-derivative analysis and regression analysis to assessment of quality of the AlSi21CuNi alloy modified with Cu-P on stage of its preparation, in aspect of obtained mechanical properties (R0,02, Rm, A5, HB. Obtained dependencies enable prediction of mechanical properties of the investigated alloy in laboratory conditions, using values of characteristic points from curves of the ATND method.

  8. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    International Nuclear Information System (INIS)

    Wei, Pei; Wei, Zhengying; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-01-01

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  9. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pei; Wei, Zhengying, E-mail: zywei@mail.xjtu.edu.cn; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-06-30

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  10. 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...

  11. The Influence of Remelting on the Properties of AlSi6Cu4 Alloy Modified by Antimony

    OpenAIRE

    Medlen D.; Bolibruchova D.

    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...

  12. Stability and migration of vacancy in V–4Cr–4Ti alloy: Effects of Al, Si, Y trace elements

    International Nuclear Information System (INIS)

    Zhang, Chong; Zhang, Pengbo; Li, Ruihuan; Zhao, Jijun; Dong, Chuang

    2013-01-01

    Addition of trace amounts of Al, Si and Y into V–4Cr–4Ti alloy is beneficial for the mechanical properties under irradiation. It is thus important to investigate the influence of solute/trace elements on stabilities, energetics and diffusion behaviors of vacancy defects. We performed first-principles calculations to evaluate vacancy–solute/trace interaction inside dilute V–X (X = Ti, Cr, Al, Si, Y) and V–4Cr–4Ti–(Al, Si, Y) alloys. With addition of Si and Y, vacancy-based complexes tend to form near Ti–Si and Ti–Y pairs, while the effect of Al is negligible. Moreover, diffusion coefficients of solute/trace element in vanadium were derived using nine-frequency model. With high binding energy and low diffusion coefficient, Si atom is strongly attractive to vacancy in vanadium matrix. Our theoretical results suggest that the interactions between vacancy and solute/trace elements play some role in the evolution of microstructures inside vanadium alloys

  13. Single layer and multilayer vacuum-arc coatings based on the nitride TiAlSiYN: composition, structure, properties

    International Nuclear Information System (INIS)

    Beresnev, V.M.; Litovchenko, S.V.; Nemchenko, U.S.; Srebnyuk, P.A.; Mazilin, B.A.; Sobol, O.V.; Mejlekhov, A.A.; Barmin, A.E.; Serenko, TA.; Pogrebnyak, A.D.; Ivanov, O.N.; Kritsyna, E.V.; Stolbovoj, V.A.; Novikov, V.Yu.; Malikov, L.V.

    2017-01-01

    Using high-technological vacuum-arc evaporation in the atmosphere of nitrogen with ion bombardment, single- and multilayer coatings based on TiAlSiYN with high mechanical characteristics were obtained: hardness of the coatings reached 49.5 GPa, resistance to wear, with the value of the critical point L_C_5 reaching 184.92 N. The peculiarities of radiation-induced effect at applying bias potential U_b were found: formation of nitride coatings based on fcc metallic lattice with the preferred orientation of crystallites with the texture axis [111], as well as simultaneous growth of hardness. Hardness of both single- and multilayer coatings increases by 40...50% at the increase of U_b from 50 to 200 V. Formation of silicon-containing layers of TiAlSiYN during the deposition contributes to reaching increased hardness, which, in the case of single-layer coating obtained at U_b = -200 V is 49.5 GPa, which corresponds to superhard state. The mechanisms of structure formation, defining the resulting mechanical characteristics of single- and multi-layer coatings based on TiAlSiYN nitride have been discussed.

  14. Electrochemical corrosion behaviour of Mg-Al alloys with thermal spray Al/SiCp composite coatings

    International Nuclear Information System (INIS)

    Pardo, A.; Feliu Jr, S.; Merino, M. C.; Mohedano, M.; Casajus, P.; Arrabal, R.

    2010-01-01

    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 un reinforced thermal spray aluminium coatings. (Author) 31 refs.

  15. Microstructure and Physical-Mechanical Properties of (TiAlSiY)N Nanostructured Coatings Under Different Energy Conditions

    Science.gov (United States)

    Smyrnova, K. V.; Pogrebnjak, A. D.; Beresnev, V. M.; Litovchenko, S. V.; Borba-Pogrebnjak, S. O.; Manokhin, A. S.; Klimenko, S. A.; Zhollybekov, B.; Kupchishin, A. I.; Kravchenko, Ya. O.; Bondar, O. V.

    2018-03-01

    Nanostructured multicomponent (TiAlSiY)N coatings were fabricated by the cathodic-arc physical vapor deposition (CA-PVD). In this study, a bias potential applied to the substrate was - 200 and - 500 V, and changes in structure and properties of coatings were investigated. Samples had a single-phase state with a face-centered cubic (FCC) lattice. Small crystallites of about 7.5 nm and texture with [110] axis were observed at - 500 V. However, lower bias potential resulted in the formation of crystallites of about 41.6 nm with [111] preferred orientation. Moreover, coatings were characterized by superhard state and demonstrated low wear, high abrasion and crack resistance. The testing of the polycrystalline cubic boron nitride (PCBN) cutting inserts covered with (TiAlSiY)N revealed an increase in the tool life coefficient during cutting by 1.66 times in comparison with the base tool material. Therefore, (TiAlSiY)N coating is a perspective material for application as a protective layer in cutting tools.

  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

    2016-08-09

    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. The Influence of T6 Heat Treatment to Hardness and Microstructure of Al-Si-Mg Alloys Materials

    International Nuclear Information System (INIS)

    Eddy Djatmiko; Budiarto

    2008-01-01

    Al-Si-Mg alloy is one of aluminium alloys that is suitable to be used as a car piston material. This is because it has some benefits such as light weight, corrosion resistance and interesting color but its mechanical properties do not meet criteria of JIS H5201. For that reason, to meet the standard, its mechanical properties need to be improved. Mechanical properties of this alloy can be improved using many ways. In this research the alloy was T6 heat treated (holding times 4 hour with treatment temperature variation of 30, 150, 180, 210, and 240 o C). Some tests were conducted to these new alloys including hardness test, impact test, phase identification and micro structural analysis. Test results showed that the change mechanical properties occurs due to increasing temperature during T6 heat treatment to these alloys. The optimum mechanical properties were obtained at treatment temperature of 210 o C. In this condition, the alloy has hardness of 93.30 HVN and impact strength of 5.13 J/cm 2 and these results fulfil JIS H5201 standard. The alloy microstructure showed hypoeutectic structure comprising primary aluminium dendrite and Al-Si-Mg eutectic mixture. The result of phase identification after T6 heat treatment showed that Al-Si-Mg alloys have α-Al phase, Si phase and MnAl 6 phase. (author)

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

    International Nuclear Information System (INIS)

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

    2003-01-01

    Al-Si-Cu hypereutectic alloys produced by spray forming are mostly used in the automotive industry, especially for cylinder liners. they the advantage of low weight associated with low coefficient of thermal expansion and excellent mechanical properties- mainly wear resistance at high temperatures. The corrosion s resistance of these alloys in fuels, particularly alcoholic media, however is not yet known. In this investigation, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation hove been used to evaluate the corrosion resistance of a hyper eutectic Al-Si-Cu alloy in alcoholic environments. the EIS tests carried out in pure ethanol, and ethanol with small additions (1 mM) of acid an 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. (Author) 13 refs

  19. Effect of dispersion hardening on impact resistance of EN AC-AlSi12Cu2Fe silumin

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2009-04-01

    Full Text Available Development of modern technology have generated supply of better and better, more resistant structural materials not attainable earlier.Weight of metal structures is of a great importance, and as a consequence, also weight of materials used for a given structure. More often, for metal structures are used lightweight metals and their alloys, from which aluminum and its alloys have become the most widespread. These alloys, based on Al-Si equilibrium system, contain additional constituents (e.g.: Mg, Cu enabling, except modification,improvement of mechanical properties obtained in result of heat treatment. The paper presents an effect of modification process and heat treatment on impact resistance of EN AC-AlSi12Cu2Fe alloy. Solutioning and ageing temperatures were selected on base of registered curves of the ATD method. For the neareutectic EN AC-AlSi12Cu2Fe silumin one obtained growth of the impact resistance both due to performed modification treatment and performed heat treatments of the alloy.

  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. Structural and magnetic study of mechanically deformed Fe rich FeAlSi ternary alloys

    International Nuclear Information System (INIS)

    Legarra, E.; Apiñaniz, E.; Plazaola, F.

    2012-01-01

    Highlights: ► Addition of Si to binary Fe–Al alloys makes the disordering more difficult. ► Si addition opposes the large volume increase found in FeAl alloys with deformation. ► Disordering induces a redistribution of non-ferrous atoms around Fe atoms in Fe 75 Al 25−x Si x and Fe 70 Al 30−x Si x . ► Addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe. ► Si inhibits the para-ferro transition found in Fe 60 Al 40 alloy with disordering. - Abstract: In this work we study systematically the influence of different Al/Si ratios on the magnetic and structural properties of mechanically disordered powder Fe 75 Al 25−x Si x , Fe 70 Al 30−x Si x and Fe 60 Al 40−x Si x alloys by means of Mössbauer spectroscopy, X-ray diffraction and magnetic measurements. In order to obtain different stages of disorder the alloys were deformed by different methods: crushing induction melted alloys and ball milling annealed (ordered) alloys using different number of balls and speed. X-ray and Mössbauer data show that mechanical deformation induces the disordered A2 structure in these alloys. The results indicate that addition of Si to binary Fe–Al alloys makes the disordering more difficult. In addition, X-ray diffraction patterns show that the normalized lattice parameter variation of the disordered alloys of each composition decreases monotonically with Si content, indicating clearly that Si addition opposes the large volume increase found in FeAl alloys with deformation. The study of the hyperfine fields indicates that there is a redistribution of non-ferrous atoms around Fe atoms with the disordering; indeed, there is an inversion of the behavior of the hyperfine field of the Fe atoms. On the other hand, the magnetic measurements indicate that addition of Si to binary Fe 75 Al 25 and Fe 70 Al 30 alloys opposes the magnetic behavior induced by Al in the magnetism of Fe.

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

    International Nuclear Information System (INIS)

    Bondarev, A.V.; Kiryukhantsev-Korneev, Ph.V.; Sheveyko, A.N.; Shtansky, D.V.

    2015-01-01

    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 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 2 O 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 2 O 3 counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H 2 SO 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 counterpart material. This was attributed

  3. 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

  4. Construction and evaluation of multi-component Zn-Al based bearing alloys (Zn-Al-Si, Zn-Al-Cu)

    International Nuclear Information System (INIS)

    Shahmiri, M.; Shahin, K.

    2001-01-01

    Zn-Al based alloys, with excellent mechanical properties, are finding increasing applications in various industries, especially bearing and bushing fields. Observed dimensional instabilities, in their multicomponent systems, (e. g. Zn-Al-Si and, Zn-Al Si-Cu), is believed to be as the result of some kinds of phase transformation, due to the temperature variations, while in service. Profound understanding of the phase transformations due to the temperature variation, requires detailed evaluations of the isothermal sections of the multi-components phase diagrams of Zn-Al-Si and, Zn-Al-Si-Cu alloy systems. In the present article, the isothermal sections of the aforementioned ternary and quaternary systems in the solid state regions have been investigated and observed phase transitions have been critically evaluated

  5. A novel yellow-emitting SrAlSi4N7:Ce3+ phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

    Science.gov (United States)

    Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

    2013-12-01

    Ce3+-doped and Ce3+/Li+-codoped SrAlSi4N7 phosphors were synthesized by gas pressure sintering of powder mixtures of Sr3N2, AlN, α-Si3N4, CeN and Li3N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi4N7:Ce3+(Ce3+/Li+) were investigated in this work. The band structure calculated by the DMol3 code shows that SrAlSi4N7 has a direct band gap of 3.87 eV. The single crystal analysis of Ce3+-doped SrAlSi4N7 indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi4N7 was identified as a major phase of the fired powders, and Sr5Al5Si21N35O2 and AlN as minor phases. Both Ce3+ and Ce3+/Li+ doped SrAlSi4N7 phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce3+/Li+-doped SrAlSi4N7 (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr0.97Al1.03Si3.997N\\94\\maccounttest14=t0005_18193 7:Ce3+0.03 with a commercial blue InGaN chip. It indicates that SrAlSi4N7:Ce3+ is a promising yellow emitting down-conversion phosphor for white LEDs.

  6. 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.

  7. 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.

  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. 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.

  10. Polymorphism in the Laves-phase precipitates of a quinternary Nb-Mo-Cr-Al-Si alloy

    International Nuclear Information System (INIS)

    Hu Yanling; Vasiliev, Alexandre; Zhang Lichun; Song, Kai; Aindow, Mark

    2009-01-01

    Transmission electron microscopy has been used to study the precipitates that develop in the A2 phase of an Nb-Mo-Cr-Al-Si alloy upon heat treatment. The precipitates include a Laves-phase that adopts the cubic C15 structure initially and the hexagonal C14 structure in the later stages of precipitation. The morphologies, orientation relationships and defect microstructures indicate that the metastable C15 phase arises due to tensile coherency stresses and that a synchroshear polymorphic transformation to the equilibrium C14 phase occurs as these relax

  11. X-ray nano-diffraction study of Sr intermetallic phase during solidification of Al-Si hypoeutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manickaraj, Jeyakumar; Gorny, Anton; Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2014-02-17

    The evolution of strontium (Sr) containing intermetallic phase in the eutectic reaction of Sr-modified Al-Si hypoeutectic alloy was studied with high energy synchrotron beam source for nano-diffraction experiments and x-ray fluorescence elemental mapping. Contrary to popular belief, Sr does not seem to interfere with the Twin Plane Re-entrant Edge (TPRE) growth mechanism of eutectic Si, but evolves as the Al{sub 2}Si{sub 2}Sr phase during the eutectic reaction at the boundary between the eutectic Si and Al grains.

  12. 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.

  13. The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al - Mg Dissimilar Metal Welding

    OpenAIRE

    Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip

    2017-01-01

    The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations that predicted silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases (-Al3Mg2 and -Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially pr...

  14. Angular distributions of fast neutrons scattered by Al, Si, P, S and Zn; Distributions angulaires des neutrons rapides diffuses par Al, Si, P, S et Zn; Usloviya raspredeleniya bystrykh nejtronov, rasseyannykh alyuminiem, kremniem, fosforom i tsinkom; Distribuciones angulares de neutrones rapidos dispersados por Al, Si, P, S y Zn

    Energy Technology Data Exchange (ETDEWEB)

    Tstjkaija, K; Tanaka, S; Maeuyama, M; Tomita, Y [Japan Atomic Energy Research Institute, Tokai-Mtjea (Japan)

    1962-03-15

    Differential scattering cross-sections of Al, Si, P, S and Zn for fast neutrons have been measured in an energy range of 3.4 to 4.6 MeV by using the time-of-flight method. Angular distributions of the inelastically scattered neutrons are nearly isotropic in all cases. These results are discussed on the basis of the Hauser-Feshbach theory. (author) [French] Les sections efficaces differentielles de diffusion de Al, Si, P, S et Zn pour des neutrons rapides ont ete mesurees dans la gamme d'energies de 3,4 a 4,6 MeV, en employant la methode du temps de vol. Les distributions angulaires des neutrons diffuses inelastiquement sont presque isotropes dans tous les cas. Les auteurs analysent ces resultats en se fondant sur la theorie de Hauser-Feshbach. (author) [Spanish] Los autores han medido por el metodo del tiempo de vuelo las secciones eficaces diferenciales de dispersion del Al, Si, P, S y Zn para neutrones rapidos de energia comprendida entre 3,4 y 4,6 MeV. Las distribuciones angulares de los neutrones dispersados inelasticamente son casi isotropicas en todos los casos. Los autores analizan los resultados obtenidos basandose en la teoria de Hauser-Feshbach . (author) [Russian] Differentsial'no e sechenie rasseyaniya alyuminiya, kremniya, fosfora, sery i tsinka dlya bystrykh nejtronov izmereno v diapazone ehnergii ot 3,4 do 4,6 Megaehlektronvol't ispol'zovanie m metoda vremeni proleta. Uglovye raspredeleniya neuprugo rasseyannykh nejtronov yavlyayutsya pochti vo vsekh sluchayakh izotropnymi. Jeti rezul'taty obsuzhdayutsya na osnove teorii Hauzera-Feshbakha. (author)

  15. A novel yellow-emitting SrAlSi4N7:Ce3+ phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

    International Nuclear Information System (INIS)

    Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

    2013-01-01

    Ce 3+ -doped and Ce 3+ /Li + -codoped SrAlSi 4 N 7 phosphors were synthesized by gas pressure sintering of powder mixtures of Sr 3 N 2 , AlN, α-Si 3 N 4 , CeN and Li 3 N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi 4 N 7 :Ce 3+ (Ce 3+ /Li + ) were investigated in this work. The band structure calculated by the DMol 3 code shows that SrAlSi 4 N 7 has a direct band gap of 3.87 eV. The single crystal analysis of Ce 3+ -doped SrAlSi 4 N 7 indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi 4 N 7 was identified as a major phase of the fired powders, and Sr 5 Al 5 Si 21 N 35 O 2 and AlN as minor phases. Both Ce 3+ and Ce 3+ /Li + doped SrAlSi 4 N 7 phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce 3+ /Li + -doped SrAlSi 4 N 7 (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr 0.97 Al 1.03 Si 3.997 N/94/maccounttest14=t0005 1 8193 7 :Ce 3+ 0.03 with a commercial blue InGaN chip. It indicates that SrAlSi 4 N 7 :Ce 3+ is a promising yellow emitting down-conversion phosphor for white LEDs. - Graphical abstract: One-phosphor converted white light-emitting diode (LED) was fabricated by combining a blue LED chip and a yellow-emitting SrAlSi4N7:Ce 3+ phosphor (see inset), which has the color rendering index of 78 and color temperature of 6300 K. - Highlights: • We reported a new yellow nitride phosphor suitable for solid state lighting. • We solved the crystal structure and evidenced a disordered Si/Al distribution. • We fabricated a high color rendering white LEDs by using a single SrAlSi4N7:Ce

  16. Continuum simulation of heat transfer and solidification behavior of AlSi10Mg in Direct Metal Laser Sintering Process

    Science.gov (United States)

    Ojha, Akash; Samantaray, Mihir; Nath Thatoi, Dhirendra; Sahoo, Seshadev

    2018-03-01

    Direct Metal Laser Sintering (DMLS) process is a laser based additive manufacturing process, which built complex structures from powder materials. Using high intensity laser beam, the process melts and fuse the powder particles makes dense structures. In this process, the laser beam in terms of heat flux strikes the powder bed and instantaneously melts and joins the powder particles. The partial solidification and temperature distribution on the powder bed endows a high cooling rate and rapid solidification which affects the microstructure of the build part. During the interaction of the laser beam with the powder bed, multiple modes of heat transfer takes place in this process, that make the process very complex. In the present research, a comprehensive heat transfer and solidification model of AlSi10Mg in direct metal laser sintering process has been developed on ANSYS 17.1.0 platform. The model helps to understand the flow phenomena, temperature distribution and densification mechanism on the powder bed. The numerical model takes into account the flow, heat transfer and solidification phenomena. Simulations were carried out for sintering of AlSi10Mg powders in the powder bed having dimension 3 mm × 1 mm × 0.08 mm. The solidification phenomena are incorporated by using enthalpy-porosity approach. The simulation results give the fundamental understanding of the densification of powder particles in DMLS process.

  17. Optimization of heat treatment parameters for additive manufacturing and gravity casting AlSi10Mg alloy

    Science.gov (United States)

    Girelli, L.; Tocci, M.; Montesano, L.; Gelfi, M.; Pola, A.

    2017-11-01

    Additive manufacturing of metals is a production process developed in the last few years to realize net shape components with complex geometry and high performance. AlSi10Mg is one of the most widely used aluminium alloys, both in this field and in conventional foundry processes, for its significant mechanical properties combined with good corrosion resistance. In this paper the effect of heat treatment on AlSi10Mg alloy was investigated. Solution and ageing treatments were carried out with different temperatures and times on samples obtained by direct metal laser sintering and gravity casting in order to compare their performance. Microstructural analyses and hardness tests were performed to investigate the effectiveness of the heat treatment. The results were correlated to the sample microstructure and porosity, analysed by means of optical microscopy and density measurements. It was found that, in the additive manufactured samples, the heat treatment can reduce significantly the performance of the alloy also because of the increase of porosity due to entrapped gas during the deposition technique and that the higher the solution temperature the higher the increase of such defects. A so remarkable effect was not found in the conventional cast alloy.

  18. The Effectiveness of Al-Si Coatings for Preventing Interfacial Reaction in Al-Mg Dissimilar Metal Welding

    Science.gov (United States)

    Wang, Yin; Al-Zubaidy, Basem; Prangnell, Philip B.

    2018-01-01

    The dissimilar welding of aluminum to magnesium is challenging because of the rapid formation of brittle intermetallic compounds (IMC) at the weld interface. An Al-Si coating interlayer was selected to address this problem, based on thermodynamic calculations which predicted that silicon would change the reaction path to avoid formation of the normally observed binary Al-Mg IMC phases ( β-Al3Mg2 and γ-Al12Mg17). Long-term static heat treatments confirmed that a Si-rich coating will preferentially produce the Mg2Si phase in competition with the less stable, β-Al3Mg2 and γ-Al12Mg17 binary IMC phases, and this reduced the overall reaction layer thickness. However, when an Al-Si clad sheet was tested in a real welding scenario, using the Refill™ friction stir spot welding (FSSW) technique, Mg2Si was only produced in very small amounts owing to the much shorter reaction time. Surprisingly, the coating still led to a significant reduction in the IMC reaction layer thickness and the welds exhibited enhanced mechanical performance, with improved strength and fracture energy. This beneficial behavior has been attributed to the softer coating material both reducing the welding temperature and giving rise to the incorporation of Si particles into the reaction layer, which toughened the brittle interfacial IMC phases during crack propagation.

  19. Synthesis and characterization of superionic (LiBr)_0_._5(AlSiO)_0_._5

    International Nuclear Information System (INIS)

    Aziz K Jahja; Safei Purnama

    2010-01-01

    Materials of LiBr silicate aluminum ionic conductor have been prepared by powder metallurgy method in which 0.5 mole of LiBr powder is mixed with about 0.5 mole silicate aluminum in liquid medium of aquadest. After mixing and homogenization, the samples are dried, compacted and heated at 600 °C for 1 hour. Characterization of materials structure was carried out by X-Ray diffraction, ionic conductivity was measured by LCR meter with frequency range of 10"-"1 to 10"5 Hz at room temperature. Results of measurement show the (LiBr)_0_._5(AlSiO)_0_._5 conductor has the structure of both LiBr and of silicate aluminum. (LiBr)_0_._5(AlSiO)_0_._5 has the highest ionic conductivity in the order of 10"-"3 S.cm"-"1 while the ionic conductivity of LiBr is found to be about 10"-"4 S.cm"-"1 and that of silicate aluminum is about 10"-"6 S.cm"-"1, all measured at room temperature. (author)

  20. Tribological Properties of AlSi12-Al₂O₃ Interpenetrating Composite Layers in Comparison with Unreinforced Matrix Alloy.

    Science.gov (United States)

    Dolata, Anna Janina

    2017-09-06

    Alumina-Aluminum composites with interpenetrating network structures are a new class of advanced materials with potentially better properties than composites reinforced by particles or fibers. Local casting reinforcement was proposed to take into account problems with the machinability of this type of materials and the shaping of the finished products. The centrifugal infiltration process fabricated composite castings in the form of locally reinforced shafts. The main objective of the research presented in this work was to compare the tribological properties (friction coefficient, wear resistance) of AlSi12/Al₂O₃ interpenetrating composite layers with unreinforced AlSi12 matrix areas. Profilometric tests enabled both quantitative and qualitative analyses of the wear trace that formed on investigated surfaces. It has been shown that interpenetrating composite layers are characterized by lower and more stable coefficients of friction (μ), as well as higher wear resistance than unreinforced matrix areas. At the present stage, the study confirmed that the tribological properties of the composite layers depend on the spatial structure of the ceramic reinforcement, and primarily the volume and size of alumina foam cells.

  1. The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

    Science.gov (United States)

    Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

    2010-03-01

    This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi.

  2. Influence of Sludge Particles on the Fatigue Behavior of Al-Si-Cu Secondary Aluminium Casting Alloys

    Directory of Open Access Journals (Sweden)

    Lorella Ceschini

    2018-04-01

    Full Text Available Al-Si-Cu alloys are the most widely used materials for high-pressure die casting processes. In such alloys, Fe content is generally high to avoid die soldering issues, but it is considered an impurity since it generates acicular intermetallics (β-Fe which are detrimental to the mechanical behavior of the alloys. Mn and Cr may act as modifiers, leading to the formation of other Fe-bearing particles which are characterized by less harmful morphologies, and which tend to settle on the bottom of furnaces and crucibles (usually referred to as sludge. This work is aimed at evaluating the influence of sludge intermetallics on the fatigue behavior of A380 Al-Si-Cu alloy. Four alloys were produced by adding different Fe, Mn and Cr contents to A380 alloy; samples were remelted by directional solidification equipment to obtain a fixed secondary dendrite arm spacing (SDAS value (~10 μm, then subjected to hot isostatic pressing (HIP. Rotating bending fatigue tests showed that, at room temperature, sludge particles play a detrimental role on fatigue behavior of T6 alloys, diminishing fatigue strength. At elevated temperatures (200 °C and after overaging, the influence of sludge is less relevant, probably due to a softening of the α-Al matrix and a reduction of stress concentration related to Fe-bearing intermetallics.

  3. On the Selective Laser Melting (SLM of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Francesco Trevisan

    2017-01-01

    Full Text Available The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM technique known as Selective Laser Melting (SLM. This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  4. Tribological Properties of AlSi11-SiCp Composite Castings Produced by Pressure Die Casting Method

    Directory of Open Access Journals (Sweden)

    Konopka Z.

    2014-08-01

    Full Text Available The measurement results concerning the abrasive wear of AlSi11-SiC particles composites are presented in paper. The method of preparing a composite slurry composed of AlSi11 alloy matrix and 10, 20% vol.% of SiC particles, as well as the method of its high-pressure die casting was described. Composite slurry was injected into metal mould of cold chamber pressure die cast machine and castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and various injection gate width values. Very good uniform arrangement of SiC particles in volume composite matrix was observed and these results were publicated early in this journal. The kinetics of abrasive wear and correlation with SiC particles arrangement in composite matrix were presented. Better wear resistance of composite was observed in comparison with aluminium alloy. Very strong linear correlation between abrasive wear and particle arrangement was observed. The conclusion gives the analysis and the interpretation of the obtained results.

  5. Validation and uncertainty estimation of fast neutron activation analysis method for Cu, Fe, Al, Si elements in sediment samples

    International Nuclear Information System (INIS)

    Sunardi; Samin Prihatin

    2010-01-01

    Validation and uncertainty estimation of Fast Neutron Activation Analysis (FNAA) method for Cu, Fe, Al, Si elements in sediment samples has been conduced. The aim of the research is to confirm whether FNAA method is still matches to ISO/lEC 17025-2005 standard. The research covered the verification, performance, validation of FNM and uncertainty estimation. Standard of SRM 8704 and sediments were weighted for certain weight and irradiated with 14 MeV fast neutron and then counted using gamma spectrometry. The result of validation method for Cu, Fe, Al, Si element showed that the accuracy were in the range of 95.89-98.68 %, while the precision were in the range 1.13-2.29 %. The result of uncertainty estimation for Cu, Fe, Al, and Si were 2.67, 1.46, 1.71 and 1.20 % respectively. From this data, it can be concluded that the FNM method is still reliable and valid for element contents analysis in samples, because the accuracy is up to 95 % and the precision is under 5 %, while the uncertainty are relatively small and suitable for the range 95 % level of confidence where the uncertainty maximum is 5 %. (author)

  6. Photoluminescence of Er-doped Si-SiO2 and Al-Si-SiO2 sputtered thin films

    International Nuclear Information System (INIS)

    Rozo, C.; Fonseca, L.F.; Jaque, D.; Sole, J.Garcia

    2008-01-01

    Er-doped Si-SiO 2 and Al-Si-SiO 2 films have been deposited by rf-sputtering being annealed afterwards. Annealing behavior of the Er 3+ : 4 I 13/2 → 4 I 15/2 emission of Er-doped Si-SiO 2 yields a maximum intensity for annealing at 700-800 deg. C. 4 I 13/2 → 4 I 15/2 peak emission for Er-doped Al-Si-SiO 2 at 1525 nm is shifted from that for Er-doped Si-SiO 2 at 1530 nm and the bandwidth increases from 29 to 42 nm. 4 I 13/2 → 4 I 15/2 emission decays present a fast decaying component related to Er ions coupled to Si nanoparticles, defects, or other ions, and a slow decaying component related to isolated Er ions. Excitation wavelength dependence and excitation power dependence for the 4 I 13/2 → 4 I 15/2 emission correspond with energy transfer from Si nanoparticles. Populating of the 4 I 11/2 level in Er-doped Si-SiO 2 involves branching and energy transfer upconversion involving two or more Er ions. Addition of Al reduces the populating of this level to an energy transfer upconversion involving two ions

  7. Simulation of spheroidisation of elongated Si-particle in Al-Si alloys by the phase-field model

    International Nuclear Information System (INIS)

    Kovacevic, I.

    2008-01-01

    The application of the phase-field model for spheroidisation of undissolvable particles during high-temperature treatment of alloys is pointed out. Modelling of the spheroidisation of elongated Si-particles during annealing of Al-Si alloy is elaborated in this paper. The driving force for spheroidisation is the minimization of the total free-energy of the system or the minimization of the ratio between the interface areas and the particle volumes. The spheroidisation kinetics of elongated Si-particle for binary Al-Si system during homogenisation of aluminium alloys simulated by the phase-field model is demonstrated. The influences of the interface energy and the homogenisation temperature on the spheroidisation kinetics is presented. The lack of knowledge of the interface energy anisotropy between Si-particle and the aluminium phase is the only reason for using isotropic interface energy in simulations. The thermodynamic driving force for the phase transformation of the silicon into the aluminium phase is computed from the data obtained from the JMatPro software for aluminium alloys

  8. Microstructure of Friction Stir Welded AlSi9Mg Cast with 5083 and 2017A Wrought Aluminum Alloys

    Science.gov (United States)

    Hamilton, C.; Kopyściański, M.; Dymek, S.; Węglowska, A.; Pietras, A.

    2018-03-01

    Wrought aluminum alloys 5083 and 2017A were each joined with cast aluminum alloy AlSi9Mg through friction stir welding in butt weld configurations. For each material system, the wrought and cast alloy positions, i.e., the advancing side or the retreating side, were exchanged between welding trials. The produced weldments were free from cracks and discontinuities. For each alloy configuration, a well-defined nugget comprised of alternating bands of the welded alloys characterized the microstructure. The degree of mixing, however, strongly depended on which wrought alloy was present and on its position during processing. In all cases, the cast AlSi9Mg alloy dominated the weld center regardless of its position during welding. Electron backscattered diffraction analysis showed that the grain size in both alloys (bands) constituting the nugget was similar and that the majority of grain boundaries exhibited a high angle character (20°-60°). Regardless of the alloy, however, all grains were elongated along the direction of the material plastic flow during welding. A numerical simulation of the joining process visualized the material flow patterns and temperature distribution and helped to rationalize the microstructural observations. The hardness profiles across the weld reflected the microstructure formed during welding and correlated well with the temperature changes predicted by the numerical model. Tensile specimens consistently fractured in the cast alloy near the weld nugget.

  9. Effects of combined additions of Sr and AlTiB grain refiners in hypoeutectic Al-Si foundry alloys

    International Nuclear Information System (INIS)

    Lu, L.; Dahle, A.K.

    2006-01-01

    Strontium is the most widely used and a very effective element for modifying the morphology of eutectic silicon, while Ti and B are commonly present in the commercial grain refiners used for Al-Si alloys. Systematic studies on the effects of combined additions of Sr and different AlTiB grain refiners on the Al + Si eutectic and primary aluminium solidification have been performed. While slight coarsening of both eutectic Si and primary aluminium grains occurs during holding, no obvious interactions are observed between Sr and AlTiB grain refiners when the addition level of grain refiners is low. As a result, a well-modified and grain refined structure was obtained. However, strong negative interactions between Sr and Al1.5Ti1.5B were observed as the addition level of the grain refiner increases. It was found that these interactions have a much more profound impact on the eutectic solidification than the primary Al solidification. The melt treated with combined additions of Sr and Al1.5Ti1.5B still shows good grain refinement efficiency even after losing its modification completely. The mechanism responsible for such negative interactions is further discussed

  10. Effects of combined additions of Sr and AlTiB grain refiners in hypoeutectic Al-Si foundry alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lu, L. [CSIRO Minerals, P.O. Box 883, Kenmore, Qld. 4069 (Australia)]. E-mail: Liming.Lu@csiro.au; Dahle, A.K. [CRC for Cast Metals Manufacturing, Division of Materials, School of Engineering, University of Queensland, Brisbane, Qld. 4072 (Australia)

    2006-11-05

    Strontium is the most widely used and a very effective element for modifying the morphology of eutectic silicon, while Ti and B are commonly present in the commercial grain refiners used for Al-Si alloys. Systematic studies on the effects of combined additions of Sr and different AlTiB grain refiners on the Al + Si eutectic and primary aluminium solidification have been performed. While slight coarsening of both eutectic Si and primary aluminium grains occurs during holding, no obvious interactions are observed between Sr and AlTiB grain refiners when the addition level of grain refiners is low. As a result, a well-modified and grain refined structure was obtained. However, strong negative interactions between Sr and Al1.5Ti1.5B were observed as the addition level of the grain refiner increases. It was found that these interactions have a much more profound impact on the eutectic solidification than the primary Al solidification. The melt treated with combined additions of Sr and Al1.5Ti1.5B still shows good grain refinement efficiency even after losing its modification completely. The mechanism responsible for such negative interactions is further discussed.

  11. On the Selective Laser Melting (SLM) of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties.

    Science.gov (United States)

    Trevisan, Francesco; Calignano, Flaviana; Lorusso, Massimo; Pakkanen, Jukka; Aversa, Alberta; Ambrosio, Elisa Paola; Lombardi, Mariangela; Fino, Paolo; Manfredi, Diego

    2017-01-18

    The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM) technique known as Selective Laser Melting (SLM). This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  12. Mechanické vlastnosti slitiny AlSi9Cu3 zpracovaného technologií SLM

    OpenAIRE

    Koutný, Filip

    2017-01-01

    Tato bakalářská práce se zabývá porovnáním mechanických vlastností hliníkové slitiny AlSi9Cu3 v odlitém stavu se stavem po zpracování technologií selective laser melting (SLM). Rešeršní část práce pojednává o problematice hliníkových slitin, především o jejich rozdělení, mechanických vlastnostech, tepelné úpravě a zpracování technologií SLM. V diskuzi je řešen návrh optimálního rozsahu procesních parametrů SLM tisku a jsou porovnány mechanické vlastnosti konvenčně odlité slitiny AlSi9Cu3 se s...

  13. Eutectic Al-Si-Cu-Fe-Mn alloys with enhanced mechanical properties at room and elevated temperature

    International Nuclear Information System (INIS)

    Wang, E.R.; Hui, X.D.; Chen, G.L.

    2011-01-01

    Highlights: → Fabricated a kind of high performance Al-Si alloy with low production costs. → Clarified two different morphologies of α-Fe and corresponding crystal structures. → Analyzed the crystallography of Cu-rich phases before and after T6 treatment. → Fracture mechanism of precipitates in experimental alloys during tensile process. -- Abstract: In this paper, we report a novel kind of eutectic Al-Si-Cu-Fe-Mn alloy with ultimate tensile strength up to 336 MPa and 144.3 MPa at room temperature and 300 o C, respectively. This kind of alloy was prepared by metal mold casting followed by T6 treatment. The microstructure is composed of eutectic and primary Si, α-Fe, Al 2 Cu and α-Al phases. Iron-rich phases, which were identified as BCC type of α-Fe (Al 15 (Fe,Mn) 3 Si 2 ), exist in blocky and dendrite forms. Tiny blocky Al 2 Cu crystals disperse in α-Fe dendrites or at the grain boundaries of α-Al. During T6 treatment, Cu atoms aggregate from the super-saturation solid solution to form GP zones, θ'' or θ'. Further analysis found that the enhanced mechanical properties of the experimental alloy are mainly attributed to the formation of α-Fe and copper-rich phases.

  14. Reduction in secondary dendrite arm spacing in cast eutectic Al-Si piston alloys by cerium addition

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.; Shahizan, N. R.; Gandouz, S.

    2017-01-01

    The effects of Ce on the secondary dendrite arm spacing (SDAS) and mechanical behavior of Al-Si-Cu-Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis (CA‒CCTA). The results showed that 0.1wt%-1.0wt% Ce addition resulted in a rapid solidification time, Δ t s, and low solidification temperature, Δ T S, whereas 0.1wt% Ce resulted in a fast solidification time, Δ t a-Al, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index ( Q) and ultimate tensile strength of (UTS) Al-Si-Cu-Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.

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

    International Nuclear Information System (INIS)

    Asghar, Z.; 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 Al 7 Cu 4 Ni, Al 4 Cu 2 Mg 8 Si 7 , Al 2 Cu, Al 15 Si 2 (FeMn) 3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300 deg. C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20 vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ∼15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4 h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si.

  16. Dry sliding wear behavior of laser clad TiVCrAlSi high entropy alloy coatings on Ti–6Al–4V substrate

    International Nuclear Information System (INIS)

    Huang, Can; Zhang, Yongzhong; Vilar, Rui; Shen, Jianyun

    2012-01-01

    Highlights: ► TiVCrAlSi high entropy alloy coatings were obtained on Ti–6Al–4V by laser cladding. ► (Ti,V) 5 Si 3 forms because the formation is accompanied of large variation on enthalpy. ► Wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. ► The wear mechanism is investigated. -- Abstract: Approximately equimolar ratio TiVCrAlSi high entropy alloy coatings has been deposited by laser cladding on Ti–6Al–4V alloy. The analysis of the microstructure by scanning electron microscopy (SEM) shows that the coating is metallurgically bonded to the substrate. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analyses show that TiVCrAlSi coating is composed of precipitates of (Ti,V) 5 Si 3 dispersed in a body-centered cubic (BCC) matrix. Intermetallic compound (Ti,V) 5 Si 3 forms because the formation is accompanied by larger variation on enthalpy, which may offset the entropy term. The dry sliding wear tests show that the wear resistance of Ti–6Al–4V is improved by laser cladding with TiVCrAlSi. The enhancement of the wear resistance is explained by the presence of the hard silicide phase dispersed in a relatively ductile BCC matrix, which allows sliding wear to occur in the mild oxidative regime for a wide range of testing conditions.

  17. 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)

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

    2011-01-01

    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-Si 3 N 4 , 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.

  18. TIPOS DE DISCURSO

    OpenAIRE

    Garcia, Afrânio; UERJ

    2012-01-01

    O professor Adilson Citelli, em seu excelente livro Linguageme persuasão, apresenta cinco tipos de discurso:§ discurso dominante§ discurso autorizado§ discurso polêmico,§ discurso lúdico§ discurso autoritário.

  19. Joining of aluminum and stainless steel using AlSi10 brazing filler: Microstructure and mechanical properties

    Science.gov (United States)

    Fedorov, Vasilii; Uhlig, Thomas; Wagner, Guntram

    2017-07-01

    Joining of dissimilar materials like stainless steel and aluminum is of special interest for automotive applications. Due to the different properties of these materials, suitable joining techniques are required. Brazing offers the possibilities to manufacture high performance joints in one step and at low joining temperatures. However, these joints often need to withstand a high number of high cyclic loads during application. Therefore, in addition to the monotonic properties, the fatigue behavior of the produced joints must be considered and evaluated. In the present work, specimens are manufactured by induction brazing using an AlSi10 filler and a non-corrosive flux. The mechanical properties are determined by tensile shear tests as well as in fatigue tests at ambient and elevated temperatures. The microstructure of the brazed joints and the fracture surfaces of the tested samples are investigated by SEM.

  20. Environment Humidity Effect on the Weight of Carbonized Na-Al-Si Glass Fabrics Recovery after Heating

    International Nuclear Information System (INIS)

    Pentjuss, E; Lusis, A; Gabrusenoks, J; Bajars, G

    2015-01-01

    Na-Al-Si glass fabrics fibres contain Na + ions that diffuse to its surface and along with CO 2 and H 2 O from atmosphere create here the shell of carbonate hydrates. The heating of fabric leads to weight loss by evolving these substances. In this work the results of weight recovery study at room relative humidity (20% – 50%) and elevated humidity (near 70%) of fabrics after its heating at different temperatures (70°C – 150°C) are compared. The experiments shoved the different weight recovery kinetics. The initial exponential stages up to 0.3 h – 0.5 h of the both recoveries are associated with water absorption and differ by its levels. In a case of lower environment humidity the later weight increase are restricted by its value, but at an elevated humidity has a maximum and followed weight increase. The reasons of observed differences are discussed

  1. 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.

  2. Transmission electron microscopy characterization of laser-clad iron-based alloy on Al-Si alloy

    International Nuclear Information System (INIS)

    Mei, Z.; Wang, W.Y.; Wang, A.H.

    2006-01-01

    Microstructure characterization is important for controlling the quality of laser cladding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the iron-based alloy laser-clad on Al-Si alloy and an unambiguous identification of phases in the coating was accomplished. It was found that there is austenite, Cr 7 C 3 and Cr 23 C 6 in the clad region; α-Al, NiAl 3 , Fe 2 Al 5 and FeAl 2 in the interface region; and α-Al and silicon in the heat-affected region. A brief discussion was given for their existence based on both kinetic and thermodynamic principles

  3. 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.

  4. Influence of Nickel Addition on Properties of Secondary AlSi7Mg0.3 Alloy

    Directory of Open Access Journals (Sweden)

    Richtárech L.

    2015-06-01

    Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by nickel. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations. Some elements eliminates iron by changing iron intermetallic phase morphology, decreasing its extent and by improving alloy properties. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of nickel as iron corrector of iron based phases.

  5. Application of the Raman technique to measure stress states in individual Si particles in a cast Al-Si alloy

    International Nuclear Information System (INIS)

    Harris, Stephen J.; O'Neill, Ann; Boileau, James; Donlon, William; Su, Xuming; Majumdar, B.S.

    2007-01-01

    While Raman spectroscopy is often used to measure stresses, the analyses are almost always limited to cases with simple stress states (uniaxial, equibiaxial). Recently we provided an experimental methodology to determine the full state of stress in Si wafers. Here we extend that methodology to interrogate stress states in Si particles embedded in an Al-Si alloy. Such determinations will ultimately be valuable for predicting ductility of cast Al, since a primary source of damage is cracking of eutectic Si particles. We combine electron back-scattered diffraction with the frequency shift, polarization and intensity of the Raman light to determine stress states. Stress states are measured both in the as-received residually stressed state and under in situ uniaxial loading. Comparison with finite element calculations shows good agreement. As an application of the technique, we show the determination of strength of an individual Si particle and compare the stress evolution with various models

  6. Al-Si alloy point contact formation and rear surface passivation for silicon solar cells using double layer porous silicon

    International Nuclear Information System (INIS)

    Moumni, Besma; Ben Jaballah, Abdelkader; Bessais, Brahim

    2012-01-01

    Lowering the rear surface recombination velocities by a dielectric layer has fascinating advantages compared with the standard fully covered Al back-contact silicon solar cells. In this work the passivation effect by double layer porous silicon (PS) (wide band gap) and the formation of Al-Si alloy in narrow p-type Si point contact areas for rear passivated solar cells are analysed. As revealed by Fourier transform infrared spectroscopy, we found that a thin passivating aluminum oxide (Al 2 O 3 ) layer is formed. Scanning electron microscopy analysis performed in cross sections shows that with bilayer PS, liquid Al penetrates into the openings, alloying with the Si substrate at depth and decreasing the contact resistivity. At the solar cell level, the reduction in the contact area and resistivity leads to a minimization of the fill factor losses.

  7. The effect of grain refinement and silicon content on grain formation in hypoeutectic Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.C.; Dahle, A.K.; StJohn, D.H.; Hutt, J.E.C. [Queensland Univ., Brisbane (Australia). Dept. of Mining, Minerals and Mater. Eng.

    1999-01-15

    The effect of increasing the amount of added grain refiner on grain size and morphology has been investigated for a range of hypoeutectic Al-Si alloys. The results show a transition in grain size at a silicon concentration of about 3 wt% in unrefined alloys; the grain size decreasing with silicon content before the transition, and increasing beyond the transition point. A change in morphology also occurs with increased silicon content. The addition of grain refiner leads to greater refinement for silicon contents below the transition point than for those contents above the transition point, while the transition point seems to remain unchanged. The slope of the grain size versus silicon content curve after the transition seems to be unaffected by the degree of grain refinement. The results are related to the competitive processes of nucleation and constitutional effects during growth and their impact on nucleation kinetics. (orig.) 13 refs.

  8. Dimensional Accuracy and Surface Roughness Analysis for AlSi10Mg Produced by Selective Laser Melting (SLM

    Directory of Open Access Journals (Sweden)

    Kamarudin K.

    2016-01-01

    Full Text Available Selective Laser Melting (SLM is an Additive Manufacturing (AM technique that built 3D part in a layer-by-layer method by melting the top surface layer of a powder bed with a high intensity laser according to sliced 3D CAD data. AlSi10Mg alloy is a traditional cast alloy that is broadly used for die-casting process and used in automotive industry due its good mechanical properties. This paper seeks to investigate the requirement SLM in rapid tooling application. The feasibility study is done by examining the surface roughness and dimensional accuracy as compared to the benchmark part produced through the SLM process with constant parameters. The benchmark produced by SLM shows the potential of SLM in a manufacturing application particularly in moulds.

  9. Structure and Mechanical Properties of the AlSi10Mg Alloy Samples Manufactured by Selective Laser Melting

    Science.gov (United States)

    Li, Xiaodan; Ni, Jiaqiang; Zhu, Qingfeng; Su, Hang; Cui, Jianzhong; Zhang, Yifei; Li, Jianzhong

    2017-11-01

    The AlSi10Mg alloy samples with the size of 14×14×91mm were produced by the selective laser melting (SLM) method in different building direction. The structures and the properties at -70°C of the sample in different direction were investigated. The results show that the structure in different building direction shows different morphology. The fish scale structures distribute on the side along the building direction, and the oval structures distribute on the side vertical to the building direction. Some pores in with the maximum size of 100 μm exist of the structure. And there is no major influence for the build orientation on the tensile properties. The tensile strength and the elongation of the sample in the building direction are 340 Mpa and 11.2 % respectively. And the tensile strength and the elongation of the sample vertical to building direction are 350 Mpa and 13.4 % respectively

  10. The Influence of Pressure Die Casting Parameters on the Castability of AlSi11-SiCp Composites

    Directory of Open Access Journals (Sweden)

    Konopka Z.

    2015-03-01

    Full Text Available The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as the method of its high-pressure die casting and the measurement results concerning the castability of the obtained composite. Composite castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and various injection gate width values. There were found the regression equations describing the change of castability of the examined composite as a function of pressure die casting process parameters. The conclusion gives the analysis and the interpretation of the obtained results.

  11. Quantitative analysis of Al-Si alloy using calibration free laser induced breakdown spectroscopy (CF-LIBS)

    Science.gov (United States)

    Shakeel, Hira; Haq, S. U.; Aisha, Ghulam; Nadeem, Ali

    2017-06-01

    The quantitative analysis of the standard aluminum-silicon alloy has been performed using calibration free laser induced breakdown spectroscopy (CF-LIBS). The plasma was produced using the fundamental harmonic (1064 nm) of the Nd: YAG laser and the emission spectra were recorded at 3.5 μs detector gate delay. The qualitative analysis of the emission spectra confirms the presence of Mg, Al, Si, Ti, Mn, Fe, Ni, Cu, Zn, Sn, and Pb in the alloy. The background subtracted and self-absorption corrected emission spectra were used for the estimation of plasma temperature as 10 100 ± 300 K. The plasma temperature and self-absorption corrected emission lines of each element have been used for the determination of concentration of each species present in the alloy. The use of corrected emission intensities and accurate evaluation of plasma temperature yield reliable quantitative analysis up to a maximum 2.2% deviation from reference sample concentration.

  12. 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.

  13. Tensile Properties Characterization of AlSi10Mg Parts Produced by Direct Metal Laser Sintering via Nested Effects Modeling

    Directory of Open Access Journals (Sweden)

    Biagio Palumbo

    2017-02-01

    Full Text Available A statistical approach for the characterization of Additive Manufacturing (AM processes is presented in this paper. Design of Experiments (DOE and ANalysis of VAriance (ANOVA, both based on Nested Effects Modeling (NEM technique, are adopted to assess the effect of different laser exposure strategies on physical and mechanical properties of AlSi10Mg parts produced by Direct Metal Laser Sintering (DMLS. Due to the wide industrial interest in AM technologies in many different fields, it is extremely important to ensure high parts performances and productivity. For this aim, the present paper focuses on the evaluation of tensile properties of specimens built with different laser exposure strategies. Two optimal laser parameters settings, in terms of both process quality (part performances and productivity (part build rate, are identified.

  14. Tensile Properties Characterization of AlSi10Mg Parts Produced by Direct Metal Laser Sintering via Nested Effects Modeling.

    Science.gov (United States)

    Palumbo, Biagio; Del Re, Francesco; Martorelli, Massimo; Lanzotti, Antonio; Corrado, Pasquale

    2017-02-08

    A statistical approach for the characterization of Additive Manufacturing (AM) processes is presented in this paper. Design of Experiments (DOE) and ANalysis of VAriance (ANOVA), both based on Nested Effects Modeling (NEM) technique, are adopted to assess the effect of different laser exposure strategies on physical and mechanical properties of AlSi10Mg parts produced by Direct Metal Laser Sintering (DMLS). Due to the wide industrial interest in AM technologies in many different fields, it is extremely important to ensure high parts performances and productivity. For this aim, the present paper focuses on the evaluation of tensile properties of specimens built with different laser exposure strategies. Two optimal laser parameters settings, in terms of both process quality (part performances) and productivity (part build rate), are identified.

  15. 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.

  16. 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.

  17. Investigating the effect of silicon surface chemical treatment on Al/Si contact properties in GaP/Si solar cells

    Science.gov (United States)

    Kudryashov, D.; Gudovskikh, A.

    2018-03-01

    In the present work, experimental studies have been carried out to reveal how chemical treatment of a silicon surface affects the properties of the Al/Si contact. It has been shown that for p-type monocrystalline silicon substrates with a resistivity of 10 ohm cm, it is possible to form an ohmic Al/Si contact by magnetron sputtering of an aluminum thin film and its further annealing at temperatures of 400 - 450 °C. In the range of annealing temperatures of 250 - 400 °C, the Si substrate treatment in the HF solution leads to a significant increase in currents on the current-voltage curves of the Al/Si contact, while in the range of 450 - 700 °C, the effect of chemical treatment of the silicon is not detected.

  18. Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Lianfeng Wang

    2018-01-01

    Full Text Available During the selective laser melting (SLM process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

  19. 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

    2016-08-01

    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.

  20. Effects of Alloying Elements on Room and High Temperature Tensile Properties of Al-Si Cu-Mg Base Alloys =

    Science.gov (United States)

    Alyaldin, Loay

    In recent years, aluminum and aluminum alloys have been widely used in automotive and aerospace industries. Among the most commonly used cast aluminum alloys are those belonging to the Al-Si system. Due to their mechanical properties, light weight, excellent castability and corrosion resistance, these alloys are primarily used in engineering and in automotive applications. The more aluminum is used in the production of a vehicle, the less the weight of the vehicle, and the less fuel it consumes, thereby reducing the amount of harmful emissions into the atmosphere. The principal alloying elements in Al-Si alloys, in addition to silicon, are magnesium and copper which, through the formation of Al2Cu and Mg2Si precipitates, improve the alloy strength via precipitation hardening following heat treatment. However, most Al-Si alloys are not suitable for high temperature applications because their tensile and fatigue strengths are not as high as desired in the temperature range 230-350°C, which are the temperatures that are often attained in automotive engine components under actual service conditions. The main challenge lies in the fact that the strength of heat-treatable cast aluminum alloys decreases at temperatures above 200°C. The strength of alloys under high temperature conditions is improved by obtaining a microstructure containing thermally stable and coarsening-resistant intermetallics, which may be achieved with the addition of Ni. Zr and Sc. Nickel leads to the formation of nickel aluminide Al3Ni and Al 9FeNi in the presence of iron, while zirconium forms Al3Zr. These intermetallics improve the high temperature strength of Al-Si alloys. Some interesting improvements have been achieved by modifying the composition of the base alloy with additions of Mn, resulting in an increase in strength and ductility at both room and high temperatures. Al-Si-Cu-Mg alloys such as the 354 (Al-9wt%Si-1.8wt%Cu-0.5wt%Mg) alloys show a greater response to heat treatment as a

  1. Influence of scandium on the microstructure and mechanical properties of A319 alloy

    International Nuclear Information System (INIS)

    Emadi, Daryoush; Rao, A.K. Prasada; Mahfoud, Musbah

    2010-01-01

    Recycling of aluminum scrap alloys by melting is gaining its importance in foundry sector. During recycling, some of the alloying elements present in scrap alloys eventually become trace/tramp impurities in the recycled alloy. These elements could potentially affect the alloy's microstructure and hence its mechanical properties. In the present work, an attempt has been made to investigate the effect of one of such trace elements on the microstructure and mechanical properties of A319 alloy. The element chosen for the present investigation is scandium (Sc). This paper discusses the effects of the additions of trace amount of Sc on the microstructure and mechanical properties of A319 alloy in as-cast, T6 and T7 heat treated conditions.

  2. 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.

  3. Mechanical behaviour of AlSiC nano composites produced by ball milling and spark plasma sintering =

    Science.gov (United States)

    Buchheim, Claudia Sofia de Andrade Redondo Murilhas

    Neste trabalho foram produzidos nanocompositos de AlSiC misturando aluminio puro com nano particulas de SiC com diâmetro de 45 - 55 nm, usando, de forma sequencial, a tecnica da metalurgia do po e a compactacao por "Spark Plasma Sintering". O composito obtido apresentava graos com 100 nm de diâmetro, encontrandose as particulas de SiC localizadas, principalmente, nas fronteiras de grao. O nanocomposito sob a forma de provetes cilindricos foi submetido a testes de compressao uniaxial e a testes de nanoindentacao para analisar a influencia das nanoparticulas de SiC, da fracao volumica de acido estearico e do tempo de moagem, nas propriedades mecânicas do material. Para efeitos de comparacao, utilizouse o comportamento mecânico do Al puro processado em condicoes similares e da liga de aluminio AA1050O. A tensao limite de elasticidade do nanocomposito com 1% Vol./Vol. de SiC e dez vezes superior a do AA1050. O refinamento de grao a escala nano constitui o principal mecanismo de aumento de resistencia mecânica. Na realidade, o Al nanocristalino sem reforco de particulas de SiC, apresenta uma tensao limite de elasticidade sete vezes superior a da liga AA1050O. A adicao de 0,5 % Vol./Vol. e de 1 % Vol./Vol. de SiC conduzem, respetivamente, ao aumento da tensao limite de elasticidade em 47 % e 50%. O aumento do tempo de moagem e a adicao de acido estearico ao po durante a moagem conduzem apenas a um pequeno aumento da tensao de escoamento. A dureza do material medida atraves de testes de nanoindentacao confirmaram os dados anteriores. A estabilidade das microestruturas do aluminio puro e do nanocomposito AlSiC, foi testada atraves de recozimento de restauracao realizado as temperaturas de 150 °C e 250 °C durante 2 horas. Aparentemente, o tratamento termico nao influenciou as propriedades mecânicas dos materiais, excepto do nanocomposito com 1 % Vol./Vol. de SiC restaurado a temperatura de 250 °C, para o qual se observou uma reducao da tensao limite de elasticidade

  4. 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

  5. Pressure effects on spin density wave in Cr rich Cr-Al, Si, Mn, Fe and Co alloys

    International Nuclear Information System (INIS)

    Mizuki, Jun-ichiro; Endoh, Yasuo; Ishikawa, Yoshikazu

    1982-01-01

    The effect of pressure on the spin density wave (SDW) state in Cr rich Cr-Al, Si, Nn, Fe and Co alloys has been elucidated by neutron diffraction studies. We found that the change of the SDW wave vector Q, by applying pressure, 1/Q. delta Q/ delta P, is linearly related to the decrease of T sub(N) with increasing pressure 1/T sub(N). delta T sub(N)/ delta P and that all the results from the Cr-Si, Fe and Co alloys fall on a single straight line independent of their concentrations. Their magnetic phase diagrams in a temperature-pressure coordinate system can be related to the alloy phase diagram by employing an empirical rule that applying pressure corresponds to a decrese in the electron to atom ratio. The non transition metal Si impurity has been found to act as an electron donor, while the effect of Al is not interpreted by the two band nesting model. (author)

  6. Intrinsic defect processes and elastic properties of Ti3AC2 (A = Al, Si, Ga, Ge, In, Sn) MAX phases

    Science.gov (United States)

    Christopoulos, S.-R. G.; Filippatos, P. P.; Hadi, M. A.; Kelaidis, N.; Fitzpatrick, M. E.; Chroneos, A.

    2018-01-01

    Mn+1AXn phases (M = early transition metal; A = group 13-16 element and X = C or N) have a combination of advantageous metallic and ceramic properties, and are being considered for structural applications particularly where high thermal conductivity and operating temperature are the primary drivers: for example in nuclear fuel cladding. Here, we employ density functional theory calculations to investigate the intrinsic defect processes and mechanical behaviour of a range of Ti3AC2 phases (A = Al, Si, Ga, Ge, In, Sn). Based on the intrinsic defect reaction, it is calculated that Ti3SnC2 is the more radiation-tolerant 312 MAX phase considered herein. In this material, the C Frenkel reaction is the lowest energy intrinsic defect mechanism with 5.50 eV. When considering the elastic properties of the aforementioned MAX phases, Ti3SiC2 is the hardest and Ti3SnC2 is the softest. All the MAX phases considered here are non-central force solids and brittle in nature. Ti3SiC2 is elastically more anisotropic and Ti3AlC2 is nearly isotropic.

  7. Kinetic study of the formation of the superconducting A15 phase in the Nb-Al-Si system

    International Nuclear Information System (INIS)

    Binh-Phung.

    1978-12-01

    So far, aluminum-containing superconductors showed excellent critical fields and temperatures. Powder Metallurgy shows the most promise in producing these particular kinds of superconductors in the near future. The scope of this research is to apply a kinetic study to observe the behavior of the Nb(Al,Si) system at elevated temperatures. From such observations, an optimized method of obtaining the A15 superconducting phase can be achieved. This study has resulted in a two step heat treatment to obtain the A15 phase. For the primary heat treatment of infiltrated rods, 600 0 C for 11 hours or 650 0 C for 1 hour was found suitable to form a barrier of intermetallic compound around the pores. For the secondary heat treatment, 1700 0 C for 15 seconds resulted in the formation of the A15 superconducting phase with a critical temperature of 18.25 0 K. A15 formation for wires is similar to infiltrated rods. The only difference is the diffusion path which is now much shorter. 600 0 C for 1 hour was found suitable for the primary heat treatment and 1700 0 C for 15 seconds was the most suitable for the secondary heat treatment. The highest critical temperature found thus far was 18.78 0 K

  8. Effect of Cr and Mn addition and heat treatment on AlSi3Mg casting alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tocci, Marialaura, E-mail: m.tocci@unibs.it [Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia (Italy); Donnini, Riccardo, E-mail: riccardo.donnini@cnr.it [National Research Council of Italy (CNR), Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), Via R. Cozzi 53, 20125 Milan (Italy); Angella, Giuliano, E-mail: giuliano.angella@cnr.it [National Research Council of Italy (CNR), Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), Via R. Cozzi 53, 20125 Milan (Italy); Pola, Annalisa, E-mail: annalisa.pola@unibs.it [Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia (Italy)

    2017-01-15

    In the present paper the effect of heat treatment on an AlSi3Mg alloy with and without Cr and Mn addition was investigated. Beside the well-known modification of the morphology of Fe-containing intermetallics, it was found that Cr and Mn allowed the formation of dispersoids in the aluminium matrix after solution heat treatment at 545 °C, as shown by scanning transmission electron microscope observations. These particles were responsible of the enhanced Vickers microhardness of the aluminium matrix in comparison with the base alloy after solution treatment and quenching, according to dispersion hardening mechanism. The presence of these particles was not affected by ageing treatment, which instead allowed the precipitation of β-Mg{sub 2}Si, as shown by the elaboration of differential scanning calorimeter curves. The formation of dispersoids and the study of their effect on mechanical properties can represent an interesting development for applications at high temperatures of casting alloys due to their thermal stability compared to other strengthening phases as β-Mg{sub 2}Si. - Highlights: •Cr and Mn successfully modified the morphology of Fe-containing intermetallics. •Cr- and Mn-dispersoids formed in the aluminium matrix during solution treatment. •Dispersion hardening was detected after solution treatment for Cr-containing alloy. •The dispersion hardening effect was maintained after ageing treatment.

  9. Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy.

    Science.gov (United States)

    Timpel, M; Wanderka, N; Schlesiger, R; Yamamoto, T; Isheim, D; Schmitz, G; Matsumura, S; Banhart, J

    2013-09-01

    The addition of 200 ppm strontium to an Al-10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning". Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

    Science.gov (United States)

    Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

    2016-01-01

    The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles. PMID:28008967

  11. Four-branched compounds coupled Si and iron-rich intermetallics in near eutectic Al-Si alloys

    International Nuclear Information System (INIS)

    Wu, Yuying; Liu, Xiangfa; Jiang, Binggang; Bian, Xiufang

    2007-01-01

    Many four-branched compounds coupled Si and iron-rich intermetallics were observed in near eutectic Al-Si alloy modified with Al-P master alloy. Such four-branched compounds have never been reported before, but in our case it seems to be commonly observed. In this work the growth characterization of the four-branched compounds are scrutinized with a JXA-8800 electron microprobe (EPMA). More deep study of the formation of four-branched compounds is performed by SEM and TEM analysis. The characterization of the four-branched compounds is that of a primary silicon in the center with four iron-rich intermetallics around. Experimental results also show that the precipitation of primary silicon is the key factor for the formation of four-branched compounds. And WHS-theory explains the growth mechanism of the four-branched compounds. In detail, subsequent twinning within the primary silicon provides four-fold coordination sites on the surface, and then the α-Al(Fe,Mn)-Si phase nucleates on the surface of the primary silicon

  12. Corrosion Behavior of Heat-Treated AlSi10Mg Manufactured by Laser Powder Bed Fusion

    Directory of Open Access Journals (Sweden)

    Marina Cabrini

    2018-06-01

    Full Text Available This experimental work is aimed at studying the effect of microstructural modifications induced by post-processing heat treatments on the corrosion behavior of silicon-aluminum alloys produced by means of laser powder bed fusion (LPBF. The manufacturing technique leads to microstructures characterized by the presence of melt pools, which are quite different compared to casting alloys. In this study, the behavior of an AlSi10Mg alloy was evaluated by means of intergranular corrosion tests according to ISO 11846 standard on heat-treated samples ranging from 200 to 500 °C as well as on untreated samples. We found that temperatures above 200 °C reduced microhardness of the alloy, and different corrosion morphologies occurred due to the modification of both size and distribution of silicon precipitates. Selective penetrating attacks occurred at melt pool borders. The intergranular corrosion phenomena were less intense for as-produced specimens without heat treatments compared to the heat-treated specimens at 200 and 300 °C. General corrosion morphologies were noticed for specimens heat treated at temperatures exceeding 400 °C.

  13. Effect of strontium on liquid structure of Al-Si hypoeutectic alloys using high-energy X-ray diffraction

    International Nuclear Information System (INIS)

    Srirangam, P.; Kramer, M.J.; Shankar, S.

    2011-01-01

    High-energy X-ray diffraction experiments were performed using a synchrotron beam source to investigate the effect of strontium on the liquid atomic structure of Al-Si hypoeutectic alloys. The high-temperature liquid diffraction experiments were carried out on Al alloys with 3, 7, 10 and 12.5 (eutectic) wt.% Si, respectively, with 0 and 0.04 wt.% addition of Sr to each of the alloys. Further, the diffraction data for all the alloys were obtained at various melt temperatures (5-220 K) above the respective liquidus temperature. It was observed that the addition of 0.04 wt.% Sr results in significant change in the liquid structure parameters, such as structure factor, pair distribution function, radial distribution function, coordination number and packing density, at any given melt temperature of the alloy. Salient observations were that, for any specific alloy and temperature, addition of Sr significantly decreases coordination number and packing density. Further, with the addition of Sr in the liquid alloy, the atomic coordination number and packing density increases with decreasing temperature and decreasing Si content of the alloy. The results coupled with prior knowledge have enabled an in-depth understanding of the nucleation environment of the solidifying phases, specifically the role of Sr in delaying the clustering tendencies (nucleation) of the eutectic Si phase.

  14. Influence of Laser Welding Speed on the Morphology and Phases Occurring in Spray-Compacted Hypereutectic Al-Si-Alloys

    Directory of Open Access Journals (Sweden)

    Thomas Gietzelt

    2016-11-01

    Full Text Available Normally, the weldability of aluminum alloys is ruled by the temperature range of solidification of an alloy according to its composition by the formation of hot cracks due to thermal shrinkage. However, for materials at nonequilibrium conditions, advantage can be taken by multiple phase formation, leading to an annihilation of temperature stress at the microscopic scale, preventing hot cracks even for alloys with extreme melting range. In this paper, several spray-compacted hypereutectic aluminum alloys were laser welded. Besides different silicon contents, additional alloying elements like copper, iron and nickel were present in some alloys, affecting the microstructure. The microstructure was investigated at the delivery state of spray-compacted material as well as for a wide range of welding speeds ranging from 0.5 to 10 m/min, respectively. The impact of speed on phase composition and morphology was studied at different disequilibrium solidification conditions. At high welding velocity, a close-meshed network of eutectic Al-Si-composition was observed, whereas the matrix is filled with nearly pure aluminum, helping to diminish the thermal stress during accelerated solidification. Primary solidified silicon was found, however, containing considerable amounts of aluminum, which was not expected from phase diagrams obtained at the thermodynamic equilibrium.

  15. Matrix Structure Evolution and Nanoreinforcement Distribution in Mechanically Milled and Spark Plasma Sintered Al-SiC Nanocomposites.

    Science.gov (United States)

    Saheb, Nouari; Aliyu, Ismaila Kayode; Hassan, Syed Fida; Al-Aqeeli, Nasser

    2014-09-19

    Development of homogenous metal matrix nanocomposites with uniform distribution of nanoreinforcement, preserved matrix nanostructure features, and improved properties, was possible by means of innovative processing techniques. In this work, Al-SiC nanocomposites were synthesized by mechanical milling and consolidated through spark plasma sintering. Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray Spectroscopy (EDS) facility was used for the characterization of the extent of SiC particles' distribution in the mechanically milled powders and spark plasma sintered samples. The change of the matrix crystallite size and lattice strain during milling and sintering was followed through X-ray diffraction (XRD). The density and hardness of the developed materials were evaluated as function of SiC content at fixed sintering conditions using a densimeter and a digital microhardness tester, respectively. It was found that milling for 24 h led to uniform distribution of SiC nanoreinforcement, reduced particle size and crystallite size of the aluminum matrix, and increased lattice strain. The presence and amount of SiC reinforcement enhanced the milling effect. The uniform distribution of SiC achieved by mechanical milling was maintained in sintered samples. Sintering led to the increase in the crystallite size of the aluminum matrix; however, it remained less than 100 nm in the composite containing 10 wt.% SiC. Density and hardness of sintered nanocomposites were reported and compared with those published in the literature.

  16. Effect of Annealing Heat Treatment to Characteristics of AlDC8 (Al-Si-Cu) Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Kyung Man; Lee, Sung-Yul; Lee, Myeong Hoon; Jeong, Jae-Hyun [Korea Maritime and Ocean University, Busan (Korea, Republic of); Baek, Tae-Sil [Pohang College, Pohang (Korea, Republic of)

    2015-12-15

    ALDC8 (Al-Si-Cu) alloy has been often corroded with pattern of intergranular corrosion in corrosive environments. Thus, in order to improve its corrosion resistance, the effect of annealing heat treatment to corrosion resistance and hardness was investigated with parameters of heating temperatures such as 100 ℃, 200 ℃, 300 ℃, 400 ℃ and 500 ℃ for 1hr. The hardness was varied with annealing temperature and slightly decreased with annealing heat treatment. However, the relation between annealing temperature and hardness agreed not well each other. Corrosion potential was shifted to noble direction and corrosion current density was also decreased with increasing annealing temperature. Moreover, both AC impedance at 10 mHz and polarization resistance on the cyclic voltammogram curve were also increased with increasing annealing temperature. Furthermore, intergranular corrosion was somewhat observed in non heat treatment as well as annealing temperatures at 100 ℃, 200 ℃ and 300 ℃, while, intergranular corrosion was not nearly observed at annealing temperature of 400 ℃, 500 ℃. Consequently, it is considered that the annealing heat treatment of ALDC8 alloy may be an available method not only to inhibit its intergranular corrosion but also to improve its corrosion resistance.

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

    International Nuclear Information System (INIS)

    Li, Chunli; Zhang, Ping; Jiang, Zhiyu

    2015-01-01

    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 LiPF 6 /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

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

    Directory of Open Access Journals (Sweden)

    Jacek Antonkiewicz

    2014-07-01

    Full Text Available 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., III. 50 t d.m., IV. 75 t d.m. and V. 100 t d.m. Application of sewage sludge resulted in the increase in yield. The content of analyzed elements in the grass mixture depended significantly on sewage sludge dose. Increasing doses of sewage sludge caused marked increase in Mn and Co contents, while they decreased Fe, Al and Si contents in the grass mixture. It was found that growing doses of sewage sludge caused an improvement of Fe to Mn ratio value in the grass mixture. Assessing the element content in the grass mixture in the view of forage value, it was found that Fe and Mn content did not meet the optimal value. Si content in plants was below the optimal value.

  19. Microstructure and Mechanical Property of 3003 Aluminum Alloy Joint Brazed with Al-Si-Cu-Zn Filler Metal

    Directory of Open Access Journals (Sweden)

    LI Xiao-qiang

    2016-09-01

    Full Text Available Al-Si-Cu-Zn filler metal was developed to braze 3003 aluminum alloy. The microstructure and fracture surface of the joint were analyzed by XRD, SEM and EDS, and the effects of brazing temperature on microstructure and property of the joint were investigated. The results show that good joints are obtained at brazing temperature of 540-580℃ for 10min. The brazed joint consists of α(Al solid solution, θ(Al2Cu intermetallic compound, fine silicon phase and AlCuFeMn+Si phase in the central zone of brazed seam, and α(Al solid solution and element diffusion layers at both the sides of brazed seam, and the base metal. The room temperature (RT shear fracture of the joint occurs at the interface between the teeth shape α(Al in the diffusion layer and the center zone of brazed seam, which is mainly characterized as brittle cleavage. As the brazing temperature increases, α(Al solid solution crystals in the diffusion zone grow up, and the interfacial bonding of the joint is in the form of interdigitation. Brazing at 560℃ for 10min, the RT shear strength of the joint reaches the maximum value of 92.3MPa, which is about 62.7% of the base material.

  20. 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.

  1. Effect of Grain Refinement and Cooling Rate on the Microstructure and Mechanical Properties of Secondary Al-Si-Cu Alloys

    Science.gov (United States)

    Timelli, Giulio; Camicia, Giordano; Ferraro, Stefano

    2014-02-01

    The effect of AlTi5B1 grain refinement and different solidification rates on metallurgical and mechanical properties of a secondary AlSi7Cu3Mg alloy is reported. While the Ti content ranges from 0.04 up to 0.225 wt.%, the cooling rate varies between 0.1 and 5.5 °C/s. Metallographic and thermal analysis techniques have been used to quantitatively examine the macro- and microstructural changes occurring with grain refiner addition at various cooling rates. The results indicate that a small AlTi5B1 addition produces the greatest refinement, while no significant reduction of grain size is obtained with a great amount of grain refiner. On increasing the cooling rate, a lower amount of AlTi5B1 master alloy is necessary to produce a uniform grain size throughout the casting. The combined addition of AlTi5B1 and Sr does not produce any reciprocal interaction or effect on primary α-Al and eutectic solidification. The grain refinement improves the plastic behavior of the alloy and increases the reliability of castings, as evidenced by the Weibull statistics.

  2. Mechanical Properties of Al-Si-Mg Alloy Castings as a Function of Structure Refinement and Porosity Fraction

    Directory of Open Access Journals (Sweden)

    Hajkowski M.

    2012-12-01

    Full Text Available During design of the casting products technology, an important issue is a possibility of prediction of mechanical properties resulting from the course of the casting solidification process. Frequently there is a need for relations describing mechanical properties of silumin alloys as a function of phase refinement in a structure and a porosity fraction, and relations describing phase refinement in the structure and the porosity fraction as a function of solidification conditions. The study was conducted on castings of a 22 mm thick plate, made of EN AC-AlSi7Mg0,3 alloy in moulds: of quartz sand, of quartz sand with chill and in permanent moulds. On the basis of cooling curves, values of cooling rate in various casting parts were calculated. The paper also presents results of examination of distance between arms in dendrites of a solid solution α (DASL, precipitations length of silicon in an eutectic (DlSi and gas-shrinkage porosity (Por as a function of cooling rate. Statistical relations of DASL, DlSi, Por as a function of cooling rate and statistical multiparameter dependencies describing mechanical properties (tensile strength, yield strength, elongation of alloy as a function of DASL, DlSi and Por are also presented in the paper.

  3. 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

  4. Optimization of Coolant Technique Conditions for Machining A319 Aluminium Alloy Using Response Surface Method (RSM)

    Science.gov (United States)

    Zainal Ariffin, S.; Razlan, A.; Ali, M. Mohd; Efendee, A. M.; Rahman, M. M.

    2018-03-01

    Background/Objectives: The paper discusses about the optimum cutting parameters with coolant techniques condition (1.0 mm nozzle orifice, wet and dry) to optimize surface roughness, temperature and tool wear in the machining process based on the selected setting parameters. The selected cutting parameters for this study were the cutting speed, feed rate, depth of cut and coolant techniques condition. Methods/Statistical Analysis Experiments were conducted and investigated based on Design of Experiment (DOE) with Response Surface Method. The research of the aggressive machining process on aluminum alloy (A319) for automotive applications is an effort to understand the machining concept, which widely used in a variety of manufacturing industries especially in the automotive industry. Findings: The results show that the dominant failure mode is the surface roughness, temperature and tool wear when using 1.0 mm nozzle orifice, increases during machining and also can be alternative minimize built up edge of the A319. The exploration for surface roughness, productivity and the optimization of cutting speed in the technical and commercial aspects of the manufacturing processes of A319 are discussed in automotive components industries for further work Applications/Improvements: The research result also beneficial in minimizing the costs incurred and improving productivity of manufacturing firms. According to the mathematical model and equations, generated by CCD based RSM, experiments were performed and cutting coolant condition technique using size nozzle can reduces tool wear, surface roughness and temperature was obtained. Results have been analyzed and optimization has been carried out for selecting cutting parameters, shows that the effectiveness and efficiency of the system can be identified and helps to solve potential problems.

  5. Effect of microstructure on mechanical and tribological properties of TiAlSiN nanocomposite coatings deposited by modulated pulsed power magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.L. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); College of Engineering, Hunan Agricultural University/Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Changsha 410128 (China); Li, Y.G.; Wu, B. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Lei, M.K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-12-31

    TiAlSiN nanocomposite coatings were deposited in a closed field unbalanced magnetron sputtering system by reactive sputtering from Ti{sub 0.475}Al{sub 0.475}Si{sub 0.05} targets using modulated pulsed power magnetron sputtering (MPPMS) under a floating substrate bias. The ratio of the nitrogen flow rate to the total gas flow rate (f{sub N{sub 2}}) was varied from 0 to 40%. The application of MPPMS as sputtering sources was aimed at generating a high ionization degree of the sputtered material and a high plasma density by using a pulsed high power approach. When f{sub N{sub 2}} = 0%, an amorphous-like structure Ti{sub 0.479}Al{sub 0.454}Si{sub 0.066} coating was deposited with a hardness of 10 GPa. When nitrogen was added, an optimized nanocomposite structure of nc-TiAlN/a-Si{sub 3}N{sub 4} formed in the TiAlSiN coating deposited at f{sub N{sub 2}} = 10%, in which 5–10 nm TiAlN nanocrystallites were embedded in a 2–3 nm thick amorphous Si{sub 3}N{sub 4} matrix. As the f{sub N{sub 2}} was increased up to 40%, the elementary composition of the coatings remained almost the same, but the grain size of nanocrystallites approached to 10–20 nm and the AlN phase gradually precipitated. A maximum hardness (H) of 33.2 GPa, a hardness to the elastic modulus (E) ratio of 0.081 and an H{sup 3}/E*{sup 2} ratio of 0.19 GPa were found in the coating deposited at f{sub N{sub 2}} = 10%. The friction coefficient of the TiAlSiN coatings was around 0.8–0.9 as sliding against a Si{sub 3}N{sub 4} counterpart under a normal load of 0.5 N. A wear rate of 2.0 × 10{sup −5} mm{sup 3} N{sup −1} m{sup −1} was measured in the TiAlSiN coatings deposited at f{sub N{sub 2}} = 20–40%. As only a low residual stress is found in the TiAlSiN coatings, we consider the complete phase separation is responsible for the enhanced mechanical and tribological properties of the nc-TiAlN/a-Si{sub 3}N{sub 4} nanocomposite coatings. - Highlights: • TiAlSiN nanocomposite coatings were prepared by

  6. 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

  7. Crystal structure and anisotropic magnetic properties of new ferromagnetic Kondo lattice compound Ce(Cu,Al,Si){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, A.; Thamizhavel, A.; Dhar, S.K. [Department of Condensed Matter Physics & Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India); Provino, A.; Pani, M.; Costa, G.A. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Institute SPIN-CNR, Corso Perrone 24, 16152 Genova (Italy)

    2017-03-15

    Single crystals of the new compound CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} have been grown by high-temperature solution growth method using a eutectic Al-Si mixture as flux. This compound is derived from the binary CeSi{sub 2} (tetragonal α-ThSi{sub 2}-type, Pearson symbol tI12, space group I4{sub 1}/amd) obtained by partial substitution of Si by Cu and Al atoms but showing full occupation of the Si crystal site (8e). While CeSi{sub 2} is a well-known valence-fluctuating paramagnetic compound, the CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} phase orders ferromagnetically at T{sub C}=9.3 K. At low temperatures the easy-axis of magnetization is along the a-axis, which re-orients itself along the c-axis above 30 K. The presence of hysteresis in the magnetization curve, negative temperature coefficient of resistivity at high temperatures, reduced jump in the heat capacity and a relatively lower entropy released up to the ordering temperature, and enhanced Sommerfeld coefficient (≈100 mJ/mol K{sup 2}) show that CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58} is a Kondo lattice ferromagnetic, moderate heavy fermion compound. Analysis of the high temperature heat capacity data in the paramagnetic region lets us infer that the crystal electric field split doublet levels are located at 178 and 357 K, respectively, and Kondo temperature (8.4 K) is of the order of T{sub C} in CeCu{sub 0.18}Al{sub 0.24}Si{sub 1.58}.

  8. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Effect of sodium and strontium modifiers on microstructure and tensile properties of LM-13 Al-Si Alloy

    International Nuclear Information System (INIS)

    Tahir, Q.A.; Ikram, N.; Ahmed, R.

    2006-01-01

    During present research work LM 13 aluminium silicon alloy was prepared using high purity aluminium ingot and various master alloys of Al-Si, Al-Cu, Al-Ni, Al-Fe and Al-Mg. A gas fired crucible pit type furnace was used to prepare various heats of LM 13 alloy. Degassing procedure was carried out by using perforated bell type plunger using the degassing tablet. Modification was performed by plunging the modifier at the bottom of the crucible containing the molten metal. Three types of modifiers sodium salt, metallic sodium and strontium in the form of Al-Sr master alloy were used in order to evaluate the microstructure and tensile properties of the alloy. Degassed, unmodified and modified test samples for metallurgical testing purposes were prepared according to the standard procedures. An optical UFX-DX Nikon microscope and Hitachi S3400N scanning electron microscope were used for the observation of microstructural studies of the samples. Similarly tensile properties were determined using Autograph AG-IS series, 20KN Shimadzu Universal Tester. However hardness measurements were carried out using Shimadzu HMV micro hardness testing machine. Experimental results proved that the addition of modifiers improved the microstructures as well as the mechanical properties of the alloy. The present result also showed that sodium and strontium modifiers had almost similar beneficial effects on the microstructure but Sr-modifier showed improved tensile properties of LM 13 alloy. However, the salt method was not so effective if the same was compared to the metallic sodium and strontium modifiers. (author)

  10. The Effect of Water Mist Cooling of Casting Die on the Solidification, Microstructure and Properties of AlSi20 Alloy

    Directory of Open Access Journals (Sweden)

    Władysiak R.

    2017-03-01

    Full Text Available Unmodified AlSi20 alloy were casted at the research station, allowing for sequential multipoint cooling using a dedicated computer- controlled program. This method allows for the formation of the microstructure of hypereutectic AlSi20 alloy and also increases hardness. Primary silicon dendrites were found in the microstructure of cooled samples. Based on these dendrites, the formation of primary silicon particles is explained. Cooling of casting die with a water mist stream causes changes in solidification, which leads to expansion of the boundary layer with columnar crystals and shrinkage of the core zone with equiaxed crystals. It also causes more regular hardness distribution around pre-eutectic Si crystals, which can lead to tensile strength and machinability improvement.

  11. Effects of multiple-step thermal ageing treatment on the hardness characteristics of A356.0-type Al-Si-Mg alloy

    International Nuclear Information System (INIS)

    Abdulwahab, M.; Madugu, I.A.; Yaro, S.A.; Hassan, S.B.; Popoola, A.P.I.

    2011-01-01

    The work outlined the hardness characteristics of thermally aged high chromium sodium modified A356.0-type Al-Si-Mg alloy using the multiple-step thermal ageing treatment (MSTAT) approach. This novel approach consists of double thermal ageing (DTAT) and single thermal ageing treatment (STAT). The investigation also includes the development of a new temperature-compensated-time parameter, P, for the studied alloy at different ageing temperatures and time considered. The results obtained in the DTAT developed for the A356.0-type Al-Si-Mg alloy showed an improvement in the precipitation hardening (PH) ability and hardness characteristics as compared to the convectional STAT temper. The observations were evidenced from the X-ray diffractometry (XRD) pattern indicating the possible strengthening phases. Equally, the hardness behavior was correlated with the microstructures using optical microscope (OPM) and scanning electron microscope equipped with energy dispersive spectroscope (SEM-EDS).

  12. Pengaruh unsur Tembaga (Cu terhadap fluiditas paduan Al-Si 11.8 wt% (ADC 12 dengan metode Vacuum Suction Test

    Directory of Open Access Journals (Sweden)

    Bambang Suharno

    2012-11-01

    Full Text Available Al-Si 11.8 wt% alloy which classified to eutectic Al-Si composition usually used to produce a flat casting product with high pressure die casting process. Alloying element become an important things to determine behavior and characteristic of aluminum. Copper added into aluminum to improve strength and hardness, but there has no many studies on the effect of copper on fluidity. This fluidity study is using vacuum suction test method and the microstructure is observed with SEM/EDS. Spectrometer test has been used to find out chemical composition of sample. The result of this study shows that with copper addition from 2.25 wt% to 3.11 wt%, the fluidity value has increased 24.11% on 680oC pouring temperature. On 3.11 wt% copper composition, fluidity value has increased 14.38% from 640oC pouring temperature to 700oC pouring temperature.

  13. Development and Characterisation of Aluminium Matrix Nanocomposites AlSi10Mg/MgAl2O4 by Laser Powder Bed Fusion

    Directory of Open Access Journals (Sweden)

    Giulio Marchese

    2018-03-01

    Full Text Available Recently, additive manufacturing techniques have been gaining attention for the fabrication of parts from aluminium alloys to composites. In this work, the processing of an AlSi10Mg based composite reinforced with 0.5% in weight of MgAl2O4 nanoparticles through laser powder bed fusion (LPBF process is presented. After an initial investigation about the effect of process parameters on the densification levels, the LPBF materials were analysed in terms of microstructure, thermo-mechanical and mechanical properties. The presence of MgAl2O4 nanoparticles involves an increment of the volumetric energy density delivered to the materials, in order to fabricate samples with high densification levels similar to the AlSi10Mg samples. However, the application of different building parameters results in modifying the size of the cellular structures influencing the mechanical properties and therefore, limiting the strengthening effect of the reinforcement.

  14. Two directional microstructure and effects of nanoscale dispersed Si particles on microhardness and tensile properties of AlSi7Mg melt-spun alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xixi, E-mail: dongxx09@mails.tsinghua.edu.cn [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); He, Liangju [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); School of Aerospace, Tsinghua University, Beijing 100084 (China); Mi, Guangbao [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Li, Peijie [National Center of Novel Materials for International Research, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2015-01-05

    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.

  15. Interface reactions in the Al-Si-SiC and Mg-Al-Al{sub 2}O{sub 3} composite systems

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.K. [Commission of the European Communities, Petten (Netherlands). Inst. for Advanced Materials; Fazal-Ur-Rehman [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Fox, S. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Flower, H.M. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; West, D.R.F.

    1995-12-31

    Structural and compositional observations are reported on the influence of the interfaces on the mechanisms and kinetics of liquid metal-ceramic reactions in Al-SiC, Al-Si-SiC, Mg-Al{sub 2}O{sub 3} and Mg-Al-Al{sub 2}O{sub 3} composites. The aluminium based materials contained up to 20 vol% SiC in particulate form, and were produced by a spray casting process; subsequently the interface reactions were studied in samples heated to temperatures up to 1100 C. The reaction product was Al{sub 4}C{sub 3} in both Al-SiC and Al-Si-SiC composites. The influence of the crystallography and topology of the SiC particle surfaces on the nucleation of the Al{sub 4}C{sub 3} has been demonstrated; surface asperities play an important role. Growth of nuclei proceeds to form continuous reaction product layers which control the subsequent kinetics. The magnesium based composites contained 5 vol% Al{sub 2}O{sub 3} fibres (3 {mu}m in diameter), and were produced by a liquid infiltration process. SD Safimax fibres with relatively low and high porosity, and also RF Saffil fibres, with a silica binder, were investigated. Fibre porosity plays a major role in accelerating the penetration of Mg into the fibres with reaction to form MgO. Silica binder on the fibre surface transforms to MgO. The reaction rate was reduced by the presence of aluminium in the matrix. The factors controlling the reactions in the aluminium and magnesium based composites are compared. (orig.)

  16. Influence of Cu on modifying the beta phase and enhancing the mechanical properties of recycled Al-Si-Fe cast alloys.

    Science.gov (United States)

    Basak, C B; Babu, N Hari

    2017-07-18

    High iron impurity affects the castability and the tensile properties of the recycled Al-Si alloys due to the presence of the Fe containing intermetallic β-Al 9 Fe 2 Si 2 phase. To date only Mn addition is known to transform the β-Al 9 Fe 2 Si 2 phase in the Al-Si-Fe system. However, for the first time, as reported here, it is shown that β-phase transforms to the ω-Al 7 Cu 2 Fe phase in the presence of Cu, after solutionization at 793 K. The ω-phase decomposes below 673 K resulting into the formation of θ-Al 2 Cu phase. However, the present thermodynamic description of the Al-Si-Fe-Cu system needs finer tuning to accurately predict the stability of the ω-phase in these alloys. In the present study, an attempt was made to enhance the strength of Al-6wt%Si-2wt%Fe model recycled cast alloy with different amount of Cu addition. Microstructural and XRD analysis were carried out in detail to show the influence of Cu and the stability range of the ω-phase. Tensile properties and micro-hardness values are also reported for both as-cast and solutionized alloys with different amount of Cu without and with ageing treatment at 473 K. The increase in strength due to addition of Cu, in Fe-rich Al-Si alloys is promising from the alloy recyclability point of view.

  17. The role of Zr and T6 heat treatment on microstructure evolution and hardness of AlSi9Cu3(Fe diecasting alloy

    Directory of Open Access Journals (Sweden)

    Vončina M.

    2017-01-01

    Full Text Available The microstructure features and hardness of AlSi9Cu3(Fe die casting alloy was investigated in the presence of Zr addition. The cast alloys were undergone the solutionizing treatment 2 h at 500°C followed by artificial aging at 180°C for 5 h. Optical microscopy and electron micro-analyzer were used to study the formation of different intermetallic phases. The hardness was tested for all samples at 25°C. The results revealed that the intermetallic phase, based on (Al,Si(Zr,Ti, forms when Zr is added in the investigated alloy, while the T6 heat treatment does not influence on the formation of Zr-bearing phase. Results also indicate that the hardness slightly increases in the AlSi9Cu3 alloy in as-cast state when Zr is added, while after T6 heat treatment increases by 50% in the alloy without Zr and by 61% in the alloy with Zr addition.

  18. Die-cast of a hypo-eutectic AL-SI alloy: influence of injection temperature on microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Santos, Silvano Leal dos; Santos, Sydney Ferreira

    2014-01-01

    Die-casting is widely used for manufacturing light alloy components for automotive industry. Among others, hypo-eutectic Al-Si alloys are currently processed by die-casting. To obtain high quality die-cast components, a better understanding on the correlations between processing parameters, microstructures, and mechanical properties are of utmost importance. In this study, we investigate the effect of injection temperature of liquid metal on the microstructure and mechanical properties of Al-Si alloy EN AC 46000 (DIN designation). The injection temperatures were 579, 589, 643, and 709 deg C. As-cast components had their microstructures analyzed by X-ray diffraction, optical and scanning electron microscopy, and X-ray energy dispersive spectroscopy. The mechanical properties were examined by micro-hardness and tensile tests. It was observed that the ultimate tensile strength slightly increased with the increase of injection temperature. The same trend was observed for micro-hardness. The amount of porosity in the samples varies in a small amount for different injection temperatures. On the other hand, the microstructure of the alloys seems more refined for higher temperatures of injection. This refinement in microstructure might play a major role on the mechanical properties of the Al-Si die-cast alloy. (author)

  19. Microstructure and Mechanical Properties of Multiphase Strengthened Al/Si/Al_2O_3/SiO_2/MWCNTs Nano composites Sintered by In Situ Vacuum Hot Pressing

    International Nuclear Information System (INIS)

    Li, J.; Jiang, X.; Zhu, D.; Zhu, M.; Shao, Z.; Johnson, S.; Luo, Z.

    2015-01-01

    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, multi phased Al/Si matrix nano composites reinforced with Al_2O_3 and multi walled carbon nano tubes (MWCNTs) have been sintered by an in situ vacuum hot-pressing method. The alumina Al_2O_3 nanoparticles were introduced by an in situ reaction of Al with SiO_2. Microstructure and mechanical properties of the sintered Al/Si/Al_2O_3/SiO_2/MWCNTs nano composites 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 nano composites. Based on the mechanical properties and microstructure of the nano composites, strengthening and fracture mechanisms by multiple reinforcements were analyzed

  20. MELLITUS TIPO 1

    Directory of Open Access Journals (Sweden)

    Luciana Vládia Carvalhêdo Fragoso

    2010-01-01

    Full Text Available Investigación de carácter cualitativo, con el objetivo de comprender las experiencias cotidianas de los adolescentes con diabetes tipo 1. Los sujetos del estudio son 14 adolescentes atendidos en una clínica para la diabetes en Fortaleza, Ceará, Brasil, de junio a octubre de 2008. La recolección de los datos se hizo a través de entrevistas semi-estructuradas y se organizaron de acuerdo al análisis de contenido de Morse y Field. Se observó que el descubrimiento de la diabetes fue un momento difícil para los adolescentes debido a los cambios que tuvieron que hacer como el control terapéutico. Hacer una dieta adecuada es muy difícil como consecuencia de estímulos internos y externos a que están sometidos y a las dificultades financieras. Los adolescentes tienen el apoyo de la familia y amigos para su tratamiento diario. Además, les gusta el servicio realizado por los profesionales de salud de la clínica. Sin embargo, hay mucho que mejorar como enfermeras en la valorización de las experiencias de la vida de los adolescentes con diabetes, como la identificación de factores que interfieren en el control metabólico.

  1. Properties of P/M forged Al-Si alloys made by premixed powders. 1. Influences of dispersion and sizes of proeutectic Si on wear resistance; Kongoho ni yotte sakuseishita Al-Si kei shoketsu tanzo gokin no tokusei. 1. Taimamosei ni oyobosu shosho Si no bunsan jotai to ryukei no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Ishijima, Z.; Ichikawa, J.; Sasaki, s.; Shikata, H. [Hitachi Powdered Metals Co. Ltd., Tokyo (Japan)

    1995-10-15

    Influences of dispersion and sizes of proeutectic Si on wear resistance of P/M Al-Si alloys using the prealloying method and premixing method have been investigated. As a result, discretely dispersed proeutectic Si showed excellent wear resistance in compassion with uniformly dispersed one. The cause is considered to be the unclosed Si soft phase which has been preferentially worn away, consequently acting on forming oil grooves and burying worn particles. Further more the existence of the optimum size of proeutectic Si on wear resistance was confirmed. In the case of finer particles, only Al-Si alloy (pin) was warned away substantially. On the other handgun the case of larger particles, both the Al-Si alloy (pin) and the mating malarial (steel disc) were excessively warned away. It is assumed therefore that the finer proeutectic Si particles are not effective as hard particles, on the contrary, larger proeutectic Si particles increase the abrasive wear against the mating material, and those buried into the mating material initiate wear of Al-Si alloy at the same time. 2 refs., 10 figs., 1 tab.

  2. mellitus tipo 2

    Directory of Open Access Journals (Sweden)

    Margarita Lazcano-Ortiz

    2008-01-01

    Full Text Available Objetivo: valorar las propiedades psicométricas de la escala de afrontamiento y proceso de adaptación de Roy en población mexicana. Materiales y métodos: la escala se aplicó a 200 participantes con diabetes mellitus tipo 2. Para validar el constructo se realizó la extracción de factores con componentes principales y rotación Varimax, con Eigenvalores por arriba de 1 y cargas de factor mayores a ,30. Resultados: seis reactivos fueron eliminados del análisis por mostrar correlación negativa con la correlación total de la escala. El análisis de componentes principales inicial reveló nueve factores con una variación explicada de 65,29%. Sin embargo, no se consideraron tres factores por contener cada uno de ellos solamente un reactivo. Por tanto, la escala final se acepta con 38 reactivos. El coeficiente de confiabilidad Alfa de Cronbach fue de, 93. Discusión: el análisis reveló seis factores, uno más de lo reportado por Roy, y con mayor variación explicada. Algunos reactivos parecen no ser bien comprendidos por los participantes. Conclusiones: este artículo aporta una aproximación metodológica para explorar la adecuación de un instrumento a una población diferente para la que originalmente fue diseñado. Se concluye que la escala tiene consistencia interna y validez de constructo incipiente, los datos reportados en este estudio deben tomarse en cuenta con cautela. Es conveniente revisar de nuevo los reactivos y adecuarlos a la cultura particular, y probar la escala de nuevo con pacientes con enfermedades crónicas degenerativas a fin de contar con instrumentos culturalmente equivalentes.

  3. 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

  4. Effects of annealing temperatures on the morphological, mechanical, surface chemical bonding, and solar selectivity properties of sputtered TiAlSiN thin films

    International Nuclear Information System (INIS)

    Rahman, M. Mahbubur; Jiang, Zhong-Tao; Zhou, Zhi-feng; Xie, Zonghan; Yin, Chun Yang; Kabir, Humayun; Haque, Md. Mahbubul; Amri, Amun; Mondinos, Nicholas; Altarawneh, Mohammednoor

    2016-01-01

    Quaternary sputtered TiAlSiN coatings were investigated for their high temperature structural stability, surface morphology, mechanical behaviors, surface chemical bonding states, solar absorptance and thermal emittance for possible solar selective surface applications. The TiAlSiN films were synthesized, via unbalanced magnetron sputtered technology, on AISI M2 steel substrate and annealed at 500 °C - 800 °C temperature range. SEM micrographs show nanocomposite-like structure with amorphous grain boundaries. Nanoindentation analyses indicate a decrease of hardness, plastic deformation and constant yield strength for the coatings. XPS analysis show mixed Ti, Al and Si nitride and oxide as main coating components but at 800 °C the top layer of the coatings is clearly composed of only Ti and Al oxides. Synchrotron radiation XRD (SR-XRD) results indicate various Ti, Al and Si nitride and oxide phases, for the above annealing temperature range with a phase change occurring with the Fe component of the substrate. UV–Vis spectroscopy, FTIR spectroscopy studies determined a high solar selectivity, s of 24.6 for the sample annealed at 600 °C. Overall results show good structural and morphological stability of these coatings at temperatures up to 800 °C with a very good solar selectivity for real world applications. - Highlights: • TiAlSiN sputtered coatings were characterized for solar selective applications. • In situ synchrotron radiation XRD were studies show the occurrence of multiple stable phases. • A high selectivity of 24.63 has been achieved for the coatings annealed at 700 °C. • Existence of XRD phases were also confirmed by XPS measurements. • At high temperature annealing the mechanical properties of films were governed by the utmost surfaces of the films.

  5. 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.

  6. A density functional theory investigation on amantadine drug interaction with pristine and B, Al, Si, Ga, Ge doped C60 fullerenes

    Science.gov (United States)

    Parlak, Cemal; Alver, Özgür

    2017-06-01

    Amantadine is a well-known drug for its treatment effect on Parkinson's disease and influenza infection or hepatitis. Heteroatom doped fullerenes have been extensively examined for their possible usage in sensor technology and medical applications as drug delivery vehicles. In this research, pristine and B, Al, Si, Ga, Ge doped C60 fullerenes and their interaction with amantadine drug molecule were investigated based on the density functional theory calculations. Findings suggest that doped C60 fullerenes might be used to detect the presence of amantadine and they might be used as drug delivery vehicles because of their moderately high adsorption energies with amantadine.

  7. Study on nanocomposite Ti-Al-Si-Cu-N films with various Si contents deposited by cathodic vacuum arc ion plating

    Energy Technology Data Exchange (ETDEWEB)

    Shi, J. [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Muders, C.M.; Kumar, A. [Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Jiang, X., E-mail: xin.jiang@uni-siegen.de [Institute of Materials Engineering, University of Siegen, Paul-Bonatz-Strasse 9-11, Siegen 57076 (Germany); Pei, Z.L.; Gong, J. [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sun, C., E-mail: csun@imr.ac.cn [State Key Laboratory of Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer XRD peaks show a tendency of decreasing intensity with increasing Si content. Black-Right-Pointing-Pointer Ti-Al-Si-Cu-N films present different microstructure with increasing Si content. Black-Right-Pointing-Pointer Films with 6 at.% Si content obtain the highest hardness, elastic modulus and H{sup 3}/E{sup 2}. Black-Right-Pointing-Pointer The wear rate decreases with an increase in hardness. - Abstract: In this study, nanocomposite Ti-Al-Si-Cu-N films were deposited on high speed steel substrates by the vacuum cathode arc ion plating (AIP) technique. By virtue of X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM), the influence of silicon content on the film microstructure and characteristics was investigated systematically, including the chemical composition, crystalline structure as well as cross-section morphologies. With increasing the silicon content, a deterioration of the preferred orientation and a dense globular structure were detected. In the meanwhile, atomic force microscopy (AFM), nano-indentation, Rockwell indenter and reciprocating test were also utilized to analyze the hardness, elastic modulus, H{sup 3}/E{sup 2}, friction coefficient, adhesive strength and wear rate of the Ti-Al-Si-Cu-N films. The results showed that an optimal silicon content correlated with the best mechanical and tribological properties of the presented Ti-Al-Si-Cu-N films existed. With increasing the silicon content, the hardness, elastic modulus and the ratio H{sup 3}/E{sup 2} first were improved gradually, and then were impaired sharply again. When the silicon content reached to 6 at.%, the film possessed the highest hardness, elastic modulus and ratio H{sup 3}/E{sup 2} of approximately 24 GPa, 218 GPa and 0.31, respectively. Besides, films containing both 6 at.% and 10 at.% Si contents obtained a relatively low friction coefficient and a good adhesive

  8. Self-standing silicon-carbon nanotube/graphene by a scalable in situ approach from low-cost Al-Si alloy powder for lithium ion batteries

    Science.gov (United States)

    Cai, Hongyan; Han, Kai; Jiang, Heng; Wang, Jingwen; Liu, Hui

    2017-10-01

    Silicon/carbon (Si/C) composite shows great potential to replace graphite as lithium-ion battery (LIB) anode owing to its high theoretical capacity. Exploring low-cost scalable approach for synthesizing Si/C composites with excellent electrochemical performance is critical for practical application of Si/C anodes. In this study, we rationally applied a scalable in situ approach to produce Si-carbon nanotube (Si-CNT) composite via acid etching of commercial inexpensive micro-sized Al-Si alloy powder and CNT mixture. In the Si-CNT composite, ∼10 nm Si particles were uniformly deposited on the CNT surface. After combining with graphene sheets, a flexible self-standing Si-CNT/graphene paper was fabricated with three-dimensional (3D) sandwich-like structure. The in situ presence of CNT during acid-etching process shows remarkable two advantages: providing deposition sites for Si atoms to restrain agglomeration of Si nanoparticles after Al removal from Al-Si alloy powder, increasing the cross-layer conductivity of the paper anode to provide excellent conductive contact sites for each Si nanoparticles. When used as binder-free anode for LIBs without any further treatment, in situ addition of CNT especially plays important role to improve the initial electrochemical activity of Si nanoparticles synthesized from low-cost Al-Si alloy powder, thus resulting in about twice higher capacity than Si/G paper anode. The self-standing Si-CNT/graphene paper anode exhibited a high specific capacity of 1100 mAh g-1 even after 100 cycles at 200 mA g-1 current density with a Coulombic efficiency of >99%. It also showed remarkable rate capability improvement compared to Si/G paper without CNT. The present work demonstrates a low-cost scalable in situ approach from commercial micro-sized Al-Si alloy powder for Si-based composites with specific nanostructure. The Si-CNT/graphene paper is a promising anode candidate with high capacity and cycling stability for LIBs, especially for the

  9. Effect of overheating degree of molten alloy on material reliability and performance stability of AlSi17CuNiMg silumin castings

    OpenAIRE

    J. Szymszal; J. Piątkowski

    2010-01-01

    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. Hav...

  10. The effect of major alloying elements on the size of the secondary dendrite arm spacing in the as-cast Al-Si-Cu alloys

    Directory of Open Access Journals (Sweden)

    M. B. Djurdjevič

    2012-01-01

    Full Text Available A comprehensive understanding of melt quality is of paramount importance for the control and prediction of actual casting characteristics. Among many phenomenons that occur during the solidification of castings, there are four that control structure and consequently mechanical properties: chemical composition, liquid metal treatment, cooling rate and temperature gradient. The cooling rate and alloy composition are among them most important. This paper investigates the effect of some major alloying elements (silicon and copper of Al-Si-Cu alloys on the size of the secondary dendrite arm spacing. It has been shown that both alloying elements have reasonable influence on the refinement of this solidification parameter.

  11. From Powders to Dense Metal Parts: Characterization of a Commercial AlSiMg Alloy Processed through Direct Metal Laser Sintering.

    Science.gov (United States)

    Manfredi, Diego; Calignano, Flaviana; Krishnan, Manickavasagam; Canali, Riccardo; Ambrosio, Elisa Paola; Atzeni, Eleonora

    2013-03-06

    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.

  12. 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.

  13. Modeling of the influence of coarsening on viscoplastic behavior of a 319 foundry aluminum alloy

    International Nuclear Information System (INIS)

    Martinez, R.; Russier, V.; Couzinié, J.P.; Guillot, I.; Cailletaud, G.

    2013-01-01

    Both metallurgical and mechanical behaviors of a 319 foundry aluminum alloy have been modeled by means of a multiscale approach. The nano-scale, represented by the coarsening of Al 2 Cu precipitates, has been modeled according to the Lifshitz–Slyozov–Wagner (LSW) law in a range of temperature going from 23 °C to 300 °C up to 1000 h aging time. Results were then compared to transmission electron microscope (TEM) observations and are in good agreement with the experimental measurements. The model allows us to know the critical radius, the volume fraction and the number of particles per μm 3 in a α-phase representative volume element (RVE). The increase in yield stress generated by the interaction of dislocations with precipitates, lattice and solid solution, is modeled on the microscale. The yield stress becomes thus a function of the precipitation state, and is time/temperature dependent. These two models were then combined into a mechanical macroscale model in order to represent the Low Cycle Fatigue (LCF) behavior of the material. An elasto-viscoplastic law has been used and all the material parameters were experimentally determined with LCF stress/strain loops for the first cycle and for the mechanical steady state. The simulation results are in good agreement with the experiments.

  14. Utilisation of mould temperature change in eliminating the Al5FeSi phases in secondary AlSi7Mg0.3 alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2017-03-01

    Full Text Available This article describes the impact of the metal mould temperature change in eliminating the adverse effect of iron in the AlSi7Mg0.3 alloy. The kind of phases based on iron to be formed in aluminium alloys is determined by the alloy chemical composition, the melt overheating temperature prior to casting, and the cooling rate during crystallisation. In the experiment, we used three various mould temperatures, and their impact on the possible change in the adverse Al5FeSi phase, excreted in a needle form to a more compact form of Chinese writing or skeleton units. The experimental part did not use melt overheat that would result in impairment of the melt, for example due to increased gassing of the melt, as well as in a greater load on the smelting unit, thus resulting in increased energy expenditure. We can conclude from the obtained results that the mould temperature change does not have an adequate effect in eliminating the adverse effect of iron in Al-Si-Mg alloys.

  15. Study of an Al-Si-Cu HPDC alloy with high Zn content for the production of components requiring high ductility and tensile properties

    Energy Technology Data Exchange (ETDEWEB)

    Vicario, Iban; Egizabal, Pedro; Galarraga, Haize; Plaza, Luis Maria; Crespo, Inigo [Fundacion Tecnalia Research and Innovation, Donostia-San Sebastien (Spain). Dept. of foundry processes

    2013-04-15

    Conventional high-pressure die casting aluminium components present certain limitations in terms of mechanical properties attainable due to the intrinsic porosity of the castings as well as the presence of iron-based brittle intermetallic phases. The present work approaches the increase in ductility and tensile strength through the analysis of the effect of the alloying elements of AlSi alloys used for high-pressure die casting. The combination of alloying elements providing the best results in terms of ductility and tensile strength were eventually selected to produce a batch of components that were thoroughly tested. The final alloy had a composition of Si 8.21, Fe 0.78, Cu 1.53, Mn 0.64, Mg 0.46, Ni 0.07, Zn 3.37, Pb 0.34, Sn 0.27, Ti 0.18 and Cr 0.04wt.%. The selected alloy performance was compared to that of the commercial AlSi9Cu3 and Silafont {sup registered} 36 alloys.

  16. Three dimensional (3D) microstructure-based finite element modeling of Al-SiC nanolaminates using focused ion beam (FIB) tomography

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Carl R. [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Molina-Aladareguia, Jon [IMDEA Materials Institute, c/Eric Kandel 2, Getafe, Madrid 28906 (Spain); Chawla, Nikhilesh, E-mail: nchawla@asu.edu [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States)

    2016-10-15

    Al-SiC nanolaminate composites show promise as high performance coating materials due to their combination of strength and toughness. Although a significant amount of modeling effort has been focused on materials with an idealized flat nanostructure, experimentally these materials exhibit complex undulating layer geometries. This work utilizes FIB tomography to characterize this nanostructure in 3D and finite element modeling to determine the effect that this complex structure has on the mechanical behavior of these materials. A sufficiently large volume was characterized such that a 1 × 2 μm micropillar could be generated from the dataset and compared directly to experimental results. The mechanical response from this nanostructure was then compared to pillar models using simplified structures with perfectly flat layers, layers with sinusoidal waviness, and layers with arc segment waviness. The arc segment based layer geometry showed the best agreement with the experimentally determined structure, indicating it would be the most appropriate geometry for future modeling efforts. - Highlights: •FIB tomography was used to determine the structure of an Al-SiC nanolaminate in 3D. •FEM was used to compare the deformation of the nanostructure to experimental results. •Idealized structures from literature were compared to the FIB determined structure. •Arc segment based structures approximated the FIB determined structure most closely.

  17. 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.

  18. Structure and properties of selected cemented carbides and cermets covered with TiN/(Ti,Al,SiN/TiN coatings obtained by the cathodic arc evaporation process

    Directory of Open Access Journals (Sweden)

    Leszek A. Dobrzañski

    2005-06-01

    Full Text Available This study presents the results of microstructural examinations, mechanical tests and service performance tests carried out on thin TiN/(Ti,Al,SiN/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 properties of the materials were determined from service tests in which continuous machining of C45E steel was carried out. The hardness of the substrate and the microhardness of the coatings were determined with a DUH 202 SHIMADZU ultra microhardness tester with a load of 70 mN. Roughness tests were also carried out before applying the coatings and after the PVD process. Cutting tests confirmed the advantages of the TiN/(Ti,Al,SiN/TiN type coatings obtained using the PVD method in the CAE mode on cemented carbides and cermets, as a material that undergoes very low abrasive, thermal and adhesion wear. These coatings extend tool life compared to commercially available uncoated tools with single and multi-layer coatings deposited using PVD/CVD methods.

  19. Blue emission in photoluminescence spectra of the red phosphor CaAlSiN3:Eu2+ at low Eu2+ concentration

    Science.gov (United States)

    Suda, Yoriko; Kamigaki, Yoshiaki; Yamamoto, Hajime

    2018-04-01

    In red phosphor CaAlSiN3:Eu2+, unintentional blue emission occurs with increasing intensity at low Eu2+ concentrations and also at low measurement temperatures. Time-resolved photoluminescence measurements were used to confirm the decrease in red emission and increase in blue emission with the decreasing Eu2+ concentration. The peak timing of blue emission occurred faster than that of red emission, and long lasting luminescence of red emission was observed as well as that of blue emission. The Eu2+ concentration dependences of the red and blue emissions were similar to those of the g values 4.75 (Eu2+) and 2.0025 (nitrogen vacancies), respectively, which were observed from electron spin resonance (ESR) measurements. The origin of the blue emission is proposed to be nitrogen vacancy defects, which had about the same ESR signal intensity as that of Eu2+ ions in CaAlSiN3:Eu2+ containing 0.01 at. % Eu2+. The possibility of red emission also arising from excited electron tunneling or thermal pathways via nitrogen vacancies is discussed. Long lasting red emission was observed, which is proposed to involve trapped electrons remaining at nitrogen vacancies, yielding blue emission and inducing red emission from Eu2+ ions.

  20. Effect of Fe, Ni, and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy under different pH conditions

    Directory of Open Access Journals (Sweden)

    Mohammad Salim Kaiser

    2018-05-01

    Full Text Available Effect of Fe, Ni and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy was studied. The test of corrosion behaviour at different environmental pH 1, 3, 5, 7, 9, 11 and 13 was performed using conventional gravimetric measurements and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM and X-ray analyser (EDX investigations. The highest corrosion rate was observed at pH 13 followed by pH 1, while in the pH range of 3.0 to 11, there is a high protection of surface due to formation of stable surface oxide film. The highest corrosion rate at pH 13 is due to presence of sodium hydroxide in the solution in which the surface oxide film is soluble. At pH 1, however, high corrosion rate can be attributed to dissolution of Al due to the surface attack by aggressive chloride ions. Presence of Fe, Ni and Cr in hyper-eutectic Al-Si automotive alloy has significant effect on the corrosion rate at both environmental pH values. Resistivity of alloy surfaces initially decreases at pH 1 and pH 13 due to formation of thin films. The SEM images of corroded samples immersed in pH 1 solution clearly show pores due to uniform degradation of the alloy. In pH 13 solution, however, the corrosion layer looks more packed and impermeable.

  1. Internal damping due to dislocation movements induced by thermal expansion mismatch between matrix and particles in metal matrix composites. [Al/SiC

    Energy Technology Data Exchange (ETDEWEB)

    Girand, C.; Lormand, G.; Fougeres, R.; Vincent, A. (GEMPPM, Villeurbanne (France))

    1993-05-01

    In metal matrix composites (MMCs), the mechanical 1 of the reinforcement-matrix interface is an important parameter because it governs the load transfer from matrix to particles, from which the mechanical properties of these materials are derived. Therefore, it would be useful to set out an experimental method able to characterize the interface and the adjacent matrix behaviors. Thus, a study has been undertaken by means of internal damping (I.D.) measurements, which are well known to be very sensitive for studying irreversible displacements at the atomic scale. More especially, this investigation is based on the fact that, during cooling of MMC's, stress concentrations originating from differences in coefficients of thermal expansion (C.T.E.) of matrix and particles should induce dislocation movements in the matrix surrounding the reinforcement; that is, local microplastic strains occur. Therefore, during I.D. measurements vs temperature these movements should contribute to MMCs I.D. in a process similar to those involved around first order phase transitions in solids. The aim of this paper is to present, in the case of Al/SiC particulate composites, new developments of this approach that has previously led to promising results in the case of Al-Si alloys.

  2. Fine-structured aluminium products with controllable texture by selective laser melting of pre-alloyed AlSi10Mg powder

    International Nuclear Information System (INIS)

    Thijs, Lore; Kempen, Karolien; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2013-01-01

    Graphical abstract: -- Abstract: This study shows that AlSi10Mg parts with an extremely fine microstructure and a controllable texture can be obtained through selective laser melting (SLM). Selective laser melting creates complex functional products by selectively melting powder particles of a powder bed layer after layer using a high-energy laser beam. The high-energy density applied to the material and the additive character of the process result in a unique material structure. To investigate this material structure, cube-shaped SLM parts were made using different scanning strategies and investigated by microscopy, X-ray diffraction and electron backscattered diffraction. The experimental results show that the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells. Consequently, the AlSi10Mg SLM products have a high hardness of 127 ± 3 Hv0.5 even without the application of a precipitation hardening treatment. Furthermore, due to the unique solidification conditions and the additive character of the process, a morphological and crystallographic texture is present in the SLM parts. Thanks to the knowledge gathered in this paper on how this texture is formed and how it depends on the process parameters, this texture can be controlled. A strong fibrous 〈1 0 0〉 texture can be altered into a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied

  3. The combined use of EBSD and EDX analyses for the identification of complex intermetallic phases in multicomponent Al-Si piston alloys

    International Nuclear Information System (INIS)

    Chen, C.-L.; Thomson, R.C.

    2010-01-01

    Multicomponent Al-Si based casting alloys are used for a variety of engineering applications, including for example, piston alloys. Properties include good castability, high strength, light weight, good wear resistance and low thermal expansion. In order for such alloys to continue operation to increasingly higher temperatures, alloy element modifications are continually being made to further enhance the properties. Improved mechanical and physical properties are strongly dependent upon the morphologies, type and distribution of the second phases, which are in turn a function of alloy composition and cooling rate. The presence of additional elements in the Al-Si alloy system allows many complex intermetallic phases to form, which make characterisation non-trivial. These include, for example, CuAl 2 , Al 3 Ni 2 , Al 7 Cu 4 Ni, Al 9 FeNi and Al 5 Cu 2 Mg 8 Si 6 phases, all of which may have some solubility for additional elements. Identification is often non-trivial due to the fact that some of the phases have either similar crystal structures or only subtle changes in their chemistries. A combination of electron backscatter diffraction (EBSD) and energy dispersive X-ray analysis (EDX) has therefore been used for the identification of the various phases. This paper will present comparisons of phase identification methodologies using EBSD alone, and in combination with chemical information, either directly or through post processing.

  4. Thermal stability of (AlSi)x(ZrVTi) intermetallic phases in the Al–Si–Cu–Mg cast alloy with additions of Ti, V, and Zr

    International Nuclear Information System (INIS)

    Shaha, S.K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D.L.

    2014-01-01

    Highlights: • Al–Si–Cu–Mg alloy was modified by introducing Zr, V, and Ti. • The chemistry of the phases was identified using SEM/EDX. • The crystal lattice parameters of the phases were characterized using EBSD. • To investigate the phase stability, XRD was performed up to 600 °C. • Thermal analysis was done to find out the possible phase transformation reactions. - Abstract: The Al–Si–Cu–Mg cast alloy was modified with additions of Ti–V–Zr to improve the thermal stability of intermetallics at increased temperatures. A combination of electron microscopy, electron backscatter diffraction, and high temperature X-ray diffraction was explored to identify phases and temperatures of their thermal stability. The micro-additions of transition metals led to formation of several (AlSi) x (TiVZr) phases with D0 22 /D0 23 tetragonal crystal structure and different lattice parameters. While Cu and Mg rich phases along with the eutectic Si dissolved at temperatures from 300 to 500 °C, the (AlSi) x (TiVZr) phases were stable up to 696–705 °C which is the beneficial to enhance the high temperature properties. Findings of this study are useful for selecting temperatures during melting and heat treatment of Al–Si alloys with additions of transition metals

  5. Crescimento de genótipos de frangos tipo caipira

    Directory of Open Access Journals (Sweden)

    R. C. Veloso

    2015-10-01

    Full Text Available RESUMOObjetivou-se com este trabalho comparar o padrão de crescimento, mediante ajustes das respectivas curvas de crescimento por modelos não lineares, bem como estudar o desenvolvimento de cortes de carcaça em relação ao peso da carcaça em diferentes genótipos de frangos tipo caipira. Foram utilizados 840 pintos de um dia, machos, distribuídos em delineamento inteiramente ao acaso, dos seguintes genótipos da linhagem Redbro: Caboclo, Carijó, Colorpak, Gigante Negro, Pesadão Vermelho, Pescoço Pelado e Tricolor. As aves foram alojadas em 28 boxes, sendo 30 aves/boxe, em galpão de alvenaria com acesso a um piquete de 45m², com quatro repetições. O peso corporal individual dos frangos foi medido ao nascer, aos 14, 28, 42, 56, 70 e 84 dias de idade. Para a determinação das curvas de crescimento do peso corporal das aves, os dados coletados foram avaliados por meio dos modelos não lineares: Brody, Gompertz, Logístico, Richards e von Bertalanffy. Foi empregado o PROC NLIN do SAS, utilizando-se o método interativo de Gauss-Newton. Os critérios usados para escolha do modelo de melhor ajuste da curva de crescimento foram o coeficiente de determinação, o desvio padrão assintótico, o desvio médio absoluto dos resíduos e o índice assintótico. As análises para obtenção dos coeficientes alométricos foram realizadas por meio do PROC GLM do SAS para os genótipos Carijó, Colorpak, Pesadão Vermelho, Pescoço Pelado e Tricolor. Foram avaliados os pesos da carcaça, do peito, das coxas, das sobrecoxas, das pernas e das asas das aves abatidas aos 85 dias de idade. Apenas as equações propostas por Gompertz, von Bertalanffy e Logístico atingiram a convergência, e o modelo proposto por von Bertalanffy foi o mais adequado para descrever o crescimento dos genótipos de frangos caipiras. Todos os cortes avaliados apresentaram crescimento tardio em relação ao peso da carcaça em genótipos de frangos tipo caipira.

  6. Role and distribution of strontium during the dissolving and grain refining process of AlSi7Mg alloy's structure

    Energy Technology Data Exchange (ETDEWEB)

    Moldovan, P.; Popescu, G.; Zsigmond, M.; Apostolescu, I. [Universitatea Politehnica, Bucharest (Romania)

    2002-07-01

    The aim of this paper is the study of the modification of AlSi7Mg alloy with two types of master alloys: AlSr10 wire type and AlSr10 block type, at a temperature of 750 C with different contents of strontium. Due to the applicability of the AlSr10 master alloy wire type, the study was mainly elaborated on the dissolving process of this one. Due to this fact we used a 10 mm diameter wire of AlSr10 master alloy, which was introduced in the melt. After the grain refining process we obtained a sample, which was cut at different heights for a better observation of the alloy structure. We can notice that the grain refining degree is not uniform along the sample. Strontium as a grain refiner equalize the qualities of sodium but is much more efficient and keeps its grain refining properties for a longer period of time. The efficiency of the two types of master alloys was compared by the grain refinement degree of AlSi7Mg alloy function of the distance till the lower part of the casting mould and by determination of the grain refinement degree function of strontium content added. We made a micrographic study of the pieces of the sample and we used an optical microscope (OLYMPUS BX 60M) and the image analyzing system was OMNIMENT EXPRESS. Analyzing the results of this study we can see that the AlSi7Mg alloy grain refining degree doesn't depend too much on the form of the master alloy (if is wire or block) but grain refining time is increased when we use block types of master alloy. Also we can see that the cooling rate has a significant influence on the grain refinement degree. The industrial application of the AlSr master alloys are mainly for the light alloys ingots producers and light alloys casting plant for the obtaining of high quality components required by automotive and aeronautical industry. (orig.)

  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. Effect of Cooling Rate on the Microstructure and Mechanical Properties of C-Mn-Al-Si-Nb Hot-Rolled TRIP Steels

    Science.gov (United States)

    Fu, B.; Y Lu, M.; Y Yang, W.; Li, L. F.; Y Zhao, Z.

    2017-12-01

    A novel thermomechanical process to manufacture hot-rolled TRIP steels has been proposed based on dynamic transformation of undercooled austenite (DTUA). The cooling rate between DTUA and isothermal bainitic treatment in the novel process is important. In the present study, effect of this cooling rate on the final microstructures and mechanical properties of a C-Mn-Al-Si-Nb TRIP steel was investigated. The results showed that the volume fractions of acicular ferrite and retained austenite were increased with the increment of cooling rate. As a consequence, higher yield strength and larger total elongation were obtained for the investigated steel with higher cooling rate. In addition, a value of 30.24 GPa% for the product of tensile strength and total elongation was acquired when the cooling rate was 25 K/s. This value has met the standard of the “Third Generation” of advanced high strength sheet steels.

  9. Drainage effect in eutectic Al-Si foam using similar alporas process; Efeito de drenagem em espumas de liga de aluminio silicio eutetico utilizando processo similar ao alporas

    Energy Technology Data Exchange (ETDEWEB)

    Filho, M.O.; Junior, A.C.S; Ferrandini, P.L. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil). Departamento de Materiais e Tecnologia; Nakazato, A.Z.; Assis, W.L.S., E-mail: mauriciooliveirafilho@hotmail.com [Universidade Federal Fluminense (UFF), Resende, RJ (Brazil). Escola de Engenharia de Volta Redonda

    2016-07-01

    Cellular materials have particular properties. This properties are very interesting in various type of industries, as construction, automobile and shipbuilding. Two reasons why metal foams are apply in more companies are difficult process control and high production costs. Therefore, this study aims to analyze the drainage effect in four samples produced with alloy Al-Si eutectic using CaCO{sub 3} as foaming agent, since this is low cost than TiH{sub 2} used normally in Alporas process and this foam have well pores uniform. For these samples has been used 700°C during all process, mixing time was 180 seconds, holding time was 150 seconds and 3,5 w.t% CaCO3. Therefore, these samples were cut transversally and analyzed what were the drainage effect on the apparent density, relative density and porosity. The free zone bubbles were noticed in all the samples. (author)

  10. The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

    Science.gov (United States)

    Fabrizi, A.; Timelli, G.

    2016-03-01

    This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al15(Fe,Mn,Cr)3Si2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al5(Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates.

  11. The influence of cooling rate and Fe/Cr content on the evolution of Fe-rich compounds in a secondary Al-Si-Cu diecasting alloy

    International Nuclear Information System (INIS)

    Fabrizi, A; Timelli, G

    2016-01-01

    This study investigates the morphological evolution of primary α-Al(Fe,Mn,Cr)Si phase in a secondary Al-Si-Cu alloy with respect to the initial Fe and Cr contents as well as to the cooling rate. The solidification experiments have been designed in order to cover a wide range of cooling rates, and the Fe and Cr contents have been varied over two levels. Metallographic and image analysis techniques have been used to quantitatively examine the microstructural changes occurring at different experimental conditions. The morphological evolution of the α-Fe phase has been also analysed by observing deep etched samples. By changing the cooling rate, α-Al 15 (Fe,Mn,Cr) 3 Si 2 dodecahedron crystals, as well as Chinese- script, branched structures and dendrites form, while primary coarse β-Al 5 (Fe,Mn)Si needles appear in the alloy with the highest Fe content at low cooling rates. (paper)

  12. Hydrothermal synthesis, characterization, and thermal properties of alumino silicate azide sodalite, Na8[AlSiO4]6(N3)2

    Science.gov (United States)

    Borhade, A. V.; Wakchaure, S. G.; Dholi, A. G.; Kshirsagar, T. A.

    2017-07-01

    First time we report the synthesis, structural characterization and thermal behavior of an unusual N3 - containing alumino-silicate sodalite mineral. Azide sodalite, Na8[AlSiO4]6(N3)2 has been synthesized under hydrothermal conditions at 433 K in steel lined Teflon autoclave. The structural and microstructural properties of azide sodalite mineral was characterized by various methods including FT-IR, XRD, SEM, TGA, and MAS NMR. Crystal structure have been refined by Rietveld method in P\\bar 43n space group, indicating that the N3 - sodalite has cubic in lattice. High temperature study was carried out to see the effect of thermal expansion on cell dimension ( a o) of azide sodalite. Thermal behavior of sodalite was also assessed by thermogravimetric method.

  13. Effect of the valence electron concentration on the bulk modulus and chemical bonding in Ta2AC and Zr2AC (A=Al, Si, and P)

    International Nuclear Information System (INIS)

    Schneider, Jochen M.; Music, Denis; Sun Zhimei

    2005-01-01

    We have studied the effect of the valence electron concentration, on the bulk modulus and the chemical bonding in Ta 2 AC and Zr 2 AC (A=Al, Si, and P) by means of ab initio calculations. Our equilibrium volume and the hexagonal ratio (c/a) agree well (within 2.7% and 1.2%, respectively) with previously published experimental data for Ta 2 AlC. The bulk moduli of both Ta 2 AC and Zr 2 AC increase as Al is substituted with Si and P by 13.1% and 20.1%, respectively. This can be understood since the substitution is associated with an increased valence electron concentration, resulting in band filling and an extensive increase in cohesion

  14. Tribological Properties of AlSi17Cu5Mg Alloy Modified with CuP Master Alloy with Various Speeds of Friction

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2016-03-01

    Full Text Available The paper presents the influence of modification with phosphorus (CuP10 on the tribological properties of the alloy AlSi17Cu5Mg coupled abrasively with cast-iron EN GJL-350. Tests of coefficient of friction and wear of mass were conducted on tribological tester T-01. An important aspect in the assessment of the tribological properties is the analysis of initial material microstructure in reference to silumin which underwent modification with phosphorus. It was found that the difference in structure of tested materials, mainly sizes of primary silicon crystals significantly influences the tribological properties whereas the speed change of the friction knot does not have such big influence.

  15. Influence of gating design on microstructure and fluidity of thin sections AA320.0 cast hypo-eutectic Al-Si alloy

    Science.gov (United States)

    Ramadan, Mohamed

    2018-05-01

    Influence of gating design especially number of ingrates on microstructure and fluidity of thin sections of 2, 4, 6 mm AA320.0 cast hypo-eutectic Al-Si alloy was evaluated for sand casting molding technique. Increasing the number of ingates improves the microstructe to be fine and more globular. About 87 μm of α-Al grain size, 0.6 α-Al grain sphericity and 37 μm dendrite arm spacing DAS are achieved by using 4 ingates in gating system. Increasing the number of ingates up to 3 increases hardness, filling area and related fluditiy of all cast samples. The minimum thickness of 2.5 mm for each ingate should be considered in order to successfully production of high quality light weight thin sections castings in sand mold.

  16. 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.

  17. Study on preparation of orange-emitting phosphor Y3Mg2AlSi2O12: Ce3+ for wLED

    Directory of Open Access Journals (Sweden)

    Yan Shirun

    2017-12-01

    Full Text Available Ce3+-doped garnet-structured orange-emitting phosphor Y3Mg2AlSi2O12:Ce3+ was prepared by sol-gel combustion using urea as a fuel.Effects of the reduction temperature,Ce3+ doping concentration on the structure,morphology,and photoluminescence property of the as-prepared phosphor were investigated by X-ray diffraction(XRD,scaning electron microscope(SEM,photoluminescence spectroscopy and UV-Vis reflection spectroscopy.The crystallinities,morphologies,and photoluminescence properties of the phosphors prepared by sol-gel combustion and solid-state reaction were compared.The reasons causing different performance of the phosphors were discussed.

  18. Geometrical Structures and Electronic Properties of Ga6 and Ga5X (X = B, C, N, O, F, Al, Si, P, S, Cl Clusters

    Directory of Open Access Journals (Sweden)

    Yanfei Hu

    2018-04-01

    Full Text Available Based on the unbiased CALYPSO (Crystal structure Analysis by Particle Swarm Optimization structure searching method in combination with density functional theory (DFT, the geometrical structures and electronic properties are investigated theoretically for Ga6 and Ga5X (X = B, C, N, O, F, Al, Si, P, S, Cl clusters. The PBE0 exchange-correlation functional and the 6-311G(d basis set is carried out to determine global minima on potential energy surfaces. The relative stabilities of the clusters are examined by the binding energies and substitution reaction. Following the predictions of the Jellium model, the Ga5B cluster with the 18 valence electrons is the most stable structure. At last, with the obtained lowest energy structures, some physical properties such as electrons transfer, molecular orbitals, and total and partial densities of states are discussed, respectively.

  19. 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.

  20. Effect of the AlCr20 Addition on the Microstructure of Secondary AlSi7Mg0.3 Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2014-06-01

    Full Text Available This paper deals with influence of chrome addition and heat treatment on segregation of iron based phases in the secondary alloy AlSi7Mg0.3 microstructure by chrome and heat treatment. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich intermetallic phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type or by heat treatment. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases.

  1. 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.

  2. The role of specific features of the electronic structure in electrical resistivity of band ferromagnets Co2Fe Z ( Z = Al, Si, Ga, Ge, In, Sn, Sb)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Perevozchikova, Yu. A.; Weber, H. W.

    2017-05-01

    The electrical resistivity ρ( T) of the band ferromagnets Co2FeZ (where Z = Al, Si, Ga, Ge, In, Sn, and Sb are s- and p-elements of Mendeleev's Periodic Table) has been investigated in the temperature range 4.2 K < T < 1100 K. It has been shown that the dependences ρ( T) of these alloys in a magnetically ordered state at temperatures T < T C are predominantly determined by the specific features of the electronic spectrum in the vicinity of the Fermi level. The processes of charge carrier scattering affect the behavior of the electrical resistivity ρ( T) only in the vicinity of the Curie temperature T C and above, as well as in the low-temperature range (at T ≪ T C).

  3. Processes and procedures for a thin film multilevel hybrid circuit metallization system based on W--Au/SiO2/Al/SiO2

    International Nuclear Information System (INIS)

    Hampy, R.E.; Knauss, G.L.; Komarek, E.E.; Kramer, D.K.; Villanueva, J.

    1976-04-01

    The processes and procedures developed for the deposition and photodefinition of a W-Au/SiO 2 /Al/SiO 2 hybrid circuit metallization system for the SLL Micro Actuator are described. The metallization system affords a high degree of miniaturization and permits effective interconnection of a mixture of semiconductor devices and passive components with both gold and aluminum terminations without creating undesirable gold-aluminum interfaces. Sputtered tungsten-gold is the first level conductor except at crossovers where tungsten only is used and aluminum is the second level conductor. Silicon dioxide serves as an insulator between the tungsten and aluminum for crossovers. Vias in the insulating layer permit tungsten-aluminum interconnections where desired. A second layer of silicon dioxide is deposited over the metallization and opened for all gold and aluminum bonding pads. Substrates used were polished sapphire and fine grained alumina. The metallization is capable of withstanding processing temperatures up to 400 0 C for short times

  4. The Influence of Pressure Die Casting Parameters on the Mechanical Properties of AlSi11/10 Vol.% SiC Composite

    Directory of Open Access Journals (Sweden)

    Konopka Z.

    2014-03-01

    Full Text Available The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as the method of its high-pressure die casting and the measurement results concerning the tensile strength, the yield point, the elongation and hardness of the obtained composite. Composite castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and various injection gate width values. There were found the regression equations describing the change of mechanical properties of the examined composite as a function of pressure die casting process parameters. The conclusion gives the analysis and the interpretation of the obtained results.

  5. The Influence of Pressure Die Casting Parameters on Distribution of Reinforcing Particles in the AlSi11/10% SiC Composite

    Directory of Open Access Journals (Sweden)

    Pasieka A.

    2013-09-01

    Full Text Available The method of pressure die casting of composites with AlSi11 alloy matrix reinforced with 10 vol. % of SiC particles and the analysis of the distribution of particles within the matrix is presented. The composite castings were produced at various values of the piston velocity in the second stage of injection, at diverse intensification pressure values, and various injection gate width values. The distribution of particles over the entire cross-section of the tensile specimen is shown. The index of distribution was determined on the basis of particle count in elementary measuring fields. The regression equation describing the change of the considered index was found as a function of the pressure die casting parameters. The conclusion presents an analysis of the obtained results and their interpretation.

  6. Drop Weight Impact Behavior of Al-Si-Cu Alloy Foam-Filled Thin-Walled Steel Pipe Fabricated by Friction Stir Back Extrusion

    Science.gov (United States)

    Hangai, Yoshihiko; Nakano, Yukiko; Utsunomiya, Takao; Kuwazuru, Osamu; Yoshikawa, Nobuhiro

    2017-02-01

    In this study, Al-Si-Cu alloy ADC12 foam-filled thin-walled stainless steel pipes, which exhibit metal bonding between the ADC12 foam and steel pipe, were fabricated by friction stir back extrusion. Drop weight impact tests were conducted to investigate the deformation behavior and mechanical properties of the foam-filled pipes during dynamic compression tests, which were compared with the results of static compression tests. From x-ray computed tomography observation, it was confirmed that the fabricated foam-filled pipes had almost uniform porosity and pore size distributions. It was found that no scattering of the fragments of collapsed ADC12 foam occurred for the foam-filled pipes owing to the existence of the pipe surrounding the ADC12 foam. Preventing the scattering of the ADC12 foam decreases the drop in stress during dynamic compression tests and therefore improves the energy absorption properties of the foam.

  7. INFLUENCE OF THE HOMOGENIZATION TEMPERATURE ON THE MICROSTRUCTURE AND PROPERTIES OF AlSi10CuNiMgMn ALLOY

    Directory of Open Access Journals (Sweden)

    Jaromir Cais

    2017-03-01

    Full Text Available The article examines the impact of changes in homogenization temperature in the hardening process on the microstructure of aluminum alloys. Samples where the research was conducted were cast from AlSi10CuNiMn alloy produced by gravity casting technology in metal mold. Subsequently, the castings were subjected to a heat treatment. In an experiment with changing temperature and staying time in the process of homogenization. The microstructure of the alloy was investigated by methods of light and electron microscopy. Examination of the microstructure has focused on changing the morphology of separated particles of eutectic silicon and intermetallic phases. Analysis of intermetallic phases was supplemented by an analysis of the chemical composition - EDS analysis. Effect of heat treatment on the properties investigated alloy was further complemented by Vickers microhardness. Investigated alloy is the result of longtime research conducted at Faculty of Production Technology and Management.

  8. Cast AlSi9Cu4 alloy with hybride strenghtened by Fe{sub x}Al{sub y}-Al{sub 2}O{sub 3} composite powder

    Energy Technology Data Exchange (ETDEWEB)

    Piatkowski, J [Department of Materials Technology, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland); Formanek, B, E-mail: jaroslaw.piatkowski@polsl.pl, E-mail: boleslaw.formanek@polsl.pl [Department of Materials Science, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland)

    2011-05-15

    The main objective of the study was to develop a technology of dispersion strenghtened hypoeutectic Al-Si alloy. The article presented the materials and technology conception for producing aluminium matrix composite AlSi9Cu4Fe alloy with hybride reinforcement of Al{sub x}Fe{sub y} intermetallic and aluminium oxide powders. Composite powder obtained in mechanical agllomerisation mixture of elemental powders. Changes in the structure were confirmed by TA and ATD thermal analyses plotting the solidification curves, which showed a decrease in temperature T{sub liq} compared to the unmodified alloy and an exothermic effect originating from the crystallisation of eutectics with alloying elements. The examinations carried out by SEM and BSE as well as the determination of local chemical composition by EDX technique have characterised the structure of the alloy as containing some binary Al-Si-Al-Cu and Al-Fe eutectics and multicomponent eutectics.

  9. Effect of Al-Si Coating on Weld Microstructure and Properties of 22MnB5 Steel Joints for Hot Stamping

    Science.gov (United States)

    Lin, Wenhu; Li, Fang; Wu, Dongsheng; Chen, Xiaoguan; Hua, Xueming; Pan, Hua

    2018-03-01

    22MnB5 hot stamping steels are gradually being used in tailor-welded blank applications. In this experiment, 1-mm-thick Al-Si coated and de-coated 22MnB5 steels were laser-welded and then hot-stamped. The chemical compositions, solidification process, microstructure and mechanical properties were investigated to reveal the effect of Al-Si coating and heat treatment. In the welded condition, the coated joints had an Al content of approximately 2.5 wt.% in the fusion zone and the de-coated joints had 0.5 wt.% Al. The aluminum promoted the δ-ferrite formation as the skeletal structure during solidification. In the high-aluminum weld, the microstructure consisted of martensite and long and band-like δ-ferrite. Meanwhile, the low-aluminum weld was full of lath martensite. After the hot stamping process, the δ-ferrite fraction increased from 10 to 24% in the coated joints and the lath martensite became finer in the de-coated joints. The tensile strengths of the coated joints or de-coated joints were similar to that before hot stamping, but the strength of the coated joints was reduced heavily after hot stamping compared to the de-coated joints and base material. The effect of δ-ferrite on the tensile properties became stronger when the fusion zone was soft and deformed first in the hot-stamped specimens. The coated weld showed a brittle fracture surface with many cleavage planes, and the de-coated weld showed a ductile fracture surface with many dimples in hot-stamped conditions.

  10. Corrosion behavior of TiN, TiAlN, TiAlSiN thin films deposited on tool steel in the 3.5 wt.% NaCl solution

    International Nuclear Information System (INIS)

    Yoo, Yun Ha; Le, Diem Phuong; Kim, Jung Gu; Kim, Sun Kyu; Vinh, Pham Van

    2008-01-01

    TiN, TiAlN and TiAlSiN hard coatings were deposited onto AISI H13 tool steel by cathodic arc plasma method. X-ray diffraction (XRD) analysis confirmed that incorporation of Al and Si into TiN led to refinement of microstructure. From the results of potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) test conducted in an aerated 3.5% NaCl solution, the TiAlSiN film showed the best corrosion resistance with the lowest corrosion current density and porosity, the highest protective efficiency and total resistance (pore resistance plus charge transfer resistance)

  11. Influence wt.% of SiC and borax on the mechanical properties of AlSi-Mg-TiB-SiC composite by the method of semi solid stir casting

    Science.gov (United States)

    Bhiftime, E. I.; Guterres, Natalino F. D. S.; Haryono, M. B.; Sulardjaka, Nugroho, Sri

    2017-04-01

    SiC particle reinforced metal matrix composites (MMCs) with solid semi stir casting method is becoming popular in recent application (automotive, aerospace). Stirring the semi solid condition is proven to enhance the bond between matrix and reinforcement. The purpose of this study is to investigate the effect of the SiC wt.% and the addition of borax on mechanical properties of composite AlSi-Mg-TiB-SiC and AlSi-Mg-TiB-SiC/Borax. Specimens was tested focusing on the density, porosity, tensile test, impact test microstructure and SEM. AlSi is used as a matrix reinforced by SiC with percentage variations (10, 15, 20 wt.%). Giving wt.% Borax which is the ratio of 1: 4 between wt.% SiC. The addition of 1.5% of TiB gives grain refinement. The use of semi-solid stir casting method is able to increase the absorption of SiC particles into a matrix AlSi evenly. The improved composite presented here can be used as a guideline to make a new composite.

  12. 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; Moon, Juhyuk; Mancio, Mauricio; Clark, Simon M.; Monteiro, Paulo J.M.

    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

  13. Atomic mobility in liquid and fcc Al-Si-Mg-RE (RE = Ce, Sc) alloys and its application to the simulation of solidification processes in RE-containing A357 alloys

    International Nuclear Information System (INIS)

    Lu, Zhao; Zhang, Lijun

    2017-01-01

    This paper first provides a critical review of experimental and theoretically-predicted diffusivities in both liquid and fcc Al-Si-Mg-RE (RE = Ce, Sc) alloys as-reported by previous researchers. The modified Sutherland equation is then employed to predict self- and impurity diffusivities in Al-Si-Mg-RE melts. The self-diffusivity of metastable fcc Sc is evaluated via the first-principles computed activation energy and semi-empirical relations. Based on the critically-reviewed and presently evaluated diffusivity information, atomic mobility descriptions for liquid and fcc phases in the Al-Si-Mg-RE systems are established by means of the Diffusion-Controlled TRAnsformation (DICTRA) software package. Comprehensive comparisons show that most of the measured and theoretically-predicted diffusivities can be reasonably reproduced by the present atomic mobility descriptions. The atomic mobility descriptions for liquid and fcc Al-Si-Mg-RE alloys are further validated by comparing the model-predicted differential scanning calorimetry curves for RE-containing A357 alloys during solidification against experimental data. Detailed analysis of the curves and microstructures in RE-free and RE-containing A357 alloys indicates that both Ce and Sc can serve as the grain refiner for A357 alloys, and that the grain refinement efficiency of Sc is much higher.

  14. Atomic mobility in liquid and fcc Al-Si-Mg-RE (RE = Ce, Sc) alloys and its application to the simulation of solidification processes in RE-containing A357 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Zhao; Zhang, Lijun [Central South Univ., Changsha (China). State Key Lab of Powder Metallurgy; Tang, Ying [Thermo-Calc Software AB, Solna (Sweden)

    2017-06-15

    This paper first provides a critical review of experimental and theoretically-predicted diffusivities in both liquid and fcc Al-Si-Mg-RE (RE = Ce, Sc) alloys as-reported by previous researchers. The modified Sutherland equation is then employed to predict self- and impurity diffusivities in Al-Si-Mg-RE melts. The self-diffusivity of metastable fcc Sc is evaluated via the first-principles computed activation energy and semi-empirical relations. Based on the critically-reviewed and presently evaluated diffusivity information, atomic mobility descriptions for liquid and fcc phases in the Al-Si-Mg-RE systems are established by means of the Diffusion-Controlled TRAnsformation (DICTRA) software package. Comprehensive comparisons show that most of the measured and theoretically-predicted diffusivities can be reasonably reproduced by the present atomic mobility descriptions. The atomic mobility descriptions for liquid and fcc Al-Si-Mg-RE alloys are further validated by comparing the model-predicted differential scanning calorimetry curves for RE-containing A357 alloys during solidification against experimental data. Detailed analysis of the curves and microstructures in RE-free and RE-containing A357 alloys indicates that both Ce and Sc can serve as the grain refiner for A357 alloys, and that the grain refinement efficiency of Sc is much higher.

  15. Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

    Science.gov (United States)

    Apparao, K. Ch; Birru, Anil Kumar

    2018-01-01

    A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

  16. Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy

    Directory of Open Access Journals (Sweden)

    Xuesong Han

    2018-03-01

    Full Text Available AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

  17. Investigation of interface property in Al/SiO2/ n-SiC structure with thin gate oxide by illumination

    Science.gov (United States)

    Chang, P. K.; Hwu, J. G.

    2017-04-01

    The reverse tunneling current of Al/SiO2/ n-SiC structure employing thin gate oxide is introduced to examine the interface property by illumination. The gate current at negative bias decreases under blue LED illumination, yet increases under UV lamp illumination. Light-induced electrons captured by interface states may be emitted after the light sources are off, leading to the recovery of gate currents. Based on transient characteristics of gate current, the extracted trap level is close to the light energy for blue LED, indicating that electron capture induced by lighting may result in the reduction of gate current. Furthermore, bidirectional C- V measurements exhibit a positive voltage shift caused by electron trapping under blue LED illumination, while a negative voltage shift is observed under UV lamp illumination. Distinct trapping and detrapping behaviors can be observed from variations in I- V and C- V curves utilizing different light sources for 4H-SiC MOS capacitors with thin insulators.

  18. Tribological Characteristics of C/C-SiC-Cu Composite and Al/SiC Composite Materials under Various Contact Conditions

    International Nuclear Information System (INIS)

    Kim, Byung-Kook; Shin, Dong-Gap; Kim, Chang-Lae; Kim, Dae-Eun; Goo, Byeong-Choon

    2017-01-01

    The surface temperature of disc brakes varies during braking, which can affect the friction and wear behavior of braking systems. In order to develop an efficient braking system, the friction and wear behaviors of brake materials need to be clearly understood. In this work, the friction and wear behavior of the C/C-SiC-Cu composite and the Al/SiC composite, which are used in disc braking systems, were investigated. Both the surface temperature and contact pressure were studied. A pin-on-reciprocating tribotester was used for this purpose, in order to control temperature and load. Results showed that the friction varied significantly with temperature and sliding distance. It was found that a transfer layer of compacted wear debris formed on the wear track of the two materials. These layers caused the surface roughness of the wear track to increase. The outcome of this work is expected to serve as a basis for the development of braking systems under various operating conditions.

  19. Tribological Characteristics of C/C-SiC-Cu Composite and Al/SiC Composite Materials under Various Contact Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byung-Kook; Shin, Dong-Gap; Kim, Chang-Lae; Kim, Dae-Eun [Yonsei Univ., Seoul (Korea, Republic of); Goo, Byeong-Choon [Korea Railroad Research Institute, Uiwang (Korea, Republic of)

    2017-01-15

    The surface temperature of disc brakes varies during braking, which can affect the friction and wear behavior of braking systems. In order to develop an efficient braking system, the friction and wear behaviors of brake materials need to be clearly understood. In this work, the friction and wear behavior of the C/C-SiC-Cu composite and the Al/SiC composite, which are used in disc braking systems, were investigated. Both the surface temperature and contact pressure were studied. A pin-on-reciprocating tribotester was used for this purpose, in order to control temperature and load. Results showed that the friction varied significantly with temperature and sliding distance. It was found that a transfer layer of compacted wear debris formed on the wear track of the two materials. These layers caused the surface roughness of the wear track to increase. The outcome of this work is expected to serve as a basis for the development of braking systems under various operating conditions.

  20. The Mechanical Properties of AlSi17Cu5 Cast Alloy after Overheating and Modification of CuP Master Alloy

    Directory of Open Access Journals (Sweden)

    Piątkowski J.

    2013-09-01

    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.

  1. 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

  2. DOE applied to study the effect of process parameters on silicon spacing in lost foam Al-Si-Cu alloy casting

    International Nuclear Information System (INIS)

    Shayganpour, A; Izman, S; Idris, M H; Jafari, H

    2012-01-01

    Lost foam casting as a relatively new manufacturing process is extensively employed to produce sound complicated castings. In this study, an experimental investigation on lost foam casting of an Al-Si-Cu aluminium cast alloy was conducted. The research was aimed in evaluating the effect of different pouring temperatures, slurry viscosities, vibration durations and sand grain sizes on eutectic silicon spacing of thin-wall castings. A stepped-pattern was used in the study and the focus of the investigations was at the thinnest 3 mm section. A full two-level factorial design experimental technique was used to plan the experiments and afterwards identify the significant factors affecting casting silicon spacing. The results showed that pouring temperature and its interaction with vibration time have pronounced effect on eutectic silicon phase size. Increasing pouring temperature coarsened the eutectic silicon spacing while the higher vibration time diminished coarsening effect. Moreover, no significant effects on silicon spacing were found with variation of sand size and slurry viscosity.

  3. 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.

  4. Synergistic effects of composition and heat treatment on microstructure and properties of vacuum die cast Al-Si-Mg-Mn alloys

    Directory of Open Access Journals (Sweden)

    Jun-jie Xu

    2018-03-01

    Full Text Available The purpose of this study was to prepare high-quality Al-Si-Mg-Mn alloy with a good combination of strength and ductility employing the vacuum-assisted high-pressure die cast process. An orthogonal study of heat treatments was conducted to design an optimized T6 heat treatment process for both Al-10%Si-0.3%Mg-Mn and Al-11%Si-0.6%Mg-Mn alloys. The results demonstrate that no obvious blisters and warpage were observed in these two alloys with solid solution treatment. After the optimal T6 heat treatment of 530°C×3h + 165°C×6h, Al-11%Si-0.6%Mg-Mn alloy has better mechanical properties, of which tensile strength, yield strength and elongation reached 377.3 MPa, 307.8 MPa and 9%, respectively. The improvement of mechanical properties can be attributed to the high density of needle-like β″(Mg5Si6 precipitation after aging treatment and the fine and spherical eutectic Si particles uniformly distributed in the α-Al matrix.

  5. 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

  6. Possibilities for using higher-tensile, water quenched and tempered AlSiMn fine-grained structural steel for reactor containments

    International Nuclear Information System (INIS)

    Wallner, F.

    1976-01-01

    On water quenching and tempering of weldable AlSiMn structural steels, particularly the grain refining process is made use of, i.e. that measure with the poorest influence on the weldability of steel. Precipitation hardening due to water quenching is, on subsequent tempering, set off to a large extent by means of precipitation resp. coagulation of iron carbides. Minimum yield points up to 580 N/mm 2 and, simultaneously, good viscosity can be obtained by means of water quenching from austeritic temperature and tempering between 550 0 C and 650 0 C, depending on tempering temperatures and sheet thickness. In the paper at hand, results are given, obtained from tests and experience with the steel Aldur 50/65 (the first figure indicates minimum yield points, the second one minimum tensile strength on sheet thickness up to 30 mm). These results are assumed to be essential, also in connection with the construction and working conditions of nuclear power plants. (orig./RW) [de

  7. Dy3+-doped nano-glass ceramics comprising NaAlSiO4 and NaY9Si6O26 nanocrystals for white light generation

    International Nuclear Information System (INIS)

    Bagga, Ruchika; Achanta, Venu Gopal; Goel, Ashutosh; Ferreira, José M.F.; Singh, Narinder Pal; Singh, Davinder Paul; Falconieri, Mauro; Sharma, Gopi

    2013-01-01

    Highlights: ► Environment safe glass ceramics were fabricated via heat treatment. ► Optical and structural properties were studied before and after heat treatment. ► White light generation with single RE 3+ ion-doping was observed under UV excitation. ► Emission color temperature was between fluorescent tube and daylight values. - Abstract: The radiative emission properties of the Dy 3+ ions in oxyfluoride glasses and glass ceramics have been investigated for the generation of white light. The X-ray diffraction pattern of the glass ceramics reveals the presence of NaAlSiO 4 nanocrystals along with secondary phase of NaY 9 Si 6 O 26 in the glass matrix after a suitable thermal treatment of the pristine glasses. Intense white light emission has been observed when the samples are excited with 350 nm light. Yellow to blue emission intensity ratios and chromaticity color coordinates have been determined from the visible luminescence spectra. All color coordinates are found to lie in the white region of the chromaticity color diagram proposing the suitability of the present studied materials for color display devices.

  8. Aluminum Matrix Composite (AlSi7Mg2Sr0.03/SiCp) Pistons Obtained by Mechanical Mixing Method

    Science.gov (United States)

    2017-01-01

    Metal matrix composites are undoubtedly a group of advanced engineering materials. Compared to unreinforced matrix material, they are characterized by increased strength, greater stiffness, increased wear resistance, better mechanical properties and dimensional stability at elevated temperatures as well as lower density. Due to its very favorable tribological properties for many years research has been conducted on the application of MMC in friction node. The article presents important technological aspects related to the production and properties of composite pistons. Under industrial conditions, a composite suspension (AlSi7Mg2Sr0.03/SiCp 10 vol %) was prepared to allow casting of the semi-finished pistons series. Machining parameters of the working surfaces of the piston were selected on the basis of the turning test made on PCD, PCNM and uncoated carbide tools. The tribological properties of the composite pistons were determined on the basis of the pin-on-disc and the abrasion wear. The scuffing tests carried out under real operating conditions have confirmed the possibility of using composite pistons in air compressors. PMID:29283419

  9. Multiscale modeling of the influence of Fe content in a Al-Si-Cu alloy on the size distribution of intermetallic phases and micropores

    International Nuclear Information System (INIS)

    Wang Junsheng; Lee, Peter D.; Li Mei; Allison, John

    2010-01-01

    A multiscale model was developed to simulate the formation of Fe-rich intermetallics and pores in quaternary Al-Si-Cu-Fe alloys. At the microscale, the multicomponent diffusion equations were solved for multiphase (liquid-solid-gas) materials via a finite difference framework to predict microstructure formation. A fast and robust decentered plate algorithm was developed to simulate the strong anisotropy of the solid/liquid interfacial energy for the Fe-rich intermetallic phase. The growth of porosity was controlled by local pressure drop due to solidification and interactions with surrounding solid phases, in addition to hydrogen diffusion. The microscale model was implemented as a subroutine in a commercial finite element package, producing a coupled multiscale model. This allows the influence of varying casting conditions on the Fe-rich intermetallics, the pores, and their interactions to be predicted. Synchrotron x-ray tomography experiments were performed to validate the model by comparing the three-dimensional morphology and size distribution of Fe-rich intermetallics as a function of Fe content. Large platelike Fe-rich β intermetallics were successfully simulated by the multiscale model and their influence on pore size distribution in shape castings was predicted as a function of casting conditions.

  10. Inhibitive effect by Psidium guajava leaf extract on the corrosion of Al-Si-Mg (SSM-HPDC alloy in simulated seawater environment

    Directory of Open Access Journals (Sweden)

    M. Abdulwahab

    2015-12-01

    Full Text Available The assessment of Psidium guajava leaf extract as corrosion inhibitor for Al-Si- Mg (SSM-HPDC alloy in 3.5%wt NaCl solution using the gravimetric based-mass loss and potentiodynamic polarization techniques was investigated. The gravimetric based mass loss test was carried out at different inhibitor concentration, time and temperature ranges of 0.1-0.5%v/v, 1-5 hrs and 30-70oC, respectively, the results revealed that Psidium guajava leaf extract in 3.5%wt NaCl solution-aluminium environment decreased the corrosion rate at various concentrations considered. Inhibition efficiency (IE as high as 63.17% at 0.5% v/v Psidium guajava leaf extract addition using the gravimetric method was demonstrated in 3.5%wt NaCl solution. The IE of 90.48% was obtained at 0.5%v/v using the potentiodynamic polarization method. The additions of Psidium guajava leaf extract as corrosion inhibitor in the solution indicate higher potential value, IE and polarization resistance with decrease in current density. The two methods used for assessment of the aluminium alloy corrosion behaviour were in agreement and mixed-type corrosion exists which obeyed the Langmuir adsorption isotherm.

  11. The Static and Fatigue Behavior of AlSiMg Alloy Plain, Notched, and Diamond Lattice Specimens Fabricated by Laser Powder Bed Fusion

    Directory of Open Access Journals (Sweden)

    Hugo Soul

    2018-04-01

    Full Text Available The fabrication of engineered lattice structures has recently gained momentum due to the development of novel additive manufacturing techniques. Interest in lattice structures resides not only in the possibility of obtaining efficient lightweight materials, but also in the functionality of pre-designed architectured structures for specific applications, such as biomimetic implants, chemical catalyzers, and heat transfer devices. The mechanical behaviour of lattice structures depends not only the composition of the base material, but also on the type and size of the unit cells, as well as on the material microstructure resulting from a specific fabrication procedure. The present work focuses on the static and fatigue behavior of diamond cell lattice structures fabricated from an AlSiMg alloy by laser powder bed fusion technology. In particular, the specimens were fabricated with three different orientations of lattice cells—[001], [011], [111]—and subjected to static tensile testing and force-controlled pull–pull fatigue testing up to 1 × 107 cycles. In parallel, the mechanical behavior of dense tensile plain and notched specimens was also studied and compared to that of their lattice counterparts. Results showed a significant effect of the cell orientation on the fatigue lives: specimens oriented at [001] were ~30% more fatigue-resistant than specimens oriented at [011] and [111].

  12. 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.

  13. Investigation on the Effect of Sub-Zero Treatment on Micro-Hardness and Microstructure of GTAW Welded Al-Si-Mg-Mn Alloy

    Science.gov (United States)

    Devanathan, R.; Yuvarajan, D.; Christopher Selvam, D.; Venkatamuni, T.

    2018-02-01

    In this work, the effect of sub-zero treatment on the mechanical properties of an Al-Si-Mg-Mn alloy welded by GTAW (gas tungsten arc welding) leads to significant softening in the welded region. The latter is due to melting and resolidification in the welded region, which have resulted in decomposition of the strengthening precipitates. The experiments were performed on GTAW welded plates of 6 mm thickness by varying the heat inputs, namely, of 370, 317.1, 277.5, 246.4, and 222 J/mm, and sub-zero treatment time periods. The Sub-Zero treatment was performed at-45°C using dry ice; hardness and microstructure investigations were performed in the welded region of the Al‒Si-Mg-Mn alloy that was studied in two different conditions, namely, as-welded and in that formed after post weld sub-zero treatment with artificial aging. It was found that the post weld Sub-Zero treatment followed by artificial aging had led to realization of significantly higher hardness values in the welded region due to the recurrence of the precipitation sequence.

  14. Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy.

    Science.gov (United States)

    Han, Xuesong; Zhu, Haihong; Nie, Xiaojia; Wang, Guoqing; Zeng, Xiaoyan

    2018-03-07

    AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut.

  15. Structural Properties of EB-Welded AlSi10Mg Thin-Walled Pressure Vessels Produced by AM-SLM Technology

    Science.gov (United States)

    Nahmany, Moshe; Stern, Adin; Aghion, Eli; Frage, Nachum

    2017-10-01

    Additive manufacturing of metals by selective laser melting (AM-SLM) is hampered by significant limitations in product size due to the limited dimensions of printing trays. Electron beam welding (EBW) is a well-established process that results in relatively minor metallurgical modifications in workpieces due to the ability of EBW to pass high-density energy to the related substance. The present study aims to evaluate structural properties of EB-welded AlSi10Mg thin-walled pressure vessels produced from components prepared by SLM technology. Following the EB welding process, leak and burst tests were conducted, as was fractography analysis. The welded vessels showed an acceptable holding pressure of 30 MPa, with a reasonable residual deformation up to 2.3% and a leak rate better than 1 × 10-8 std-cc s-1 helium. The failures that occurred under longitudinal stresses reflected the presence of two weak locations in the vessels, i.e., the welded joint region and the transition zone between the vessel base and wall. Fractographic analysis of the fracture surfaces of broken vessels displayed the ductile mode of the rupture, with dimples of various sizes, depending on the failure location.

  16. Influence of Sr, Fe and Mn content and casting process on the microstructures and mechanical properties of AlSi7Cu3 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zaidao [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France); Limodin, Nathalie; Tandjaoui, Amina; Quaegebeur, Philippe [Laboratoire de Mécanique de Lille (LML), FRE 3723, Ecole Centrale de Lille, 59651 Villeneuve d' Ascq (France); Osmond, Pierre [PSA Peugeot Citröen, Direction de la Recherche et de l' Innovation Automobile, Route de Gisy-78943, Vélizy-Villacoublay Cedex (France); Balloy, David [Unité Matériaux et Transformations, UMR CNRS 8207, Univ. Lille 1, 59655 Villeneuve d' Ascq (France)

    2017-03-24

    The effects of Strontium (Sr), Iron (Fe) and Manganese (Mn) additions, casting process (i.e., cooling rate) on the microstructures and mechanical properties of AlSi7Cu3 alloy were investigated. 2D and 3D metallographic and image analysis have been performed to measure the microstructural changes occurring at different Sr, Fe and Mn levels and casting process. The evolution of mechanical properties of the alloys has been monitored by Brinell and Vickers hardness measurement and tensile tests. Addition of Sr slightly refines the eutectic silicon particles but it also introduces more pores. The combined addition of Fe and Mn induces an increase of Fe-rich intermetallic compounds which include both α-Al{sub 15}(Fe,Mn){sub 3}Si{sub 2} and β-Al{sub 5}FeSi phase, while the volume fraction of porosity decreases with the Fe and Mn content increase. The secondary dendrite arm spacing slightly decreases with the addition of Sr, Fe and Mn alloying elements.

  17. Correlations Between Arrangement of Reinforcing Particles and Mechanical Properties in Pressure Die Cast AlSi11-SiC Composites

    Directory of Open Access Journals (Sweden)

    Konopka Z.

    2014-06-01

    Full Text Available The work presents the investigation results concerning the structure of composite pressure die castings with AlSi11 alloy matrix reinforced with SiC particles. Examination has been held for composites containing 10 and 20 volume percent of SiC particles. The arrangement of the reinforcing particles within the matrix has been qualitatively assessed in specimens cut out of the castings. The index of distribution was determined on the basis of particle count in elementary measuring fields. The tensile strength, the yield point and elongation of the obtained composite were measured. Composite castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and various injection gate width values. The regression equation describing the change of the considered arrangement particles index and mechanical properties were found as a function of the pressure die casting parameters. The infuence of particle arrangement in composite matrix on mechanical properties these material was examined and the functions of correlations between values were obtained. The conclusion gives the analysis and the interpretation of the obtained results.

  18. Aluminum Matrix Composite (AlSi7Mg2Sr0.03/SiCp Pistons Obtained by Mechanical Mixing Method

    Directory of Open Access Journals (Sweden)

    Maciej Dyzia

    2017-12-01

    Full Text Available Metal matrix composites are undoubtedly a group of advanced engineering materials. Compared to unreinforced matrix material, they are characterized by increased strength, greater stiffness, increased wear resistance, better mechanical properties and dimensional stability at elevated temperatures as well as lower density. Due to its very favorable tribological properties for many years research has been conducted on the application of MMC in friction node. The article presents important technological aspects related to the production and properties of composite pistons. Under industrial conditions, a composite suspension (AlSi7Mg2Sr0.03/SiCp 10 vol % was prepared to allow casting of the semi-finished pistons series. Machining parameters of the working surfaces of the piston were selected on the basis of the turning test made on PCD, PCNM and uncoated carbide tools. The tribological properties of the composite pistons were determined on the basis of the pin-on-disc and the abrasion wear. The scuffing tests carried out under real operating conditions have confirmed the possibility of using composite pistons in air compressors.

  19. Effect of Mn and AlTiB Addition and Heattreatment on the Microstructures and Mechanical Properties of Al-Si-Fe-Cu-Zr Alloy.

    Science.gov (United States)

    Yoo, Hyo-Sang; Kim, Yong-Ho; Lee, Seong-Hee; Son, Hyeon-Taek

    2018-09-01

    The microstructure and mechanical properties of as-extruded Al-0.1 wt%Si-0.2 wt%Fe- 0.4 wt%Cu-0.04 wt%Zr-xMn-xAlTiB (x = 1.0 wt%) alloys under various annealing processes were investigated and compared. After the as-cast billets were kept at 400 °C for 1 hr, hot extrusion was carried out with a reduction ratio of 38:1. In the case of the as-extruded Al-Si-Fe-Cu-Zr alloy at annealed at 620 °C, large equiaxed grain was observed. When the Mn content is 1.0 wt%, the phase exhibits a skeleton morphology, the phase formation in which Mn participated. Also, the volume fraction of the intermetallic compounds increased with Mn and AlTiB addition. For the Al-0.1Si-0.2Fe-0.4Cu-0.04Zr alloy with Mn and AlTiB addition from 1.0 wt%, the ultimate tensile strength increased from 100.47 to 119.41 to 110.49 MPa. The tensile strength of the as-extruded alloys improved with the addition of Mn and AlTiB due to the formation of Mn and AlTiB-containing intermetallic compounds.

  20. Effect of high-intensity ultrasonic irradiation on the modification of solidification microstructure in a Si-rich hypoeutectic Al-Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Das, A., E-mail: A.Das@swansea.ac.uk [Materials Research Centre, School of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Kotadia, H.R. [Brunel Centre for Advanced Solidification Technology, Brunel University, Uxbridge, UB8 3PH (United Kingdom)

    2011-02-15

    Effect of high-intensity ultrasound irradiation in modifying complex solidification microstructure is explored in a high Si containing Al-Si alloy and the origin of microstructural changes explained on the basis of nucleation and growth behaviour. Complete suppression of dendritic growth and dramatic refinement to globular morphology were observed for primary {alpha}-Al grains. Strong supportive evidence is presented towards enhanced and prolonged heterogeneous nucleation triggered by cavitation induced increase in the equilibrium melting point and effective dissipation of latent heat at the solidification front. Morphological evolution of eutectic Si and intermetallic particles is found to be dominated by coarsening and spherodisation from strong fluid flow in areas of intense cavitation near the ultrasonic radiator. Outside the region of direct energy transfer, Si particle morphology appears to be controlled predominantly by the imposed cooling conditions. Extremely fine and short Si-platelets observed in the intergranular spaces near the radiator are explained on the basis of probable rapid cooling of final liquid pockets of small volume and large surface area, rather than refinement through ultrasound.

  1. Carbon-shell-constrained silicon cluster derived from Al-Si alloy as long-cycling life lithium ion batteries anode

    Science.gov (United States)

    Su, Junming; Zhang, Congcong; Chen, Xiang; Liu, Siyang; Huang, Tao; Yu, Aishui

    2018-03-01

    Although silicon is the most promising anode material for Li-ion batteries, large volume expansion during lithiation and delithiation is the main obstacle limiting the commercial application of silicon anodes. There are two ways to alleviate volume expansion and prevent further pulverization of a Si anode: fabrication of a rational nanostructure possessing void spaces and uniform distribution of the conducting sites, without a good balance effect in mitigating the limiting factors and enhancing battery performance. In this paper, we propose a novel nanostructure - a carbon-shell-constrained Si cluster (Si/C shell) with both adequate void space and good distribution of electrical contact sites to guarantee homogeneous lithiation in the initial cycle. Benefiting from the ability to maintain electrical conductivity of the outer carbon shell, even after cluster fragmentation, the Si/C shell synthesized from low-cost commercial Al-Si alloy spheres can deliver 0.03% capacity loss from 100th to 1000th cycles at a current density of 1 A g-1. The Si/C shell sample with the dual functional structure mentioned above can also maintain its own nanostructure during cycling and deliver excellent rate performance. It is a concise and scalable strategy which can simplify the preparation of other alloy anode materials for Li-ion batteries.

  2. On the role of heat and mass transfer into laser processability during selective laser melting AlSi12 alloy based on a randomly packed powder-bed

    Science.gov (United States)

    Wang, Lianfeng; Yan, Biao; Guo, Lijie; Gu, Dongdong

    2018-04-01

    A newly transient mesoscopic model with a randomly packed powder-bed has been proposed to investigate the heat and mass transfer and laser process quality between neighboring tracks during selective laser melting (SLM) AlSi12 alloy by finite volume method (FVM), considering the solid/liquid phase transition, variable temperature-dependent properties and interfacial force. The results apparently revealed that both the operating temperature and resultant cooling rate were obviously elevated by increasing the laser power. Accordingly, the resultant viscosity of liquid significantly reduced under a large laser power and was characterized with a large velocity, which was prone to result in a more intensive convection within pool. In this case, the sufficient heat and mass transfer occurred at the interface between the previously fabricated tracks and currently building track, revealing a strongly sufficient spreading between the neighboring tracks and a resultant high-quality surface without obvious porosity. By contrast, the surface quality of SLM-processed components with a relatively low laser power notably weakened due to the limited and insufficient heat and mass transfer at the interface of neighboring tracks. Furthermore, the experimental surface morphologies of the top surface were correspondingly acquired and were in full accordance to the calculated results via simulation.

  3. 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)

  4. Effect of Different Variants of Heat Treatment on Mechanical Properties of the AlSi17CuNiMg Alloy

    Directory of Open Access Journals (Sweden)

    Jarco A.

    2016-06-01

    Full Text Available Dispersion hardening, as the main heat treatment of silumins having additions of copper and magnesium, results in considerable increase of tensile strength and hardness, with simultaneous decrease of ductility of the alloy. In the paper is presented an attempt of introduction of heat treatment operation consisting in homogenizing treatment prior operation of the dispersion hardening, to minimize negative effects of the T6 heat treatment on plastic properties of hypereutectoidal AlSi17CuNiMg alloy. Tests of the mechanical properties were performed on a test pieces poured in standardized metal moulds. Parameters of different variants of the heat treatment, i.e. temperature and time of soaking for individual operations were selected basing on the ATD (Thermal Derivation Analysis diagram and analysis of literature. The homogenizing treatment significantly improves ductility of the alloy, resulting in a threefold increase of the elongation and more than fourfold increase of the impact strength in comparison with initial state of the alloy. Moreover, the hardness and the tensile strength (Rm of the alloy decrease considerably. On the other hand, combination of the homogenizing and dispersion hardening enables increase of elongation with about 40%, and increase of the impact strength with about 25%, comparing with these values after the T6 treatment, maintaining high hardness and slight increase of the tensile strength, comparing with the alloy after the dispersion hardening.

  5. The high temperature synthesis of CsAlSiO 4-ANA, a new polymorph in the system Cs 2OAl 2O 3SiO 2. I. The end member of ANA type of zeolite framework

    Science.gov (United States)

    Dimitrijevic, R.; Dondur, V.; Petranovic, N.

    1991-12-01

    High temperature phase transformations of Cs + exchanged zeolites were investigated. Above 1000°C, CsX, CsY (FAU), and Cs, ZK-4 (LTA) frameworks recrystallized in a pollucite phase. A Cs + loaded mordenite recrystallized at 1300°C in the orthorhombic CsAlSi 5O 12 phase. A Cs + exchanged zeolite A at 960°C recrystallized in a mixture of two polymorphic CsAlSiO 4 phases having different (Al,Si)O 4 frameworks. The unstable orthorhombic CsAlSiO 4ABW phase has a topotactic transition at 1150°C into an ordered low CsAlSiO 4-ANA framework. Further calcination produces, at 1200°C, transformation of the low CsAlSiO 4-ANA phase to the more stable high CsAlSiO 4-ANA polymorph having cubic ( a 0 = 13.6595 (5) Å) symmetry and an ordered SiAl distribution. The crystal structure of high CsAlSiO 4ANA, a new polymorph in the system Cs 2OAl 2O 3SiO 2, was determined using X-ray Rietveld analyses and 29Si MAS NMR spectroscopy.

  6. 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

  7. Phase formation in as-solidified and heat-treated Al-Si-Cu-Mg-Ni alloys: Thermodynamic assessment and experimental investigation for alloy design

    Energy Technology Data Exchange (ETDEWEB)

    Farkoosh, A.R., E-mail: amir.rezaeifarkoosh@mail.mcgill.ca [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada); Javidani, M. [Laval University, Department of Mining, Metallurgy and Materials Engineering, Aluminum Research Center - REGAL, 1065 Ave de la Medecine, Quebec, Canada G1V 0A6 (Canada); Hoseini, M. [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada); Larouche, D. [Laval University, Department of Mining, Metallurgy and Materials Engineering, Aluminum Research Center - REGAL, 1065 Ave de la Medecine, Quebec, Canada G1V 0A6 (Canada); Pekguleryuz, M. [Department of Mining and Materials Engineering, McGill University, 3610 University, Aluminum Research Center - REGAL, Montreal, Quebec, Canada H3A 2B2 (Canada)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Phase formation in Al-Si-Ni-Cu-Mg-Fe system have been investigated. Black-Right-Pointing-Pointer T-Al{sub 9}FeNi, {gamma}-Al{sub 7}Cu{sub 4}Ni, {delta}-Al{sub 3}CuNi and {epsilon}-Al{sub 3}Ni are formed at different Ni levels. Black-Right-Pointing-Pointer Thermally stable Ni-bearing precipitates improved the overaged hardness. Black-Right-Pointing-Pointer It was found that Ni:Cu and Ni:Fe ratios control the precipitation. Black-Right-Pointing-Pointer {delta}-Al{sub 3}CuNi phase has more contribution to strength compare to other precipitates. - Abstract: Thermodynamic simulations based on the CALPHAD method have been carried out to assess the phase formation in Al-7Si-(0-1)Ni-0.5Cu-0.35Mg alloys (in wt.%) under equilibrium and non-equilibrium (Scheil cooling) conditions. Calculations showed that the T-Al{sub 9}FeNi, {gamma}-Al{sub 7}Cu{sub 4}Ni, {delta}-Al{sub 3}CuNi and {epsilon}-Al{sub 3}Ni phases are formed at different Ni levels. By analyzing the calculated isothermal sections of the phase diagrams it was revealed that the Ni:Cu and Ni:Fe ratios control precipitation in this alloy system. In order to verify the simulation results, microstructural investigations in as-cast, solution treated and aged conditions were carried out using electron probe microanalysis (EPMA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, cooling curve analysis (CCA) was also performed to determine the freezing range of the new alloys and porosity formation during solidification. Hardness measurements of the overaged samples showed that in this alloy system the {delta}-Al{sub 3}CuNi phase has a greater influence on the overall strength of the alloys compared to the other Ni-bearing precipitates.

  8. Improving High-Temperature Tensile and Low-Cycle Fatigue Behavior of Al-Si-Cu-Mg Alloys Through Micro-additions of Ti, V, and Zr

    Science.gov (United States)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2015-07-01

    High-temperature tensile and low-cycle fatigue tests were performed to assess the influence of micro-additions of Ti, V, and Zr on the improvement of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in the as-cast condition. Addition of transition metals led to modification of microstructure where in addition to conventional phases present in the Al-7Si-1Cu-0.5Mg base, new thermally stable micro-sized Zr-Ti-V-rich phases Al21.4Si4.1Ti3.5VZr3.9, Al6.7Si1.2TiZr1.8, Al2.8Si3.8V1.6Zr, and Al5.1Si35.4Ti1.6Zr5.7Fe were formed. The tensile tests showed that with increasing test temperature from 298 K to 673 K (25 °C to 400 °C), the yield stress and tensile strength of the present studied alloy decreased from 161 to 84 MPa and from 261 to 102 MPa, respectively. Also, the studied alloy exhibited 18, 12, and 5 pct higher tensile strength than the alloy A356, 354 and existing Al-Si-Cu-Mg alloy modified with additions of Zr, Ti, and Ni, respectively. The fatigue life of the studied alloy was substantially longer than those of the reference alloys A356 and the same Al-7Si-1Cu-0.5Mg base with minor additions of V, Zr, and Ti in the T6 condition. Fractographic analysis after tensile tests revealed that at the lower temperature up to 473 K (200 °C), the cleavage-type brittle fracture for the precipitates and ductile fracture for the matrix were dominant while at higher temperature fully ductile-type fracture with debonding and pull-out of cracked particles was identified. It is believed that the intermetallic precipitates containing Zr, Ti, and V improve the alloy performance at increased temperatures.

  9. 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.

  10. 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

  11. High-pressure phase relations in the composition of albite NaAlSi3O8 constrained by an ab initio and quasi-harmonic Debye model, and their implications

    Science.gov (United States)

    Deng, L.; Liu, X.; Liu, H.; Dong, J.

    2010-12-01

    The high pressure physical-chemical behaviors of feldspar in subducted slab are very important to the geodynamic process in the deep interior of the Earth. Albite (NaAlSi3O8;Ab) is one of the few end members in the feldspar family, and its high-P behavior is obviously a prerequisite to the full understanding of the physical-chemical properties of feldspar at high pressures. So far it has been well accepted that Ab breaks down to the phase assemblage of Jadeite+Stishovite(NaAlSi2O6; Jd, SiO2; St,JS hereafter) at ~9-10 GPa. The JS phase assemblage might be stable up to ~23 GPa, and eventually directly change into the phase assemblage of calcium-ferrite type NaAlSiO4 (Cf) +2St (CS hereafter). However, some independent researches suggest there is an intermediate phase Na-hollandite (Na-Hall; a phase with the composition of NaAlSi3O8 and the structure of hollandite) between JS phase assemblage transition into CS phase assemblage (Liu 1978; Tutti 2007; Sekine and Ahrens, 1992; Beck et al., 2004). Whether Na-Hall is a thermodynamic stable phase under high P-T conditions remains unknown. In this work, phase relations in the composition of albite NaAlSi3O8 at pressures up to 40 GPa were constrained by a theoretical method that combines the ab initio calculation and quasi-harmonic Debyemodel. First, the P-T dependence of the thermodynamic potentials of the individual phase, St, Cf, Jd and the hypothetical Na-Holl were derived. Our results are generally in consistent agreement with available experimental data and previous theoretical predictions. Second, the Gibbs free energy of the hypothetical Na-Holl phase was compared with that of the phase assemblages JS and CS. Our results show that the Na-Holl phase is not a thermodynamically stable phase over the studied P-T conditions of 0-40 GPa and 100-600 K, which rules it out as a possible intermediate phase along the transition path from the JS phase assemblage to CS phase assemblage. Our calculations have predicted that the JS

  12. 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.

  13. Characterization of cylinder liners produced with hypereutectic Al-Si alloys and investigation of corrosion behaviour in synthetic automotive condensed solution

    International Nuclear Information System (INIS)

    Santos, Hamilta de Oliveira

    2006-01-01

    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

  14. 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.

  15. 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.

  16. Magnetocrystalline anisotropy constants, rotational hysteresis energy and magnetic domain structure in UFe6Al6, UFe9AlSi2 and ScFe10Si2 intermetallic compounds

    International Nuclear Information System (INIS)

    Wyslocki, J.J.; Pawlik, P.; Wochowski, K.; Kotur, B.; Bodak, O.I.

    1996-01-01

    The magnetic torque, T, was applied to determine the anisotropy constants K 1 and K 2 of the UFe 6 Al 6 , UFe 9 AlSi 2 and ScFe 10 Si 2 compounds. The mechanism of magnetization reversal processes in these compounds was investigated on the basis of the analysis of the rotational hysteresis energy, W r and rotational hysteresis integral, R, calculated from the magnetic torque curves. Applying the powder pattern method, magnetic domain structures were observed. Moreover, the fundamental parameters of the domain structure were determined. (orig.)

  17. 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.

  18. Catarata e diabetes mellitus tipo 1

    OpenAIRE

    Pizzol,Melissa Manfroi Dal; Esteves,Jorge Freita; Sccoco,Caio Augusto; Roggia,Murilo Felix; Rosa,Carolina Maurente da; Lambert,José Humberto Franco; Canani,Luís Henrique

    2008-01-01

    OBJETIVO: Avaliar a prevalência de catarata e seus fatores de risco em uma população portadora de diabetes mellitus tipo 1 (DM1). MÉTODOS: Estudo de casos e controles de um banco de dados de 181 pacientes (362 olhos) com diagnóstico de diabetes mellitus tipo 1. Os pacientes foram classificados como casos quando apresentavam diagnóstico de catarata. As variáveis estudadas foram a presença ou não de retinopatia diabética, tratamento com panfotocoagulação, presença de hipertensão arterial sistêm...

  19. The role of the bimodal distribution of ultra-fine silicon phase and nano-scale V-phase (AlSi2Sc2) on spark plasma sintered hypereutectic Al–Si–Sc alloys

    International Nuclear Information System (INIS)

    Raghukiran, Nadimpalli; Kumar, Ravi

    2016-01-01

    Hypereutectic Al–Si and Al–Si–Sc alloys were spark plasma sintered from corresponding gas-atomized powders. The microstructures of the Al–Si and Al–Si–Sc alloys possessed remarkably refined silicon particles in the size range of 0.38–3.5 µm and 0.35–1.16 µm respectively in contrast to the silicon particles of size greater than 100 µm typically found in conventionally cast alloys. All the sintered alloys exhibited significant ductility of as high as 85% compressive strain without failure even with the presence of relatively higher weight fraction of the brittle silicon phase. Moreover, the Al–Si–Sc alloys have shown appreciable improvement in the compressive strength over their binary counterparts due to the presence of intermetallic compound AlSi 2 Sc 2 of size 10–20 nm distributed uniformly in the matrix of those alloys. The dry sliding pin-on-disc wear tests showed improvement in the wear performance of the sintered alloys with increase in silicon content in the alloys. Further, the Al–Si–Sc ternary alloys with relatively lesser silicon content exhibited appreciable improvement in the wear resistance over their binary counterparts. The Al–Si–Sc alloys with bimodal distribution of the strengthening phases consisting of ultra-fine (sub-micron size) silicon particles and the nano-scale AlSi 2 Sc 2 improved the strength and wear properties of the alloys while retaining significant amount of ductility.

  20. Thermal stability of (AlSi){sub x}(ZrVTi) intermetallic phases in the Al–Si–Cu–Mg cast alloy with additions of Ti, V, and Zr

    Energy Technology Data Exchange (ETDEWEB)

    Shaha, S.K. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Czerwinski, F., E-mail: Frank.Czerwinski@nrcan.gc.ca [CanmetMATERIALS, Natural Resources Canada, 183 Longwood Road South, Hamilton, Ontario L8P 0A5 (Canada); Kasprzak, W. [CanmetMATERIALS, Natural Resources Canada, 183 Longwood Road South, Hamilton, Ontario L8P 0A5 (Canada); Friedman, J.; Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)

    2014-11-10

    Highlights: • Al–Si–Cu–Mg alloy was modified by introducing Zr, V, and Ti. • The chemistry of the phases was identified using SEM/EDX. • The crystal lattice parameters of the phases were characterized using EBSD. • To investigate the phase stability, XRD was performed up to 600 °C. • Thermal analysis was done to find out the possible phase transformation reactions. - Abstract: The Al–Si–Cu–Mg cast alloy was modified with additions of Ti–V–Zr to improve the thermal stability of intermetallics at increased temperatures. A combination of electron microscopy, electron backscatter diffraction, and high temperature X-ray diffraction was explored to identify phases and temperatures of their thermal stability. The micro-additions of transition metals led to formation of several (AlSi){sub x}(TiVZr) phases with D0{sub 22}/D0{sub 23} tetragonal crystal structure and different lattice parameters. While Cu and Mg rich phases along with the eutectic Si dissolved at temperatures from 300 to 500 °C, the (AlSi){sub x}(TiVZr) phases were stable up to 696–705 °C which is the beneficial to enhance the high temperature properties. Findings of this study are useful for selecting temperatures during melting and heat treatment of Al–Si alloys with additions of transition metals.

  1. Core–shell structured FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite cores with tunable insulating layer thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang, E-mail: ligq-wust@mail.wust.edu.cn [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

    2015-11-15

    Graphical abstract: - Highlights: • FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores were prepared. • SiO{sub 2} surrounding FeSiAl were replaced by Al{sub 2}O{sub 3} during sintering process. • Fe{sub 3}Si particles were separated by Al{sub 2}O{sub 3} with tunable thickness in composite cores. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than FeSiAl core. • The insulating layer between ferromagnetic particles can reduce core loss. - Abstract: FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses have been synthesized via a modified Stöber method combined with following high temperature sintering process. Most of the conductive FeSiAl particles could be coated by insulating SiO{sub 2} using the modified Stöber method. During the sintering process, the reaction 4Al + 3SiO{sub 2} ≣ 2α-Al{sub 2}O{sub 3} + 3Si took place and the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher resistivity and lower core loss than the raw FeSiAl core. Based on this, several types of FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses were selectively prepared by simply varying TEOS contents. The thickness of Al{sub 2}O{sub 3} insulating layer and resistivity of Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores increased with increasing the TEOS contents, while the permeability and core loss changed in the opposite direction.

  2. 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.

  3. Projectile-z3 and -z4 corrections to basic Bethe-Bloch stopping power theory and mean excitation energies of Al, Si, Ni, Ge, Se, Y, Ag and Au

    International Nuclear Information System (INIS)

    Porter, L.E.; Bryan, S.R.

    1980-01-01

    Three independent sets of measurements of the stopping power of solid elemental targets for alpha particles were previously analyzed in terms of basic Bethe-Bloch theory with the low velocity projectile-z 3 correction term included. These data for Al, Si, Ni, Ge, Se, Y, Ag and Au have now been analyzed with the Bloch projectile-z 4 term and a revised projectile-z 3 term incorporated in the Bethe-Bloch formula, the projectile-z 3 revision having been effected by variation of the single free parameter of the projectile-z 3 effect formalism. The value of this parameter, fixed at 1.8 in previous studies, which counteracts inclusion of the projectile-z 4 term is 1.3 +- 0.1 for all target elements except Si. (orig.)

  4. Electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Guezlane, M. [Department of Physics, Faculty of Science, University of Batna, 05000 Batna (Algeria); Baaziz, H., E-mail: baaziz_hakim@yahoo.fr [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); El Haj Hassan, F., E-mail: hassan.f@ul.edu.lb [Université Libanaise, Faculté des Sciences (I), Laboratoire de Physique et d’Electronique (LPE), Elhadath, Beirut (Lebanon); Charifi, Z. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Djaballah, Y. [Laboratoire d’étude Physico-Chimique des Matériaux, Département de Physique, Faculté des Sciences, Université de Batna, Rue Chahid Boukhlouf, 05000 Batna (Algeria)

    2016-09-15

    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 Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) full Heusler alloys, with L2{sub 1} 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 Co{sub 2}Cr{sub x}Fe{sub 1−x}X 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. - Highlights: • We present electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys. • The calculated phase diagram indicates a significant phase miscibility gap. • The computed band structures of ternary compounds using GGA, EVGGA and mBJ schemes indicate an indirect band gap (Γ-X) for the ternary compounds Co{sub 2}FeAl, Co{sub 2}CrAl, Co{sub 2}FeSi and Co{sub 2}CrSi while both alloys have a direct band gap. • The quasi-harmonic Debye model is successfully applied to determine the thermal properties.

  5. Divergência genética entre genótipos de frangos tipo caipira

    Directory of Open Access Journals (Sweden)

    R. C. Veloso

    2015-10-01

    Full Text Available RESUMOObjetivou-se com este trabalho verificar a divergência genética entre sete genótipos de frangos tipo caipira da linhagem Redbro utilizando as características de desempenho por meio de técnicas de análise multivariada. Foram utilizados 840 pintos de um dia, machos, distribuídos em delineamento inteiramente ao acaso, dos seguintes genótipos: Caboclo, Carijó, Colorpak, Gigante Negro, Pesadão Vermelho, Pescoço Pelado e Tricolor. Após a consistência dos dados, foram avaliadas as seguintes variáveis: ganho em peso médio diário, consumo de ração médio diário e conversão alimentar, para os períodos: 1 a 28, 1 a 56, 1 a 70 e 1 a 84 dias de idade; peso corporal ao nascimento, aos 28, 56, 70 e aos 84 dias de idade. O desempenho dos genótipos foi avaliado por meio da análise de variância multivariada e da função discriminante linear de Fisher, usando os testes do maior autovalor de Roy e da união-interseção de Roy para as comparações múltiplas. O estudo da divergência genética foi feito por meio da análise por variáveis canônicas e pelo método de otimização de Tocher. Os genótipos Caboclo e Gigante Negro apresentaram médias canônicas diferentes dos demais genótipos. As duas primeiras variáveis canônicas explicaram 97,41% da variação entre os genótipos. A divergência genética entre os genótipos avaliados permitiu a formação de quatro grupos com os seguintes genótipos: grupo 1 - Colorpak; grupo 2 - Pesadão Vermelho e Pescoço Pelado; grupo 3 - Carijó e Tricolor; e grupo 4 - Caboclo e Gigante Negro.

  6. 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

  7. O oraloma da diabetes melitos tipo 1 vs diabetes melitos tipo 2 - um estudo comparativo

    OpenAIRE

    Brás, Vítor Daniel Moreira

    2013-01-01

    A Diabetes Melitos é uma doença de grande prevalência a nível mundial e os seus mecanismos fisiopatológicos não são ainda totalmente conhecidos. Actualmente, a terapêutica seguida em casos de Diabetes Melitos é eminentemente sintomática consistindo na administração de insulina nos casos de Diabetes Melitos tipo 1 ou quando se verifica a falência das células beta do pâncreas de pacientes com Diabetes Melitos tipo 2, ou no controlo da glicemia nos casos de Diabetes Melitos ...

  8. Diabetes tipo II e resolvinas D1

    OpenAIRE

    Silva, Isabel Alexandra Marques Batista da

    2015-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz A diabetes é um problema de saúde pública crescente com o envelhecimento da população, os maus hábitos alimentares e o sedentarismo. A obesidade poderá ser causa ou consequência da diabetes tipo II, sendo também um problema crescente de saúde pública. Esta monografia tem como objetivo estudar, com base no conhecimento atual, se as resolvinas D1 são uma alternativa viável na terapêutica da diab...

  9. Estereótipos e mulheres na cultura marroquina

    OpenAIRE

    Sadiqi,Fatima

    2008-01-01

    Estereótipos sobre as mulheres no Marrocos podem ser caracterizados como crenças culturais incompletas e inexatas mantidas por algumas pessoas e que se encontram inscritos em expressões lingüísticas ou em discursos subliminares. A cultura popular marroquina emprega representações poderosas para transmitir e sustentar tais estereótipos. Embora existam alguns estereótipos positivos, a maioria dos estereótipos sobre as mulheres no Marrocos é negativa e reflete ditames patriarcais subliminares qu...

  10. MAX phase – Alumina composites via elemental and exchange reactions in the Ti{sub n+1}AC{sub n} systems (A=Al, Si, Ga, Ge, In and Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Cuskelly, Dylan, E-mail: dylan.cuskelly@uon.edu.au; Richards, Erin; Kisi, Erich, E-mail: Erich.Kisi@newcastle.edu.au

    2016-05-15

    Extension of the aluminothermal exchange reaction synthesis of M{sub n+1}AX{sub n} phases to systems where the element ‘A’ is not the reducing agent was investigated in systems TiO{sub 2}–A–Al–C for A=Al, Si, Ga, Ge, In and Sn as well as Cr{sub 2}O{sub 3}–Ga–Al–C. MAX phase-Al{sub 2}O{sub 3} composites were made in all systems except those with A=Ga or In. The effectiveness of conversion to MAX phases was generally in the range 63–96% without optimisation of starting ratios. Optimisation in the Ti–Si–C system gave a MAX phase component with >98% Ti{sub 3}SiC{sub 2}. - Graphical abstract: A range of Ti{sub n+1}AX{sub n} phases with different A elements were synthesised directly from the M oxide via exchange reactions. The process has now been shown to be general in all the systems marked in green in the table. - Highlights: • Ti{sub n+1}AC{sub n} phases were produced via a single step exchange reaction. • 3 MAX phase systems were successful via this method for the first time. • Cr{sub 2}GeC was also able to be produced via an exchange reaction. • The interconversion reaction in MAX phases is more general than previously thought.

  11. Effect of Al2Cu precipitates size and mass transport on the polarisation behaviour of age-hardened Al-Si-Cu-Mg alloys in 0.05 M NaCl

    International Nuclear Information System (INIS)

    Vieira, A.C.; Pinto, A.M.; Rocha, L.A.; Mischler, S.

    2011-01-01

    Research highlights: → Influence of the size distribution of Al-Cu phases on the electrochemical behaviour of well defined alloys under controlled mass transport conditions (RDE). → Oxygen reduction occurs only the Al 2 Cu phases. → 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 2 Cu phase, on the corrosion behaviour of the alloy. Three different size distributions of the Al 2 Cu phase were obtained through appropriate heat treatments. The cathodic reduction of oxygen was found to occur mainly on the Al 2 Cu phases acting as preferential cathodes. Small sized Al 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.

  12. 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.

  13. Effect of the Die Temperature and Blank Thickness on the Formability of a Laser-Welded Blank of a Boron Steel Sheet with Removing Al-Si Coating Layer

    Directory of Open Access Journals (Sweden)

    M. S. Lee

    2014-05-01

    Full Text Available Reducing carbon emissions has been a major focus in the automobile industry to address various environmental issues. In particular, studies on parts comprised of high strength sheets and light car bodies are ongoing. Accordingly, this study examined the use of boron steel, which is commonly used in high strength sheets. Boron steel is a type of sheet used for hot stamping parts. Although it has high strength, the elongation is inferior, which reduces its crash energy absorption capacity. To solve this problem, two sheets of different thickness were welded so the thin sheet would absorb crash energy and the thick sheet would work as a support. Boron steel, however, may show weakening at the welding spot due to the Al-Si coating layer used to prevent oxidation from occurring during the welding process. Therefore, a certain part of the coating layer of a double-thickness boron steel sheet that is welded in the hot stamping process is removed through laser ablation, and the formability of the hot-work was examined.

  14. ''114''-type nitrides LnAl(Si{sub 4-x}Al{sub x})N{sub 7}O{sub δ} with unusual [AlN{sub 6}] octahedral coordination

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Saifang; Ouyang, Xin [School of Materials Science and Technology, China University of Geosciences, Beijing (China); Department of Chemical and Materials Engineering, University of Auckland (New Zealand); Huang, Zhaohui; Fang, Minghao; Liu, Yan-gai [School of Materials Science and Technology, China University of Geosciences, Beijing (China); Cao, Peng; Gao, Wei [Department of Chemical and Materials Engineering, University of Auckland (New Zealand); Zujovic, Zoran; Soehnel, Tilo [School of Chemical Sciences, University of Auckland (New Zealand); Price, Jason R. [Australian Synchrotron, Clayton, VIC (Australia); Avdeev, Maxim [Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Que, Meidan [School of Electronic and Information Engineering, Xi' an Jiaotong University (China); Suzuki, Furitsu; Kido, Tsuyoshi; Kaji, Hironori [Institute for Chemical Research, Kyoto University (Japan)

    2017-03-27

    Aluminum-nitrogen six-fold octahedral coordination, [AlN{sub 6}], is unusual and has only been seen in the high-pressure rocksalt-type aluminum nitride or some complex compounds. Herein we report novel nitrides LnAl(Si{sub 4-x}Al{sub x})N{sub 7}O{sub δ} (Ln=La, Sm), the first inorganic compounds with [AlN{sub 6}] coordination prepared via non-high-pressure synthesis. Structure refinements of neutron powder diffraction and single-crystal X-ray diffraction data show that these compounds crystallize in the hexagonal Swedenborgite structure type with P6{sub 3}mc symmetry where Ln and Al atoms locate in anticuboctahedral and octahedral interstitials, respectively, between the triangular and Kagome layers of [SiN{sub 4}] tetrahedra. Solid-state NMR data of high-purity La-114 powders confirm the unusual [AlN{sub 6}] coordination. These compounds are the first examples of the ''33-114'' sub-type in the ''114'' family. The additional site for over-stoichiometric oxygen in the structure of 114-type compounds was also identified. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Effects of {gamma}-ray irradiation on the C-V and G/{omega}-V characteristics of Al/SiO{sub 2}/p-Si (MIS) structures

    Energy Technology Data Exchange (ETDEWEB)

    Doekme, Ilbilge [Science Education Department, Faculty of Education, Ahi Evran University, Kirsehir (Turkey)], E-mail: ilbilgedokme@gazi.edu.tr; Durmus, Perihan; Altindal, Semsettin [Physics Department, Faculty of Arts and Sciences, Gazi University, 06500 Teknikokullar, Ankara (Turkey)

    2008-03-15

    The effect of the {sup 60}C{sub o} ({gamma}-ray) exposure on the electrical characteristics of Al/SiO{sub 2}/p-Si (MIS) structures has been investigated using capacitance-voltage (C-V) and conductance-voltage (G/{omega}-V) measurements. The MIS structures were stressed with a bias of 0 V during {sup 60}C{sub o}{gamma}-sources irradiation with the total dose range from 0 to 25 kGy. The C-V and G/{omega}-V characteristics were measured at 500 kHz and room temperature before and after {sup 60}C{sub o}{gamma}-ray irradiation. The results indicated that {gamma}-irradiation caused an increase in the barrier height {phi}{sub B}, interface states N{sub ss} and depletion layer width W{sub D} obtained from reverse bias C-V measurements. The series resistance R{sub s} profile for various radiation doses was obtained from forward and reverse bias C-V and G/{omega}-V measurements. Both C-V and G/{omega}-V characteristics indicate that the total dose radiation hardness of MIS structures may be limited by the decisive properties of the SiO{sub 2}/Si interface to radiation-induced damage. After {gamma}-irradiation, the decrease in capacitance of MIS structure results in the increase in the semiconductor depletion width.

  16. Influence of pores on crack initiation in monotonic tensile and cyclic loadings in lost foam casting A319 alloy by using 3D in-situ analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Long, E-mail: longwang_calt@163.com [Univ. Lille, CNRS, Centrale Lille, Arts et Metiers Paris tech, FRE 3723 – LML – Laboratoire de Mecanique de Lille, F-59000 Lille (France); Limodin, Nathalie; El Bartali, Ahmed; Witz, Jean-François; Seghir, Rian [Univ. Lille, CNRS, Centrale Lille, Arts et Metiers Paris tech, FRE 3723 – LML – Laboratoire de Mecanique de Lille, F-59000 Lille (France); Buffiere, Jean-Yves [Laboratoire Matériaux, Ingénierie et Sciences (MATEIS), CNRS UMR5510, INSA-Lyon, 20 Av. Albert Einstein, 69621 Villeurbanne (France); Charkaluk, Eric [Univ. Lille, CNRS, Centrale Lille, Arts et Metiers Paris tech, FRE 3723 – LML – Laboratoire de Mecanique de Lille, F-59000 Lille (France)

    2016-09-15

    Lost Foam Casting (LFC) process is replacing the conventional gravity Die Casting (DC) process in automotive industry for the purpose of geometry optimization, cost reduction and consumption control. However, due to lower cooling rate, LFC produces in a coarser microstructure that reduces fatigue life. In order to study the influence of the casting microstructure of LFC Al-Si alloy on damage micromechanisms under monotonic tensile loading and Low Cycle Fatigue (LCF) at room temperature, an experimental protocol based on the three dimensional (3D) in-situ analysis has been set up and validated. This paper focuses on the influence of pores on crack initiation in monotonic and cyclic tensile loadings. X-ray Computed Tomography (CT) allowed the microstructure of material being characterized in 3D and damage evolution being followed in-situ also in 3D. Experimental and numerical mechanical fields were obtained by using Digital Volume Correlation (DVC) technique and Finite Element Method (FEM) simulation respectively. Pores were shown to have an important influence on strain localization as large pores generate enough strain localization zones for crack initiation both in monotonic tensile and cyclic loadings.

  17. Influence of pores on crack initiation in monotonic tensile and cyclic loadings in lost foam casting A319 alloy by using 3D in-situ analysis

    International Nuclear Information System (INIS)

    Wang, Long; Limodin, Nathalie; El Bartali, Ahmed; Witz, Jean-François; Seghir, Rian; Buffiere, Jean-Yves; Charkaluk, Eric

    2016-01-01

    Lost Foam Casting (LFC) process is replacing the conventional gravity Die Casting (DC) process in automotive industry for the purpose of geometry optimization, cost reduction and consumption control. However, due to lower cooling rate, LFC produces in a coarser microstructure that reduces fatigue life. In order to study the influence of the casting microstructure of LFC Al-Si alloy on damage micromechanisms under monotonic tensile loading and Low Cycle Fatigue (LCF) at room temperature, an experimental protocol based on the three dimensional (3D) in-situ analysis has been set up and validated. This paper focuses on the influence of pores on crack initiation in monotonic and cyclic tensile loadings. X-ray Computed Tomography (CT) allowed the microstructure of material being characterized in 3D and damage evolution being followed in-situ also in 3D. Experimental and numerical mechanical fields were obtained by using Digital Volume Correlation (DVC) technique and Finite Element Method (FEM) simulation respectively. Pores were shown to have an important influence on strain localization as large pores generate enough strain localization zones for crack initiation both in monotonic tensile and cyclic loadings.

  18. Comprometimento medular por linfoma tipo Burkitt: relato de um caso

    Directory of Open Access Journals (Sweden)

    Murillo Côrtes Drummond

    1985-06-01

    Full Text Available Registro de caso de linfoma tipo Burkitt com comprometimento intrarraqueano em criança de três anos de idade. Considerações sobre esse tipo de tumor são feitas em função do caso observado e de dados da literatura.

  19. Lesao óssea em leucemias agudas linfoblásticas tipo T e TIPO nao T / nao B

    OpenAIRE

    Martins, Fernando Lopes

    2013-01-01

    Resumo: O AUTOR APRESENTA OS RESULTADOS DO ESTUDO RADIOLÓGICO DE ESQUELETO DE 61 PACIENTES PORTADORES DE LEUCEMIA AGUDA LINFOBLÁSTICA, CORRELACIONANDO A PRESENÇA OU NÃO DE Lesões ÓSSEAS COM A CLASSIFICAÇÃO IMUNOLÓGICA DE LAL TIPO T E TIPO não T / não B

  20. Tipos especiales de niños

    Directory of Open Access Journals (Sweden)

    Mercedes Rodrigo Bellido

    1946-09-01

    Full Text Available En las tres últimas lecciones han sido expuestas algunas consideraciones referentes a niños y adolescentes desde el nacimiento hasta el dintel de la juventud. En todas ellas hemos procurado poner de relieve la necesidad de individualizar el conocimiento de cada niño para obtener mejores resultados en su adaptación a su futura vida de adultos, En todas ellas  nos hemos referido al llamado niño normal. Nos corresponde en la lección de hoy ocuparnos can la superficialidad característica de estas charlas tipo-muestrario, de otras categorías de niños muy dignos de interés.. quienes unas por exceso, otros por defecto, otros por dificultades de adaptación por diferentes causas, se desvían de la línea media de la normalidad. Consideramos que no está fuera del lugar, aquí, el tema de los niños excepcionales y por el contrario que es necesario intensificar el estudio de los trastornos de la vida mental y emocional de los niños en la preparación de los estudiantes de Medicina. Y no es nuestra solo esta opinión; no hace mucho tiempo en la Medical School de Ia Universidad de Minnessota hemos sabido que se ha hecho un intento de considerar y evaluar factores emocionales ambientales sobre las mismas bases que los descubrimientos fisiológicos.

  1. Solid state reaction synthesis of Ba0.75Sr0.25AlSi2O8 - Al2O3 ceramic composites from mechanically activated precursor mixtures

    Directory of Open Access Journals (Sweden)

    Ramos-Ramírez, M. V.

    2014-06-01

    Full Text Available Ceramic composites with Ba0.75Sr0.25AlSi2O8 (SBAS/Al2O3 mass ratios of: 1 90/10, 2 70/30, and 3 50/50, were in situ synthesized at 900-1500 °C/5 h from mixtures of fly ash, BaCO3, SrCO3 and Al2O3. The green mixtures were mechanically activated for 0, 4 and 8 h in an attrition mill. As a result, the solid state reactions were faster and occurred at lower temperatures. Only the SBAS and Al2O3 phases were obtained at 1300-1500°C, with the SBAS present in composition 1 achieving full conversion from its hexagonal (Hexacelsian into its monoclinic (Celsian form, with or without milling. The higher nominal SBAS content of composition 1 facilitated in it the mentioned conversion, in comparison with the other two studied compositions, which required to be mechanically activated for times that increased with increasing Al2O3 content, in order to attain in them similarly high Hexacelsian to Celsian conversions. The mechanical properties of the synthesized materials increased with increasing milling time, sintering temperature and Al2O3 content. Thus, the best mechanical properties were obtained for composition 3 milled for 8 h and sintered at 1500 °C.Compósitos cerámicos con relaciones Ba0.75Sr0.25AlSi2O8 (SBAS/Al2O3 en masa de: 1 90/10, 2 70/30, y 3 50/50, fueron sintetizados in situ a 900-1500 °C/5 h usando mezclas de cenizas volantes, BaCO3, SrCO3 y Al2O3 . Las mezclas en verde fueron activadas mecánicamente por 0, 4 y 8 h en un molino de atrición. Como resultado, las reacciones en el estado sólido fueron más rápidas y ocurrieron a menores temperaturas. A 1300-1500°C sólo se obtuvo las fases SBAS y Al2O3 , con el SBAS presente en la composición 1 transformado completamente de su forma hexagonal (Hexacelsiana a la monoclínica (Celsiana, con o sin molienda. El mayor contenido nominal de SBAS en esa composición facilitó dicha conversión, en comparación con las otras dos composiciones estudiadas, las cuales requirieron ser activadas mec

  2. Metaheuristics-Assisted Combinatorial Screening of Eu2+-Doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N Compositional Space in Search of a Narrow-Band Green Emitting Phosphor and Density Functional Theory Calculations.

    Science.gov (United States)

    Lee, Jin-Woong; Singh, Satendra Pal; Kim, Minseuk; Hong, Sung Un; Park, Woon Bae; Sohn, Kee-Sun

    2017-08-21

    A metaheuristics-based design would be of great help in relieving the enormous experimental burdens faced during the combinatorial screening of a huge, multidimensional search space, while providing the same effect as total enumeration. In order to tackle the high-throughput powder processing complications and to secure practical phosphors, metaheuristics, an elitism-reinforced nondominated sorting genetic algorithm (NSGA-II), was employed in this study. The NSGA-II iteration targeted two objective functions. The first was to search for a higher emission efficacy. The second was to search for narrow-band green color emissions. The NSGA-II iteration finally converged on BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors in the Eu 2+ -doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N compositional search space. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor, which was synthesized with no human intervention via the assistance of NSGA-II, was a clear single phase and gave an acceptable luminescence. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor as well as all other phosphors that appeared during the NSGA-II iterations were examined in detail by employing powder X-ray diffraction-based Rietveld refinement, X-ray absorption near edge structure, density functional theory calculation, and time-resolved photoluminescence. The thermodynamic stability and the band structure plausibility were confirmed, and more importantly a novel approach to the energy transfer analysis was also introduced for BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    The precipitation of Al 2 Cu 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 Al 2 Cu 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. (paper)

  4. 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

  5. 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.

  6. OTROS TIPOS ESPECÍFICOS DE DIABETES MELLITUS

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    DRA. M. Gabriela Sanzana G.

    2016-03-01

    En las “Diabetes Atípicas” (no incluidas en la clasificación ADA, se mencionan la DM tipo 2 en niños y adolescentes, favorecida por el aumento de la obesidad y del sedentarismo; la diabetes propensa a la cetosis, que debutan en cetoacidosis, con etiopatogenia y evolución de DM2; los Latent Autoinmune Diabetes of Adults (LADA, DM tipo 1 de lenta aparición y la diabetes postrasplante.

  7. Método predictivo de volatilidad tipo cambio

    Directory of Open Access Journals (Sweden)

    Jeffrey Viales Abellán

    2011-01-01

    Full Text Available Las series temporales descritas por precios de ciertos activos financieros tales como el de las acciones y divisas presentan dos principales características, excesos de kurtosis y clustering de volatilidad. Para recoger estas características se han utilizado modelos no lineales tales como los modelos Garch o Volatilidad Condicionada y los modelos de Volatilidad Estocástica, ambos tipos de modelo son empleados para la gestión del riesgo cambiario a corto plazo; el primer tipo de modelos definen la volatilidad en función de la misma volatilidad rezagada y de los shocks (innovaciones de volatilidad; el segundo tipo de modelos son similares a los modelos Garch con la variante de que la volatilidad incluye por si misma un término aleatorio de tipo proceso Wienner2; estos modelos son empleados para simular caminatas aleatorias del tipo de cambio con volatilidades simuladas por las ecuación estocásticas de volatilidad.En el presente trabajo se analizará el desempeño del modelo Garch en comparación a las medidas de volatilidad utilizadas actualmente para la gestión del riesgo cambiario; sus implicaciones para la gestión de riesgos.

  8. Experimental Determination of the Effect of the Ratio of B/Al on Glass Dissolution along the Nepheline (NaAlSiO4) – Malinkoite (NaBSiO4) Join

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M; Reed, Lunde R; Shaw, Wendy J; McGrail, B Peter; Icenhower, Jonathan P; Windisch, Charles F; Cordova, Elsa A; Broady, Johnathan W

    2010-03-27

    The dissolution kinetics of five glasses along the NaAlSiO4-NaBSiO4 join were used to evaluate how the structural variations associated with boron-aluminum substitution affect the rate of dissolution. The composition of each glass varied inversely in mol% of Al2O3 (5 to 25 mol%) and B2O3 (20 to 0 mol%) with Na2O (25 mol%) and SiO2 (50 mol%) making up the remaining amount, in every case Na/(Al+B) = 1.0. Single-pass flow-through experiments (SPFT) were conducted under dilute conditions as a function of solution pH (from 7.0 to 12.0) and temperature (from 23° to 90°C). Analysis by 27Al and 29Si MAS-NMR suggests Al (~98% [4]Al) and Si atoms (~100% [4]Si) occupy a tetrahedral coordination whereas, B atoms occupy both tetrahedral ([4]B) and trigonal ([3]B) coordination. The distribution of [3]B fractionated between [3]B(ring) and [3]B(non-ring) moieties, with the [3]B(ring)/[3]B(non-ring) ratio increases with the B/Al ratio. The MAS-NMR results also indicated an increase in the fraction of [4]B with an increase in the B/Al ratio. But despite the changes in the B/Al ratio and B coordination, the 29Si spectra maintain a chemical shift between -88 to -84 ppm for each glass. Unlike the 29Si spectra, the 27Al resonances shift to more positive values with an increase in the B/Al ratio which suggests mixing between the [4]Al and [3]B sites, assuming avoidance between tetrahedral trivalent cations ([4]Al-O-[4]B avoidance). Raman spectroscopy was use to augment the results collected from MAS-NMR and demonstrated that NeB4 (glass sample with the highest B content) was glass-glass phase separated (e.g., heterogeneous glass). Results from SPFT experiments suggest a forward rate of reaction and pH power law

  9. La Planta única como tipo resistente a la escala

    OpenAIRE

    Colmenares Vilata, Silvia

    2014-01-01

    El sistema capitalista ha generado dos de los modelos espaciales de indiferencia funcional más extremos: por un lado, el espacio tecnificado y repetido del edificio de oficinas en altura, encarnado por la ?planta tipo? y, por otro, el espacio diáfano y extenso del gran contendor, que responde a la lógica de lo que llamaremos ?planta única?. En los edificios construidos para la industria automovilística y bélica americana se encuentra el germen de un tipo que servirá de modelo para los nuevos ...

  10. Reação de resistência tipo I e tipo II a Giberela em cultivares de trigo

    Directory of Open Access Journals (Sweden)

    Rafael Hansen Alves

    2013-09-01

    Full Text Available O objetivo deste trabalho foi avaliar as reações de resistência tipo I e tipo II à giberela em 28 cultivares de trigo em casa de vegetação. A inoculação de Fusarium graminearum foi realizada no estádio de florescimento. Para a resistência tipo I, a avaliação foi feita 21 dias após a inoculação. Foi determinada a severidade no estádio de espiga seca e a porcentagem de grãos giberelados. A avaliação da severidade foi feita pela porcentagem de espiguetas infectadas, no estádio de espiga verde atribuindo-se uma nota em uma escala linear de zero (nenhuma infecção a 100 (100% de espiguetas infectadas. Para a resistência tipo II, as avaliações foram realizadas aos 7, 14 e 21 dias após a inoculação, contando-se as espiguetas com sintomas da doença, excluindo as duas espiguetas que foram inoculadas. As cultivares Frontana, BRS 177, BRS 179, BRS Umbu, BRS Camboim, Abalone, Ônix, Pampeano e Fundacep 30 apresentaram menor severidade da doença e menor porcentagem de grãos giberelados, demonstrando serem fontes de resistência tipo I. As cultivares BRS Guamirim, CD 120, Onix, Rubi, Fundacep 50, BRS 179, Pampeano, Abalone, CD 114, IPR 85, Safira, BRS Louro, CD 117, CDF 2002116, CD 115, BRS 177, CD 0529 e BRS Camboim apresentaram a menor área abaixo da curva de progresso da doença, demonstrando a presença da resistência do tipo II.

  11. Tipos de pasteurização e agentes coagulantes na fabricação do queijo tipo prato

    OpenAIRE

    Ramos, Thaís de Melo

    2013-01-01

    O presente trabalho foi realizado com os objetivos de avaliar a influência do tipo de pasteurização pelos sistemas de aquecimento indireto high temperature short time, ou HTST, e injeção direta de vapor (IDV), e avaliar a influência de duas diferentes enzimas coagulantes na fabricação do queijo tipo prato. O delineamento experimental utilizado neste experimento foi um fatorial 2 x 2 x 5 inteiramente casualizado, sendo dois sistemas de pasteurização (HTST e IDV), duas enzimas coagulantes e cin...

  12. Diabetes mellitus tipo 2 y osteoartritis primaria de rodilla

    Directory of Open Access Journals (Sweden)

    Rubén Daniel Arellano-Pérez Vertti

    2017-07-01

    Full Text Available Señor editor: Es nuestro interés dar a conocer los resultados del estudio sobre la asociación entre diabetes tipo 2 y osteoartritis primaria de rodilla en una población del norte de México.

  13. 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.

  14. Parâmetros de desempenho e carcaça de genótipos de frangos tipo caipira

    Directory of Open Access Journals (Sweden)

    R.C. Veloso

    2014-08-01

    Full Text Available Objetivou-se com este trabalho avaliar as características de desempenho e de carcaça de sete genótipos de frangos tipo caipira da linhagem Redbro. Foram utilizados 840 pintos de um dia, machos, distribuídos em delineamento inteiramente ao acaso, dos seguintes genótipos: Caboclo, Carijó, Colorpak, Gigante Negro, Pesadão Vermelho, Pescoço Pelado e Tricolor. Os frangos foram alojados em 28 boxes, sendo 30 frangos por boxe, em galpão de alvenaria com acesso a um piquete de 45m², em quatro repetições. As características de desempenho (conversão alimentar, ganho em peso médio diário, consumo de ração médio diário foram avaliadas nos períodos: um a 28, um a 56, um a 70 e um a 84 dias de idade. O peso corporal foi avaliado aos 28, 56, 70 e 84 dias de idade. As características de carcaça (peso e rendimento de carcaça, peito e pernas foram obtidas a partir do abate de dois frangos por boxe, aos 85 dias de idade. As análises estatísticas foram realizadas utilizando-se o "proc glm" do SAS. Verificou-se que, em todos os períodos, os frangos do genótipo Colorpak apresentaram maior peso corporal, consumo de ração médio diário, ganho em peso médio diário e melhor conversão alimentar. Entretanto, os genótipos Caboclo e Gigante Negro apresentaram menores consumo de ração médio diário, ganho de peso médio diário e pior conversão alimentar. Quanto ao rendimento de cortes, observou-se que os genótipos Caboclo e Gigante Negro apresentaram os menores valores, e o Carijó, Colorpak, Pesadão Vermelho, Pescoço Pelado e Tricolor obtiveram os melhores rendimentos de pernas. Para o rendimento de peito, o Carijó e o Pesadão Vermelho obtiveram os maiores valores. A escolha do genótipo deve ser feita de acordo com o interesse do mercado, pois há diferenças no desempenho e no rendimento de carcaça e dos cortes.

  15. Riesgo de tipo de cambio: cobertura con instrumentos financieros

    OpenAIRE

    Gutiérrez Blanco, Vidal

    2017-01-01

    RESUMEN: En el siguiente trabajo se hace una pequeña aproximación al mercado de divisas, explicando qué es el tipo de cambio y cuál es el riesgo que conlleva operar con monedas de diferentes países. En primer lugar, se define el mercado de divisas, poniendo énfasis sobre el hecho de que es el mercado más grande y líquido del mundo, y se identifican cuáles son las principales operaciones llevadas a cabo en este mercado. Seguidamente, se ha explicado lo que es el tipo de cambio, cuáles son l...

  16. A IDENTIFICAÇÃO DE TIPOS DE LIDERANÇA A PARTIR DE ARQUÉTIPOS

    Directory of Open Access Journals (Sweden)

    Adriana Nunes Lacerda e Prestupa

    2009-09-01

    junguianos analisados por Moore e Gillette (1993 foram relacionados com características de líderes dentro do contexto organizacional. Desta forma foi possível apresentar uma tipologia rica e aplicável, onde o individuo pode se identificar e também entender o processo e a maturação das características dos arquétipos estudados para melhor desempenho dentro das organizações.

  17. Análisis estadístico exploratorio de dos tipos de secado de quinua

    OpenAIRE

    Mena Reinoso, Angel Patricio

    2015-01-01

    El presente trabajo “Análisis Estadístico Exploratorio de dos Tipos de Secado de Quinua” permite realizar una validación estadística del tipo de secador que posea una alta eficiencia, rendimiento en el secado de este tipo de cereal (Chenopodium quinoa Willd). Para el efecto se empleó el secador de bandejas y un secador solar tipo invernadero, el experimento se llevó a cabo con tres tipos de muestras, una con cascara y las otras escarificadas. La quinua fue sometida a un secado ...

  18. Síndrome de Waardenburg tipo I: relato de caso

    Directory of Open Access Journals (Sweden)

    Patricia Capua Vieira da Silva

    2011-06-01

    Full Text Available A síndrome de Waardenburg tipo I é uma desordem auditivo-pigmentária que inclui, entre outros, perda auditiva neurossensorial congênita não progressiva, telecanto, distúrbios pigmentares de íris, cabelo e pele. Indivíduos afetados podem ter maior risco de: defeitos no tubo neural, fendas labial e palatina, anormalidades nos membros e doença de Hirschsprung. O diagnóstico é clínico, sendo necessários dois critérios maiores ou um maior e dois menores. PAX3 é o único gene conhecido associado à síndrome, sendo, entretanto, mais usado no aconselhamento genético. Quanto ao diagnóstico diferencial, podemos citar: outras causas de perda auditiva neurossensorial congênita não progressiva, outros tipo de síndrome de Waardenburg, piebaldismo, albinismo, vitiligo e síndrome de Teitz. Neste trabalho, apresenta-se um paciente masculino de 11 anos com diagnóstico de síndrome de Waardenburg tipo I. Ressalta-se a importância do oftalmologista no auxílio do diagnóstico deste raro quadro sistêmico, uma vez que inclui algumas alterações oftalmológicas. O diagnóstico precoce da síndrome permite estimulação adequada para a perda auditiva, assim como medidas preventivas em caso de gestantes afetadas no aconselhamento genético.

  19. Tipos do Herbário Prisco Bezerra - EAC

    Directory of Open Access Journals (Sweden)

    Maria Stela Bezerra da Silva

    1990-01-01

    Full Text Available Com o presente trabalho pretende-se contribuir para a divulgação dos tipos do Herbário Prisco Bezerra - EAC. Um levantamento realizado no acervo do Herbário revelou o registro de dez tipos. Sete deles pertencentes à família Leguminosae distribuídas entre as subfamilias Caesalpinioideae: Peltogyne crenulata, Sentia dardanoi, Moldenhawera acuminata, Chamaecrista duckeana, Papilionoideae: Aeschynomene monteiroi, Cranocarpus gracilis e Mimosoideae: Mimosa niomarlei; dois, pertencentes à família Erythroxylaceae. As espécies Erythroxylum tianguanum e Erythroxylum bezerrae e um à família Euphorbiaceae: Dalechampia fernandesii recentemente descrita por G. Webster. Os tipos são apresentados na seqüência das indicações: nome das famílias, seguido do epíteto específico, habitat, com a transferência de todas as informações mencionadas na ficha de exsicata do material, bem como, a fotografia correspondente. Citam-se também alguns aspectos característicos das espécies, para melhor visualização dos detalhes fotográficos.The present paper repasts the type specimens in the Herbário Prisco Bezerra (University of Ceará. The Herbário has ten type, of which seven are Leguminosae: Peltoqyne crenulata, Senna dardanoi, Moldenhawera acuminata Chamaecrista duckeana, Aeschynomene monteiroi, Cranocarpus gracilis, Mimosa niomarlei, two the Erythroxylaceae: Erythroxylum tianquanum and Erythroxylum bezerrae and one Euphorbiaceae: Dalechampia fernandesii. Additional informations for these exsicata is presented.

  20. Estresse em mulheres com Diabetes mellitus tipo 2

    OpenAIRE

    Lessmann, Juliana Cristina; Silva, Denise Maria Guerreiro Vieira da; Nassar, Silvia Modesto

    2011-01-01

    OBJETIVO: O objetivo do estudo foi investigar a relação entre estresse e Diabetes Mellitus Tipo 2 em mulheres. MÉTODO: Estudo transversal prospectivo, desenvolvido com 147 mulheres, utilizando a Escala de Estresse Percebido (PSS). RESULTADOS: Houve associação entre as variáveis testadas, sendo possível inferir que as mulheres com estresse elevado são as que vivenciaram sofrimento e apresentam controle glicêmico alterado, ou seja, com valores superiores a 180 mg/dL. A maioria relatou sofriment...

  1. Diabetes tipo 2 y obesidad leve: tratamiento quirúrgico

    OpenAIRE

    Lanzaren S,Enrique

    2013-01-01

    Introducción: En la actualidad la diabetes mellitus tipo 2 (DM2) y la obesidad representan un serio problema de salud, comportándose como enfermedades epidémicas. Existe un gran interés en explorar distintas opciones de tratamiento de la DM2 en pacientes que no tienen obesidad mórbida. Objetivo: Reportar los parámetros de control glicémico en pacientes con DM2 y obesidad leve sometidos a bypass gástrico (BPG) a 3 años de seguimiento. Metodología: Estudio clínico prospectivo que incluye pacien...

  2. Tipos de Tiempo en el periodo de Semana Santa Vallisoletana.

    OpenAIRE

    Miranda Martín, Javier

    2017-01-01

    El propósito del proyecto es el análisis y la caracterización de ciertos tipos de tiempo a partir de los datos observados de la Base de Datos Climatológica del Observatorio de Valladolid. Los datos analizados corresponden a los ocho días de Semana Santa de un periodo de 37 años que comprenden entre los años 1981 y 2017. Grado en Geografía y Ordenación del Territorio

  3. Atrofia muscular espinal tipo 1: enfermedad de Werdnig-Hoffmann

    OpenAIRE

    Zárate-Aspiros, Romeo; Rosas-Sumano, Ana Beatriz; Paz-Pacheco, Alberto; Fenton-Navarro, Patricia; Chinas-López, Silvet; López-Ríos, José Antonio

    2013-01-01

    Introducción. Las atrofias musculares espinales de la infancia son enfermedades neuromusculares hereditarias, autosómicas, recesivas, caracterizadas por la degeneración de las neuronas motoras del asta anterior de la médula espinal. La atrofia muscular espinal tipo I (enfermedad de Werdnig-Hoffmann) es la forma más severa. Se inicia in útero o durante los primeros meses de vida. La muerte suele ocurrir antes de los dos años de edad. Caso clínico. Lactante de 6 meses de edad que ingresa al Ser...

  4. Fundamentos del Tipo de Cambio Real en Chile

    OpenAIRE

    Rodrigo Cerda; Alvaro Donoso; Aldo Lema

    2003-01-01

    Un modelo basado en la relación gasto-producto (efecto Salter-Swan) y los términos de intercambio, habría predicho un incremento más pronunciado del tipo de cambio real (TCR) en Chile durante la segunda mitad de los '80, una caída menos acentuada entre 1990 y 1997, y un aumento más fuerte a partir de 1998 cuando irrumpió la crisis financiera internacional. Este trabajo incorpora en forma exhaustiva otros factores en la determinación de largo plazo del TCR, tanto de oferta como de demanda. Usa...

  5. Propiedades y aplicaciones de piezocomposites tipo címbalo

    Directory of Open Access Journals (Sweden)

    Ochoa, P.

    2001-08-01

    Full Text Available The metal-ceramic composite actuators, moonies and cymbals consist in capped piezoceramic disks with metallic endcaps having cavities inside. These cavities favour the amplification of direct and reverse piezoelectric effects. These actuators fill the gap between high displacement low generative force bimorph actuators and low displacement high generative force multilayer ceramic actuators. The moonie actuator can give displacements greater than 100 mm, maximum generative force of 3N to several N´s, response time of 20 to 100 ms, and low fatigue test response for more than 107 cycles. Cymbals actuators shows twice as big as displacement than moonie for the studied size, much higher generative force and the possibility to avoid the temperature dependence of the displacement for selected materials. Properties of cymbal actuators can be tailored trough the selection of materials. Also, cymbal actuators can be tuned to adopt different resonance frequencies.

    Los composites metal-cerámica tipo luna y címbalo consisten en discos piezoeléctricos encapsulados con cápsulas metálicas que poseen una cavidad. Esta cavidad favorece la amplificación de los efectos piezoeléctricos directo e inverso. Estos actuadores llenan el escalón entre actuadores multicapa, con desplazamientos pequeños y fuerzas generativas elevadas, y actuadores bimorfos, con desplazamientos grandes y fuerzas generativas pequeñas. El actuador tipo luna alcanza desplazamientos de más de 100mm, fuerzas generativas máximas de hasta varios N´s, tiempos de respuesta desde 20 hasta 100ms, y baja respuesta en ensayos de fatiga a más de 107 ciclos. Los actuadores tipo címbalo muestran desplazamientos dos veces mayores que los obtenidos con actuadores tipo luna para el mismo tamaño, fuerzas generativas mucho mayores y la posibilidad de eliminar la dependencia del desplazamiento con la temperatura mediante selección de los materiales. Además poseen unas caracter

  6. Metalografía a color en aleaciones Al-Si comerciales. Optimización de las técnicas de caracterización microestructural mediante microscopía óptica de reflexión

    Directory of Open Access Journals (Sweden)

    Vander-Voort, G. F.

    2010-10-01

    Full Text Available The present demand on alloy production with improved quality requires the optimization of the metallographic procedures used on its characterization. Traditional etching techniques commonly 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 the Weck reagent. 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.La demanda de aleaciones con calidades optimizadas conlleva la mejora continua de estas calidades, lo que viene suscitando la necesidad de mejora y optimización permanentes de las técnicas de caracterización metalográfica. Las técnicas de ataque tradicionales, utilizadas en la observación microscópica de las aleaciones de aluminio, no permiten un análisis detallado de la evolución microestructural de las fases presentes ni de parte de los mecanismos que rigen la solidificación. En el presente trabajo, se explora el potencial de la metalografía en color aplicada a las estructuras de solidificación de aleaciones Al-Si 12. Se ha utilizado un procedimiento de ataque en color, basado en un reactivo desarrollado porWeck para aleaciones de aluminio. El empleo de esta técnica ha permitido la evaluación cualitativa de la microestructura. La técnica ha permitido revelar características microestructurales que los métodos de ataque en blanco-negro no revelan.

  7. Diabetes mellitus tipo 2 y resistencia a la insulina

    Directory of Open Access Journals (Sweden)

    Enrique Cipriani-Thorne

    2010-07-01

    Full Text Available Se analizó la literatura de los últimos 15 años para poder objetivar los temas que son materia de esta comunicación. En primer lugar se analiza en qué consiste el llamado Síndrome Metabólico, sus características; a continuación se resume la historia natural de la Diabetes Mellitus tipo II y su patogenia. Se revisa la importancia de la resistencia a la insulina en el músculo estriado principal órgano de combustión de la glucosa y el factor mitocondrial de la resistencia a la insulina. Se analiza además la importancia de resistencia a la insulina con respecto al metabolismo del hígado y en particular a las alteraciones del metabolismo del colesterol y de los triglicéridos. Se hace un comentario extenso de cómo así la Diabetes Mellitus Tipo II es considerada en la actualidad como una enfermedad de origen inflamatorio y por último se discuten las consecuencias de la hiperinsulinemia, dado que el exceso de insulina es producido por el bloqueo en la línea metabólica de su acción más no en su línea de producir proliferación tisular.(Rev Med Hered 2010;21:160-170.

  8. formales o categorías tipo interfase?

    Directory of Open Access Journals (Sweden)

    Julio Alfonso Piña López

    2011-01-01

    Full Text Available Se analiza la relación entre los fenómenos básicos y los fenómenos del desarrollo y la personalidad, en términos de si los primeros deberían concebirse como condición de existencia necesaria y suficiente de los segundos, y, a su vez, si los unos y los otros lo son de los últimos. Se concluye que dependiendo de cómo se plantee dicha relación, es que eventualmente tendrá sentido la construcción de teorías formales sobre el desarrollo y la personalidad, o bien caracterizar ambos fenómenos como categorías tipo interfase con fines de predicción.

  9. Terapêutica da diabetes mellitus tipo 1

    OpenAIRE

    Antunes, Ana Luisa Lopes

    2009-01-01

    Introdução: Diabetes Mellitus (DM) é uma doença metabólica de etiologia múltipla caracterizada por hiperglicemia crónica com distúrbios no metabolismo dos hidratos de carbono, lípidos e proteínas, por deficiências na secreção e/ou acção da insulina. A descoberta da insulina em 1921, foi um grande marco na sua terapêutica, aumentando a esperança e qualidade de vida dos doentes, nomeadamente na DM tipo 1. Tornou-se um fármaco salvador de vidas (life saving). A primeira a ser comercializad...

  10. Tipo abstracto de datos "Biblioteca" Library Abstract data type

    Directory of Open Access Journals (Sweden)

    Silvana Temesio Vizoso

    2010-12-01

    Full Text Available Análisis de la descripción bibliográfica desde un punto de vista conceptual a partir de la especificación formal: tipo abstracto de datos "biblioteca". Se detallan otros abordajes usando el modelo entidad-relación y el lenguaje XML. Se concluye la relevancia del enfoque abstracto y su aplicabilidad genérica en un sujeto de cambio permanente.Analysis of bibliographic description from a conceptual point of view from the formal specification: "library" abstract data type. Other approaches are detailed using the entity-relationship model and XML language. We conclude the relevance of abstract approach and its general applicability in a subject of constant change.

  11. Tipos de socialización y desesperanza aprendida

    Directory of Open Access Journals (Sweden)

    Sandro Macassi

    1988-12-01

    Full Text Available 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 arribo y permanencia en la capital, evidenció que el único predictor de DA es el grado de instrucción, correlacionándose negativamente. Los resultados se discuten a la luz de la realidad peruana.

  12. Uso de la metformina en la diabetes mellitus tipo II

    Directory of Open Access Journals (Sweden)

    Yohana Salazar ÁLvarez

    2011-03-01

    Full Text Available Metformina es una biguanida eficaz en el control metabólico de la diabetes mellitus tipo II, no insulinodependiente cuando el control dietético falla. Dada su probada eficacia y actual accesibilidad en el mercado de medicamentos en Cuba, para ser utilizada a nivel primario de atención no solo en pacientes sintomáticos sino en la población en riesgo, se presenta este artículo cuyo propósito es actualizar a los especialistas de Medicina General Integral y Medicina Interna acerca de aspectos de interés relacionados con este medicamento, como: interacciones medicamentosas, enfermedades concomitantes, la biotransformación de la droga y los posibles efectos adversos que se pueden asociar a su uso. Se presentan consideraciones finales acerca del uso de esta droga.

  13. Compatibilidad sexual entre dos tipos de Hylocerus (Cactaceae

    Directory of Open Access Journals (Sweden)

    Roberta Castillo M

    2003-09-01

    Full Text Available 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 en la cantidad de frutos que lograron su desarrollo. Se midieron algunas variables para detectar la influencia del progenitor paterno en algunas características del fruto. Los testigos se obtuvieron de flores polinizadas libremente. El diseño experimental utilizado fue completamente al azar, con 15 repeticiones por tratamiento. Se encontró que Uqroo1 es autocompatible, mientras que Uqroo2 es autoincompatible. Los testigos de ambos tipos alcanzaron el mismo peso, y los frutos de Uqroo2 logrados por polinización cruzada tuvieron un peso similar al de los testigos o fueron significativamente mas pesados. Algunas variables resultaron positivamente correlacionados; el coeficiente entre el número de semillas y el peso total del fruto fue de r = 0.84. La correlación mas alta (r = 0.97 resultó entre el peso total y el peso de la pulpa. En los frutos obtenidos por polinización cruzada prevalecieron las características del progenitor materno. Se recomienda cultivar la Pitahaya blanca con otro tipo de pitahaya, además de Uqroo1There are two types of pitahaya that are cultivated in Yucatan Peninsula of Mexico. They differ mainly in the skin color of the fruit, one of them has a red skin (Uqroo1, while the other has a light yellow skin (Uqroo2 both belong to Hylocereus undatus (Haworth Britt. & Rose. The yellow skin pitahaya is the sweetest. The studies were conducted using the methods of self pollination and cross pollination, with direct crosses and

  14. Efectos del tipo de diabetes, estrategias de afrontamiento, sexo y optimismo en el apoyo social

    OpenAIRE

    Rondón, José E.; Lugli, Zoraide

    2013-01-01

    Se desea conocer el efecto del tipo de diabetes, las estrategias de afrontamiento, el sexo, y el optimismo sobre las redes sociales y el apoyo social percibido por sujetos con diabetes. Participaron 103 hombres y 197 mujeres divididos en diabéticos tipo

  15. DESENVOLVIMENTO DE MUDAS DE REPOLHO EM DIFERENTES TIPOS SUBSTRATOS

    Directory of Open Access Journals (Sweden)

    Rebyson Bissaco Guidinelle

    2017-05-01

    Full Text Available Resumo: O objetivo deste trabalho foi avaliar o crescimento vegetativo de mudas de repolho, em diferentes tipos de substrato orgânicos. O experimento foi conduzido em uma casa de vegetação utilizando três substratos, S1 - Comercial; S2 - Vermicomposto; S3 - Serapilheira. Os parâmetros morfoagronômicos avaliados foram o comprimento das mudas, sendo: altura parte aérea (APA, comprimento da maior raiz (CMR e altura total das plântulas (AT que é o somatório da APA e CMR. Os substratos apresentaram diferenças significativas entre si, sendo que a Serapilheira apresentou os melhores resultados de desenvolvimento vegetativo juntamente com o vermicomposto. Concluindo-se que a produção de mudas de repolho pode ser feita a partir de substratos orgânicos alternativos, recomendando a substituição total dos substratos comerciais, visando menor custo na produção das mudas, garantindo boa produtividade e qualidade das mudas de repolho das cultivares estudadas.

  16. Demencia tipo Alzheimer, deterioro cognitivo y toma de decisiones

    Directory of Open Access Journals (Sweden)

    Aurora Moreno

    2011-04-01

    Full Text Available El objetivo de este trabajo es el de conocer cómo es la toma de decisiones en la Demencia Tipo Alzheimer (DTA en situaciones de incertidumbre, si se manifiesta la tendencia al riesgo o no, y la relación que guarda la ejecución con el status cognitivo en cada una de las áreas evaluadas por los test de cribado del deterioro cognitivo propios de las demencias. Participaron 10 pacientes con DTA, y comparados con 10 sujetos controles. Se utilizó la Prueba Cartas (basada en la Iowa Gambling Task, donde los sujetos deben elegir entre varias opciones que entrañan más o menos riesgo, y una batería de cribado del deterioro cognitivo. Los resultados reflejaron que los sujetos con DTA en etapas iniciales presentan cierta tendencia al riesgo en las decisiones que toman y no desarrollan patrones estratégicos de elección. Parece que el deterioro cognitivo y el grado de afectación en las distintas áreas se relaciona con la forma en que toman decisiones.

  17. Estresse em mulheres com Diabetes mellitus tipo 2

    Directory of Open Access Journals (Sweden)

    Juliana Cristina Lessmann

    2011-06-01

    Full Text Available OBJETIVO: O objetivo do estudo foi investigar a relação entre estresse e Diabetes Mellitus Tipo 2 em mulheres. MÉTODO: Estudo transversal prospectivo, desenvolvido com 147 mulheres, utilizando a Escala de Estresse Percebido (PSS. RESULTADOS: Houve associação entre as variáveis testadas, sendo possível inferir que as mulheres com estresse elevado são as que vivenciaram sofrimento e apresentam controle glicêmico alterado, ou seja, com valores superiores a 180 mg/dL. A maioria relatou sofrimento decorrente de problemas nas relações interpessoais, óbito, doença de familiares e solidão. CONCLUSÃO: Mulheres com DM2 que convivem com estresse e/ou sofrimento constituem grupo vulnerável ao desenvolvimento de agravos à saúde demandando aos serviços de saúde o desenvolvimento de estratégias que modifiquem esta situação.

  18. Funcionamiento psicofisiológico y susceptibilidad a la sintomatología premenstrual en mujeres Tipo A y Tipo B

    Directory of Open Access Journals (Sweden)

    Francesc Palmero

    2002-01-01

    Full Text Available El presente trabajo se centra en explorar el papel que juega el componente emocional del Patrón de Conducta Tipo A (PCTA en diversas áreas relacionadas con la salud. En este contexto nuestra investigación desarrolla dos objetivos diferenciados. El primero trata de constatar la relación entre determinadas características del PCTA y el mecanismo psicofisiológico en una tarea experimental de estrés real (situación de examen, considerando si existen diferencias entre los dos grupos de personas, Tipo A y Tipo B, tanto en la dimensión tónica como en la dimensión fásica de la tasa cardiaca. El segundo de nuestros objetivos trata de establecer la relación existente entre determinadas características del PCTA y la experiencia de sintomatología relacionada con el ciclo menstrual, considerando tanto la sintomatología premenstrual global, como la sintomatología premenstrual específica, diferenciando tres grandes grupos de síntomas: fisiológicos, psicológicos y conductuales. La muestra final estuvo conformada por 28 mujeres Tipo A y 29 mujeres Tipo B. Los instrumentos utilizados fueron el inventario de Actividad de Jenkins (JAS, el calendario menstrual de síntomas de registro diario (CMSRD y un polígrafo que permitió registrar la tasa cardiaca. En cuanto a nuestro primer objetivo, los datos hacen pensar en la existencia de distintos perfiles psicofisiológicos en ambos grupos de mujeres; en el segundo objetivo, parece que las mujeres Tipo A experimentan de forma clara más síntomas psicológicos que las mujeres Tipo B.

  19. O uso de politetrafluoroetileno expandido em tireoplastia tipo I

    Directory of Open Access Journals (Sweden)

    Mello-Filho Francisco Veríssimo de

    2003-01-01

    Full Text Available A paralisia unilateral de prega vocal (PUPV em abdução é uma alteração que produz grande desconforto ao paciente, principalmente pelos distúrbios fonatórios causados. Atualmente dispomos de uma variedade de métodos para seu tratamento. OBJETIVO: Verificar a eficiência, vantagens e desvantagens do uso da fita de politetrafluoretileno expandido (PTFE-e, na medialização de prega vocal (PV paralisada, em abdução. FORMA DE ESTUDO: Coorte Longitudinal. MATERIAL E MÉTODOS: Foram estudados quatro pacientes com diagnóstico clínico-laringoscópico de disfonia por PPVU, em abdução há pelo menos um ano. Os pacientes foram submetidos a avaliação fonoaudiológica e a tireoplastia tipo I para medialização da PV com fita de PTFE-e. Durante o seguimento pós-operatório procedeu-se videolaringoscopia, tomografia computadorizada e fonoterapia. RESULTADOS: Todos os pacientes estão satisfeitos com a qualidade vocal, apresentam medialização estável da PV com a fonocirurgia e bons resultados à avaliação fonoaudiológica. Um paciente apresentou extrusão intra-operatória da fita de PTFE-e, sendo feito um segundo procedimento, sem complicações, seis meses depois. CONCLUSÃO: Na opinião dos autores a fita de PTFE-e se presta com eficiência ao tratamento da PUPV, sem apresentar riscos importantes.

  20. Intervenciones Farmaceuticas en pacientes con Diabetes Mellitus Tipo 2

    Directory of Open Access Journals (Sweden)

    Gladys Mabel Maidana

    Full Text Available Resumen Introducción: La Atención Farmacêutica es la provision responsable de la farmacoterapia con el propósito de alcanzar resultados concretos que mejoren la calidad de vida de los pacientes. Objetivo: Evaluar el impacto de las intervenciones farmacéuticas en pacientes con Diabetes Mellitus Tipo 2. Metodologia: Ensayo Clínico Aleatorizado, con medición de variables antes y después. No probabilísti-co. De conveniencia. Participaron 32 pacientes del grupo intervenido y 32 en grupo control. Se realizaron entrevistas mensuales en un periodo de intervención farmacéutica de 6 meses (desde octubre 2011 hasta junio 2012. Se registraron solo 3 abandonos. Resultados: La edad de los pacientes fue 55,6±10,6 anos. Los pacientes del grupo intervenido mejoraron la glicemia en 34%, donde 24 pacientes tenian el valor (< 130 mg/dL; la hemoglobina glicosilada mejoró 1,9%, donde 15 pacientes lograron los parámetros deseados (< 6,5%. La calidad de vida del grupo inter-venido aumentó de (56,3 a 71,3 % y fue medido con el cuestionario SF-36. En el grupo intervenido se encontraron 80 problemas relacionados con medicamentos, en 27 pacientes, se resolvieron 59; al final del estudio 12 pacientes resolvieron todos los problemas relacionados con medicamentos; se realizaron 254 intervenciones farmacêuticas, el nivel de conocimiento de los pacientes sobre la enfermedad mejoró en 41%, el conocimiento sobre sus medicamentos mejoró en 53%. Conclusión: Las intervenciones farmacêuticas mejoraron los parámetros clínicos de glicemia, hemoglobina glicosilada, optimizaron el uso de medicamentos, disminuyeron los problemas relacionados con medicamentos, mejoraron la calidad de vida de los pacientes.

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

    Science.gov (United States)

    Velasco, Eulogio; Nino, Jose

    2011-07-01

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

  2. Modification of Al-Si (13%) alloy using different modifiers

    International Nuclear Information System (INIS)

    Ikram, N.; Raza, M.R.; Ahmad, R.

    2007-01-01

    During present research work LM 13 aluminium silicon alloy was prepared using high purity aluminium ingot and various master alloys of AI-Si, AI-Cu, AI-Ni, AIFe, AI-Mn and AI-Mg. A gas fired crucible pit type furnace was used to prepare various heats of LM 13 alloy. Degassing procedure was carried out by using perforated bell type plunger using the degassing tablet. Modification was performed by plunging the modifier at the bottom of the crucible containing the molten metal. Three types of modifiers sodium salt, metallic sodium and strontium in the form of AI-Sr master alloy were used in order to evaluate the microstructure and tensile properties of the alloy. Degassed, unmodified and modified test samples for metallurgical testing purposes were prepared according to the standard procedures. (author)

  3. Production of Al-Si-Fe-Xalloys by Powder Mettalurgy

    Czech Academy of Sciences Publication Activity Database

    Školáková, A.; Novák, P.; Vojtěch, D.; Kubatík, Tomáš František

    2014-01-01

    Roč. 14, č. 3 (2014), s. 437-441 ISSN 1213-2489. [Mezinárodní konference „Mikroskopie a nedestruktivní zkoušení materiálů/3./. Litoměřice, 22.10.2014-24.10.2014] Institutional support: RVO:61389021 Keywords : Aluminium alloys * powder metallurgy * NiTi * mechanical alloying * reactive sintering Subject RIV: JG - Metallurgy http://journal.strojirenskatechnologie.cz/templates/obalky_casopis/XIV_2014-3.pdf

  4. Quality evaluation of cast Al-SiCp composites

    International Nuclear Information System (INIS)

    Adalarasu, S.; Mahadevan, S.; Satyanarayana, K.G.; Pai, B.C.; Pillai, R.M.

    1996-01-01

    This paper presents a methodology for using x-ray radiography and ultrasonic for testing the soundness and distribution of dispersoids and identifying the casting defects in a cast aluminium cast alloy matrix SiCp composites. The ultrasonic inspection could detect in 6061-SiCp cast composites 1) the presence of low levels of locked in stresses and 2) existence of local imperfection due to the combined effects of the local solidification condition and the presence of the dispersoids which were not possible through x-ray radiography. This clearly suggests that ultrasonic test can be used as a powerful NDE tool for screening the composite ingots. (author)

  5. Shape rheocasting of unmodified Al-Si binary eutectic

    CSIR Research Space (South Africa)

    Curle, UA

    2011-02-01

    Full Text Available a solidification temperature range. Silicon leads the aluminium coupled crystal growth subjected to convection by induction during thermal arrest. The semi-solid structure during thermal arrest is captured after rheo-processing and casting....

  6. Chemical leaching of rapidly solidified Al-Si binary alloys

    International Nuclear Information System (INIS)

    Yamauchi, I.; Takahara, K.; Tanaka, T.; Matsubara, K.

    2005-01-01

    Various particulate precursors of Al 100-x Si x (x = 5-12) alloys were prepared by a rapid solidification process. The rapidly solidified structures of the precursors were examined by XRD, DSC and SEM. Most of Si atoms were dissolved into the α-Al(fcc) phase by rapid solidification though the solubility of Si in the α-Al phase is negligibly small in conventional solidification. In the case of 5 at.% Si alloy, a single α-Al phase was only formed. The amount of the primary Si phase increased with increase of Si content for the alloys beyond 8 at.% Si. Rapid solidification was effective to form super-saturated α-Al precursors. These precursors were chemically leached by using a basic solution (NaOH) or a hydrochloric acid (HCl) solution. All Al atoms were removed by a HCl solution as well as a NaOH solution. Granules of the Si phase were newly formed during leaching. The specific surface area was about 50-70 m 2 /g independent of Si content. The leaching behavior in both solutions was slightly different. In the case of a NaOH solution, the shape of the precursor often degenerated after leaching. On the other hand, it was retained after leaching by a HCl solution. Fine Si particles precipitated in the α-Al phase by annealing of as-rapidly solidified precursors at 773 K for 7.2 x 10 3 s. In this case, it was difficult to obtain any products by NaOH leaching, but a few of Si particles were obtained by HCl leaching. Precipitated Si particles were dissolved by the NaOH solution. The X-ray diffraction patterns of leached specimens showed broad lines of the Si phase and its lattice constant was slightly larger than that of the pure Si phase. The microstructures of the leached specimens were examined by transmission electron microscopy. It showed that the leached specimens had a skeletal structure composed of slightly elongated particles of the Si phase and quite fine pores. The particle size was about 30-50 nm. It was of comparable order with that evaluated by Scherer's equation. Leaching of rapidly solidified precursors was effective to form skeletal structures composed of fine Si particles with pores

  7. Diseño de antenas tipo DRA (Dielectric Resonator Antennas)

    OpenAIRE

    Soria Gallego, Juan

    2013-01-01

    En este trabajo se va a estudiar un tipo de antenas conocidas como antenas resonantes dieléctricas (DRA) desde el punto de vista de diseño y características radiantes, así como de sus posibles aplicaciones. Las DRAs son un tipo de antenas cada vez más usadas ya que presentan numerosas ventajas respecto a otro tipo de antenas, entre ellas que son fáciles de diseñar, baratas y muy eficientes. Por ello, cada vez aparecen nuevos diseños y nuevas aplicaciones. Entre ellas se ha extendido el uso...

  8. Influencia del contacto precoz, nacionalidad, tipo de parto y prematuridad en la lactancia materna

    OpenAIRE

    Ana Belén Laviña Castan

    2015-01-01

    Conocer si en el HUMS existe asociación entre lactancia materna y nacionalidad, prematuridad, tipo de parto, contacto precoz piel con piel. Estudio de cohortes, en una muestra de 541 puérperas del HUMS en octubre-noviembre 2011. Las variables: nacionalidad, tipo de parto, contacto precoz, parto prematuro e inicio lactancia materna se recogieron antes del alta hospitalaria mediante cuestionario. A los dos meses postparto se contactó telefónicamente con las madres para conocer el tipo de lactan...

  9. Actividad hidráulica de un cemento belítico obtenido a partir de cenizas volantes tipo C: influencia del aditivo y tipo de curado

    OpenAIRE

    Goñi, S.; Guerrero, A.

    2006-01-01

    En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A). Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C) como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 días, ...

  10. Actividad hidráulica de un cemento belítico obtenido a partir de cenizas volantes tipo C: influencia del aditivo y tipo de curado

    OpenAIRE

    Goñi Elizalde, Sara; Guerrero Bustos, Ana María

    2006-01-01

    En este trabajo se discute la influencia del tipo de curado y de un aditivo reductor de la demanda de agua en la actividad hidráulica de un cemento belítico de cenizas volantes de alto contenido en cal denominado (CBCV-2-A). Este cemento ha sido sintetizado por una ruta húmeda hidrotermal con posterior calcinación, empleando ceniza volante de alto contenido en cal (ASTM tipo C) como materia prima. La actividad hidráulica se ha estudiado en la pasta de cemento, durante un periodo de 180 ...

  11. Genótipos de haptoglobina e hipertensão refratária em pacientes com diabete melito tipo 2

    Directory of Open Access Journals (Sweden)

    Vânia Pereira Albuquerque Wobeto

    2011-10-01

    Full Text Available FUNDAMENTO: Tem sido sugerido que o polimorfismo da haptoglobina pode influenciar na patogênese das complicações microvasculares e macrovasculares em pacientes diabéticos. OBJETIVO: O objetivo principal deste estudo transversal foi de realizar uma investigação da existência ou não de uma associação entre os genótipos de haptoglobina e a prevalência de eventos isquêmicos cardiovasculares (angina estável, angina instável e infarto agudo do miocárdio, hipertensão arterial sistêmica, hipertensão refratária, obesidade e dislipidemia em 120 pacientes com diabete melito tipo 2, seguidos no Hospital Universitário da Unicamp, em Campinas, Estado de São Paulo. MÉTODOS: A genotipagem da haptoglobina foi realizada por reações em cadeia da polimerase alelo-específicas. As frequências dos genótipos de haptoglobina foram comparadas com a presença/ausência de doença cardiovascular, hipertensão arterial sistêmica, hipertensão refratária, obesidade e dislipidemia; medições de pressão arterial sistólica e diastólica; glicemia, colesterol (total, lipoproteínas de alta densidade - HDL e lipoproteínas de baixa densidade - LDL e triglicerídeos; assim como níveis de creatinina sérica. RESULTADOS: Embora nenhuma associação entre o genótipo de haptoglobina e a presença de doença cardiovascular tenha sido identificada, encontramos um excesso significativo de pacientes com o genótipo Hp2-1 entre as pessoas com hipertensão refratária, que também apresentavam uma maior pressão arterial sistólica e diastólica e níveis de colesterol total e LDL. CONCLUSÃO: Nossos resultados sugerem que os pacientes com diabete melito tipo 2 com o genótipo Hp2-1 podem apresentar uma maior chance de desenvolver hipertensão refratária. Estudos adicionais em populações diabéticas são necessários para confirmar esses achados.

  12. Resgate vegetativo por alporquia de genótipos adultos de urucum (Bixa orellana L.

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    Nilton César Mantovani

    2010-09-01

    Full Text Available Este trabalho teve por objetivos avaliar a técnica de alporquia visando ao resgate vegetativo de genótipos de urucum (Bixa orellana L. e a obtenção de plantas fornecedoras de propágulos para processos de propagação clonal. Foram utilizadas dez plantas matrizes de urucum, com 12 anos de idade, obtidas partindo do cruzamento artificial entre os genótipos "Fruto Verde Piloso" X "Fruto Vermelho Liso". Os alporques foram realizados em ramos de 1 a 2 cm de diâmetro, utilizando-se como substrato uma mistura de vermiculita e musgo. Foi avaliado o efeito (1 do tipo de anelamento da casca dos ramos (total ou parcial, com 1 cm de comprimento, (2 do AIB (ácido indol-3-butírico a 0 e 4,92 mM aplicado em papel filtro e (3 do tipo de proteção dos alporques (filmes plásticos transparente ou preto ou tecido tencel, no enraizamento de alporque dos dez genótipos. A técnica de alporquia proporcionou o enraizamento de ramos dos dez genótipos avaliados, com eficiência variável de 20 a 100%, havendo efeito do genótipo sobre a frequência de enraizamento. A sobrevivência desses alporques foi de 100% após o plantio quando estes foram produzidos com anelamento total, tratados com AIB e protegidos com plástico transparente. Em casa de vegetação os alporques desenvolveram ramos partindo da brotação de gemas caulinares constituindo estoques de explantes apropriados para serem utilizados como estacas ou como fontes de segmentos nodais para a propagação in vitro desta espécie.

  13. Diabetes tipo 2 en niños: Serie de casos

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    Helard Manrique-Hurtado

    2015-01-01

    Full Text Available Objetivos: Describir las características clínicas y bioquímicas de un grupo de niños y adolescentes con diagnóstico reciente de diabetes tipo 2. Material y métodos: Estudio descriptivo, retrospectivo, tipo de serie de casos. Se definió caso al niño o adolescente con glucosa plasmática en ayunas mayor a 126 mg/dl, ausencia de antiGAD y péptido C mayor a 1,5 ng/dl. Se excluyeron a los pacientes con diagnóstico previo de diabetes mellitus tipo 1, diabetes tipo MODY o diabetes secundaria a uso de fármacos. Resultados: La edad media fue 14,3 años, 59% fueron mujeres y 43% tenía por lo menos un padre con diabetes tipo 2. Al momento del diagnóstico, el índice de masa corporal fue 32,8 kg/m2, 85% tenía acantosis nigricans y 68% estaba en estadio Tanner IV y V. El tratamiento inicial incluyó el uso de hipoglicemiantes orales en 75% de los casos, siendo más frecuente el uso de metformina (64,3%. Solamente el 41% de los pacientes recibía algún tipo de insulina. Conclusiones: Los niños y adolescentes con diabetes tipo 2, tienen una frecuencia aumentada de obesidad/sobrepeso, acantosis nigricans y antecedente familiar de DM2. En general, tienen mal control metabólico y reciben metformina como tratamiento inicial.

  14. Tiberiobardiite, Cu9Al(SiO3OH2(OH12(H2O6(SO41.5·10H2O, a New Mineral Related to Chalcophyllite from the Cretaio Cu Prospect, Massa Marittima, Grosseto (Tuscany, Italy: Occurrence and Crystal Structure

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    Cristian Biagioni

    2018-04-01

    Full Text Available The new mineral species tiberiobardiite, ideally Cu9Al(SiO3OH2(OH12(H2O6(SO41.5·10H2O, has been discovered in the Cretaio Cu prospect, Massa Marittima, Grosseto, Tuscany, Italy, as very rare, light green, vitreous, tabular {0001}, pseudo-hexagonal crystals, up to 200 μm in size and 5 μm in thickness, associated with brochantite. Electron microprobe analysis gave (in wt %, average of 5 spot analyses: SO3 10.37, P2O5 3.41, As2O5 0.05, SiO2 8.13, Al2O3 5.54, Fe2O3 0.74, CuO 62.05, and ZnO 0.03, for a total of 90.32. Based on an idealized O content of 42 atoms per formula unit, assuming the presence of 16 H2O groups and 13.5 cations (without H, the empirical formula of tiberiobardiite is (Cu8.69Al0.21Fe0.10Σ9.00Al1.00(Si1.51P0.54Σ2.05S1.44O12.53(OH13.47·16H2O. The main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity]: 9.4 (s, 4.67 (s, 2.576 (m, 2.330 (m, and 2.041 (mw. The crystal structure study revealed tiberiobardiite to be trigonal, space group R 3 ¯ , with unit-cell parameters a = 10.6860(4, c = 28.3239(10 Å, V = 2801.0(2 Å3, and Z = 3. The crystal structure was refined to a final R1 = 0.060 for 1747 reflections with Fo > 4σ (Fo and 99 refined parameters. Tiberiobardiite is the Si-analogue of chalcophyllite, with Si4+ replacing As5+ through the coupled substitution As5+ + O2− = Si4+ + (OH−. The name tiberiobardiite honors Tiberio Bardi (b. 1960 for his contribution to the study of the mineralogy of Tuscany.

  15. La volatilidad del tipo de cambio paralelo en Venezuela 2005-2015

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    Laura Daniela Castillo Paredes

    2017-02-01

    Full Text Available El tipo de cambio paralelo constituye una de las principales variables económicas para la toma de decisiones en Venezuela. Para analizar el comportamiento de esta variable tomando en cuenta sus características inherentes, exceso de curtosis, persistencia y asimetría, se hace una síntesis teórica de los principales modelos estocásticos de volatilidad y, se estima un conjunto de modelos. El modelo que mejor ajusta el comportamiento de la variable es un EGARCH (1,1, que captura el efecto asimétrico de las perturbaciones estocásticas sobre la serie. Ante choques negativos (depreciación del tipo de cambio paralelo, la volatilidad asociada se incrementa, pero para choques positivos (apreciación del tipo de cambio paralelo, se mantiene constante.

  16. Biometria e armazenamento de sementes de genótipos de cacaueiro

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    Lucimara Ribeiro Venial

    2017-03-01

    Full Text Available Genótipos de Theobroma cacao L. devem ser melhor estudados, para se identificar aqueles que produzem sementes mais desenvolvidas e viáveis após o armazenamento. Objetivou-se com este trabalho estudar a biometria e dois tempos de armazenamento de sementes de genótipos de cacaueiro. A biometria foi avaliada em oito genótipos de cacaueiro (tratamentos. Foram instalados testes de germinação em delineamento inteiramente ao acaso, no esquema fatorial 8 x 2 (genótipos: CCN51, PH16, CEPEC2002, Ipiranga, SJ02, PS1319, TSH1188 e Comum x dois períodos de armazenamento: 0 e dois dias. O genótipo TSH1188 apresentou maior comprimento, relação comprimento/largura, espessura e massa de 100 sementes. A absorção de água das sementes recém-colhidas dos genótipos é lenta, justificada pelos altos teores de água, o que não caracteriza padrão-trifásico. Os teores de água reduziram em média 2,3 vezes nas sementes armazenadas em relação às recém-colhidas. A germinação das sementes recém-colhidas dos genótipos foi de 100%. Após o armazenamento, as sementes do PS1319 apresentaram a menor redução da germinação (39%, enquanto as dos PH16, CEPEC2002 e SJ02 reduziram 96%. A velocidade de germinação foi maior e o tempo médio menor que dois dias nas sementes recém-colhidas do PS1319, indicando serem mais tolerante à dessecação. Sugere-se o uso dos genótipos TSH1188 e PS1319 em programas de melhoramento genético.

  17. Ictiosis congénita tipo laminar, reporte de un caso.

    OpenAIRE

    Joaquín Saavedra D.; María José Sierralta S.; Cristian Saavedra D; Vanesa Rivera C; Francisco Cerda C.

    2014-01-01

    RESUMEN INTRODUCCIÓN: La ictiosis tipo laminar es una enfermedad dermatológica infrecuente perteneciente al grupo de las llamadas genodermatosis. Es una forma de ictiosis congénita que es evidente desde el nacimiento. PRESENTACIÓN DEL CASO: Recién nacido por cesárea, sexo masculino, de 36 semanas de gestación, adecuado para la edad gestacional y con APGAR 8. Antecedentes familiares: padres no consanguíneos y hermano con ictiosis tipo laminar. Luego de nacer es hospital...

  18. Espiritualidad e incertidumbre ante la enfermedad en personas con diabetes mellitus tipo 2

    OpenAIRE

    Gómez Palencia, Isabel Patricia

    2010-01-01

    Objetivo: Determinar la relación entre espiritualidad e incertidumbre presente en personas con situación crónica por diabetes mellitus tipo II. Metodología: abordaje cuantitativo de tipo correlacional de corte transversal, midiendo la espiritualidad con la escala de perspectiva espiritual de Reed, y la incertidumbre con la escala de Mishel. La muestra incluye 163 pacientes, distribuidos en la institución de la ESE Cartagena de Indias; y Fundación MEDICUS “Casa del diabético de Car...

  19. Espiritualidad e incertidumbre ante la enfermedad: adultos diabéticos tipo 2

    OpenAIRE

    Gómez Palencia, Isabel Patricia; Durán de Villalobos, María Mercedes

    2013-01-01

    El objetivo principal de este artículo es determinar la relación entre espiritualidad e incertidumbre presente en personas con situación crónica por diabetes mellitus tipo 2 en instituciones de servicio de salud en Cartagena, Colombia. El estudio fue realizado con un método descriptivo transversal, correlacional.Asimismo, la muestra fue de 163 pacientes que tuvieran como mínimo dos meses de haber sido diagnosticados con diabetes mellitus tipo 2; los instrumentos utilizados fueron la escala de...

  20. Atividade física na criança com diabetes tipo 1

    OpenAIRE

    Miculis,Cristiane P.; Mascarenhas,Luis P.; Boguszewski,Margaret C. S.; Campos,Wagner de

    2010-01-01

    OBJETIVO: Abordar os aspectos práticos da realização segura de atividade física e esportes em crianças e adolescentes portadores de diabetes tipo 1. FONTES DOS DADOS: A pesquisa dos artigos foi conduzida em fontes de dados nacionais (SciELO) e internacionais (PubMed/MEDLINE), assim como nas próprias referências dos artigos encontrados, adotando como limites: artigos publicados nos últimos 10 anos, preferencialmente conduzidos em crianças e adolescentes com diabetes tipo 1, sendo em sua maiori...