WorldWideScience

Sample records for al si fe

  1. Al versus Si competition in FeSiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain)], E-mail: estibaliz.legarra@ehu.es; Apinaniz, E. [Dpto. Fisica Aplicada I, Escuela de Ingenieria Tecnica Superior, Universidad del Pais Vasco, Alameda de Urquijo s/n 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain); Pierna, A.R. [Chemical Engineering and Environmental Department, UPV/EHU, Box 1379, 20008 San Sebastian (Spain)

    2008-10-15

    In FeSiAl alloys, when Si substitutes for Al, important changes take place in the magnetism as well as in the structural properties. Alloys in the two composition series Fe{sub 75}Al{sub 25-x}Si{sub x} (x=0, 7.5, 12.5, 17.5, 25) and Fe{sub 70}Al{sub 30-x}Si{sub x} (x=0, 9, 15, 21, 30) were prepared by induction melting; afterwards they were crushed and then annealed in order to recover the DO{sub 3} stable phase. The deformed FeAl samples show larger lattice parameters than the ordered ones; however, this difference ({delta}a) decreases when Si substitutes for Al until it becomes zero (i.e. until the ordered samples and the deformed ones have the same lattice parameters). This trend is the same for both sample series and does not depend on the Fe content of the alloy. However, the magnetization has a different behaviour depending on the Fe content. For deformed Fe{sub 75}Al{sub 25-x}Si{sub x} alloys the saturation magnetization decreases with increasing Si content while for Fe{sub 70}Al{sub 30-x}Si{sub x} deformed alloys the saturation magnetization has a plateau in which the saturation magnetization values do not vary.

  2. Influence of Si content and heat treatment on microstructure of Al-Fe-Si alloys

    Institute of Scientific and Technical Information of China (English)

    Zhao Yuhua; Wang Xiubin; Liu Yulin; Wang Chao

    2014-01-01

    The effect of Si addition and heat treatment on the Al-5wt.%Fe al oy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3Fe phase. It was found that the addition of 3.0wt.% Si made the al oy present the finest and wel -distributed primary Al3Fe phase, but the Al3Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si al oy. After heat treatment for 28 hours at 590 ºC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si al oys was granulated; the phase transformation from metastable platelet Al3FeSi and blocky Al8Fe2Si to stable Al5FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradual y.

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

    Science.gov (United States)

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

    2016-04-20

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

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

    Science.gov (United States)

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

    2016-04-01

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

  5. Addition of iron for the removal of the {beta}-AlFeSi intermetallic by refining of {alpha}-AlFeSi phase in an Al-7.5Si-3.6Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Belmares-Perales, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Zaldivar-Cadena, A.A., E-mail: azaldiva70@hotmail.com [Facultad de Ingenieria Civil, Departamento de Ecomateriales y Energia, Instituto de Ingenieria Civil, Av. Fidel Velasquez and Av. Universidad S/N, Cd. Universitaria, San Nicolas de los Garza, N.L. 66450 (Mexico)

    2010-10-25

    Addition of iron into the molten metal for the removal of the {beta}-AlFeSi intermetallic by refining of {alpha}-AlFeSi phase has been studied. Solidification conditions and composition determine the final microstructure and mechanical properties of a casting piece. It is known that increasing the iron content will produce an increasing of the {alpha}-AlFeSi and {beta}-AlFeSi phases. This phenomenon was confirmed with calculations made by Thermo-Calc{sup TM} software and validated with experimental results, however, the technique of iron addition in this study plays an important role on the solidification kinetics of these iron phases because the refining of {alpha}-AlFeSi and removal of {beta}-AlFeSi phases can be improved. Final results showed an improvement in mechanical properties by removal and refining of {beta}-AlFeSi and {alpha}-AlFeSi phases, respectively. This study shows a new method of removal of {beta}-AlFeSi that could be adopted in the aluminum smelting industry in aluminum alloys with a low cooling rate with a secondary dendritic spacing of about 37 {mu}m.

  6. Al-Fe-Si、Al-Mn-Si与Al-Fe-Mn-Si体系热力学描述的更新%Update of Al-Fe-Si, Al-Mn-Si and Al-Fe-Mn-Si thermodynamic descriptions

    Institute of Scientific and Technical Information of China (English)

    陈海林; 陈清; 杜勇; Johan BRATBERG; Anders ENGSTR(O)M

    2014-01-01

    采用Calphad方法对Al-Fe-Mn-Si四元系及其子体系进行热力学评估.首先,通过考虑文献中最新的实验研究结果以及对部分三元化合物应用新的热力学模型,修正Al-Fe-Si三系的热力学描述,显著地改善了整个成分范围内、尤其是富Al角的液相面投影图.随后,对三元化合物α-AlMnSi和β-AlMnSi采用新的模型,精修Al-Mn-Si体系富Al角的热力学描述.然后,通过模拟α-AlMnSi相在Al-Fe-Mn-Si体系中的固溶度,优化Al-Fe-Mn-Si四元系富Al角的热力学描述.在优化时,对α-AlMnSi作特殊考虑并加入限制条件,以确保其不会在Al-Fe-Si三元系中变得稳定.最后,将所获得的热力学描述加入TCAL数据库,通过一系列的相平衡计算与凝固模拟、以及与商业铝合金的实验数据的比较,对所获得的热力学描述进行全面的验证.更新后的TCAL数据库能够可靠地预测Al-Fe-Si基与Al-Fe-Mn-Si基合金中的相形成.

  7. 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.

  8. Electronic structure and magnetism on FeSiAl alloy: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso Schwindt, V.; Sandoval, M.; Ardenghi, J.S.; Bechthold, P.; González, E.A.; Jasen, P.V., E-mail: pjasen@uns.edu.ar

    2015-09-01

    Density functional theory (DFT) calculation has been performed to study the electronic structure and chemical bonding in FeSiAl alloy. These calculations are useful to understand the magnetic properties of this alloy. Our results show that the mean magnetic moment of Fe atoms decreases due to the crystal structure and the effect of Si and Al. Depending on the environment, the magnetic moment of one Fe site (Fe{sub 1}) increases to about 14.3% while of the other site (Fe{sub 2}) decreases to about 25.9% (compared with pure bcc Fe). All metal–metal overlap interactions are bonding and slightly weaker than those found in the bcc Fe structure. The electronic structure (DOS) shows an important hybridization among Fe, Si and Al atoms, thus making asymmetric the PDOS with a very slight polarization of Al and Si atoms. Our study explains the importance of crystal structure in determining the magnetic properties of the alloys. FeSiAl is a good candidate for electromagnetic interference shielding combining low price and good mechanical and magnetic properties. - Highlights: • The mean magnetic moment of the Fe atoms decreases compared to bcc Fe. • There are strong bonding interactions among the Fe, Si and Al atoms. • This structure has a stable ferromagnetism. • The Fe–Fe bonds distances elongates and are weaker than those in the bcc Fe.

  9. Interactions between solute atoms in Fe-Si-Al-C alloys as studied by mechanical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sinning, H.-R., E-mail: hr.sinning@tu-bs.de [Institut fuer Werkstoffe, Technische Universitaet Braunschweig, Braunschweig (Germany); Golovin, I.S. [Physics of Metals Department, Moscow Institute of Steel and Alloys, Moscow (Russian Federation); Physics of Metals and Materials Science Department, Tula State University, Tula (Russian Federation); Strahl, A. [Institut fuer Fachdidaktik der Naturwissenschaften, TU Braunschweig (Germany); Sokolova, O.A. [Physics of Metals and Materials Science Department, Tula State University, Tula (Russian Federation); Sazonova, T. [Institut fuer Werkstoffe, Technische Universitaet Braunschweig, Braunschweig (Germany)

    2009-09-15

    In Fe-Si-Al-C alloys, point-defect relaxation includes both the interstitial carbon Snoek-type relaxation, split into a 'pure iron' (Fe-C-Fe) Snoek peak and an 'interstitial-substitutional' (Fe-C-Me; Me = Al, Si) peak, and the substitutional Zener relaxation. The influence of Al and Si, with varying Al/Si ratio, on these effects is used to study the qualitative characteristics of substitutional-interstitial (Si-C, Al-C) and substitutional-substitutional (Al-Al, Si-Si, Al-Si) interactions in these alloys. Concerning the latter, there is a mutual compensation of the elastic distortion fields, produced in the Fe matrix by the relatively bigger Al and smaller Si atoms, respectively, which largely suppresses the Zener relaxation in the ternary Fe-Si-Al alloys, probably without affecting the elastic dipole strength of interstitial carbon. From the kinetic behavior of the two components of the Snoek-type relaxation, it is concluded that the substitutional-interstitial interaction is generally attractive and sufficient for modifying the distribution of the C atoms, but not for trapping to become dominant.

  10. Evolution of Fe Bearing Intermetallics During DC Casting and Homogenization of an Al-Mg-Si Al Alloy

    Science.gov (United States)

    Kumar, S.; Grant, P. S.; O'Reilly, K. A. Q.

    2016-06-01

    The evolution of iron (Fe) bearing intermetallics (Fe-IMCs) during direct chill casting and homogenization of a grain-refined 6063 aluminum-magnesium-silicon (Al-Mg-Si) alloy has been studied. The as-cast and homogenized microstructure contained Fe-IMCs at the grain boundaries and within Al grains. The primary α-Al grain size, α-Al dendritic arm spacing, IMC particle size, and IMC three-dimensional (3D) inter-connectivity increased from the edge to the center of the as-cast billet; both α c-AlFeSi and β-AlFeSi Fe-IMCs were identified, and overall α c-AlFeSi was predominant. For the first time in industrial billets, the different Fe-rich IMCs have been characterized into types based on their 3D chemistry and morphology. Additionally, the role of β-AlFeSi in nucleating Mg2Si particles has been identified. After homogenization, α c-AlFeSi predominated across the entire billet cross section, with marked changes in the 3D morphology and strong reductions in inter-connectivity, both supporting a recovery in alloy ductility.

  11. Modification of β-Al5FeSi Compound in Recycled Al-Si-Fe Cast Alloy by Using Sr, Mg and Cr Additions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of Sr, Mg, Cr, Sr/Mg and Sr/Cr combined additions on the Fe-containing intermetallic phase in a recycled Al-Si-Fe cast alloy are investigated. The experimental results show that the additions of Cr and Sr/Cr successfully modified the platelet and flake-like β-AlsFeSi phases (β-compound) into the fibrous α-Al8Fe2Si (α-compound). The additions of Sr and Sr/Mg were less effective to modify the β-compound into the α-compound, while the eutectic Si was fully modified into the fibrous morphology. A small secondary dendrite arm spacing (DAS) was found in the Sr-added, Cr-added and Sr/Cr-added alloys, especially in a steel mold. The Sr, Sr/Cr and Sr/Mg combined additions modify the eutectic Si simultaneously. A sludge phase was found in the addition of Cr-added, Sr/Cr-added and Mg-added alloys, especially in the graphite mold casting. The volume fraction of β-compounds was decreased by the addition of various modifying elements.The Cr and Sr/Cr combined additions are very effective to modify the β-compound for the recycled Al-Si-Fe based alloys.

  12. Seebeck effect of Fe-Al-Si alloy and low temperature thermoelectric properties; Fe-Al-Si gokin no zebekku koka oyobi teion netsugen netsuden henkan tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Shoda, M.; Kado, M.; Tsuji, T.; Suzuki, R.; Ono, K. [Kyoto University, Kyoto (Japan)

    1998-01-25

    In order to effectively utilize unutilized low heat sources, the Seebeck effect and thermoelectric conversion properties of Fe-Al-Si alloy were investigated. Unutilized low heat sources at temperatures below 600 K have small energy density generally, but their total quantity is huge. High-efficiency electric power conversion utilizing these sources is expected. In order to realize the expectation, thermoelectric power generation is most suitable as a direct energy conversion system of completely stand-still type having no driving components. The Fe-Al-Si based alloy was taken as the object of the investigation because of the following reasons: Al and Si have a wide solid solution range against Fe, and 3p orbit electrons of the respective elements are expected capable of changing the electron state in the vicinity of Fermi surface, which is characteristic to the transition metal, Fe; the alloy has electric conductivity even under low temperatures including subzero temperatures; and the alloy elements are affluently available as natural resources. Measurements were performed on such thermoelectric properties as Seebeck coefficient (thermoelectric capability), electric conductivity and thermal conductivity. As a result, it was made clear that iron-based p-n junction elements in Fe13%Al12%Si(p)-Fe12%Al(n) exhibit highest performance in this alloy system. In addition, the measured thermoelectric properties were used to derive the theoretical surface specific output power of the elements. 9 refs., 10 figs., 1 tab.

  13. Phase equilibria and structural investigations in the system Al-Fe-Si.

    Science.gov (United States)

    Marker, Martin C J; Skolyszewska-Kühberger, Barbara; Effenberger, Herta S; Schmetterer, Clemens; Richter, Klaus W

    2011-12-01

    The Al-Fe-Si system was studied for an isothermal section at 800 °C in the Al-rich part and at 900 °C in the Fe-rich part, and for half a dozen vertical sections at 27, 35, 40, 50 and 60 at.% Fe and 5 at.% Al. Optical microscopy and powder X-ray diffraction (XRD) was used for initial sample characterization, and Electron Probe Microanalysis (EPMA) and Scanning Electron Microscopy (SEM) of the annealed samples was used to determine the exact phase compositions. Thermal reactions were studied by Differential Thermal Analysis (DTA). Our experimental results are generally in good agreement with the most recent phase diagram versions of the system Al-Fe-Si. A new ternary high-temperature phase τ12 (cF96, NiTi2-type) with the composition Al48Fe36Si16 was discovered and was structurally characterized by means of single-crystal and powder XRD. The variation of the lattice parameters of the triclinic phase τ1 with the composition Al2+x Fe3Si3-x (-0.3 < x < 1.3) was studied in detail. For the binary phase FeSi2 only small solubility of Al was found in the low-temperature modification LT-FeSi2 (ζβ ) but significant solubility in the high-temperature modification HT-FeSi2 (ζα ) (8.5 at.% Al). It was found that the high-temperature modification of FeSi2 is stabilized down to much lower temperature in the ternary, confirming earlier literature suggestions on this issue. DTA results in four selected vertical sections were compared with calculated sections based on a recent CALPHAD assessment. The deviations of liquidus values are significant suggesting the need for improvement of the thermodynamic models.

  14. Effect of iron addition on the crystal structure of the α-AlFeMnSi phase formed in the quaternary Al-Fe-Mn-Si system

    Directory of Open Access Journals (Sweden)

    Luna-Álvarez, S.

    2011-12-01

    Full Text Available Cubic and hexagonal α-phases, formed during thermal analysis experiments and specific isothermal treatments, have been analyzed for a series of Al-Mn-Si alloys with different iron contents. In these alloys, the Fe/Mn weight ratio was varied from 0.1 to 8.4. This study shows that in Al-Fe-Mn-Si alloys with Fe/Mn weight ratios up to 4, the a-phase has a cubic crystal structure, while in alloys with a Fe/Mn weight ratio of 5.3 or more, the a-phase has a hexagonal crystal structure. Hence, the critical Fe/Mn weight ratio for the cubic to hexagonal crystal structure transition falls between 4 and 5.3 for the studied alloys.Las fases α de estructura cristalina cúbica y hexagonal, formadas durante los ensayos de análisis térmico y tratamientos isotérmicos específicos, han sido analizadas para una serie de aleaciones Al-Mn-Si con diferente contenido de hierro. En estas aleaciones, la relación en peso Fe/Mn se varió de 0,1 a 8,4. Este estudio muestra que las aleaciones Al-13,4Si-1,1 Mn-Fe con relación en peso Fe/Mn menor o igual a 4, la fase a presenta estructura cristalina cúbica, mientras que en aleaciones con una relación Fe/Mn igual o mayor a 5,3, la fase a presenta estructura cristalina hexagonal. Por lo tanto, la relación crítica Fe/Mn para la transición de estructura cristalina de cúbica a hexagonal se encuentra entre 4 y 5,3 para las aleaciones estudiadas.

  15. Crystal structure of the ternary compound {gamma}-Al{sub 3}FeSi

    Energy Technology Data Exchange (ETDEWEB)

    Roger, Jerome; Jeanneau, Erwann; Viala, Jean-Claude [UMA CNRS no. 5615, Claude Bernard Lyon 1 Univ., Villeurbanne (France). Lab. des Multimateriaux et Interfaces

    2011-07-01

    Ternary iron silicide aluminide {gamma}-Al{sub 3}FeSi crystals were grown from two Al-Fe-Si melts quenched in cold water. The crystal structures were determined from single-crystal X-ray data: trigonal symmetry, space group R-3 (n 148), unit cell parameters a = 10.2223(2) A, c = 19.6791(4) A (V = 1781 A{sup 3}) for the Si-poorer crystal and a = 10.1987(2) A, c = 19.5320(3) A (V = 1759 A{sup 3}) for the Si-richer one. The structure of {gamma}-Al{sub 3}FeSi may be described in terms of Al-cubes connected together by Al-Al pairs. The structure contains also Al cuboctaedra with one Fe-Al mixed atom in the center. The average chemical formula obtained from the refinements is Al{sub 3}FeSi. This phase shows a partial disorder on the aluminium network because of the substitution of aluminum atoms by silicon. This substitution mechanism is at the origin of the large homogeneity range of this phase. (orig.)

  16. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    Science.gov (United States)

    Zhang, Yu; Zhou, Ting-dong

    2017-03-01

    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  17. Research Advance on Magnetocaloric Effect of La-Fe-M(Al, Si) Compounds

    Institute of Scientific and Technical Information of China (English)

    肖素芬; 陈云贵; 郝春; 吴金平; 涂铭旌

    2004-01-01

    Recent research progress on magnetocaloric effect of La-Fe-M(M=Al,Si)compounds was presented.La-Fe-M(M=Al,Si)compounds of high Fe content are excellent soft magnetic materials with NaZn13 structure.The Curie temperature of the compounds can be increased by substituting small amount of Co for Si,Al.The La(Fe1-yCoy)xSi13-x compounds with an appropriate ratio of Co and Si can produce giant magnetocaloric effect comparable to that for Gd5Si2Ge2 at room temperature.The La(FexSi1-x)13 doped with H can also produce giant magnetocaloric effect at room temperature,which is much greater than that for Gd.For La(FexSi1-x)13 compounds with low Si or high Si contents.The nature of phase transition near Curie temperature induced by temperature and magnetic field was described in detail.

  18. Kinetics of the β-AlFeSi to α-Al(FeMn)Si transformation in Al-Mg-Si alloys

    NARCIS (Netherlands)

    Kuijpers, N.C.W.

    2004-01-01

    Among all the process steps of the production of aluminium extrusion products, the homogenisation of Al-Mg-Si aluminium billets is a very important one, since it gives significant changes in the microstructure of the alloy, leading to an improved extrudability of the material and improved properties

  19. [Release of Si, Al and Fe in red soil under simulated acid rain].

    Science.gov (United States)

    Liu, Li; Song, Cun-yi; Li, Fa-sheng

    2007-10-01

    bstract:A laboratory leaching experiment on simulated acid rain was carried out using soil columns. The release of Si, Al and Fe from soils and pH values of eluates were investigated. The results showed that under the given leaching volume, the release amounts of cations were influenced by the pH value of simulated acid rain, while their response to acid rain was different. Acid rain led to Si release, nearly none of Fe. Within the range from pH 3.0 to 5.6, a little Al release but mass Al only release at the pH below 3.0, both Si and Al had a declining release ability with the undergoing eluviation. At pH 2.5, the release amounts of Si and Al, especially Al, increased significantly with the strengthened weathering process of soil mineral. With an increase of the leaching amount of acid rain, the release of Si and Al increased, but acceleration of Si was slower than Al which was slower and slower. When the soil pH falling down to a certain grade, there are negative correlation between pH and both Al and DOC concentration of eluate. released, but most of Al derived from the aluminosilicates dissolved. Acid deposition can result in solid-phase alumino-organics broken and Al released, but most of Al derived from the aluminosilicates dissolved.

  20. Fabrication of a ZnO:Al/Amorphous-FeSi2 Heterojunction at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    XU Jia-Xiong; YAO Ruo-He; LIU Yu-Rong

    2011-01-01

    A prototype ZnO:A1/amorphous-FeSi2 heterojunction was successfully prepared on a glass substrate by magnetron sputtering at room temperature.The structural and electrical properties of as-deposited FeSi2 thin fihns were investigated using x-ray diffraction,Raman scattering,resistivity.and carrier lifetime measurement.The FeSi2 thin film showed an amorphous phase with resistivity of 9.685Ω·cm and carrier lifetime of 9.5μs.The prototype ZnO:Al/amorphous-FeSi2 heterojunction exhibited a rectifying property of the diode from the dark current-voltage characteristic.This propert was evaluated using the shunt resistance and diode ideal factor.The experimental results suggest that the amorphous-FeSi2 thin film has promising applications in hetero junction devices with low thermal budget and low product cost.Recently,the β-FeSi2 thin film has been proposed as a promising material for applications in optoelectronic and microelectronic devices.Its band gap of about 0.85eV leads to a light emission at about 1.55 μm,which matches with the minimum absorption window of silica-based optical fibers.[1] The extremely high optical absorption coefficient (higher than 1 × 105cm-1 at 1.0eV) makes it useful as a thin film solar cell material.[2] In addition,β-FeSi2 is environmentally friendly since Fe and Si are non-toxic and abundant in the Earth's crust.[3]%A prototype ZnO:Al/amorphous-FeSi2 heterojunction was successfully prepared on a glass substrate by magnetron sputtering at room temperature. The structural and electrical properties of as-deposited FeSi2 thin Rims were investigated using x-ray diffraction, Raman scattering, resistivity, and carrier lifetime measurement. The FeSi'2 thin film showed an amorphous phase with resistivity of 9.685 Ω·cm and carrier lifetime of 9.5 μs. The prototype ZnO:Al/amorphous-FeSi2 heterojunction exhibited a rectifying property of the diode from the dark current-voltage characteristic. This propert was evaluated using the shunt resistance

  1. Solidification Sequence and Evolution of Microstructure During Rheocasting of Four Al-Si-Mg-Fe Alloys with Low Si Content

    Science.gov (United States)

    Payandeh, Mostafa; Jarfors, Anders E. W.; Wessén, Magnus

    2016-03-01

    Four Al-Si-Mg-Fe alloys with Si contents varying from 1.6 to 4.5 wt pct were rheocast, using the RheoMetal™ process to prepare slurry and cast in a vertical high-pressure die casting machine. Particle size and Si concentration in the α-Al particles in the slurry and in the as-rheocast component were investigated. A uniform distribution of Si in the globular α 1-Al particles was achieved in the slurry. In the rheocast samples, measurement of the α 1-Al particles showed that these particles did not increase significantly in size during pouring and secondary solidification. The two additional α-Al particles types, α 2-Al particles and α 3-Al particles, were identified as being a result of two discrete nucleation events taking place after slurry production. The Si concentration in the α 2-Al and α 3-Al particles indicated that the larger α 2-Al particles precipitated before the α 3-Al particles. In addition, in the as-rheocast condition, the Si distribution inside the α 1-Al particles showed three distinct zones; an unaffected zone, a transition zone, and in some cases the start of a dendritic/cellular zone. The phenomenon of dendritic growth of globular α 1-Al particles during secondary solidification occurred concomitantly with the final eutectic reaction and increased with increasing amount of the Al-Si eutectic phase.

  2. Microwave absorption capability of microcapsules by coating FeSiAlCr with SiO2

    Science.gov (United States)

    Huang, Weirong; Zhang, Penghua; Yan, Wenjing; Zhou, Liang; Xu, Hui

    2012-10-01

    Electromagnetic wave absorption of microcapsules by coating FeSiAlCr with SiO2 is investigated. The absorption amplitude of the microcapsules is found to increase significantly in the lower frequency of microwave compared with the corpuscles of FeSiAlCr alloy. Reflection loss (RL) exceeding -10 dB can be obtained for all frequencies within 2.6-7.3 GHz, covering half of the S-band, and the whole C-band when the absorber layer thickness is 2 mm. The maximum RL can exceed -18 dB at 4.3 GHz, while the RL is only -4 dB with the corpuscles of FeSiAlCr alloy. The reason is that the microcapsules's conductance is decreased and the absorption of electromagnetic wave in the microcapsule materials is easier.

  3. Flaky FeSiAl alloy-carbon nanotube composite with tunable electromagnetic properties for microwave absorption

    Science.gov (United States)

    Huang, Lina; Liu, Xiaofang; Chuai, Dan; Chen, Yaxin; Yu, Ronghai

    2016-01-01

    Flaky FeSiAl alloy/multi-wall carbon nanotube (FeSiAl/MWCNT) composite was fabricated by facile and scalable ball milling method. The morphology and electromagnetic properties of the FeSiAl alloy can be well tuned by controlling the milling time. It is found that the magnetic loss of the FeSiAl alloy is improved by optimizing the milling time due to the increased anisotropy field. Meanwhile the addition of MWCNTs enhances the dielectric loss of the composite by increasing the interfacial polarizations, dipolar polarizations and conductive paths. Relative to conventional FeSiAl absorbers, the FeSiAl/MWCNT composite exhibits greatly improved microwave absorption performance with advantages of strong absorption and small thickness. The minimum reflection loss of the composite reaches −42.8 dB at 12.3 GHz at a very thin thickness of 1.9 mm. PMID:27762327

  4. Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

    Directory of Open Access Journals (Sweden)

    Pei-Chung Lin

    2016-08-01

    Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

  5. Electrical and Photoconductivity Properties of Al/CdFe2O4/p-Si/Al Photodiode

    Directory of Open Access Journals (Sweden)

    Mehmet Çavaş

    2016-01-01

    Full Text Available In the present study, we have investigated the effects of illumination intensity on the optical and electrical characteristics of the Al/CdFe2O4/p-Si/Al photodiode. A thin film of CdFe2O4 was fabricated using the sol-gel spin coating method that allows good thickness control and low-cost manufacturing as compared to alternative techniques. The current-voltage (I-V of the Al/CdFe2O4/p-Si/Al photodiode was measured in the dark and under different illumination intensities. The photocurrent increased with higher luminous intensity and its sensitivity has a strong dependence on the reverse bias rising from 1.08⁎10-7 A under dark conditions to 6.11⁎10-4 A at 100 mW/cm2 of illumination. The parameters of the photodiode such as ideality factor and barrier height were calculated using the thermionic emission model. The ideality factor of the Al/CdFe2O4/p-Si/Al photodiode was found to be 4.4. The barrier height was found to be 0.88 eV. The capacitance-voltage (C-V characteristics measured at different frequencies have strongly varied with frequency, decreasing with frequency. Consequently, the resulting interface density (Dit value of the Al/CdFe2O4/p-Si/Al photodiode also decreased with higher frequency. Similarly, the fitted series resistance of the Al/CdFe2O4/p-Si/Al photodiode has declined with higher frequency.

  6. Influence of addition of Si in FeAl alloys: Theory

    Science.gov (United States)

    Apiñaniz, E.; Legarra, E.; Plazaola, F.; Garitaonandia, J. S.

    The magnetic behaviour of Fe-based magnetic systems has been studied theoretically and experimentally for many years [E.P. Wohlfath, K.H.J. Buschow, Handbook of Ferromagnetic Materials, vol. 4, North-Holland Elsevier Science Publishers, Amsterdam, New York, Oxford, Tokyo, 1988 (Chapter 1)]. Starting with Al dissolved in Fe, the first stable structure is the D03 cubic structure and it exists over the range 23-37 at% Al. In this range these alloys present interesting magnetic properties. The other stable compound existing over a wide range of composition is FeAl which is also cubic, with the B2 structure (CsCl), and it exists over the range 37-50 at% Al. On the other hand, the FeAlSi alloys show the D03 structure, but do not show the B2 structure. The effect of Si in these alloys is double; on the one hand, it contributes to the decrease of the lattice parameter which, as reported by Nogues et al. [Phys. Rev. B 74 (2006) 024407], has a major influence on the magnetism and, on the other hand, having one more p electron than the Al atom, it promotes the charge transfer from Si to Fe atoms, as reported by Legarra et al. [Hyperfine Interact. 169 (2006) 1217-1222]. In this work, we perform ab-initio electronic calculations by means of tight binding linear muffin-tin orbital (TBLMTO) and Vienna Ab-initio Simulation Package (VASP) in order to study the magnetic contribution of Si/Al substitution in the FeAl alloys.

  7. Valence Electron Structure and Transforming Temperature of the Metastable Phase Al8Fe4Nd in Rapid Solidified (RS) Al-Fe-V-Si-Nd Alloy%快凝Al-Fe-V-Si-Nd合金中亚稳相Al8Fe4Nd的价电子结构及相变温度

    Institute of Scientific and Technical Information of China (English)

    林锦新; 庞华; 曾梅光

    1999-01-01

    应用固体与分子经验电子理论,对快凝(RS)Al-Fe-V-Si-Nd合金中的复杂相Al8Fe4Nd的价电子结构进行了计算分析,并研究了相变温度与键络断开温度的关系. 计算显示在Al8Fe4Nd合金相中存在12种共价键, Fe-Fe, Al(1)-Al(1)., Fe-Al(2), Al(1)-Al(2)键属于强键集团, Fe-Al(1), Al(2)-Al(2), Al(1)-Al(2)., Al(1)-Al(1), Nd-Al(1), Nd-Al(2)键为次强键, 而Nd-Fe, Al(2)-Al(2)键是弱键. 分析表明, Al8Fe4Nd的分解与Nd-Al(1), Nd-Al(2)的断键温度有直接的关系,当温度升高至380 ℃后, Nd-Al(1), Nd-Al(2)键将全部断裂,直接导致Al8Fe4Nd的分解而发生转变.

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

    Science.gov (United States)

    Jain, Syadwad

    In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the

  9. Nanocrystalline soft magnetic alloys with zero magnetostriction in Fe-Zr-Al and Fe-Zr-Si base systems

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, A. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    1996-12-31

    A new type of nanocrystalline soft magnetic alloy with nearly zero magnetostriction ({lambda}s) was found to be formed by partial crystallization of amorphous Fe{sub 89}Zr{sub 7}B{sub 2}Al{sub 2} and Fe{sub 87}Zr{sub 7}B{sub 2}Si{sub 4} alloys. The crystallization of these amorphous alloys takes place through two stages: Am {yields} bcc-Fe(Al or Si) - Am {yields} bcc-Fe(Al or Si) - Fe{sub 3}(Zr, B). The bcc-Fe and amorphous phases can exist in a wide temperature range of 773 to 973 K in the case of annealing for 3.6 ks. The particle size and interparticle spacing are 15 and 20 nm, respectively, regardless of the difference in Al and Si. The remaining amorphous phase contains enriched Zr contents and the enrichment causes the increase in the thermal stability of the amorphous phase which enables the formation of the nanoscale bcc structure in the wide temperature range. The dissolution of 2 at% Al or 4% Si leads to the nearly zero {lambda} s for the nanoscale bcc alloys range of about 800 to 930 K and the permeability ({mu}e) exceeds 10{sup 4} for the alloys with zero {lambda} s. The highest {mu}e at 1 kHz and saturation magnetization (Bs) are 1.6.10{sup 4} and 1.61 T. respectively for Fe{sub 89}Zr{sub 7}B{sub 2}Al{sub 2} and 1.4.10{sup 4} and 1.56 T. respectively, for Fe{sub 87}Zr{sub 7}B{sub 2}Si{sub 4}. The simultaneous achievement of zero {lambda} s, high {mu}e and high Bs which were not obtained for nanocrystalline Fe-Si-B-Cu-Nb and Fe-M-B (M=Zr, Hf or Nb) alloys is important for future progress of the present soft magnetic alloys obtained by annealing in a wide range. (orig.).

  10. Synthesis and Characterization of In Situ Dendritic/Particulate α-Al(Fe,TM)Si Phase Reinforced Al Matrix Composites

    Science.gov (United States)

    Hou, L. G.; Wang, Shuai; He, Z. B.; Zhang, D.; Wang, X. D.; Zhuang, L. Z.; Zhang, J. S.

    2016-12-01

    The strength and ductility of transition metallic element alloyed Al alloys could be inevitably and severely weakened if these elements appeared as coarse intermetallics. Present studies aimed to optimize the morphologies and sizes of these intermetallics via composition design and process selection so as to decrease their detrimental effects to the properties. It is shown that the dendritic α-Al(Fe,TM)Si phase solidified as primary phase can be refined into small dendrites or micro- and submicro-sized particles via controlling the cooling rate and alloy composition, and this phase exhibits better heat resistance. After spark plasma sintering (SPS) the atomized alloy powders, the bulk aluminum matrix composites (AMCs) were successfully prepared and well strengthened by the uniformly distributed particulate α-Al(Fe,TM)Si phase. These sintered bulk composites also possess good heat resistance that might facilitate their application for some heat-resistant parts. The transmission electron microscope (TEM) and high-resolution TEM (HRTEM) results indicate these α-Al(Fe,TM)Si phases possesses body-centered-cubic structure with a lattice constant of 1.25 to 1.27 nm. The solidification or phase formation of these alloys is discussed as well as the densification process for the SPS of powders. The present studies indicate a possibility to prepare in situ small dendritic/particulate α-Al(Fe,TM)Si phase reinforced AMCs by using the casting process and controlling the normal impurity elements in Al alloys.

  11. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  12. 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.

  13. Simulation of the X relaxation in FeAlMe (Me = Co, Cr, Mn, Si) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Blanter, M.S. [Moscow State Academy of Instrumental Engineering and Information Science, Stromynka 20, Moscow (Russian Federation)]. E-mail: mike@blanter.msk.ru; Golovin, I.S. [Institute of Materials, Technical University of Braunschweig, Langer Kamp 8, D-38106 Braunschweig (Germany); Sinning, H.-R. [Institute of Materials, Technical University of Braunschweig, Langer Kamp 8, D-38106 Braunschweig (Germany)

    2006-12-20

    We have studied the influence of alloying elements (Me) on the X relaxation in Fe-Al-C alloys, which is supposed to be due to stress-induced diffusion of the carbon atoms in the vicinity of vacancies in the D0{sub 3} ordered Fe{sub 3}Al. The short-range chemical interaction and long-range elastic interaction between C and Me atoms affect (1) the configuration energies of the carbon atoms, (2) the short-range order in the Fe-Al-Me-C solid solution and (3) the X relaxation, and these effects have been examined by computer simulation. It is demonstrated that Me atoms can enhance, diminish or completely suppress the X relaxation. The results of the simulation agree with the experimental findings for Co, Cr, Mn and Si as alloying elements (Me), if adequate parameters are chosen for the C-Me interaction, and are consistent with the proposed mechanism for the X relaxation.

  14. Impact of CrSiTi and NiSi on the Thermodynamics, Microstructure, and Properties of AlCoCuFe-Based High-Entropy Alloys

    Science.gov (United States)

    Wang, Xiao-Rong; Wang, Zhao-Qin; Lin, Tie-Song; He, Peng; Sekulic, Dusan P.

    2016-05-01

    Aiming to solve the problem of spontaneous combustion on titanium via electrospark deposition (ESD), two AlCoCuFe-based high-entropy alloys (HEAs), AlCoCuFe- x ( x = CrSiTi, NiSi), were produced by vacuum arc melting as electrodes in ESD process. The thermodynamic analysis of AlCoCuFe-based HEAs were carried out using the concept of mixing enthalpy matrix and a powerful thermodynamic calculation toolbox (HEA-Thermo-Calcu). The microstructure and mechanical properties of the two alloys were investigated. The AlCoCuFeCrSiTi alloy contains a body-centered cubic (BCC) phase and a face-centered cubic (FCC) phase. The AlCoCuFeNiSi alloy is composed of two BCC phases and an FCC phase. Addition of CrSiTi and NiSi to AlCoCuFe-based alloys makes the enthalpy of mixing to be sizably more negative than for the other AlCoCuFe-based HEAs. Notwithstanding the fact that the thermodynamic parameters do not agree with Yang's proposition, the two alloys form simple solid solutions. The electronegativity difference (Δ χ) favors a formation of the solid solution when Δχ ≤ 14.2. The hardness of AlCoCuFe- x ( x = CrSiTi, NiSi) alloys reaches 935 HV and 688 HV, respectively. The yield strength, fracture strength, and ultimate strain of AlCoCuFeNiSi are larger, i.e., 29, 30, and 45%, respectively, than those of the AlCoCuFeCrSiTi alloy.

  15. Electromagnetic Filtration of Primary Fe-Rich Phases from Al-Si Alloy Melt

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Electromagnetic filtration of primary Fe-rich phases(complex compound of AIFeSiMn)from Al-Si alloy melt containing 1.2 wt pct Fe have been studied by theoretical analysis and on a selfdesigned electromagnetic filtration equipment. The principle of the electromagnetic filtration is that the EMF(electromagnetic force)scarcely acts on the primary Fe-rich phases having low electric conductivity, which are then moved in the direction opposite to that of the EMF.Experimental results show that the primary Fe-rich phases are separated from Al-Si alloy melt and are collected in the filter while the melt is in horizontal flow.The removal efficiency of the primary iron-phases(η)calculated is less as the greatest flow velocity of the melt(uM)and the height of the filter (2h) are larger,while it becomes larger as EMF, operating distance of electromagnetic force (x) and particle size (dp) become larger. lt has been confirmed that the primary iron-phases larger than 20 μm can be removed efficiently by theoretical analysis and experiments. This new technique is high efficient and available for continuously flowing melts as compared with natural settling and filtration methods, which offer a possibility for recycling high quality aluminum alloys.

  16. Effect of Wavelike Sloping Plate Rheocasting on Microstructures of Hypereutectic Al-18 pct Si-5 pct Fe Alloys

    Science.gov (United States)

    Guan, Ren-Guo; Zhao, Zhan-Yong; Lee, Chong Soo; Zhang, Qiu-Sheng; Liu, Chun-Ming

    2012-04-01

    To refine and spheroidize the microstructures of hypereutectic Al-Si-Fe alloys, a novel method of wavelike sloping plate (WSP) rheocasting was proposed, and the effect of the WSP rheocasting on the microstructures of hypereutectic Al-18 pct Si-5 pct Fe alloys was investigated. The results reveal that the morphologies of the primary Si crystal, the Al18Si10Fe5, and the Al8Si2Fe phases can be improved by the WSP rheocasting, and various phases tend to be refined and spheroidized with the decrease of the casting temperature. The alloy ingots with excellent microstructures can be obtained when the casting temperature is between 943 K and 953 K (670 °C and 680 °C). During the WSP rheocasting, the crystal nucleus multiplication, inhibited grain growth, and dendrite break-up take place simultaneously, which leads to grain refinement of the alloys.

  17. Differential thermal analysis of Al[sub 8]FeMnSi[sub 2] intermetallic phase particles

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Valdes, A.; Pech-Canul, M.I.; Mendez-Nonell, M.; Sukiennik, M. (Unidad Saltillo (Mexico). Centro de Investigacion y de Estudios Avanzados del IPN)

    1994-02-15

    This paper is concerned with the use of differential thermal analysis to determine melting point, enthalpy and entropy of fusion of the Al[sub 8]FeMnSi[sub 2] intermetallic phase, currently present in Al-Si-Fe-Mn alloys as polyhedral precipitates. The procedure includes the evaluation of the enthalpy from measurements of the area under the peak of transformation on melting. The particular of this phase were obtained through preferential chemical dissolution of the matrix from several Al-Si-Fe-Mn alloys, as was discussed in a previous work.

  18. Magnetic properties and crystallization behavior of nanocrystalline FeSiBPCuAl alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Magnetic properties and crystallization behavior of nanocrystalline (Fe83.3Si4B8P4Cu0.7)100-xAlx (x=0-1.5 at%) alloys were investigated in this study.Experimental results show that coercive force decreases and saturation magnetization slightly decreases with the increase of Al content,but the glass forming ability has been improved at the same time.Crystallization behavior including the evolution of microstructure has also been studied.The growth of α-Fe precipitated from the matrix is quick when it is annealed by conventional method and the mean size of α-Fe grains increases from below 2-3 nm to 18-29 nm.Nanocrystalline (Fe83.3Si4B8P4Cu0.7)99Al1 alloy with coercive force of 8.9 A/m and saturation magnetization of 187 emu/g is probably a promising candidate in the field of soft magnetic materials.

  19. The solidification and structure of Al-17wt.%Si alloy modified with intermetallic phases containing Ti and Fe

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2011-10-01

    Full Text Available The article describes the process of casting and solidification of Al-17wt.%Si alloy that have been modified with composite powdercontaining the intermetallic phases of Ti and Fe. The chemical and phase composition of the applied modifier was described with thefollowingformula:FeAlx–TiAlx–Al2O3. Applying the method of thermal analysis ATD, the characteristic parameters of the solidificationprocess were determined, and exo-and endothermic effects of the modifying powder on the run of the silumin solidification curves wereobserved. By the methods of light, scanning, and X-ray microscopy, the structure of alloy and the chemical composition of the dispersionhardening precipitates were examined. A change in the morphology of Al-Si eutectic from the lamellar to fibrous type was reportedtogether with changes in the form of complex eutectics of an Al-Si-Ti and Al-Si-Fe type and size reduction of primary silicon crystals.

  20. Microstructural evolution of Al-20Si-5Fe alloy during rapid solidification and hot consolidation

    Institute of Scientific and Technical Information of China (English)

    M. Rajabi; M. Vahidi; A. Simchi; P. Davami

    2009-01-01

    Al-20Si-5Fe melt was rapidly solidified into particles and ribbons and then consolidated to near full density by hot pressing at 400℃/250 MPa/1 h. According to the eutectic-growth and dendritic-growth velocity models, the solidification front velocity and the amount of under-cooling were estimated for the particles with different sizes. Values of 0.43-1.2 cm/s and 15-28 K were obtained. The secondary dendrite arm spacing revealed a cooling rote of 6×10~5 K/s for the particles with an average size of 20 μm. Solidification models for the ribbons yielded a cooling rate of 5×10~7 K/s. As a result of the higher cooling rate, the melt-spun ribbons exhibited considerable microstructural refinement and modification, The size of the primary silicon decreased from approximately 1 μm to 30 nm while the formation of iron-containing inter-metallic compounds was suppressed, Supersaturation of the aluminum marx in an amount of~7 at.% Si was noticed from the XRD patterns. During the hot consolidation process, coarsening of the primary silicon particles and precipitation of β-Al_5FeSi phase were observed. Evalua-tion of the compressive strength and hardness of the alloy indicated an improvement in mechanical properties due to the microstructural modification.

  1. Thermodynamics of Fe-C-j (j = Al, Si, P, S) Melts

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-chuan; WANG Shi-jun; ZHOU Yun; DONG Yuan-chi; LI Wen-chao

    2005-01-01

    Based on a proposed method, the mathematical expressions between carbon solubility in Fe-C-j (j=Al, Si, P, S) melts and temperature were obtained. The expressions show the relation of the affecting factors of component j and temperature on carbon solubility, and the activity interaction coefficient of j upon carbon depends on atomic number, covalent radius and electro-negativity. The affecting factors of four elements on carbon solubility are all negative. There is a linear relationship between covalent radius and electro-negativity.

  2. Combined effects of ultrasonic vibration and manganese on Fe-containing inter-metallic compounds and mechanical properties of Al-17Si alloy with 3wt.%Fe

    Directory of Open Access Journals (Sweden)

    Lin Chong

    2013-05-01

    Full Text Available The research studied the combined effects of ultrasonic vibration (USV and manganese on the Fe-containing inter-metallic compounds and mechanical properties of Al-17Si-3Fe-2Cu-1Ni (wt.% alloys. The results showed that, without USV, the alloys with 0.4wt.% Mn or 0.8wt.% Mn both contain a large amount of coarse plate-like δ-Al4(Fe,MnSi2 phase and long needle-like β-Al5(Fe,MnSi phase. When the Mn content changes from 0.4wt.% to 0.8wt.% in the alloys, the amount and the length of needle-like β-Al5(Fe,MnSi phase decrease and the plate-like δ-Al4(Fe,MnSi2 phase becomes much coarser. After USV treatment, the Fe-containing compounds in the alloys are refined and exist mainly as δ-Al4(Fe,MnSi2 particles with an average grain size of about 20 μm, and only a small amount of β-Al5(Fe,MnSi phase remains. With USV treatment, the ultimate tensile strengths (UTS of the alloys containing 0.4wt.%Mn and 0.8wt.%Mn at room temperature are 253 MPa and 262 MPa, respectively, and the ultimate tensile strengths at 350 °C are 129 MPa and 135 MPa, respectively. It is considered that the modified morphology and uniform distribution of the Fe-containing inter-metallic compounds, which are caused by the USV process, are the main reasons for the increase in the tensile strength of these two alloys.

  3. Thermoelectric properties of Fe and Al double substituted MnSi{sub γ} (γ~1.73)

    Energy Technology Data Exchange (ETDEWEB)

    Barczak, S.A.; Downie, R.A.; Popuri, S.R. [Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Decourt, R.; Pollet, M. [CNRS, ICMCB, UPR 9048, Pessac F-33600 (France); Univ. Bordeaux, ICMCB, UPR 9048, Pessac, F-33600 (France); Bos, J.W.G., E-mail: j.w.g.bos@hw.ac.uk [Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2015-07-15

    Two series of Fe and Al double substituted MnSi{sub γ} chimney ladders with a nominal valence electron count, VEC=14 per transition metal were prepared (γ=1.75). Simultaneous replacement of Mn with Fe and Si with Al yielded the Mn{sub 1−x}Fe{sub x}Si{sub 1.75−x}Al{sub x} series while the second Mn{sub 1−x}Fe{sub x}Si{sub 1.75–1.75x}Al{sub 2x} series follows the pseudo-binary between MnSi{sub 1.75} and FeAl{sub 2}. Scanning electron microscopy and elemental mapping revealed that ~60% of the nominal Al content ends up in the product with the remainder lost to sublimation, and that up to 7% Al can be substituted in the main group sublattice. Profile analysis of X-ray powder diffraction data revealed gradual changes in the cell metrics, consistent with the simultaneous substitution of Fe and Al in a fixed ratio. All samples are p-type with VEC≈13.95 from the structural data and ~1×10{sup 21} holes cm{sup −3} from variable temperature Seebeck measurements. The substituted samples have lower electrical resistivities (ρ{sub 300} {sub K}=2–5 mΩ cm) due to an improved microstructure. This leads to increased thermoelectric power factors (largest S{sup 2}/ρ=1.95 mW m{sup −1} K{sup −2}) compared to MnSi{sub γ}. The thermal conductivity for the Mn{sub 0.95}Fe{sub 0.05}Si{sub 1.66}Al{sub 0.1} sample is 2.7 W m{sup −1} K{sup −1} between 300 and 800 K, and is comparable to literature data for the parent material. - Graphical abstract: The crystal structure, microstructure and thermoelectric properties of Fe and Al double substituted MnSi{sub γ} (γ~1.73) have been investigated. - Highlights: • Up to 7% Al can be substituted in MnSi{sub γ} when co-doped with Fe. • Improved microstructure and reduced electrical resistivities for Al substituted samples. • Largest power factor 1.95 mW m{sup −1} K{sup −2} and best estimated ZT=0.5.

  4. Hydrodechlorination of (CH₃)₃SiCHCl₂ over Pd, Ni, Co and Fe supported on AlF₃

    Indian Academy of Sciences (India)

    RATEB HINA; ISAM ARAFA; OMAR ENNAB

    2017-03-01

    Gas phase hydrodechlorination (HDC) process of Me ₃SiCHCl ₂ was studied in a flow reactor at 200◦C using a 2% metal loading (w/w) of four different monometallic catalysts (Pd/AlF ₃, Ni/AlF₃,Co/AlF ₃and Fe/AlF ₃). The catalysts were prepared by sol-gel method and structurally examined by BET method, FT-IR and XPS techniques. The XPS technique showed that NiII, FeIII and CoIII exist as oxides. The major products in the HDC process of Me ₃SiCHCl ₂ were identified by GC and GC-MS and found to include Me ₃SiCH ₂Cl, Me ₃SiCl, and Me4Si. The effect of these catalysts on the quantitative conversion, selectivity and conversionrates are reported.

  5. Effects of Nb and Si on densities of valence electrons in bulk and defects of Fe3Al alloys

    Institute of Scientific and Technical Information of China (English)

    邓文; 钟夏平; 黄宇阳; 熊良钺; 王淑荷; 郭建亭; 龙期威

    1999-01-01

    Positron lifetime measurements have been performed in binary Fe3Al and Fe3Al doping with Nb or Si alloys. The densities of valence electrons of the bulk and microdefects in all tested samples have been calculated by using the positron lifetime parameters. Density of valence electron is low in the bulk of Fe3Al alloy. It indicates that, the 3d electrons in a Fe atom have strong-localized properties and tend to form covalent bonds with Al atoms, and the bonding nature in Fe3Al is a mixture of metallic and covalent bonds. The density of valence electron is very low in the defects of Fe3Al grain boundary, which makes the bonding cohesion in grain boundary quite weak. The addition of Si to Fe3Al gives rise to the decrease of the densities of valence electrons in the bulk and the grain boundary thus the metallic bonding cohesion. This makes the alloy more brittle. The addition of Nb to Fe3Al results in the decrease of the ordering energy of the alloy and increases the density of valence electron and th

  6. Effects of Al and Si addition on the structure and properties of CoFeNi equal atomic ratio alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, T.T., E-mail: zuott1986.520@163.com [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Li, R.B., E-mail: lirb@sdju.edu.cn [School of Mechanical Engineering, Shanghai Dianji University, Shanghai 200245 (China); Ren, X.J., E-mail: X.J.Ren@ljmu.ac.uk [School of Engineering, Liverpool John Moores University, Liverpool 611310 (United Kingdom); Zhang, Y., E-mail: drzhangy@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2014-12-15

    In this work, a series of Al{sub x}CoFeNi and CoFeNiSi{sub x} high-entropy alloys (HEAs) of different Al and Si molar ratio (x=0, 0.25, 0.5, 0.75 and 1)were designed and, the effects of Al and Si addition on the structure and properties of the materials was investigated by a systematic study on the phase, microstructure, mechanical behavior, electrical and magnetic properties. It was found that the amounts of Al and Si additions strongly influence the phase structures of the alloys; high molar ratio of Al element can change the FCC structure to BCC structure, while more Si addition can lead to new compounds. Both Al and Si addition can increase the yield strength and hardness with the sacrifice of plasticity and, the effect of adding Si on the mechanical properties is more significant than that of adding Al. Characterization of the magnetic properties and hysteresis loops revealed that, all these alloys show typical ferromagnetic behavior. The saturation magnetization decreases from 151.3 emu/g (x=0) to 101.8 emu/g (x=1) when changing the Al content; and decreases from 151.3 emu/g (x=0) to 80.5 emu/g (x=0.75) with changing the Si content. Si addition can decrease the saturation magnetization more significantly than Al addition. The opposite trend can be found in the effects of the alloying element on the electrical resistivity with varying Al or Si content, adding Si can increase the electrical resistivity from 16.7 μΩ cm to 82.89 μΩ cm. It was also found that, the alloys also undergo very small magnetostriction, which is essential to ensure that the materials are not stressed when an external magnetic field is applied (or conversely, that external stresses do not disrupt the magnetic properties). - Highlights: • Multi-component Al{sub x}CoFeNi and CoFeNiSi{sub x} high-entropy alloys are designed. • The Al or Si content strongly influences the phase structure. • Both Al and Si addition can increase the yield strength and reduce the ductility. • The

  7. Structural relaxation in Fe(Co)SiAlGaPCB amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Borrego, J.M., E-mail: jmborrego@us.es [Dpto. Física de la Materia Condensada, Instituto de Ciencia de Materiales, C.S.I.C., Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Blázquez, J.S. [Dpto. Física de la Materia Condensada, Instituto de Ciencia de Materiales, C.S.I.C., Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Lozano-Pérez, S.; Kim, J.S. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Conde, C.F.; Conde, A. [Dpto. Física de la Materia Condensada, Instituto de Ciencia de Materiales, C.S.I.C., Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain)

    2014-01-25

    Highlights: • Structural relaxation of a Fe(Co)SiAlGaPCB amorphous alloys was studied by DSC. • Two relaxation times were use to fit the experimental values of different magnitudes. • HRTEM images suggest some medium range structural order in the amorphous. -- Abstract: The structural relaxation of multicomponent Fe(Co)SiAlGaPCB amorphous alloys was investigated calorimetrically for annealed samples over a wide temperature range below the glass transition temperature. Upon heating, the annealed samples exhibit an endothermic reaction (enthalpy relaxation) starting around the annealing temperature and continuing over a temperature range of about 50–140 K, that it is followed by a broad exothermic reaction. Changes in the heat flow curves with annealing temperature and time were analyzed. Experimental values of the overall enthalpy change, ΔH, the peak temperature of the difference in heat flow between the annealed and the as-quenched samples, T{sub p}, and Curie temperature, T{sub C}, were fitted by exponential functions including two relaxation times. Values of the two relaxation times are the same for different annealing temperatures regardless the considered property. Saturation values of these magnitudes show a linear dependence with the inverse of the annealing temperature. Tiny domains (2–3 nm in diameter) in the matrix observed by spherical aberration corrected high-resolution transmission electron microscopy could be attributed to some medium-range order in the atomic structure of these quenched alloys.

  8. Preparation and characterization of MnZn/FeSiAl soft magnetic composites

    Science.gov (United States)

    Li, Jing; Peng, Xiaoling; Yang, Yanting; Ge, Hongliang

    2017-03-01

    In this paper, MnZn ferrites were used as coating agents to prepare MnZn/FeSiAl soft magnetic composites (SMCs) in order to improve the magnetic property, because of the higher permeability of magnetic MnZn ferrites than that of traditional coatings which are always nonmagnetic. The effects of molding pressure, annealing temperature, and content of insulation on the soft magnetic properties of MnZn/FeSiAl SMCs were studied. With increasing molding pressure, the effective permeability of the SMCs increased firstly and then decreased, while the core loss decreased firstly and then increased, and both have the best performance at 1.6 GPa. The permeability increased with increasing temperature, reached the maximum value at 660 °C and then decreased, while the core loss decreased with increasing temperature to 700 °C and then increased. The permeability increased with increasing MnZn content from 0.1 to 3% and then decreased, while the D-C bias property continuously increased.

  9. 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.

  10. CaO+SiO2+Al2O3+MgO+FeO五元渣系中FeO活度的研究%Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags

    Institute of Scientific and Technical Information of China (English)

    吕庆; 赵丽树; 王成立; 张淑会; 李福民; 刘增勋

    2008-01-01

    Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags were determined at 1673 K by electrochemical measurements of the solid electrolyte cell: Mo |Mo+MoO2[ZrO2(MgO)[Fe+(CaO-SiO2-Al2O3-MgO-FeO)+Ag|Fe. The influences of slag compositions and basicity on FeO activities were analyzed. The results reveal that, for slags of fixed (%CaO)/(%SiO2) ratio, MgO and Al2O3 content, there was an increase of FeO activities with increase of FeO content. For slags with constant {(%CaO)+ (%MgO)}/(%SiO2) ratio, fixed FeO and Al,2O3 content, FeO activities decreased when MgO content increased from 5% to 10%, and increased with the increase of MgO content when it was over 10%. The FeO activities increased when (%CaO)/(%SiO2) ratio changed from 1.03 to 1.30 in the slags of constant MgO, FeO and Al2O3 content.

  11. Ab initio study of Fe{sub 2}MnZ (Al, Si, Ge) Heusler alloy using GGA approximation

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Vivek Kumar, E-mail: vivek.jain129@gmail.com; Jain, Vishal, E-mail: vivek.jain129@gmail.com; Lakshmi, N., E-mail: vivek.jain129@gmail.com; Venugopalan, K., E-mail: vivek.jain129@gmail.com [Department of Physics, Mohanlal Sukhadia University, Udaipur-313001 (India)

    2014-04-24

    Density functional theory based on FP-LAPW method used to investigate the electronic structure of Fe{sub 2}MnZ, shows that the total spin magnetic moment shows a trend consistent with the Slater–Pauling curve. The Fe and Mn magnetic moment depend on choice of Z element although the magnetic moment of Z element is negative and less than 0.1 μ{sub B}. Spin polarization calculations evidence 100% spin polarization for Fe{sub 2}MnSi. Fe{sub 2}MnAl and Fe{sub 2}MnGe show metallic behavior with 93%, 98% spin polarization.

  12. Energy Parameters of Interfacial Layers in Composite Systems: Graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and Semiconductor (Si,Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb

    Directory of Open Access Journals (Sweden)

    B.P. Koman

    2015-12-01

    Full Text Available On the basis of the non-equilibrium thermodynamics relations and the surface physics phenomena we calculate adhesion and energy parameters to characterize the interfacial interactions in graphene – (Si, Cu, Fe, Co, Au, Ag, Al, Ru, Hf, Pb and semiconductor (Si, Ge – (Fe, Co, Cu, Al, Au, Cr, W, Pb systems. We analyze trends of the interfacial energy, interfacial tension, work of adhesion and the energy of adhesive bonds on the contacting element’s atomic number in the periodic table and on the electronegativity difference of interacting elements. Thus, this work provides theoretical basis for the development of new composite materials.

  13. Neutronic Analysis on Potential Accident Tolerant Fuel-Cladding Combination U3Si2-FeCrAl

    Directory of Open Access Journals (Sweden)

    Shengli Chen

    2017-01-01

    Full Text Available Neutronic performance is investigated for a potential accident tolerant fuel (ATF, which consists of U3Si2 fuel and FeCrAl cladding. In comparison with current UO2-Zr system, FeCrAl has a better oxidation resistance but a larger thermal neutron absorption cross section. U3Si2 has a higher thermal conductivity and a higher uranium density, which can compensate the reactivity suppressed by FeCrAl. Based on neutronic investigations, a possible U3Si2-FeCrAl fuel-cladding system is taken into consideration. Fundamental properties of the suggested fuel-cladding combination are investigated in a fuel assembly. These properties include moderator and fuel temperature coefficients, control rods worth, radial power distribution (in a fuel rod, and different void reactivity coefficients. The present work proves that the new combination has less reactivity variation during its service lifetime. Although, compared with the current system, it has a little larger deviation on power distribution and a little less negative temperature coefficient and void reactivity coefficient and its control rods worth is less important, variations of these parameters are less important during the service lifetime of fuel. Hence, U3Si2-FeCrAl system is a potential ATF candidate from a neutronic view.

  14. Mg, Al, Si, Ca, Ti, Fe, and Ni abundance for a sample of solar analogues

    Science.gov (United States)

    López-Valdivia, Ricardo; Bertone, Emanuele; Chávez, Miguel

    2017-01-01

    We report on the determination of chemical abundances of 38 solar analogues, including 11 objects previously identified as super metal-rich stars. We have measured the equivalent widths for 34 lines of 7 different chemical elements (Mg, Al, Si, Ca, Ti, Fe, and Ni) in high-resolution (R ˜ 80 000) spectroscopic images, obtained at the Observatorio Astrofísico Guillermo Haro (Sonora, Mexico), with the Cananea High-resolution Spectrograph. We derived chemical abundances using ATLAS12 model atmospheres and the Fortran code MOOG. We confirmed the super metallicity status of 6 solar analogues. Within our sample, BD+60 600 is the most metal-rich star ([Fe/H]=+0.35 dex), while for HD 166991 we obtained the lowest iron abundance ([Fe/H]=-0.53 dex). We also computed the so-called [Ref] index for 25 of our solar analogues, and we found, that BD+60 600 ([Ref]=+0.42) and BD+28 3198 ([Ref]=+0.34) are good targets for exoplanet search.

  15. Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

  16. Galvanomagnetic properties of Fe{sub 2}YZ (Y = Ti, V, Cr, Mn, Fe, Ni; Z = Al, Si) heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kourov, N. I., E-mail: kourov@imp.uran.ru; Marchenkov, V. V.; Belozerova, K. A. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Weber, H. W. [Atominstitut, Vienna University of Technology (Austria)

    2015-11-15

    The Hall effect and the magnetoresistance of Fe{sub 2}YZ Heusler alloys, where Y = Ti, V, Cr, Mn, Fe, and Ni, are the 3d transition metals and Z = Al and Si are the s, p elements of the third period of the periodic table, are studied at T = 4.2 K in magnetic fields H ≤ 100 kOe. It is shown that, in the high-field limit (H > 10 kOe), the value and the sign of the normal (R{sub 0}) and anomalous (R{sub s}) Hall coefficients change anomalously during transition from paramagnetic (Y = Ti, V) to ferromagnetic (Y = Cr, Mn, Fe, Ni) alloys. These coefficients have different signs for all alloys. Constant R{sub s} in the ferromagnetic alloys is positive, proportional to the residual resistivity ratio (R{sub s} ∝ ρ{sub 0}{sup 3.1}), and inversely proportional to spontaneous magnetization. The magnetoresistance of the alloys is a few percent and has a negative sign. A positive addition to transverse magnetoresistance is only detected in high magnetic fields, H > 10 kOe.

  17. Multiple quasicrystal approximants with the same lattice parameters in Al-Cr-Fe-Si alloys

    Science.gov (United States)

    He, Zhanbing; Li, Hua; Ma, Haikun; Li, Guowu

    2017-01-01

    By means of atomic-resolution high-angle annular dark-field scanning transmission electron microscopy, we found three types of giant approximants of decagonal quasicrystal in Al-Cr-Fe-Si alloys, where each type contains several structural variants possessing the same lattice parameters but different crystal structures. The projected structures of these approximants along the pseudo-tenfold direction were described using substructural blocks. Furthermore, the structural relationship and the plane crystallographic groups in the (a, c) plan of these structural variants was also discussed. The diversity of quasicrystal approximants with the same lattice parameters was shown to be closely related to the variety of shield-like tiles and their tiling patterns. PMID:28084405

  18. Enhancement in soft magnetic and ferromagnetic ordering behaviour through nanocrystallisation in Al substituted CoFeSiBNb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohanta, Ojaswini [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Basumallick, A. [Bengal Engineering and Science University, Shibpur, West Bengal (India); Mitra, A. [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Panda, A.K., E-mail: akpanda@nmlindia.or [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India)

    2010-01-15

    The effect of substituting Al for Si in Co{sub 36}Fe{sub 36}Si{sub 4-x}Al{sub x}B{sub 20}Nb{sub 4}, (X=0, 0.5, 1.0, 1.5, 2.0 at%) alloys prepared in the form of melt-spun ribbons have been investigated. All the alloys were amorphous in their as-cast state. The onset of crystallization as observed using differential scanning calorimetry (DSC) was found to rise at low Al content up to X=1 at% beyond which there was a decreasing trend. The alloys also exhibited glass transition at 'T{sub g}'. Microstructural studies of optimally annealed samples indicated finer dispersions of nanoparticles in amorphous matrix which were identified as bcc-(FeCo)Si and bcc-(FeCo)SiAl nanophases by X-ray diffraction technique. Alloy with optimum content of Al around X=1 at% exhibited stability in coercivity at elevated temperatures. Though Al addition is known to lower magnetostriction, such consistency in coercivity may also be attributed towards lowering in the nanoparticle size compared to X=0 alloy. In the nanostructured state, the alloy containing optimum Al content (X=1) exhibited further enhancement in ferromagnetic ordering or the Curie temperature by 100 K compared to alloy without Al. Such addition also attributed to better frequency response of coercivity and low core losses.

  19. Role of aluminium addition on structure of Fe substituted Fe73.5−Si13.5B9Nb3Cu1Al alloy ribbons

    Indian Academy of Sciences (India)

    Gautam Agarwal; Himanshu Agrawal; M Srinivas; B Majumdar; N K Mukhopadhyay

    2013-08-01

    The investigation has dealt with the structure and magnetic properties of rapidly solidified and annealed Fe73.5−Si13.5B9Nb3Cu1Al ( = 0, 2, 4, 6 at%) ribbons prepared by melt spinning. Complete amorphous structure was obtained in as-spun ribbons of = 0 and 2 at% compositions, whereas structure of ribbons containing higher Al was found to be partially crystalline. Detailed thermal analyses of the alloys and the melt spun ribbons revealed that the glass forming ability in the form of x/l (ratio between crystallization and liquidus temperature) is the highest for 2 at% Al alloys and decreases with further addition of Al. Annealing of all as spun ribbons resulted in the precipitation of nanocrystalline phase embedded in amorphous matrix in the form of either 3 phase or -Fe(Si/Al) solid solution depending on the initial composition of the alloy. Only -Fe(Si/Al) solid solution was formed in 2 at% Al ribbons whereas ordered DO3 structure was found to be stabilized in other ribbons including 0 at% Al. A detailed study on determination of precision lattice parameter of nanocrystalline phase revealed that the lattice parameter increases with the addition of Al indicating the partitioning behaviour of Al in nanocrystalline phase.

  20. Be/W and W/Be bilayers deposited on Si substrates with hydrogenated Fe-Cr and Fe-Cr-Al interlayers for plasma facing components

    Science.gov (United States)

    Greculeasa, S. G.; Palade, P.; Schinteie, G.; Lungu, G. A.; Porosnicu, C.; Jepu, I.; Lungu, C. P.; Kuncser, V.

    2016-12-01

    Be/W and W/Be bilayers, of interest in regard to the specific behavior of plasma facing components (PFCs) were deposited on Si substrates by thermionic vacuum arc, with Fe, Fe-Cr and Fe-Cr-Al interlayers. The interlayers, with compositions approaching the one of the reduced activation steels used in supporting PFCs, were subsequently annealed in hydrogen atmosphere. The multilayers were characterized with respect to morphologic, structural, diffusional and atomic intermixing aspects via XRD, XRR, X-ray photoemission spectroscopy and Mössbauer spectroscopy. All as-prepared samples present partially amorphous structures. A main α-Fe phase is observed, as well as (superparamagnetic) secondary Fe oxides, metallic Fe with Si, Cr, W and Be neighbors, Be-rich Fe-Be and Fe-Si phases. High amounts of tungsten and tungsten oxides were also evidenced in the Fe layer. The strong atomic intermixing of W and Be layers was indirectly supported by the unusual densities of W and Be layers and 57Fe Mössbauer spectroscopy results.

  1. Study on Electronic Conductivity of CaO-SiO2-Al2O3-FeOx Slag System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A study on electronic conductivity of CaO-SiO2-Al2O3-FeOx slag system with Wagner polarization technique was carried out. The experimental data show that electronic conductivity is consisted of free electron conductivity and electron hole conductivity and both are related to the content of Fe3+ and Fe2+. Free electron condu ctivity is decreasing and electron hole conductivity is increasing while Fe3 + changes to Fe2+. There is a maximum electronic conductivity at some ratio of ferric ions Fe3+ to totalion content. Under the experimental conditions, the electronic conductivity is in the range of 10-4-10-2 S/cm.

  2. Powder metallurgical processing of a SiC particle reinforced Al-6wt.%Fe alloy

    OpenAIRE

    Staniek, G.; Lehnert, F.; Peters, M; Bunk, W.; Kaysser, W.

    1993-01-01

    Discontinuously reinforced aluminum alloys for elevated temperatures with a matrix hardened by intermetallic phases generally have to be produced by powder metallurgy because of their high content of alloying elements. The objective of this investigation was the evaluation of powder metallurgical processing for an A16Fe powder alloy containing various fractions and volume contents of SiC particles. During processing, the effect of powder mixing on SiC particle distribution in the extruded pro...

  3. First-principles study of the electronic and magnetic properties of Fe{sub 2}MnAl, Fe{sub 2}MnSi and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5}

    Energy Technology Data Exchange (ETDEWEB)

    Belkhouane, M. [Laboratoire d' Étude des Matériaux and Instrumentations Optiques, Département de Physique, Faculté des Sciences Exactes, Université de Sidi Bel Abbès, Sidi Bel Abbès 22000 (Algeria); Amari, S. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Yakoubi, A. [Laboratoire d' Étude des Matériaux and Instrumentations Optiques, Département de Physique, Faculté des Sciences Exactes, Université de Sidi Bel Abbès, Sidi Bel Abbès 22000 (Algeria); Tadjer, A.; Méçabih, S. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R., E-mail: khenata_rabah@yahoo.fr [LPQ3M Laboratory, Institute of Science and Technology, University of Mascara, 2900 (Algeria)

    2015-03-01

    In this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler compounds Fe{sub 2}MnAl, Fe{sub 2}MnSi and alloy Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} are presented. We have applied the full-potential linearized augmented plane waves plus local orbitals (FP-L/APW+lo) method based on the density functional theory (DFT). For the exchange and correlation potential the generalized-gradient approximation (GGA) is used. It is shown that the calculated lattice constants and spin magnetic moments are in good agreement with the available theoretical and experimental data. The calculated atomic resolved densities of states of Fe{sub 2}MnAl, Fe{sub 2}MnSi indicate half-metallic behavior with vanishing electronic density of states for minority spin at the Fermi level, which yields perfect spin polarization while for Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} shows nearly half-metallic behavior with small spin-down electronic density of states at the Fermi level. - Highlights: • FP-L/APW+lo method, within generalized-gradient approximation have been applied • The structural, electronic and magnetic properties of Fe{sub 2}MnAl, Fe{sub 2}MnSi and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} are studied • Our calculated lattice constants and spin magnetic moments are in good agreement with the available theoretical and experimental data • Fe{sub 2}MnAl, Fe{sub 2}MnSi are half-metals and Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} nearly half-metals.

  4. High-field magnetization of heusler alloys Fe2 XY ( X = Ti, V, Cr, Mn, Fe, Co, Ni; Y = Al, Si)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Belozerova, K. A.; Weber, H. W.

    2015-10-01

    The magnetization curves of ferromagnetic Heusler alloys Fe2 XY (where X = Ti, V, Cr, Mn, Fe, Co, Ni are transition 3 d elements and Y = Al, Si are the s and p elements of the third period of the Periodic Table) have been measured at T = 4.2 K in the field range H ≤ 70 kOe. It has been shown that the high-field ( H ≥ 20 kOe) magnetization is described within the Stoner model.

  5. Effect of nitrogenation on magnetism for Y{sub 2}Fe{sub 17-x}(SiAl){sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, K. [Faculty of Science, Ehime University, Matsuyama 790 (Japan); Mori, Y. [Faculty of Science, Ehime University, Matsuyama 790 (Japan); Asano, M. [Faculty of Science, Ehime University, Matsuyama 790 (Japan); Kamimori, T. [Faculty of Science, Ehime University, Matsuyama 790 (Japan); Tange, H. [Faculty of Science, Ehime University, Matsuyama 790 (Japan); Goto, M. [Faculty of Science, Ehime University, Matsuyama 790 (Japan)

    1995-02-09

    The magnetic moment ({mu}) of the host compounds Y{sub 2}Fe{sub 17-x}M{sub x} (M=Si, Si{sub 0.7}Al{sub 0.3}, Al) decreases gradually with x irrespective of M and of the unit cell volume. After that, {mu} decreases steeply with x. {mu} increases about 15% after nitrogenation. {mu} of nitrides decreases with x which is similar to that of the host compounds. However, the range of x, where {mu} decreases gradually with x, is narrower than that of host compounds. This result shows that polarization of the 3d-band is enhanced by nitrogenation. ((orig.)).

  6. The effects of individual metal contents on isochrones for C, N, O, Na, Mg, Al, Si, and Fe

    CERN Document Server

    Beom, Minje; Ferguson, Jason W; Kim, Y -C

    2016-01-01

    The individual characteristics of C, N, O, Na, Mg, Al, Si, and Fe on isochrones have been investigated in this study. Stellar models have been constructed for various mixtures in which the content of each element is changed up to the extreme value reported in recent studies, and the changes in isochrone shape have been analyzed for the various mixtures. To express the abundance variation of different elements with a single parameter, we have focused on the relative changes in the total number of metal ions. A review of the shape changes revealed that Na, Mg, and Al work the same way in stellar models, as the well-known fact that C, N, and O have the same reactions in the stellar interior. In addition, it was found that in high-metallicity conditions the influence of Si and Fe on the red giant branch becomes smaller than that of Na, Mg, and Al closer to the tip. Furthermore, the influence of Fe on the main sequence is larger than that of Na, Mg, Al, and even Si.

  7. Post-irradiation examination of AlFeNi cladded U 3Si 2 fuel plates irradiated under severe conditions

    Science.gov (United States)

    Leenaers, A.; Koonen, E.; Parthoens, Y.; Lemoine, P.; Van den Berghe, S.

    2008-04-01

    Three full size AlFeNi cladded U 3Si 2 fuel plates were irradiated in the BR2 reactor of the Belgian Nuclear Research Centre (SCK·CEN) under relatively severe, but well defined conditions. The irradiation was part of the qualification campaign for the fuel to be used in the future Jules Horowitz reactor in Cadarache, France. After the irradiation, the fuel plates were submitted to an extensive post-irradiation campaign in the hot cell laboratory of SCK·CEN. The PIE shows that the fuel plates withstood the irradiation successfully, as no detrimental defects have been found. At the cladding surface, a multilayered corrosion oxide film has formed. The U-Al-Si layer resulting from the interaction between the U 3Si 2 fuel and the Al matrix, has been quantified as U(Al,Si) 4.6. It is found that the composition of the fuel particles is not homogenous; zones of USi and U 3Si 2 are observed and measured. The fission gas-related bubbles generated in both phases show a different morphology. In the USi fuel, the bubbles are small and numerous while in U 3Si 2 the bubbles are larger but there are fewer.

  8. The influence of microchemistry on the recrystallization texture of cold-rolled Al-Mn-Fe-Si alloys

    OpenAIRE

    Huang, K.; Y. J. Li; Marthinsen, K

    2015-01-01

    The recrystallization textures of a cold-rolled Al-Mn-Fe-Si model alloy with three different microchemistry states after non-isothermal annealing were studied. The microstructure and texture evolution have been characterized by EBSD. It is clearly demonstrated that the actual microchemistry state as determined by the homogenization procedure strongly influence the recrystallized grain size and recrystallization texture after nonisothermal annealing. High Mn content in solid solution promotes ...

  9. Microstructural Evolution during Isothermal Annealing of a Cold-Rolled Al-Mn-Fe-Si Alloy with Different Microchemistry States

    OpenAIRE

    Huang, Ke; Li, Yan Jun; Marthinsen, Knut

    2014-01-01

    In this paper, investigation of the softening behaviour of a supersaturated Al-Mn-Fe-Si alloy during annealing after cold rolling has been carried out. Two different homogenization conditions were considered, of which one gives a condition of a large amount of small pre-existing dispersoids, i.e. providing a significant static Zener drag, while the other gives a condition where both concurrent precipitation and dispersoid drag effects are limited. The homogenized samples with different microc...

  10. TOPICAL REVIEW: Rational design of new materials for spintronics: Co2FeZ (Z=Al, Ga, Si, Ge

    Directory of Open Access Journals (Sweden)

    Benjamin Balke et al

    2008-01-01

    Full Text Available Spintronic is a multidisciplinary field and a new research area. New materials must be found for satisfying the different types of demands. The search for stable half-metallic ferromagnets and ferromagnetic semiconductors with Curie temperatures higher than room temperature is still a challenge for solid state scientists. A general understanding of how structures are related to properties is a necessary prerequisite for material design. Computational simulations are an important tool for a rational design of new materials. The new developments in this new field are reported from the point of view of material scientists. The development of magnetic Heusler compounds specifically designed as material for spintronic applications has made tremendous progress in the very recent past. Heusler compounds can be made as half-metals, showing a high spin polarization of the conduction electrons of up to 100% in magnetic tunnel junctions. High Curie temperatures were found in Co2-based Heusler compounds with values up to 1120 K in Co2FeSi. The latest results at the time of writing are a tunnelling magnet resistance (TMR device made from the Co2FeAl0.5Si0.5 Heusler compound and working at room temperature with a (TMR effect higher than 200%. Good interfaces and a well-ordered compound are the precondition to realize the predicted half-metallic properties. The series Co2FeAl1- xSix is found to exhibit half-metallic ferromagnetism over a broad range, and it is shown that electron doping stabilizes the gap in the minority states for x=0.5. This might be a reason for the exceptional temperature behaviour of Co2FeAl0.5Si0.5 TMR devices. Using x-ray diffraction (XRD, it was shown conclusively that Co2FeAl crystallizes in the B2 structure whereas Co2FeSi crystallizes in the L21 structure. For the compounds Co2FeGa or Co2FeGe, with Curie temperatures expected higher than 1000 K, the standard XRD technique using laboratory sources cannot be used to easily distinguish

  11. Microstructure and mechanical properties of spray-deposited Al-Si-Fe-Cu-Mg alloy containing Mn

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Al-20Si-5Fe-3Cu-lMg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited hypereutectic Al-Si alloy were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, TEM (Transmission Electron Microscope) and HREM (High-resolution Electron Microscope), DSC (Differential Scanning Calorimetry), microhardness measurement, and tensile tests. The effects of Mn on the microstructural evolution of the highsilicon aluminum alloy after extrusion and heat treatment have been examined. The results show that two kinds of phases, i.e. S (Al2CuMg) and σ(Al5Cu6Mg2), precipitated from matrix and improved the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300℃). The tensile test results indicate that the spray-deposited Al-20Si-SFe-3Cu-1Mg alloy has better strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.

  12. Magnetic transition induced by mechanical deformation in Fe{sub 60}Al{sub 40−x}Si{sub x} ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E., E-mail: estibaliz.legarra@ehu.es [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Apiñaniz, E. [Dpto. Fisica Aplicada I, Universidad del Pais Vasco, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain)

    2014-02-15

    Highlights: • Fe{sub 60}Al{sub 40−x}Si{sub x} alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe{sub 60}Al{sub 40−x}Si{sub x} alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe{sub 60}Al{sub 40} alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition.

  13. Effects of TiFe Intermetallic Compounds on the Tensile Behavior of Ti-4Al-4Fe-0.25Si Alloy

    Science.gov (United States)

    Lee, Sang Won; Kim, Kyong Min; Park, Chan Hee; Hong, Jea Keun; Yeom, Jong-Taek; Shih, Donald S.

    2017-02-01

    The effect of the B2 (ordered BCC) intermetallic compound TiFe on the tensile behavior of the Ti-4Al-4Fe-0.25Si alloy was investigated. The nucleation mechanism of TiFe was dependent on the solution temperature, and the solution treatment and aging temperatures were also important to the final alloy. The presence of intra-granular TiFe, which nucleated at α' (HCP) sites during aging, resulted in alloy brittleness. Alternatively, the presence of inter-granular TiFe, which nucleated only at nano-sized α (HCP) sites during aging, resulted in an excellent combination of strength and ductility compared to the original microstructure.

  14. Structure and properties of cast and splat-quenched high-entropy Al-Cu-Fe-Ni-Si alloys

    Science.gov (United States)

    Bashev, V. F.; Kushnerov, O. I.

    2017-01-01

    The effect of the composition and cooling rate of the melt on the microhardness, phase composition, and fine-structure parameters of as-cast and splat-quenched (SQ) high-entropy (HE) Al-Cu-Fe-Ni-Si alloys was studied. The quenching was performed by conventional splat-cooling technique. The cooling rate was estimated to be 106 K/s. Components of the studied HE alloys were selected taking into account both criteria for designing and estimating their phase composition, which are available in the literature and based on the calculations of the entropy and enthalpy of mixing, and the difference between atomic radii of components as well. According to X-ray diffraction data, the majority of studied Al-Cu-Fe-Ni-Si compositions are two-phase HE alloys, the structure of which consists of disordered solid solutions with bcc and fcc structures. At the same time, the Al0.5CuFeNi alloy is single-phase in terms of X-ray diffraction and has an fcc structure. The studied alloys in the as-cast state have a dendritic structure, whereas, after splat quenching, the uniform small-grained structure is formed. It was found that, as the volume fraction of bcc solid solution in the studied HE alloys increases, the microhardness increases; the as-cast HE Al-Cu-Fe-Ni-Si alloys are characterized by higher microhardness compared to that of splat-quenched alloys. This is likely due to the more equilibrium multiphase state of as-cast alloys.

  15. Fabrication and characterization of nanocrystalline Al/Al12(Fe,V)3Si alloys by consolidation of mechanically alloyed powders

    Institute of Scientific and Technical Information of China (English)

    Hamid Ashrafi; Rahmatollah Emadi; Mohammad Hosein Enayati

    2014-01-01

    The aim of this study was to produce bulk nanocrystalline Al/Al12(Fe,V)3Si alloys by mechanical alloying (MA) and subsequent hot pressing (HP) of elemental powders. A nanostructured Al-based solid solution was formed by MA of elemental powders for 60 h. After HP of the as-milled powders at 550°C for 20 min, the Al12(Fe,V)3Si phase was precipitated in a nanocrystalline Al matrix. Scanning electron microscopy (SEM) images of the bulk samples represented a homogeneous and uniform microstructure that was superior to those previously obtained by rapid solidification–powder metallurgy (RS–PM). Nanostructured Al−8.5Fe−1.3V−1.7Si and Al−11.6Fe−1.3V−2.3Si alloys ex-hibited high HV hardness values of~205 and~254, respectively, which are significantly higher than those reported for the RS–PM counter-parts.

  16. Magnetic field control and wavelength tunability of SPP excitations using Al2O3/SiO2/Fe structures

    Science.gov (United States)

    Kaihara, Terunori; Shimizu, Hiromasa; Cebollada, Alfonso; Armelles, Gaspar

    2016-09-01

    Here, we show the high wavelength tunability and magnetic field modulation of surface plasmon polaritons (SPPs) of a waveguide mode that Double-layer Dielectrics and Ferromagnetic Metal, Al2O3/SiO2/Fe, trilayer structures exhibit when excited in the Otto configuration of attenuated total reflection setup. First by modeling, and then experimentally, we demonstrate that it is possible to tune the wavelength at which the angular dependent reflectance of these structures reaches its absolute minimum by simply adjusting the SiO2 intermediate dielectric layer thickness. This precise wavelength corresponds to the cut-off condition of SPPs' waveguide mode supported by the proposed structure, and it can be then switched between two values upon magnetization reversal of the Fe layer. In this specific situation, a large enhancement of the transverse magneto-optical effect is also obtained.

  17. 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.

  18. Deformation Localization and Shear Fracture of a Rapidly Solidified Al-Fe-V-Si Alloy at Elevated Temperature

    Institute of Scientific and Technical Information of China (English)

    Yongbo XU

    2007-01-01

    The tensile and fatigue behavior of a dispersoid strengthened, powder metallurgy Al-Fe-V-Si alloy at ambient and elevated temperatures was investigated. The results show that the strength and ductility of the alloy decrease significantly with increasing temperature and decreasing strain rate. Micro-structural examinations reveal that this change in mechanical behavior with increasing temperature is related to the mode of deformation of the alloy. Further observations show that localized shear deformation is responsible for the losses in both strength and ductility of the alloy at elevated temperature.

  19. Effect of melt spinning variables on the structure and properties of a dispersion strengthened Al-Fe-V-Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.N.; Little, S.D. [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering

    1995-04-15

    Skinner, et al, have developed a series of quaternary Al-Fe-V-Si alloys, with a view to replace titanium alloys for applications at temperatures up to 650 K. One among them is FVS 1212 (Fe-11.5%, v-1.4%, Si-2.2%, Al-bal). The structure of this alloy is essentially a dispersion of Al{sub 12} (Fe,V){sub 3} dispersoids ({alpha} particles) in aluminum matrix. Though the particles have resistance to coarsening at temperature sup to 650 K, they confer brittleness at room temperature making low-temperature fabrication of this alloy difficult. Since the flow stress is greater when the clustering increases, it may be implied that the drag increases with increase in clustering. As a corollary, dispersion of fine dispersoids, would evidently lead to lower flow stress. This indicates that if the Zener drag is reduced to a sufficiently low value by proper dispersion of fine particles, the flow stress would decrease causing a shift towards superplasticity. This provided the impetus for a basic investigation involving the relationship between the microstructure (and properties) and rapid solidification conditions, so that a desirable starting material could be prepared. It may be mentioned in this connection that the previous investigators chose the rapid solidification conditions to get ribbons varying over a narrow range in thickness. Thus, the cooling rates in these investigations may be presumed to be varied over a small range. It was thus felt by the present investigators that work involving variation of the cooling rate over a larger range would probably provide additional clues for achievement of superplasticity in the dispersion strengthened aluminum alloy under consideration.

  20. Effect of Co substitution on magnetic properties and magnetic entropy changes in LaFe11.83Si0.94Al0.23 Compounds

    Institute of Scientific and Technical Information of China (English)

    Shen Jun; Li Yang-Xian; Wang Fang; Wang Guang-Jun; Zhang Shao-Ying

    2004-01-01

    Effect of Co substitution on magnetic properties and magnetic entropy changes in LaFe11.83Si0.94Al0.23 compounds has been investigated by means of magnetization measurements. X-ray diffraction shows the prepared compounds to be single phase with the cubic NaZn13-type structure. Substitution of Co for Fe leads to an increase of Curie temperature of the material. The magnetic entropy changes in LaFe11.83Si0.94Al0.23 and LaFe1L03Co0.80Si0.94Al0.23 compounds are 21.8J/(kg.K) to 16.9J/(kg.K) under a magnetic field change of 0-5T at Curie temperature, respectively. Giant magnetic entropy changes are attributed to the higher magnetization and the rapid change in magnetization at Curie temperature.

  1. Search for half-metallic magnets with large half-metallic gaps in the quaternary Heusler alloys CoFeTiZ and CoFeVZ (Z=Al, Ga, Si, Ge, As, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Lun [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Laboratory of Optical Information Technology and School of Science, Wuhan Institute of Technology, Wuhan 430073 (China); Yi, Lin [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Gao, G.Y., E-mail: guoying_gao@mail.hust.edu.cn [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-06-01

    We investigate the electronic structure and magnetic properties of the twelve quaternary Heusler alloys CoFeTiZ and CoFeVZ (Z=Al, Ga, Si, Ge, As, Sb) by using the first-principles calculations. It is shown that only CoFeTiSi, CoFeTiAs and CoFeVSb are half-metallic ferromagnets with considerable half-metallic gaps of 0.31, 0.18 and 0.17 eV, respectively. CoFeTiAl and CoFeTiGa are conventional semiconductors, and other alloys exhibit nearly half-metallicity or their half-metallic gaps are almost zero eV. We also find that the half-metallicities of CoFeTiSi, CoFeTiAs and CoFeVSb can be preserved under appropriate uniform and in-plane strains. The considerable half-metallic gaps and the robust half-metallicities under uniform and in-plane strains make CoFeTiSi, CoFeTiAs and CoFeVSb promising candidates for spintronic applications. - Highlights: • CoFeTiSi, CoFeTiAs and CoFeVSb have considerable half-metallic gaps. • Total magnetic moments obey the Slater–Pauling behavior of quaternary Heusler half-metals. • CoFeTiSi, CoFeTiAs and CoFeVSb retain half-metallicity under uniform and in-plane strains.

  2. Giant tunnel magnetoresistance at room temperature using Co{sub 2}Fe(SiAl) full Heusler alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Inomata, Koichiro [National Institute for Materials Science, Tsukuba (Japan); Tohoku University, Sendai (Japan); CREST-JST, Saitama (Japan); Ikeda, Naomichi [Tohoku University, Sendai (Japan); CREST-JST, Saitama (Japan); Tezuka, Nobuki [Tohoku University, Sendai (Japan)

    2007-07-01

    Half-metallic ferromagnets (HMFs) are a key material for spintronics, which have a band gap at the Fermi level (EF) for one spin direction and thus exhibit 100% spin polarization at the EF. Full Heusler alloys, in particular, are promising as a half metal, because a number of which have been predicted to be HMFs and have a high Curie temperature. Here we report the giant TMR observation at room temperature (RT) for the MTJ using Co{sub 2}Fe(Si,Al) (CFSA) electrodes. We first investigate the structure of the sputtered CFSA films on a Cr-buffered MgO(001) substrate in an ultrahigh vacuum by post annealing at various temperatures. Next we fabricate the epitaxially grown spin-valve type MTJs on a Cr-buffered MgO(001) substrate with Co{sub 2}FeSi{sub 0.5}Al{sub 0.5} full-Heusler alloys for top and bottom electrodes and an MgO barrier with different thicknesses. The bottom CFAS film is post-annealed at 673 K after the deposition at RT, followed by the deposition of the other films at RT. The junctions are the annealed at various temperatures, and then microfabricated into 100 mm{sup 2} using the electron beam lithography and Ar ion milling. We have successfully grown the highly ordered CFSA full-Heusler films for top and bottom electrodes. As a result we have attained the giant TMR over 200% at RT.

  3. Estimation of fracture parameters for Al-SiC and Al-Fe2O3 metal matrix composites

    Science.gov (United States)

    Jacob, S.; Sridhar, R.; Irudaya Raja, S. Joseph

    2017-03-01

    In this paper silicon carbide and iron oxide is reinforced with aluminum matrix. The prepared composite provide high strength than the commercial composite. It provides high elastic properties and high service temperature. Since this material have great scope in space application it has been chosen for estimation of fracture toughness. Hence grain size of the samples increased this is due to the effect of reinforcement bonding with aluminum matrix. The CMOD test has been carried out for this Purpose. Microscopic examination has shown that with increase in of reinforcement test confirmed that with increase in reinforcement ratio the fracture toughness also increased. In this work specimens have been preferred with and without addition of SiC and Fe2O3 to compare the influence. The results are compared and it has been studied that Fracture Toughness increased significantly by addition of inclusions.

  4. 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)

  5. Magnetic and structural properties of Co{sub 2}FeAl thin films grown on Si substrate

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, Mohamed, E-mail: belmeguenai.mohamed@univ-paris13.fr [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Tuzcuoglu, Hanife [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France); Gabor, Mihai; Petrisor, Traian [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Tiusan, Coriolan [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Street Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F-54506 Vandoeuvre (France); Berling, Dominique [IS2M (CNRS-LRC 7228), 15 rue Jean Starcky, Université de Haute-Alsace, BP 2488, 68057 Mulhouse-Cedex (France); Zighem, Fatih; Mourad Chérif, Salim [LSPM (CNRS-UPR 3407) 99 Avenue Jean-Baptiste Clément Université Paris 13, 93430 Villetaneuse (France)

    2015-01-01

    The correlation between magnetic and structural properties of Co{sub 2}FeAl (CFA) thin films of different thicknesses (10 nmSi/SiO{sub 2} substrates and annealed at 600 °C has been studied. x-ray diffraction (XRD) measurements revealed an (011) out-of-plane textured growth of the films. The deduced lattice parameter increases with the film thickness. Moreover, pole figures showed no in-plane preferential growth orientation. The magneto-optical Kerr effect hysteresis loops showed the presence of a weak in-plane uniaxial anisotropy with a random easy axis direction. The coercive field, measured with the applied field along the easy axis direction, and the uniaxial anisotropy field increase linearly with the inverse of the CFA thickness. The microstrip line ferromagnetic resonance measurements for in-plane and perpendicular applied magnetic fields revealed that the effective magnetization and the uniaxial in-plane anisotropy field follow a linear variation versus the inverse CFA thickness. This allows deriving a perpendicular surface anisotropy coefficient of −1.86 erg/cm{sup 2}. - Highlights: • Various Co{sub 2}FeAl thin films were grown on a Si(001) substrates and annealed at 600 °C. • The thickness dependence of magnetic and structural properties has been studied. • X-ray measurements revealed an (011) out-of-plane textured growth of the films. • The easy axis coercive field varies linearly with the inverse CFA thickness. • The effective magnetization increases linearly with the inverse film thickness.

  6. High-pressure, temperature elasticity of Fe- and Al-bearing MgSiO3: implications for the Earth's lower mantle

    CERN Document Server

    Zhang, Shuai; Liu, Tao; Stackhouse, Stephen; Militzer, Burkhard

    2015-01-01

    Fe and Al are two of the most important rock-forming elements other than Mg, Si, and O. Their presence in the lower mantle's most abundant minerals, MgSiO_3 bridgmanite, MgSiO_3 post-perovskite and MgO periclase, alters their elastic properties. However, knowledge on the thermoelasticity of Fe- and Al-bearing MgSiO_3 bridgmanite, and post-perovskite is scarce. In this study, we perform ab initio molecular dynamics to calculate the elastic and seismic properties of pure, Fe^{3+}- and Fe^{2+}-, and Al^{3+}-bearing MgSiO_3 perovskite and post-perovskite, over a wide range of pressures, temperatures, and Fe/Al compositions. Our results show that a mineral assemblage resembling pyrolite fits a 1D seismological model well, down to, at least, a few hundred kilometers above the core-mantle boundary, i.e. the top of the D'' region. In D'', a similar composition is still an excellent fit to the average velocities and fairly approximate to the density. We also implement polycrystal plasticity with a geodynamic model to ...

  7. Perspectives on the exploitation of CuZnAl alloys, FeMnSi-based alloys and ZrO{sub 2}-containing shape-memory ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, T.Y. [Shanghai Jiao Tong Univ. (St. Helena). School of Materials Science and Engineering

    2002-07-01

    Cu-Zn-Al alloys possess advantages for exploitation such as low cost, easy fabrication and excellent shape memory effect (SME). The deficiencies of Cu-Zn-Al shape memory alloys, i.e. the appearance of the stabilization of martensite, degradation of SME in prolonged application and the rather low fatigue life, can be overcome by various processing such as immediate up-quenching, alloying addition for retarding the incubation of bainite formation and grain refinement. Fe-Mn-Si based alloys are one-way shape memory material with high strength, high action temperatures, good workability and low cost. Addition of nitrogen or rare earth (RE) elements can considerably strengthen the austenite and lower the Neel temperature in Fe-Mn-Si alloys. Partial replacement of Mn with Cr and addition of RE elements to Fe-Mn-Si may reduce its stacking fault energy. Nitrogen and RE elements also lower the M{sub s} temperature of Fe-Mn-Si and Fe-Mn-Si-Cr, stabilizing the austenite after shape recovery. The newly developed Fe-25Mn-6Si-5Cr-0.14N alloy possesses not only a complete shape memory recovery with a recoverable strain of 3% through only one cycle of training, but also the nice corrosion resistance in aqueous solution of NaOH and NaCl. The SME of Fe-Mn-Si-RE is superior to that of Fe-Mn-Si, e.g. its recoverable strain is about two-fold larger than that of Fe-Mn-Si when the pre-strain {epsilon}>3%. The exploitation of the Fe-Mn-Si-Cr-N and Fe-Mn-Si-RE alloys as coupling materials seems to be foresighted. Studies on (8{proportional_to}12)mol%CeO{sub 2}-(0.25{proportional_to}0.75)mol%Y{sub 2}O{sub 3}-ZrO{sub 2} with various grain size and density after different sintering processes show that 8mol%CeO{sub 2}-0.5mol%Y{sub 2}O{sub 3}-ZrO{sub 2} fabricated by sintering at 1773 K for 6 hours exhibits best SME, i.e. a complete shape memory recovery and a recoverable strain of 1.2% at high temperatures (above 773 K). The shape memory ceramics 8Ce-0.5Y-TZP is worthy to be developed. (orig.)

  8. Steam Oxidation of FeCrAl and SiC in the Severe Accident Test Station (SATS)

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-01

    Numerous research projects are directed towards developing accident tolerant fuel (ATF) concepts that will enhance safety margins in light water reactors (LWR) during severe accident scenarios. In the U.S. program, the high temperature steam oxidation performance of ATF solutions has been evaluated in the Severe Accident Test Station (SATS) at Oak Ridge National Laboratory (ORNL) since 2012 [1-3] and this facility continues to support those efforts in the ATF community. Compared to the current UO2/Zr-based alloy fuel system, alternative cladding materials can offer slower oxidation kinetics and a smaller enthalpy of oxidation that can significantly reduce the rate of heat and hydrogen generation in the core during a coolant-limited severe accident [4-5]. Thus, steam oxidation behavior is a key aspect of the evaluation of ATF concepts. This report summarizes recent work to measure steam oxidation kinetics of FeCrAl and SiC specimens in the SATS.

  9. Low-temperature negative thermal expansion behavior of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shaopeng [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Huang, Rongjin, E-mail: huangrongjin@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); Li, Wen [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Wang, Wei [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); Zhao, Yuqiang [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China); University of Chinese Academy of Sciences, Beijing (China); Li, Laifeng, E-mail: laifengli@mail.ipc.ac.cn [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing (China)

    2015-10-15

    The cubic NaZn{sub 13}-type LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x}(x = 0.2, 0.3, 0.4 and 0.5) compounds with different Si content were fabricated by conventional arc-melting method, the structures of which were confirmed by powder X-ray diffraction (XRD) measurement at ambient temperature. Besides, the thermal expansion and magnetic properties of these samples were also researched by means of a strain gage and a physical property measurement system (PPMS). Significantly, it was found that the negative thermal expansion (NTE) behavior have been remarkably enhanced with substituting Al with Si atoms. Furthermore, the NTE operation-temperature window concurrently shifts toward a higher temperature region. The variable temperature XRD results indicate that LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} retain cubic NaZn{sub 13}-type structure when temperature varies from 20 K to 270 K, including the temperature region where NTE occurs. The further theoretical analysis combined with magnetic characterization reveal that the improvement of NTE behavior is attributed to the enhancement of Fe–Fe magnetic exchange interactions with doping Si atoms. It is noteworthy that this study displays a new pathway to improve the NTE property of La(Fe,Al){sub 13}-based compounds at low temperature region, which highlights the potential applications of NTE materials in cryogenic engineering. - Highlights: • Negative thermal expansion of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} was improved by introducing Si. • The structure of LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} was studied by X-ray diffraction measurement. • We analyze the mechanism of NTE in LaFe{sub 11.2}Al{sub 1.8−x}Si{sub x} by magnetic measurement.

  10. Tuning Fermi level of Cr{sub 2}CoZ (Z=Al and Si) inverse Heusler alloys via Fe-doping for maximum spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Saini, Hardev S. [Department of Physics, Panjab University, Chandigarh-160014 (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Reshak, Ali H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India)

    2014-12-15

    We report full potential treatment of electronic and magnetic properties of Cr{sub 2−x}Fe{sub x}CoZ (Z=Al, Si) Heusler alloys where x=0.0, 0.25, 0.5, 0.75 and 1.0, based on density functional theory (DFT). Both parent alloys (Cr{sub 2}CoAl and Cr{sub 2}CoSi) are not half-metallic frromagnets. The gradual replacement of one Cr sublattice with Fe induces the half-metallicity in these systems, resulting maximum spin polarization. The half-metallicity starts to appear in Cr{sub 2−x}Fe{sub x}CoAl and Cr{sub 2−x}Fe{sub x}CoSi with x=0.50 and x=0.25, respectively, and the values of minority-spin gap and half-metallic gap or spin-flip gap increase with further increase of x. These gaps are found to be maximum for x=1.0 for both cases. An excellent agreement between the structural properties of CoFeCrAl with available experimental study is obtained. The Fermi level tuning by Fe-doping makes these alloys highly spin polarized and thus these can be used as promising candidates for spin valves and magnetic tunnelling junction applications. - Highlights: • Tuning of E{sub F} in Cr{sub 2}CoZ (Z=Al, Si) has been demonstrated via Fe doping. • Effect of Fe doping on half-metallicity and magnetism have been discussed. • The new alloys have a potential of being used as spin polarized electrodes.

  11. The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys.

    Science.gov (United States)

    Gebhardt, T; Music, D; Ekholm, M; Abrikosov, I A; Vitos, L; Dick, A; Hickel, T; Neugebauer, J; Schneider, J M

    2011-06-22

    We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Néel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

  12. Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

    Science.gov (United States)

    Nedelkoski, Zlatko; Kuerbanjiang, Balati; Glover, Stephanie E.; Sanchez, Ana M.; Kepaptsoglou, Demie; Ghasemi, Arsham; Burrows, Christopher W.; Yamada, Shinya; Hamaya, Kohei; Ramasse, Quentin M.; Hasnip, Philip J.; Hase, Thomas; Bell, Gavin R.; Hirohata, Atsufumi; Lazarov, Vlado K.

    2016-11-01

    Halfmetal-semiconductor interfaces are crucial for hybrid spintronic devices. Atomically sharp interfaces with high spin polarisation are required for efficient spin injection. In this work we show that thin film of half-metallic full Heusler alloy Co2FeSi0.5Al0.5 with uniform thickness and B2 ordering can form structurally abrupt interface with Ge(111). Atomic resolution energy dispersive X-ray spectroscopy reveals that there is a small outdiffusion of Ge into specific atomic planes of the Co2FeSi0.5Al0.5 film, limited to a very narrow 1 nm interface region. First-principles calculations show that this selective outdiffusion along the Fe-Si/Al atomic planes does not change the magnetic moment of the film up to the very interface. Polarized neutron reflectivity, x-ray reflectivity and aberration-corrected electron microscopy confirm that this interface is both magnetically and structurally abrupt. Finally, using first-principles calculations we show that this experimentally realised interface structure, terminated by Co-Ge bonds, preserves the high spin polarization at the Co2FeSi0.5Al0.5/Ge interface, hence can be used as a model to study spin injection from half-metals into semiconductors.

  13. Preparation and properties of magnetic alumina microspheres with a γ-Fe2O3/SiO2 core and Al2O3 shell

    Institute of Scientific and Technical Information of China (English)

    Qingtao Fu; Tingting He; Lianqing Yu; Yongming Chai; Chenguang Liu

    2011-01-01

    Magnetic alumina composite microspheres with γ-Fe2O3 core/Al2O3 shell structure were prepared by the oil column method.A dense silica layer was deposited on the surface of γ-Fe2O3 particles(denoted as γ-Fe2O3/SiO2)with a desired thickness to protect the iron oxide core against acidic or high temperature conditions.γ-Fe2O3/SiO2/Al2O3 particles with about 85 wt% Al2O3 were obtained and showed to be suitable for practical applications as a magnetic catalyst or catalyst support due to their magnetic properties and pore structure.The products were characterized with scanning electron microscope(SEM)and transmission electron microscope(TEM),nitrogen adsorption-desorption,and vibrating sample magnetometer(VSM).The specific surface area and pore volume of the γ-Fe2O3/SiO2/Al2O3 composite microspheres calcined at 500 ℃ were 200 m2/g and 0.77 cm3/g,respectively.

  14. Analysis of the Fe-Ce-O-C- M phase diagrams ( M = Ca, Mg, Al, Si) by constructing a component-solubility surface

    Science.gov (United States)

    Mikhailov, G. G.; Makrovets, L. A.; Smirnov, L. A.; Dresvyankina, L. E.

    2016-06-01

    Analysis of the ternary phase diagrams of Ce2O3- and CeO2-containing oxide systems allowed us to find the oxide compounds that form during steel deoxidizing with cerium and with cerium together with aluminum, calcium, magnesium, or silicon. The temperature dependences of the equilibrium constants of formation of Ce2O3 oxides and Ce2O3 · Al2O3, Ce2O3 · 11Al2O3, Ce2O3 · 2SiO2, 7Ce2O3 · 9SiO2 and Ce2O3 · SiO2 compounds are found. Surfaces for the component solubility in metallic melts Fe-Al-Ce-O-C, Fe- Ca-Ce-O-C, Fe-Mg-Ce-O-C, and Fe-Si-Ce-O-C are constructed. Nonmetallic inclusions that form in the course of experimental melts of St20 steel after its deoxidizing with silicocalcium and rare-earth metal (REM)-containing master alloys in a ladle furnace after degassing are studied. Phase inhomogeneity of the inclusions is found. As a rule, they consist of phases classified into the following three groups: oxide-sulfide, sulfide-oxide, and multiphase oxide-sulfide melt. Calcium aluminates are found to be components of complex sulfide-oxide noncorrosive inclusions.

  15. Dependence of dynamic magnetization and magneto-transport properties of FeAlSi films with oblique sputtering studied via spin rectification effect

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Wee Tee; Ong, C. K. [Department of Physics, Center for Superconducting and Magnetic Materials, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Zhong, Xiaoxi, E-mail: xiaoxi.zhong@gmail.com [Department of Physics, Center for Superconducting and Magnetic Materials, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2014-09-15

    FeAlSi (Sendust) is known to possess excellent soft magnetic properties comparable to traditional soft magnetic alloys such as NiFe (Permalloy), while having a relatively higher resistance for lower eddy current losses. However, their dynamic magnetic and magneto-transport properties are not well-studied. Via the spin rectification effect, we electrically characterize a series of obliquely sputtered FeAlSi films at ferromagnetic resonance. The variations of the anisotropy fields and damping with oblique angle are extracted and discussed. In particular, two-magnon scattering is found to dominate the damping behavior at high oblique angles. An analysis of the results shows large anomalous Hall effect and anisotropic magneto-resistance across all samples, which decreases sharply with increasing oblique incidence.

  16. Characterization of Fe/C catalysts supported on Al{sub 2}O{sub 3}, SiO{sub 2} and TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lodya, J A L; Manzini, S S [Sasol Technology, R and D, 1 Klasie Havenga Road, Sasolburg 1947 (South Africa); Seda, T [Western Washington University, Physics Department, Bellingham, WA 98225 (United States); Strydom, A M, E-mail: lonzeche.lodya@sasol.co [University of Johannesburg, Phys. Department, PO Box 524, Auckland Park 2006 (South Africa)

    2010-01-01

    Structural and magnetic properties of Fe/C catalysts synthesized by ball milling and deposited onto Al{sub 2}O{sub 3}, SiO{sub 2} and TiO{sub 2} supports are reported. Ball milling {alpha}-Fe and C in the presence of these supports produced peculiar solid solutions in which antiferromagnetic and ferrimagnetic iron phases doped with Al, Si and Ti coexist. Moessbauer spectroscopy and powder X-ray diffraction data show no evidence of any Fe{sub x}C phase. Instead, oxidation took place even though carbon (graphite) was present. All the catalysts were found to exhibit strong metal-support interactions, with the strongest interactions found in the TiO{sub 2} supported catalyst.

  17. Optimization of exchange bias in Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} Heusler alloy layers

    Energy Technology Data Exchange (ETDEWEB)

    Hirohata, Atsufumi, E-mail: ah566@ohm.york.ac.uk [Department of Electronics, University of York, Heslington, York YO10 5DD (United Kingdom); PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012 (Japan); Izumida, Keisuke; Ishizawa, Satoshi; Nakayama, Tadachika [Department of Electrical Engineering, Nagaoka University of Technology, Nagaoka 940-2188 (Japan); Sagar, James [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)

    2014-05-07

    We have fabricated and investigated IrMn{sub 3}/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} stacks to meet the criteria for future spintronic device applications which requires low-temperature crystallisation (<250 °C) and a large exchange bias H{sub ex} (>500 Oe). Such a system would form the pinned layer in spin-valve or tunnel junction applications. We have demonstrated that annealing at 300 °C which can achieve crystalline ordering in the Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} layer giving ∼80% of the predicted saturation magnetisation. We have also induced an exchange bias of ∼240 Oe at the interface. These values are close to the above criteria and confirm the potential of using antiferromagnet/Heusler-alloy stacks in current Si-based processes.

  18. The Influence of Processing Conditions on Microchemistry and the Softening Behavior of Cold Rolled Al-Mn-Fe-Si Alloys

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2016-03-01

    Full Text Available Using different homogenization treatments, different initial microchemistry conditions in terms of solid solution levels of Mn, and number densities and sizes of constituents and dispersoids were achieved in an Al-Mn-Fe-Si model alloy. For each homogenized condition, the microchemistry and microstructure, which further change both during deformation and subsequent annealing, were quantitatively characterized. The influence of the different microchemistries, with special focus on different particle structures (constituents and dispersoids, on the softening behavior during annealing after cold rolling and the final grain structure has been systematically studied. Time-Temperature-Transformation diagrams with respect to precipitation and recrystallization as a basis for analysis of the degree of concurrent precipitation during back-annealing have been established. Densely distributed fine pre-existing dispersoids and/or conditions of significant concurrent precipitation strongly slows down recrystallization kinetics and lead to a grain structure of coarse and strongly elongated grains. At the lowest annealing temperatures, recrystallization may even be completely suppressed. In conditions of low number density and coarse pre-existing dispersoids, and limited additional concurrent precipitation, recrystallization generally results in an even, fine and equi-axed grain structure. Rough calculations of recrystallized grain size, assuming particle stimulated nucleation as the main nucleation mechanism, compare well with experimentally measured grain sizes.

  19. Calculation of the effect of alloy characteristics on the permanent expansion of cold compacted hypereutectic Al-Si-Fe-X powder after thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Timmermans, G.; Froyen, L. [Katholieke Univ. Leuven (Belgium). Dept. Metaalkunde en Toegepaste Materiaalkunde

    1999-02-19

    For the atomized powder Al-17Si-5Fe-3.5Cu-1.1Mg-0.6Zr (wt%), investigated in this work, a permanent elongation of about 0.8% of a bar shape sample of a green product (cold compacted powder) is measured by Thermo Mechanical Analysis after a first thermal cycle up to 470 C, when a heating rate of 5 C/min or 1 C/min is applied. This 0.8% is the average of 10 measurements. In subsequent cycles, there is no extra permanent expansion anymore, indicating the mainly irreversible character. The irreversible part of the expansion mainly occurs between 200 and 300 C, where Si is precipitating, as detected by X-Ray Diffractometry (XRD) and Differential Scanning Calorimetry (DSC). This Si-precipitation from supersaturated Al solid solutions is observed by many researchers, using also XRD Al line shift analysis and microscopy techniques.

  20. Tululite, Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36: a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

    Science.gov (United States)

    Khoury, Hani N.; Sokol, Ella V.; Kokh, Svetlana N.; Seryotkin, Yurii V.; Nigmatulina, Elena N.; Goryainov, Sergei V.; Belogub, Elena V.; Clark, Ian D.

    2016-02-01

    Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800-850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the "Mottled Zone" Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios ( 0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20-100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+ 2.23Si0.95Mn3+ 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space

  1. Effect of ZrSiO{sub 4} on the corrosion behavior of MgO-FeAl{sub 2}O{sub 4} composite refractory materials

    Energy Technology Data Exchange (ETDEWEB)

    Bahtli, Tuba [Necmettin Erbakan Univ., Konya (Turkey). Faculty of Engineering and Architecture; Aksel, Cemail [Anadolu Univ., Eskisehir (Turkey). Dept. of Materials Science and Engineering; Kavas, Taner [Afyon Kocatepe Univ., Afyonkarahisar (Turkey). Dept. of Materials Science and Engineering; Turkish Ceramic Society, Istanbul (Turkey)

    2016-07-01

    In this study, the corrosion behavior of refractory materials that were produced by incorporating ZrSiO{sub 4} (zircon) at different ratios into MgO-FeAl{sub 2}O{sub 4} (hercynite) were investigated. The values of density and open porosity of those samples were also measured, and the corrosion behaviors of those materials produced were examined. After performing corrosion tests, the corrosion resistance of composite refractory materials were determined by measuring the penetration distances and spreading areas. The incorporation of ZrSiO{sub 4} into MgO-FeAl{sub 2}O{sub 4} generally decreased the porosity of composite refractory materials, and consequently reduced the penetration distances and spreading area values of the corroded regions of refractories as well. In addition, the formation of new phases and the microstructural changes which occurred were determined by XRD measurements and SEM analyses. On the basis of microstructural characterization carried out in the interface of clinker-refractory, the following observations had been determined: (i) Ca{sup 2+} and Y{sup 3+} elements forming CaZrO{sub 3} were located together in the same regions, (ii) forsterite phase was formed due to the reaction between SiO{sub 2}, which is released after dissociation of zircon as ZrO{sub 2} and SiO{sub 2} during sintering, and MgO, (iii) the formation of new CaZrO{sub 3} and forsterite (Mg{sub 2}SiO{sub 4}) phases made a barrier effect against clinker, and (iv) the amount of CaO decreased based on the EDX analysis made from clinker to refractory in a corroded region. The penetration of clinker to refractory showed a minimum level for the composition of MgO-5 wt.-% FeAl{sub 2}O{sub 4}-5 wt.-% ZrSiO{sub 4} and an improvement by about 38 % as compared to MgO-5 wt.-% FeAl{sub 2}O{sub 4}. This improvement is associated with a long service life of MgO-FeAl{sub 2}O{sub 4}-ZrSiO{sub 4} refractories for industrial applications.

  2. Fabrication of highly spin-polarized Co2FeAl0.5Si0.5 thin-films

    Directory of Open Access Journals (Sweden)

    M. Vahidi

    2014-04-01

    Full Text Available Ferromagnetic Heusler Co2FeAl0.5Si0.5 epitaxial thin-films have been fabricated in the L21 structure with saturation magnetizations over 1200 emu/cm3. Andreev reflection measurements show that the spin polarization is as high as 80% in samples sputtered on unheated MgO (100 substrates and annealed at high temperatures. However, the spin polarization is considerably smaller in samples deposited on heated substrates.

  3. Microstructure of laser-welded joints of Fe-Mn-Al-Si TRIP/TWIP steels%Fe-Mn-Al-Si系TRIP/TWIP钢激光焊接接头的微观组织研究

    Institute of Scientific and Technical Information of China (English)

    谢盼; 伍翠兰; 艾倍倍; 陈汪林; 陈燕; 陈亚

    2013-01-01

    采用光纤激光器对两种锰含量分别为20wt.%和29wt.%的Fe-Mn-Al-Si系TRIP/TWIP钢进行激光焊接.利用扫描电子显微镜(SEM)、能谱仪(EDS)、电子背散射衍射仪(EBSD)和透射电子显微镜(TEM)对接头的显微组织进行研究.结果表明:靠近熔合线的焊缝组织以柱状晶为主,而焊缝心部为细小的等轴晶且出现大量AlN纳米颗粒;焊缝组织的孪晶界比例比母材的大幅度降低,但仍然达到了15.8%;熔合线宽1 μm,富Fe、Mn而贫Al、Si;焊缝在凝固过程中,先形成γ-奥氏体,当遇到应力集中时发生局部ε-马氏体的相变来缓解应力,避免裂纹形成.%Two types of Fe-Mn-Al-Si TRIP/TWIP steels with different Mn concentrations,which are respectively 20 wt% and 29 wt%,were welded by fiber laser welding technique.The microstructures of the weld joints were investigated using scanning electron microscope (SEM),X-ray energy disperse spectroscopy (EDS),electron backscatter diffraction technology (EBSD) and transmission electron microscopy (TEM).The results show that the fusion zone (FZ) adjacent to the fusion lines was made up of columnar grains while the centre of the FZ consisted of equiaxed grains,in which a great deal of AlN nano-particles were formed.The fraction of twin boundaries of FZ is about 15.8% although the twin boundaries have decreased greatly compared with that of the base materials.The fusion lines are rich in Fe and Mn but lack of Al and Si.In the process of solidification of the FZ,the austenite first formed and some austenite transformed into ε-martensite at the stress concentration regions,which can relieve some stress and prevent formation cracks.

  4. Evolution of Inclusions in Fe-13Cr Treated by CaO-SiO2-Al2O3-Based Top Slag

    Science.gov (United States)

    Wang, Qi; Wang, Lijun; Zhai, Jun; Li, Jianmin; Chou, Kuo-Chih

    2017-02-01

    Experiments were carried out to determine the effect of Al2O3 in the slag of the CaO-SiO2-Al2O3-MgO-CaF2 system on the cleanness of Fe-13Cr stainless steel deoxidized by ferrosilicon. Increasing the Al2O3 content in basicity = 2.28 slag can reduce the usage of CaF2 and benefit the obtainment of a good kinetic condition for inclusion removal, but over 21 pct would lead to a higher total oxygen content in the melt and make the inclusion composition more complex. It is found that increasing basicity in 16 pct Al2O3 slag would have a good deoxidation ability and accelerate the transformation from high Al2O3 inclusions to low melting point CaO-Al2O3-SiO2-MgO system inclusions, but basicity over 2.58 would lead to high content of [Al] in liquid steel, which would promote the formation of MgO-Al2O3 inclusions. Therefore, it is not suitable to add a high content of Al2O3 into high-basicity slag. Adding Al2O3 into slag of 2.28 in basicity until a content of 16 pct could achieve inclusion plastication within 45 minutes without Ca treatment, which has potential application in industrial production.

  5. Corrosion behavior of Fe-Si metallic coatings added with NiCrAlY in an environment of fuel oil ashes at 700 C

    Energy Technology Data Exchange (ETDEWEB)

    Salinas-Bravo, V.M.; Porcayo-Calderon, J.; Romero-Castanon, T. [Instituto de Investigaciones Electricas, Gerencia de Procesos Termicos., Av. Reforma 113, C.P. 62490 Col. Palmira. Temixco. Morelos (Mexico); Dominguez-Patino, G.; Gonzalez-Rodriguez, J.G. [U.A.E.M. Centro de Investigaciones en Ingenieria y Ciencias Aplicadas., Av. Universidad 1001, C.P. 62210, Col. Chamilpa. Cuernavaca, Morelos (Mexico)

    2005-07-01

    Electrochemical potentiodynamic polarization curves and immersion tests for 300 h at 700 C in a furnace have been used to evaluate the corrosion resistance of Fe-Si metallic coatings added with up to 50 wt.% of NiCrAIY. The corrosive environment was fuel oil ashes from a steam generator. The composition of fuel oil ashes includes high content of vanadium, sodium and sulfur. The results obtained show that only the addition of 20 wt.% NiCrAlY to the Fe-Si coating improves its corrosion resistance. The behavior of all tested coatings is explained by the results obtained from the analysis of every coating using electron microscopy and energy dispersive X-ray analysis. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  6. Strong perpendicular magnetic anisotropy in Co2FeAl0.5Si0.5 film sandwiched by MgO layers

    Institute of Scientific and Technical Information of China (English)

    Wang Sheng; Li Xiao-Qi; Bai Li-Juan; Xu Xiao-Guang; Miao Jun; Jiang Yong

    2013-01-01

    Co2FeAl0.5Si0.5 (CFAS)-based multilayers sandwiched by MgO layers have been deposited and annealed at different temperatures.Perpendicular magnetic anisotropy (PMA) with the magnetic anisotropy energy density Ku ≈2.5× 106 erg/cm3 (1 erg =10-7 J) and the coercivity Hc =363 Oe (1Oe =79.9775 A.m-1) has been achieved in the Si/SiO2/MgO (1.5 nm)/CFAS (2.5 nm)/MgO (0.8 nm)/Pt (5 nm) film annealed at 300 ℃.The strong PMA is mainly due to the top MgO layer.The structure can be used as top magnetic electrodes in half-metallic perpendicular magnetic tunnel junctions.

  7. Effects of wavelike sloping plate rheocasting and spheroidisation on microstructures and properties of Al-18%Si-5%Fe alloy%WSP流变铸造与球化处理对Al-18%Si-5%Fe合金组织和性能的影响

    Institute of Scientific and Technical Information of China (English)

    管仁国; 曹富荣; 赵占勇; 黄红乾; 张秋生; 王超

    2011-01-01

    A novel method of preparing hypereutectic Al-Si-Fe alloy was proposed by wavelike sloping plate (WSP) rheocasting device, and the rheocasting and spheroidisation treatment of Al-18%Si-5%Fe alloy were investigated. The results reveal that the morphologies of primary crystal Si, Al18SiioFe5 and Al8Si2Fe phase in this alloy can be improved obviously by WSP rheocasting. With the decrease of pouring temperature, various phases tend to be refined and spheroidised. The formation of microstmctures in this alloy originates from three mechanisms such as crystal nucleus multiplication brought by crystallization rain, crystal restraining growth under strong cooling of sloping plate and crystal break-up under flow shear. The WSP rheocasting and spheroidisation treatment further improve the microstructure of Al-18%Si-5%Fe alloy. The Vickers hardness of the alloy is 87.5. The wear rate of Al-18%Si-5%Fe alloy under dry friction is 5.4 mg/h.%提出了波浪形倾斜板流变铸造(WSP)装置制备过共晶Al-Si-Fe合金的方法,对Al-18%Si-5%Fe合金流变铸造与球化处理进行研究.结果表明,WSP流变铸造可以明显改善合金中初晶硅、Al18Si10Fe5和Al8Si2Fe相的形貌.随着浇注温度降低,各相趋于细化和球化.WSP流变铸造过程中合金组织的形成源于3种机制:结晶雨带来的晶核增殖,斜板强冷却作用下晶体抑制生长和流动剪切作用下晶体破碎.WSP流变铸造与球化处理进一步改善Al- 18%Si-5%Fe合金组织,合金维氏硬度达到87.5.在干摩擦条件下Al-18%Si-5%Fe合金的磨损率达到5.4 mg/h.

  8. 离心铸造Al-Fe-Si合金自生FGM的研究%In-situ Functionally Gradient Materials(FGM) of Al-Fe-Si Alloy by Centrifugal Casting

    Institute of Scientific and Technical Information of China (English)

    徐自立; 魏伯康; 林汉同

    2001-01-01

    对几种不同的Al-Fe-Si合金进行了离心铸造。试验表明,在离心力场下合金中的初生相发生径向移动,但不同尺寸形态的初生相移动的效果不同,同时引起元素浓度的不同变化。初生相分布及元素浓度的倾斜变化,将带来相关性能的梯度变化,形成一定意义下的梯度功能材料。%Some various Al-Fe-Si alloys by centrifugal casting was conducted. The results showed that under the centrifugal field, primary phase in alloy migrated along the radical direction but the migration effects of the primary phase with various sizes were different. Meanwhile, the element concentration has different variation under the centrifugal field. The sloping changes of the primary phase distribution and the element concentration would results in the gradient variation of relevant properties and form functionally gradient materials to certain extent.

  9. First-principles study of the Hume-Rothery electron concentration rule in Al-Cu-(Fe,Ru)-Si 1/1-cubic approximants

    Science.gov (United States)

    Asahi, Ryoji; Kontsevoi, O. Y.; Mizutani, U.; Takeuchi, T.; Freeman, A. J.

    2006-03-01

    To elucidate the Hume-Rothery electron concentration rule, we determined the self-consistent electronic structures of the Al108Ru24Cu6Si6 and Al108Fe24Cu6Si6 1/1-1/1-1/1 approximants containing 144 atoms in each Pm-3 cubic unit cell using the full-potential linearized augmented plane wave (FLAPW) method [1], now running on massively parallel computer platforms. A significant pseudogap was found around the Fermi level for both alloys in the calculated densities of states, which should contribute to stabilization of the system. The FLAPW wave functions provide a direct observation of the Brillouin zone resonance in the Fermi surface [2]: a Fourier analysis of the wave functions confirms the Hume-Rothery matching rule 2kF=K where the reciprocal lattice vectors K consist of 543, 550, and 710 planes highly degenerate at the N point. Consequently, an effective electron concentration per atom (e/a) was evaluated to be 0.8 for both Ru and Fe in these structures making a sharp contrast with the previously assumed empirical value of -2.7 proposed by Raynor [3]. [1] Wimmer et al., Phys. Rev. B 24, 864 (1981). [2] Asahi et al., Phys. Rev. B 72, 125102 (2005). [3] Raynor, Prog. Metal Phys. 1, 1 (1949).

  10. Effects of Fe2O3 content on microstructure and mechanical properties of CaO-Al2O3-SiO2 system%Fe2O3含量对CaO-Al2O3-SiO2系微晶玻璃显微组织与力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    任祥忠; 张卫; 章勇; 张培新; 刘剑洪

    2015-01-01

    The effects of Fe2O3 content on the microstructure and mechanical properties of the CaO−Al2O3−SiO2 system were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron spin resonance (ESR), and Mössbauer spectroscopy. The results show that the addition of Fe2O3 does not affect the main crystalline phase in the prepared glasses, but it reduces the crystallisation peak temperature, increases the crystallisation activation energy, and reduces the crystal granularity. The ESR results indicate that Fe2O3 can promote crystallization, as it leads to the phase separation of the CaO−Al2O3−SiO2 system due to axial distortion. Moreover, Fe2O3 alters the network structure of the CaO−Al2O3−SiO2 system, allowing Fe3+ to enter octahedral sites that exhibit higher symmetry than tetrahedral sites. All of these factors are favourable to increasing the bending strength. The Mössbauer results reveal that there are two types of coordination for both Fe3+and Fe2+and the bending strength of the CaO−Al2O3−SiO2 system increases with the amount of six-coordinate Fe3+. The increasing interaction between Fe3+and Fe2+can also enhance the bending strength of the CaO−Al2O3−SiO2 system. The microhardness of the CaO−Al2O3−SiO2 system was determined to be HV 896.9 and the bending strength to be 217 MPa under the heat treatment conditions of nucleation temperature of 700 °C and nucleation time of 2 h, crystallization temperature of 910 °C and crystallization time of 3 h.%采用差热分析(DTA)、X 射线衍射(XRD)、扫描电镜(SEM)、电子顺磁共振(ESR)和 Mössbauer 谱等技术研究 Fe2O3含量对 CaO−Al2O3−SiO2系微晶玻璃显微组织与力学性能的影响。结果表明:Fe2O3的加入不改变CaO−Al2O3−SiO2系微晶玻璃析出的主晶相类型,但使体系的析晶峰温度降低,析晶活化能增加和析出晶体的粒度减小。ESR测试结果表明,Fe2O3的加入

  11. Direct band-gap measurement on epitaxial Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} Heusler-alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Alhuwaymel, Tariq F. [Department of Electronics, University of York, York YO10 5DD (United Kingdom); National Nanotechnology Center, KACST, Riyadh (Saudi Arabia); Carpenter, Robert; Yu, Chris Nga Tung; Kuerbanjiang, Balati; Lazarov, Vlado K. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Abdullah, Ranjdar M.; El-Gomati, Mohamed [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Hirohata, Atsufumi, E-mail: atsufumi.hirohata@york.ac.uk [Department of Electronics, University of York, York YO10 5DD (United Kingdom); PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012 (Japan)

    2015-05-07

    In this study, a newly developed band-gap measurement technique has been used to characterise epitaxial Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (CFAS) films. The CFAS films were deposited on MgO(001) substrate by ultra high vacuum molecular beam epitaxy. The band-gap for the as deposited films was found to be ∼110 meV when measured at room temperature. This simple technique provides a macroscopic analysis of the half-metallic properties of a thin film. This allows for simple optimisation of growth and annealing conditions.

  12. Input Correlations for Irradiation Creep of FeCrAl and SiC Based on In-Pile Halden Test Results

    Energy Technology Data Exchange (ETDEWEB)

    Terrani, K. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Karlsen, T. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-05-01

    Swelling and creep behavior of wrought FeCrAl alloys and CVD-SiC, two candidate accident tolerant fuel cladding materials, are being examined using in-pile tests at the Halden reactor. The outcome of these tests are material property correlations that are inputs into fuel performance analysis tools. The results are discussed and compared with what is available in literature from irradiation experiments in other reactors or out-of-pile tests. Specific recommendation on what correlations should be used for swelling, thermal, and irradiation creep for each material are provided in this document.

  13. The antiphase boundary in half-metallic Heusler alloy Co2Fe(Al,Si): atomic structure, spin polarization reversal, and domain wall effects

    Science.gov (United States)

    Nedelkoski, Zlatko; Sanchez, Ana M.; Ghasemi, Arsham; Hamaya, Kohei; Evans, Richard F. L.; Bell, Gavin R.; Hirohata, Atsufumi; Lazarov, Vlado K.

    2016-11-01

    Atomic resolution scanning transmission electron microscopy reveals the presence of an antiphase boundary in the half-metallic Co2Fe(Al,Si) full Heusler alloy. By employing the density functional theory calculations, we show that this defect leads to reversal of the sign of the spin-polarization in the vicinity of the defect. In addition, we show that this defect reduces the strength of the exchange interactions, without changing the ferromagnetic ordering across the boundary. Atomistic spin calculations predict that this effect reduces the width of the magnetic domain wall compared to that in the bulk.

  14. Catalytic properties of Fe/SiO2-Al2O3 systems, obtained via sol-gel method

    Science.gov (United States)

    Kon'kova, T. V.; Gordienko, M. G.; Alekhina, M. B.; Men'shutina, N. V.

    2017-03-01

    The high efficacy of iron-containing catalysts based on SiO2-Al2O3 systems obtained via sol-gel method in the oxidative destruction of carmoisine azo dye in aqueous solutions is demonstrated. It is found that the stability of the catalysts with respect to the leaching of iron ions into a solution during catalysis grows along with the aluminum content in the composition of aluminosilicate supports. It is concluded that the synthesized catalysts are promising materials for purifying wastewaters contaminated with organic dyes.

  15. Solid-state reactions during mechanical alloying of ternary Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems: A review

    Science.gov (United States)

    Hadef, Fatma

    2016-12-01

    The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe-Al-X systems, in order to improve mainly Fe-Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems.

  16. Effect of Mn addition on Fe-rich intermetallics morphology and dry sliding wear investigation of hypereutectic Al-17.5%Si alloys

    Directory of Open Access Journals (Sweden)

    Cyrus Bidmeshki

    2016-07-01

    Full Text Available The effect of Manganese addition on the iron-rich intermetallics and wear behavior of Al-17.5%Si hypereutectic alloys has been studied. Dry sliding wear tests have been conducted using a pin-on-disk machine under different normal loads of 18, 51, 74 and 100 N and at a constant sliding speed of 0.3 m/s. The addition of 1.2 wt.% Fe to the base alloy increased the wear rate due to the formation of needle beta intermetallics. Introducing 0.6 wt.% Mn to the iron-rich alloy changed the beta intermetallics into the modified alpha phases, and therefore reduced the detrimental effect of iron. Mn addition up to 0.9 wt.% to the 1.8Fe alloy did not impede formation of needle-like intermetallic compounds and had no positive effect on the modification of microstructure.

  17. Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米湿敏陶瓷薄膜的Sol-Gel制备%PREPARATION OF Fe2O3-Al2O3-SiO2-TiO2 ANTIBACTERIAL NANOMETRE HUMIDITY SENSITIVE CERAMIC MEMBRANES BY SOL-GEL PROCESSING

    Institute of Scientific and Technical Information of China (English)

    刘儒平; 俞康泰

    2005-01-01

    利用溶胶凝胶法制成了Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米湿敏陶瓷薄膜.用扫描电镜和原子力显微镜对膜的表面形貌和显微结构进行表征,分析了处理方式对膜的表面形貌和微观结构的影响.制成的Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米湿敏陶瓷薄膜具有广谱抗菌、高效、无毒、持久和耐热等特点.湿敏特性测试结果表明:Fe2O3-Al2O3-SiO2-TiO2抗菌、纳米陶瓷薄膜制品的感湿灵敏度高,具有较好的响应特性和稳定性.

  18. Growth of Co2FeAl Heusler alloy thin films on Si(100) having very small Gilbert damping by Ion beam sputtering.

    Science.gov (United States)

    Husain, Sajid; Akansel, Serkan; Kumar, Ankit; Svedlindh, Peter; Chaudhary, Sujeet

    2016-06-30

    The influence of growth temperature Ts (300-773 K) on the structural phase ordering, static and dynamic magnetization behaviour has been investigated in ion beam sputtered full Heusler alloy Co2FeAl (CFA) thin films on industrially important Si(100) substrate. The B2 type magnetic ordering is established in these films based on the clear observation of the (200) diffraction peak. These ion beam sputtered CFA films possess very small surface roughness of the order of subatomic dimensions (<3 Å) as determined from the fitting of XRR spectra and also by AFM imaging. This is supported by the occurrence of distinct Kiessig fringes spanning over the whole scanning range (~4°) in the x-ray reflectivity (XRR) spectra. The Gilbert damping constant α and effective magnetization 4πMeff are found to vary from 0.0053 ± 0.0002 to 0.0015 ± 0.0001 and 13.45 ± 00.03 kG to 14.03 ± 0.04 kG, respectively. These Co2FeAl films possess saturation magnetization ranging from 4.82 ± 0.09 to 5.22 ± 0.10 μB/f.u. consistent with the bulk L21-type ordering. A record low α-value of 0.0015 is obtained for Co2FeAl films deposited on Si substrate at Ts ~ 573 K.

  19. Energy of precipitation of Al2Cu and α-AlFeSi phase from the AlCu3 alloy and the shape of precipitates

    Directory of Open Access Journals (Sweden)

    M. Vončina

    2009-01-01

    Full Text Available AlCu3 alloy was examined with the triple simple thermal analysis (TETA, the simultaneous thermal analysis (STA, the computer simulation using Thermo-Calc program and with the metallographic analyses. The energy of solidification and melting of the primary and the eutectic phase, and the energy of the Al2Cu precipitation were determined, and these can be evidently seen from the curves of simultaneous thermal analysis.

  20. Nano-structure formation of Fe-Pt perpendicular magnetic recording media co-deposited with MgO, Al{sub 2}O{sub 3} and SiO{sub 2} additives

    Energy Technology Data Exchange (ETDEWEB)

    Safran, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary)]. E-mail: safran@mfa.kfki.hu; Suzuki, T. [Akita Research Institute of Advanced Technology (AIT), 4-21 Sanuki, Araya, Akita 010-1623 (Japan); Ouchi, K. [Akita Research Institute of Advanced Technology (AIT), 4-21 Sanuki, Araya, Akita 010-1623 (Japan); Barna, P.B. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary); Radnoczi, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences 1121 Budapest, Konkoly-Thege ut 29-33 (Hungary)

    2006-02-21

    Perpendicular magnetic recording media samples were prepared by sputter deposition on sapphire with a layer sequence of MgO seed-layer/Cr under-layer/FeSi soft magnetic under-layer/MgO intermediate layer/FePt-oxide recording layer. The effects of MgO, Al{sub 2}O{sub 3} and SiO{sub 2} additives on the morphology and orientation of the FePt layer were investigated by transmission electron microscopy. The samples exhibited (001) orientation of the L1 FePt phase with the mutual orientations of sapphire substrate//MgO(100)[001]//Cr(100)[11-bar0]//FeSi(100)[11-bar0]//MgO(100) [001]//FePt(001)[100]. The morphology of the FePt films varied due to the co-deposited oxides: The FePt layers were continuous and segmented by stacking faults aligned at 54{sup o} to the surface. Films with SiO{sub 2} addition, beside the oriented columnar FePt grains, exhibited a fraction of misoriented crystallites due to random repeated nucleation. Al{sub 2}O{sub 3} addition resulted in a layered structure, i.e. an initial continuous epitaxial FePt layer covered by a secondary layer of FePt-Al{sub 2}O{sub 3} composite. Both components (FePt and MgO) of the MgO-added samples were grown epitaxially on the MgO intermediate layer, so that a nano-composite of intercalated (001) FePt and (001) MgO was formed. The revealed microstructures and formation mechanisms may facilitate the improvement of the structural and magnetic properties of the FePt-oxide composite perpendicular magnetic recording media.

  1. Property of AlCrCoFeNiMoTi0.75 Si0.25 High-entropy Alloy Coating Tool Prepared by Laser Cladding%激光熔覆AlCrCoFeNiMoTi0.75Si0.25高熵合金涂层刀具的性能

    Institute of Scientific and Technical Information of China (English)

    张爱荣; 梁红玉; 李烨

    2013-01-01

    利用激光熔覆技术制备了AlCrCoFeNiMoTi0.75Si025高熵合金涂层刀具,研究了激光快速凝固和经过1 000℃退火处理的AlCrCoFeNiMoTi0.75Si0.25高熵合金涂层微观组织和硬度、摩擦磨损性能,并比较了普通高速钢及高熵合金涂层刀具的切削加工性能.结果表明:激光熔覆AlCrCoFeNiMoTi0.5Si0.5高熵合金涂层的主要相结构为bcc相,涂层具有较好的高温稳定性.激光熔覆高熵合金涂层刀具表面硬度高,摩擦因数小,断屑效果好,被加工材料表面光洁度高.%AlCrCoFeNiMoTi0.75Si0.25 high-entropy alloy coated cutting tools was prepared by laser cladding.The microstructure,hardness,friction and wear properties of the AlCrCoFeNiMoTi0.75Si0.25 high-entropy alloy coatings prepared by laser rapid solidification and annealing treatment at 1 000 ℃ were studied.The machinability of the high-speed-steel tools and high-entropy alloy coated tools was compared.Results show that the main alloy structure of the coating is a body centered cubic (BCC) and the coating performs high tempera ture stability.The high-entropy coated cutting tool is characterized by higher hardness,lower friction coefficient,better chip breaker,and better surface finish of the machined materials.

  2. Perpendicular magnetic anisotropy in Ta/Pd/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta structured films

    Energy Technology Data Exchange (ETDEWEB)

    Fu, H.R.; You, C.Y., E-mail: caiyinyou@xaut.edu.cn; Zhang, X.; Tian, N.

    2015-07-15

    In this work, the perpendicular magnetic anisotropy (PMA) was realized in Ta/Pd/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta films, but not observed in Ta/Pd/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/Ta films without MgO cap layer. A strong PMA had been achieved for a thick Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} layer about 4.8 nm at the annealing temperature of 300 °C. Inserted Pd layer between Ta and Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} layers was crucial to obtain PMA in Ta/Pd/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta structured films. However, the thickness of inserted Pd layer has no significant effect on the value (K{sub eff}) of PMA. The films annealed at 300 °C remain a similar K{sub eff} of around 1.23×10{sup 6} erg/cm{sup 3} while the inserted Pd layer is beyond a critical thickness.

  3. Effects of annealing condition and Al content on novel Fe73.5Si13.5B9Cu1Nb3-xAlx alloys

    Institute of Scientific and Technical Information of China (English)

    LIU Haishun; DU Youwei; MIAO Xiexing; HAN Kui; SHEN Xiaopeng; BU Wankui

    2008-01-01

    The annealing condition,Al content,and field amplitude dependences of the complex permeability for Nb-poor Finemet type alloys,Fe73.5Si13.5B9Cu1Nb3-xAlx (x=0,0.5,1.5,2.0,and 3.0),were investigated using an impedance analyzer and X-ray diffraction.The results show that different Al contents lead to different optimum annealing conditions,and the Al content exerts a distinct effect on microstructure thus resulting in a variety of real permeability value.For the samples annealed at 793 K for 0.5 h,the real permeability increases with an increase in Al content when the Al content is below 2.0 at.%; as for those annealed at 793 K for 1 h and at 813 K for 0.5 h,an overall increase in real permeability can be obtained compared to those annealed at 793 K for 0.5 h.The permeability under different field amplitudes is also studied and it is found that the relaxation frequency in the lower frequency region tends to moving toward a higher frequency with an increase in field amplitude.All these might be because of the role of Nb in the annealing process and the solubility of Al in the amorphous matrix and nanocrystallized crystallites.

  4. Proton induced K X-ray production cross sections of the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0 MeV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Bertol, Ana Paula Lamberti [Programa de Pós Graduação em Física, PPGFis, Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre, RS (Brazil); Hinrichs, Ruth [PPGFis and Instituto de Geociências, UFRGS (Brazil); Vasconcellos, Marcos A.Z. [PPGFis and Instituto de Física, UFRGS (Brazil)

    2015-12-15

    Proton induced K-shell ionization cross sections were obtained for the elements Al, Si, Ti, Fe, and Ni in the 0.7–2.0 MeV energy range. The accuracy of these fundamental parameters is essential for PIXE analysis and the data in the literature present a considerable spread, mainly for Al and Si. The values obtained for Ti, Fe and Ni are compatible with the current theories and the experimental results reported in the literature. However, Al and Si cross sections present important differences from theoretical and experimental data. We propose values for the fluorescent yields of Al and Si that are compatible with recent results and can be incorporated in the computations of K X-ray production cross sections.

  5. The Perovskite to Post-Perovskite phase transition in Al-bearing (Mg,Fe)SiO3: A XANES in-situ analysis at the Fe K-edge

    Science.gov (United States)

    Andrault, D.; Munoz, M.; Bolfan-Casanova, N.; Guignot, N.; Perrillat, J.; Aquilanti, G.; Pascarelli, S.

    2008-12-01

    Phase transition from perovskite (Pv) to Post-Pv (PPv) phase in MgSiO3 has been studied by many groups since its discovery in 2004 (1,2) and the different studies find similar transition pressures. The effect of Al and Fe on the phase transition remains more controversial. The most recent studies suggest an increase of the transition pressure with increasing Fe-content (3,4), but other experimental work (5) as well as ab-initio calculations (6) show the opposite effect. The effect of Al was reported to increase slightly the pressure transition to the CaIrO3 form (4,7), but its influence on the Fe3+ content in the PPv phase has not been documented yet. By means of in situ study of the Fe K-edge fine structures (XANES), we investigated the phase relations between Pv and PPv phases for three different Al-(Mg,Fe)SiO3 compositions. For this, we synthesized various Pv and PPv mixtures using laser-heated diamond anvil cell (DAC) for pressures between 60 and 170 GPa. The sample's mineralogy, i.e. the Pv and PPv phase fractions, was determined using in-situ X-ray diffraction at the ID27 beamline of the ESRF (8,9). Then, we probed the Fe speciation, i.e. the Fe concentration in each phases, in-situ in the DAC using the µ-XANES mapping technique available at the ID24 beamline (10,11). Both pieces of information were combined to retrieve the Fe partitioning coefficient between the two high-pressure phases. Our results show that Fe partitions strongly into the PPv phase, which implies a very large binary loop of coexistence of the two phases. Thus, at the core-mantle boundary pressure (135 GPa), the Pv and PPv phase always coexist for all geophysically relevant Al-(Mg,Fe)SiO3 compositions, and the Fe-content in the PPv-phase is only a few percent. References: 1. M. Murakami, K. Hirose, K. Kawamura, N. Sata, Y. Ohishi, Science 304, 855 (2004). 2. A. R. Oganov, S. Ono, Nature 430, 445 (2004). 3. S. Tateno, K. Hirose, N. Sata, Y. Ohishi, Phys. Earth Planet. Inter. 160, 319 (2007

  6. Selection of heat treatments temperature of AlSi13Cu2Fe silumin on base of ATD method

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2008-08-01

    Full Text Available Nowadays tendency connected with reduction of design structures’ mass effects in growing significance of usage of silumins, which are the most widespread alloys of aluminum. Mechanical and technological properties of machine parts manufactured from Al-Si alloys are determined by their structure. In case of cast parts, structure of alloy is a derivative of properly performed process of melting and pouring, as well as design of the casting and mould. Mechanical properties of alloys destined to machine parts made in casting process can be upgraded by modification. Possible heat treatment performed for a cast products effects in further improvement of their mechanical properties, based on precipitation processes. Selection of proper parameters of heat treatment process impacts directly on reduction of production costs of the castings.The paper presents an attempt of implementation of ATD method to determination of solution heat treatment and ageing treatment of AK132 silumin. Obtained results concern registered curves of ATD method, strength tests and determination of an effect of heat treatment temperatures on Rm tensile strength of modified AK132 silumin. On base of preliminary tests results there was determined an impact of temperature changes of solution heat treatment and ageing treatment on Rm tensile strength of AK132 silumin.

  7. Co{sub 2}FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P. [LSPM (CNRS-UPR 3407), 99 avenue Jean-Baptiste Clément, Université Paris 13, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F–54506 Vandoeuvre (France)

    2014-01-28

    10 nm and 50 nm Co{sub 2}FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T{sub a}), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T{sub a}, while the uniaxial anisotropy field is nearly unaffected by T{sub a} within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T{sub a}. Finally, the FMR linewidth decreases when increasing T{sub a}, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10{sup −3} and 1.3×10{sup −3} for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

  8. Isothermal corrosion Fe3Si alloy in liquid zinc

    Institute of Scientific and Technical Information of China (English)

    Wen jun Wang; Junping Lin; Yanli Wang; Guoliang Chen

    2007-01-01

    The isothermal corrosion testing,microscopic examination and the performance of Fe3Si alloy as materials of construction for bath hardware in continuous hot-dipping lines were studied.The corrosion of Fe3Si alloy in molten zinc was controlled by attacking the grain boundaries preferentially.Aluminum reacted with iron of Fe3Si alloy firstly while the samples were immersed in molten zinc,although aluminum contents in the molten zinc were very low.The phase of reaction product was thought to be Fe2Al5.The corrosion rate of the Fe3Si alloy in molten zinc was determined to be approximately 2.9×10-3 mm/h,therefore the liquid zinc corrosion resistance of Fe3Si alloy was very weak.

  9. 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.

  10. Modelling Equilibrium and Fractional Crystallization in the System MgO-FeO-CaO-Al2O3-SiO2

    Science.gov (United States)

    Herbert, F.

    1985-01-01

    A mathematical modelling technique for use in petrogenesis calculations in the system MgO-FeO-CaO-Al2O3-SiO2 is reported. Semiempirical phase boundary and elemental distribution information was combined with mass balance to compute approximate equilibrium crystallization paths for arbitrary system compositions. The calculation is applicable to a range of system compositions and fractionation calculations are possible. The goal of the calculation is the computation of the composition and quantity of each phase present as a function of the degree of solidification. The degree of solidification is parameterized by the heat released by the solidifying phases. The mathematical requirement for the solution of this problem is: (1) An equation constraining the composition of the magma for each solid phase in equilibrium with the liquidus phase, and (2) an equation for each solid phase and each component giving the distribution of that element between that phase and the magma.

  11. Effect of Annealing Time for Quenching CuAl7Fe5Ni5W2Si2 Bronze on the Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2012-04-01

    Full Text Available This paper presents the influence of annealing time 30, 60 and 120 min at 1000°C for quenching CuAl7Fe5Ni5W2Si2 bronze in 10% water solution of NaCl, on the microstructure and mechanical properties. The presented results concern the species newly developed aluminum-iron-nickel bronze, with additions W and Si.In order to determine changes in the microstructure of the hardened bronze metallographic studies were performed on cylindrical samples of diameter 10 mm, on the metallographic microscope with digital image analysis, X-ray phase analysis, EDX point with the digital recording on the computer. Specified percentage of the microstructure of martensite and bainite, participation of proeutectoid α phase in the microstructure, grain size of former β phase, the amount of dissolved κ phase.It was found that in the microstructure of bronze in the cast state, there are a number of intermetallic phases of κ type. At interphase boundaries of primary intermetallic faceted precipitates, especially rich in tungsten (IM_W, nucleate and grow dendritic primary intermetallic κI phases, with chemical composition similar to the type of Fe3Si iron silicide.Dissolved, during the heating, in the β phase are all the intermediate phase included in the microstructure, with the exception of primary intermetallic phases of tungsten and κI. Prolongation of the isothermal annealing causes coagulation and coalescence of primary phases. In microstructure of the bronze after quenching obtained the α phase precipitation on the grain boundary of secondary β phase, coarse bainite and martensite, for all annealing times. With the change of annealing time are changed the relative proportions of individual phases or their systems, in the microstructure. In the microstructure of bronze, hold at temperature of 1000°C for 60 min, after quenching martensitic microstructure was obtained with the primary phases, and the least amount of bainite.

  12. Comparison of thermoelectric properties of nanostructured Mg2Si, FeSi2, SiGe, and nanocomposites of SiGe–Mg2Si, SiGe–FeSi2

    Directory of Open Access Journals (Sweden)

    Amin Nozariasbmarz

    2016-10-01

    Full Text Available Thermoelectric properties of nanostructured FeSi2, Mg2Si, and SiGe are compared with their nanocomposites of SiGe–Mg2Si and SiGe–FeSi2. It was found that the addition of silicide nanoinclusions to SiGe alloy maintained or increased the power factor while further reduced the thermal conductivity compared to the nanostructured single-phase SiGe alloy. This resulted in ZT enhancement of Si0.88Ge0.12–FeSi2 by ∼30% over the broad temperature range of 500-950 °C compared to the conventional Si0.80Ge0.20 alloy. The Si0.88Ge0.12–Mg2Si nanocomposite showed constantly increasing ZT versus temperature up to 950 °C (highest measured temperature reaching ZT ∼ 1.3. These results confirm the concept of silicide nanoparticle-in-SiGe-alloy proposed earlier by Mingo et al. [Nano Lett. 9, 711–715 (2009].

  13. Effect of two-stage isothermal annealing on microstructure CuAl10Fe5Ni5 bronze with additions of Si, Cr, Mo, W and C

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2011-07-01

    Full Text Available The aim of this study was to investigate the effect of a two-step isothermal annealing respectively at 1000 ̊C for 30 min, then at the range of 900÷450 ̊C increments 50 ̊C on the microstructure CuAl10 Ni5Fe5 bronze with additions of Si, Cr, Mo, W and C, cast into sand moulds. The study concerned the newly developed species, bronze, aluminium-iron-nickel with additions of Si, Cr, Mo, W and C. In order to determine the time and temperature for the characteristic of phase transitions that occur during heat treatment of the test method was used thermal and derivation analysis (TDA. The study was conducted on cylindrical test castings cast in the mould of moulding sand. It was affirmed that one the method TDA can appoint characteristic for phase transformations points about co-ordinates: τ (s, t ( ̊ C, and to plot out curves TTT for the studied bronze with their use. It was also found that there is a fiveisothermalannealingtemperatureranges significantly altering the microstructure of examined bronze.

  14. 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 steel with Al-Si coating steel without any 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.

  15. Microstructure and magnetic properties of nanostructured (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} alloy produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Boukherroub, N. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Laggoun, A. [UR-MPE, M' hamed Bougara University, Boumerdes 35000 (Algeria); Hemmous, M. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Martínez-Blanco, D. [SCTs, University of Oviedo, EPM, 33600 Mieres (Spain); Blanco, J.A. [Department of Physics, University of Oviedo, Calvo Sotelo St., 33007 Oviedo (Spain); Souami, N. [Nuclear Research Centre of Algiers, 02 Bd Frantz Fanon, BP 399 Alger-Gare, Algiers (Algeria); Gorria, P. [Department of Physics and IUTA, EPI, University of Oviedo, 33203 Gijón (Spain); Bourzami, A. [Laboratoire d' Etudes des Surfaces et Interfaces des Matériaux Solides (LESIMS), Université Sétif1, 19000 Sétif (Algeria); Lenoble, O. [Institut Jean Lamour, CNRS-Université de Lorraine, Boulevard des aiguillettes, BP 70239, F-54506 Vandoeuvre lès Nancy (France)

    2015-07-01

    We report on how the microstructure and the silicon content of nanocrystalline ternary (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} powders (x=0, 5, 10, 15 and 20 at%) elaborated by high energy ball milling affect the magnetic properties of these alloys. The formation of a single-phase alloy with body centred cubic (bcc) crystal structure is completed after 72 h of milling time for all the compositions. This bcc phase is in fact a disordered Fe(Al,Si) solid solution with a lattice parameter that reduces its value almost linearly as the Si content is increased, from about 2.9 Å in the binary Fe{sub 80}Al{sub 20} alloy to 2.85 Å in the powder with x=20. The average nanocrystalline grain size also decreases linearly down to 10 nm for x=20, being roughly half of the value for the binary alloy, while the microstrain is somewhat enlarged. Mössbauer spectra show a sextet thus suggesting that the disordered Fe(Al,Si) solid solution is ferromagnetic at room temperature. However, the average hyperfine field diminishes from 27 T (x=0) to 16 T (x=20), and a paramagnetic doublet is observed for the powders with higher Si content. These results together with the evolution of both the saturation magnetization and the coercive field are discussed in terms of intrinsic and extrinsic properties. - Highlights: • Single-phase nanocrystalline (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} (x=0, 5, 10, 15 and 20 at%) powders were successfully fabricated by mechanical alloying for a milling time of 72 h. • The insertion of Si atoms leads to a unit-cell contraction and a decrease in the average crystallite size. • The hyperfine and magnetic properties of (Fe{sub 0.8}Al{sub 0.2}){sub 100–x}Si{sub x} were influenced by the Si content.

  16. Hot-Dip Aluminizing of Low Carbon Steel Using Al-7Si-2Cu Alloy Baths

    OpenAIRE

    Prashanth Huilgol; Suma Bhat; K. Udaya Bhat

    2013-01-01

    Hot-dip aluminizing of low carbon steel was done in molten Al-7Si-2Cu bath at 690°C for dipping time ranging from 300 to 2400 seconds. Characterization of the intermetallics layer was done by using scanning electron microscope with energy dispersive spectroscopy. Four intermetallic phases, τ5-Al7Fe2Si, θ-FeAl3, η-Fe2Al5, and τ1-Al2Fe3Si3, were identified in the reaction layer. τ5- Al7Fe2Si phase was observed adjacent to aluminum-silicon topcoat, θ-FeAl3 between τ5 and η-Fe2Al5, η-Fe2Al5 adjac...

  17. Menzerite-(Y) a New Species {(Y REE)(Ca Fe2plus)2}[(Mg Fe2plus)(Fe3plus Al)](Si3)O12 from a Felsic Granulite Parry Sound Ontario and a New Garnet End-member (Y2Ca)Mg2(SiO4)3

    Energy Technology Data Exchange (ETDEWEB)

    E Grew; J Marsh; M Yates; B Lazic; T Armbruster; A Locock; S Bell; M Dyar; H Bernhardt; O Medenbach

    2011-12-31

    Menzerite-(Y), a new mineral species, forms reddish brown cores, n = 1.844 (20), up to 70 {micro}m across, rimmed successively by euhedral almandine containing up to 2.7 wt% Y{sub 2}O{sub 3} and by K-feldspar in a felsic granulite on Bonnet Island in the interior Parry Sound domain, Grenville Orogenic Province, Canada. It is named after Georg Menzer (1897-1989), the German crystallographer who solved the crystal structure of garnet. Single-crystal X-ray-diffraction results yielded space group Ia3d, a = 11.9947(6) {angstrom}. An electron-microprobe analysis of the grain richest in Y (16.93 wt% Y{sub 2}O{sub 3}) gave the following formula, normalized to eight cations and 12 oxygen atoms: {l_brace}Y{sub 0.83}Gd{sub 0.01}Dy{sub 0.05}Ho{sub 0.02}Er{sub 0.07}Tm{sub 0.01}Yb{sub 0.06}Lu{sub 0.02}Ca{sub 1.37}Fe{sub 0.49}{sup 2+}Mn{sub 0.07}{r_brace} [Mg{sub 0.55}Fe{sub 0.42}{sup 2+}Fe{sub 0.58}{sup 3+}Al{sub 0.35} V{sub 0.01}Sc{sub 0.01}Ti{sub 0.08}](Si{sub 2.82}Al{sub 0.18})O{sub 12}, or {l_brace}(Y,REE)(Ca,Fe{sup 2+}){sub 2}{r_brace}[(Mg,Fe{sup 2+})(Fe{sup 3+},Al)](Si{sub 3})O{sub 12}. Synchrotron micro-XANES data gave Fe{sup 3+}/{Sigma}Fe = 0.56(10) versus 0.39(2) calculated from stoichiometry. The scattering power refined at the octahedral Y site, 17.68 epfu, indicates that a relatively light element contributes to its occupancy. Magnesium, as determined by electron-microprobe analyses, would be a proper candidate. In addition, considering the complex occupancy of this site, the average Y-O bond length of 2.0244(16) {angstrom} is in accord with a partial occupancy by Mg. The dominance of divalent cations with Mg > Fe{sup 2+} and the absence of Si at the octahedral Y site (in square brackets) are the primary criteria for distinguishing menzerite-(Y) from other silicate garnet species; the menzerite-(Y) end-member is {l_brace}Y{sub 2}Ca{r_brace}[Mg{sub 2}](Si{sub 3})O{sub 12}. The contacts of menzerite-(Y) with almandine are generally sharp and, in places, cuspate. It is

  18. Effect of Al3+ Doping on Structure and Electrochemical Performance of Li2FeSiO4%Al3+掺杂对Li2FeSiO4结构和电化学性能影响的研究

    Institute of Scientific and Technical Information of China (English)

    兰建云; 赵敏寿; 王艳芝; 乔玉卿

    2011-01-01

    Adopting CH3COOLi-2H2O, C^A-HA FeC^C^-SHA Al2 (SO4)3-18H2O and CgHaAtSi as starting raw material, U2Fe1^Al(Si04/C (*=0.00, 0.01, 0.03, 0.05) electrode material was prepared by hydrothermal assisted sol-gel method and two-step heating solid-state reaction. The structure of the material was studied by IR, XRD, FE-SEM and EDS. The magnetic performance of the material was tested by superconducting quantum interference device (SQUID) and the distribution of the material's particle size was measured by ZetaPAL laser particle size analyzer. The results show that the electrochemical performance is desirable when the molar ratio of lithium acetate and citric acid was 4:1 and the dopant of Al3* was 3%, and the solution was refluxed at 80 *C for 24 h, then dried. The precursor was calcined for 5 h at 350 X. And 13 h at 700 t, and the size of the composite was about 150 nm and aggregation phenomenon wasn't found. The discharge capacity of initial cycle is 127 mAh-g"1, 103.6 mAh-g'1 and 91 mAh-g"1 under the ratio of 0.1C (16 mA-g"1), 0.2C and 0.5C, respectively and there is no significant degradation even after 15 times cycling, and the cycle stability of material is very well.%以CH3COOLi· 2H2O、C6H8O7·H2O、FeC6H5O7·5H2O、Al2(SO4)3· 18H2O和C8H20O4Si为起始原料,采用水热辅助溶胶凝胶法及二次煅烧合成了Li2Fe 1-xAlxSi O4/C(x=0.00、0.01、0.03、0.05)正极材料.用IR、XRD、FE-SEM、EDS等方法对材料的晶体结构进行了表征,用ZetaPAL粒度分析仪测量了其粒径分布范围,用SQUID(超导量子干涉仪)测定了样品的磁性,用恒流充/放电对其电化学性能进行了测试.结果表明:n乙酸锂:n柠檬酸=4:1、掺Al3+量为3%,80℃回流24h,350℃恒温煅烧5h,700℃恒温13 h,所得试样颗粒集中分布在150 nm左右且未出现团聚.在0.1C(16 mA·g-1)、0.2C、0.5C下的首次放电比容量为127 mAh·g-1、103.6 mAh·g-1和91 mAh·g-1,15次循环后无明显衰减,具有很好的循环稳定性.

  19. Microstructural Characterization of Beryllium Treated Al-Si Alloys

    Directory of Open Access Journals (Sweden)

    M. F. Ibrahim

    2015-01-01

    Full Text Available The present study was carried out on B356 and B357 alloys using the thermal analysis technique. Metallographic samples prepared from these castings were examined using optical microscopy and FESEM. Results revealed that beryllium causes partial modification of the eutectic Si, similar to that reported for magnesium additions. Addition of 0.8 wt.% Mg reduces the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, but no Sr, formation of a Be-Fe phase was detected at 611°C, close to that of α-Al. The Be-Fe phase precipitates in script-like form at or close to the β-Al5SiFe platelets. A new reaction, composed of fine particles of Si and π-Fe phase, was observed to occur near the end of solidification in high Mg-, high Fe-, and Be-containing alloys. The amount of this reaction decreased with the addition of Sr. Occasionally, Be-containing phase particles were observed as part of the reaction. Addition of Be has a noticeable effect on decreasing the β-Al5FeSi platelet length; this effect may be enhanced by addition of Sr. Beryllium addition also results in precipitation of the β-Al5FeSi phase in nodular form, which lowers its harmful effects on the alloy mechanical properties.

  20. Incorporation of Ba in Al and Fe pollucite

    Science.gov (United States)

    Vance, Eric R.; Gregg, Daniel J.; Griffiths, Grant J.; Gaugliardo, Paul R.; Grant, Charmaine

    2016-09-01

    Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs(1-2x)BaxAlSi2O6 aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl2Si2O8 phases. The effect of Ba substitution in pollucite-structured CsFeSi2O6 was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe2+ formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs+ + Fe3+ ↔ Ba2+ + Ni2+ scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi2O6 to be very leach resistant.

  1. Melting features and viscosity of SiO2-CaO-MgO-Al2O3-FeO nickel slag in laterite metallurgy

    Directory of Open Access Journals (Sweden)

    Pan C.

    2013-01-01

    Full Text Available Physic-chemical properties of slag at high temperature were very important for the production of ferronickel alloy by pyrometallurgical process. It determines the operation efficiency, metal recovery ratio, energy consumption and the distribution of elements (like S and P between the slag and metal. In the present work, the effect of slag basicity on melting features and viscosity of the slag was investigated. The basicity of the SiO2-CaO-MgO-Al2O3-FeO quinary slag system varied from 0.76 to 0.99. The results showed that: 1 all the slag samples began to soften at the same temperature; 2 the softening temperature, melting temperature and flowing temperature decreased with the increase of basicity from 0.76 to 0.92, after that, the temperatures would increase sharply. 3 the inflection point temperature of viscosity-temperature curve became larger and larger with the increase of basicity within 0.76 ~ 0.99.

  2. Study of the productivity of MWCNT over Fe and Fe–Co catalysts supported on SiO2, Al2O3 and MgO

    Directory of Open Access Journals (Sweden)

    S.A. Shokry

    2014-06-01

    Full Text Available In the present study, multi-walled carbon nanotubes (MWCNT were prepared in good quality and quantity, MWCNT were produced using the catalytic chemical vapor deposition (CCVD technique and the carbon source was acetylene. Different catalysts were synthesized based on iron and a mixture of iron and cobalt metal supported on SiO2, Al2O3 or MgO. The effect of parameters such as iron concentration, support type, bimetallic catalyst and the method of catalyst preparation has been investigated in the production of MWCNT. The quality of as-made nanotubes was investigated by the high-resolution transmission electron microscopy (HRTEM and thermogravimetric analysis (TGA. The best yield of MWCNT was 30 times of the amount of the used catalyst. The high yield of MWCNT was gained by 40 wt.% Fe on alumina support which was prepared by the sol–gel method. TEM analysis was done for the carbon deposit, which revealed that the walls of the MWCNT were graphitized, with regular inner channel and uniform diameter. It reflected a reasonable degree of purity. The TGA showed that MWCNT was decomposed at 635 °C by a small rate indicating a high thermal stability and well crystalline formation of the produced MWCNT.

  3. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Mohammad Shakiba

    2016-06-01

    Full Text Available The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002–0.31 wt % was investigated by uniaxial compression tests conducted at different temperatures (400 °C–550 °C and strain rates (0.01–10 s−1. The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  4. Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel

    Directory of Open Access Journals (Sweden)

    Xianming Zhao

    2014-12-01

    Full Text Available A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.% steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10−3/s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite (soft phase and ultrafine austenite lamellae (50–200 nm, strong and ductile phase is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

  5. The effect of Al, Si and Fe contents (selective dissolution on soil physical properties at the northern slope of Mt. Kawi

    Directory of Open Access Journals (Sweden)

    I Nita

    2015-04-01

    Full Text Available A toposequence at the northern slope of Mt. Kawi (East Java, having andic properties, were studied. Soil samples at various horizons from five profiles along the toposequence were selected for this study. Selective dissolution analyses (oxalate acid, pyrophosphate and dithionite citrate extractions were performed to predict the amorphous materials, as reflected from the extracted Si, Al, and Fe. The contents of these three constituents were then correlated to the soil physical properties. The andic characters were indicated by low bulk density (0.43-0.88 g/cm3 and considerable amounts of Alo (1.3-4.2% and Feo (0.6-2%, which tended to increase with depth. As a consequence, high content of total pores (>70% and water content at pF 0, 2.54, and 4, as well as strong aggregate stability were detected (MWD of 2.4-4.5 mm and 1.4-4.5 mm, respectively, in Andisols and Non-Andisols. Water content at pF 0, 2.54, and 4, were significantly affected by respectively %Sio, % Fed, % Fep, and % Fed. However, bulk density was closely related to %Ald only.

  6. Generation and evolution of nanoscale AlP and Al{sub 13}Fe{sub 4} particles in Al-Fe-P system

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Huan; Gao, Tong; Zhu, Xiangzhen; Wu, Yuying; Qian, Zhao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

    2015-02-15

    Highlights: • Diffusion and gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al{sub 13}Fe{sub 4} clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al{sub 13}Fe{sub 4} nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated.

  7. Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

    Institute of Scientific and Technical Information of China (English)

    Chong-yu Liu; Peng-fei Yu; Xiao-ying Wang; Ming-zhen Ma; Ri-ping Liu

    2014-01-01

    An Al–Mg–Si–Cu–Fe alloy was solid-solution treated at 560°C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180°C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420°C, and then increased;the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180°C rolling water-quenched alloy were also improved by the presence ofβ″phase. Above 420°C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.

  8. Cristallochimie des biotites ferro-alumineuses dans le système Na2O-K2O-FeO-Fe2O3-Al2O3-SiO3-SiO2-H2O-HF. Analyse par spectrométries vibrationnelles et Mössbauer.

    OpenAIRE

    Boukili, Boubker

    1995-01-01

    CE TRAVAIL CONCERNE L'ETUDE CRISTALLOCHIMIQUE DES BIOTITES FERRO-ALUMINEUSES DE SYNTHESE DANS LE SYSTEME NA20-K20-FE0-FE203-AL203-SI02-H20-HF, EN FONCTION DE LA TEMPERATURE ET DE LA FUGACITE D'OXYGENE. LES METHODES DE CARACTERISATION EMPLOYEES SONT LA DIFFRACTION X ET LES SPECTROMETRIES INFRAROUGE, RAMAN ET MOSSBAUER. EN L'ABSENCE DE FLUOR, LE FER FERRIQUE SE REPARTIT ENTRE SITES TETRA- ET OCTAEDRIQUES, SA TENEUR GLOBALE AUGMENTE AVEC LA FUGACITE D'OXYGENE. EN CONDITIONS HYDROTHERMALES, L'OXY...

  9. Effect of Sulfur on Liquidus Temperatures in the ZnO-"FeO"-Al2O3-CaO-SiO2-S System in Equilibrium with Metallic Iron

    Science.gov (United States)

    Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

    2011-10-01

    The phase equilibria in the ZnO-"FeO"-Al2O3-CaO-SiO2-S system have been determined experimentally in equilibrium with metallic iron. A pseudoternary section of the form ZnO-"FeO"-(Al2O3+CaO+SiO2) for CaO/SiO2 = 0.71 (weight), (CaO+SiO2)/Al2O3 = 5.0 (weight), and fixed 2.0 wt pct S concentration has been constructed. It was found that the addition of 2.0 wt pct S to the liquid extends the spinel primary phase field significantly and decreases the size of the wustite primary phase field. The liquidus temperature in the wustite primary phase field is decreased by approximately 80 K and the liquidus temperature in the spinel primary phase field is decreased by approximately 10 K with addition of 2.0 wt pct S in the composition range investigated. It was also found that iron-zinc sulfides are present in some samples in the spinel primary phase field, which are matte appearing at low zinc concentrations and sphalerite (Zn,Fe)S at higher zinc concentrations. The presence of sulfur in the slag has a minor effect on the partitioning of ZnO between the wustite and liquid phases but no effect on the partitioning of ZnO between the spinel and liquid phases.

  10. 彩色铝粉Fe2O3/SiO2/Al的液相沉积制备与表征%Preparation and characterization of colored aluminum powder Fe2O3/SiO2/Al by liquid deposition

    Institute of Scientific and Technical Information of China (English)

    韩凯; 张赢超; 叶红齐

    2011-01-01

    采用分步液相沉积法在片状铝粉表面包覆SiO2与Fe2O3双层薄膜制备了具有金属光泽的彩色铝粉,以彩度与光泽度为主要评价指标,探讨Fe2O3用量与pH值对铝粉包覆效果的影响,利用原子力显微镜(AFM)、扫描电子显微镜(SEM)和X射线衍射(XRD)等手段对包覆前后的铝粉进行表征.结果表明:当SiO2包覆量为20%(质量分数)时,随着Fe2O3膜厚的增加,铝粉颜色由浅黄→金黄→红黄过渡,光泽度下降;当m(Fe2O3)∶m(SiO2)∶m(Al)=0.75∶0.2∶1时,铝粉具有良好的彩度与光泽度,铝粉表面粗糙度由5.05 nm增大到20.6 nm;反应过程pH值对Fe2O3包覆效果有重要影响,pH值宜控制在3.9~4.0;表面活性剂PVP的加入有利于提高Fe2O3膜层与SiO2和Al基体的结合力,从而提高颜色稳定性.%The colored aluminum flake powder with metallic luster was prepared by encapsulating SiO2 and Fe2O3 double-layer film via step liquid-phase deposition method. Using the chromaticity and gloss as the main targets, the influence of Fe2O3 amount and pH value on the coating effect was studied. The unencapsulated and encapsulated aluminum powders were characterized by AFM, SEM and XRD. The results show that when the amount of SiO2 is 20% (mass fraction), with the increase of Fe2O3 amount, the aluminum powder changed colors from pale-yellow to golden-yellow, and then to red-yellow, and the gloss is reduced. Under the condition of m(Fe2O3):m(SiO2):m(Al)= 0.75:0.2:1, the encapsulated sample has good chromaticity and gloss synchronously, and the surface roughness of the aluminum powder increases from 5.05 nm to 20.6 nm. Furthermore, pH value should be controlled between 3.9 to 4.0. The addition of PVP is helpful to improve the color stability property of the aluminum powder, the Fe2O3 film is firmly combined with SiO2 and Al.

  11. Hot-Dip Aluminizing of Low Carbon Steel Using Al-7Si-2Cu Alloy Baths

    Directory of Open Access Journals (Sweden)

    Prashanth Huilgol

    2013-01-01

    Full Text Available Hot-dip aluminizing of low carbon steel was done in molten Al-7Si-2Cu bath at 690°C for dipping time ranging from 300 to 2400 seconds. Characterization of the intermetallics layer was done by using scanning electron microscope with energy dispersive spectroscopy. Four intermetallic phases, τ5-Al7Fe2Si, θ-FeAl3, η-Fe2Al5, and τ1-Al2Fe3Si3, were identified in the reaction layer. τ5- Al7Fe2Si phase was observed adjacent to aluminum-silicon topcoat, θ-FeAl3 between τ5 and η-Fe2Al5, η-Fe2Al5 adjacent to base material, and τ1-Al2Fe3Si3 precipitates within Fe2Al5 layer. The average thickness of Fe2Al5 layer increased linearly with square root of dipping time, while for the rest of the layers such relationship was not observed. The tongue-like morphology of Fe2Al5 layer was more pronounced at higher dipping time. Overall intermetallic layer thickness was following parabolic relationship with dipping time.

  12. The role of Pt underlayer on the magnetization dynamics of perpendicular magnetic anisotropy Pt/Co2FeAl0.5Si0.5/MgO

    Science.gov (United States)

    Besbas, Jean; Loong, Li Ming; Wu, Yang; Yang, Hyunsoo

    2016-06-01

    We investigate the role of Pt on the magnetization dynamics of Pt/Co2FeAl0.5Si0.5/MgO with perpendicular magnetic anisotropy using the time resolved magneto-optic Kerr effect. Pt/Co2FeAl0.5Si0.5/MgO shows ultrafast magnetization dynamics comparable to 3d ferromagnets and can be fully demagnetized. The demagnetization time τd ˜ 0.27 ps and magnetic heat capacity are independent of the Pt underlayer, whereas the value of the electron-phonon coupling time τe ˜ 0.77 ps depends on the presence of the Pt layer. We further measure the effective damping αeff ˜ 1 that does not scale as the inverse demagnetization time (1/τd), but is strongly affected by the Pt layer.

  13. Microstructure of hot dip coated Fe-Si steels

    Energy Technology Data Exchange (ETDEWEB)

    Danzo, I. Infante, E-mail: ivonneeugenia.infantedanzo@ugent.be; Verbeken, K., E-mail: Kim.Verbeken@UGent.be; Houbaert, Y., E-mail: Yvan.Houbaert@UGent.be

    2011-12-30

    Hot dipping is a coating technique pre-eminently used in industry to galvanize machine parts or steel sheets for constructional applications. However, other hot dipping applications have been developed in order to have a positive effect on specific material properties. For instance, in Fe-Si electrical steels, a Si/Al rich top layer is applied and followed by diffusion annealing to increase the electrical resistivity of the material and consequently, lower the power losses. Hot dipped aluminised mild steels have been developed with increased corrosion resistance for high temperature applications by the development of a dense Al{sub 2}O{sub 3} layer. Regardless of the type of steel coated and the intended application, after the interaction between the molten Al and the solid material, three constituents are formed: Fe{sub 2}Al{sub 5}, FeAl{sub 3} and an Al-rich alloy. The structural morphology, which can negatively affect the wear resistance and the thermal stability, also appears to be highly dependent on the chemical composition of the base material. To study thermo-mechanical and compositional effects on the coating behavior after hot dipping, cold rolling with different reductions was performed on different Fe-Si materials. It was demonstrated that hardness differences between the layers caused crack formation inside the Fe{sub 2}Al{sub 5} layer during subsequent deformation. The present work reports the results obtained on materials that were hot dipped in a hypo-eutectic Al + 1 wt.% Si bath. The bath was used to coat Fe-Si steel substrates with variable silicon content with dipping times ranging from 1 to 20 s. Before dipping, the samples were heated to 700 Degree-Sign C and subsequently immersed in the liquid bath at temperatures of 710 Degree-Sign C, 720 Degree-Sign C and 740 Degree-Sign C. To further evaluate the interactions between Al, Si and Fe, a diffusion annealing treatment at 1000 Degree-Sign C was performed. The main diffusing elements during this

  14. Perpendicular magnetic anisotropy in Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO bottom electrodes for magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.Q.; Wu, Y.; Gao, S.; Xu, X.G., E-mail: xgxu@ustb.edu.cn; Miao, J.; Jiang, Y., E-mail: yjiang@ustb.edu.cn

    2013-10-31

    Perpendicular magnetic anisotropy (PMA) was achieved in annealed Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (CFAS)/MgO-based multilayers with good thermal stability up to 400 °C and a large anisotropy energy density K{sub u} over 2.0 × 10{sup 5} J/m{sup 3}. The thickness of the full-Heusler CFAS film to maintain PMA is up to 4.8 nm in which the co-existence of disordered A2, ordered B2 and fully ordered L2{sub 1} structures is observed. X-ray photoelectron spectroscopy analysis demonstrates that the origin of the PMA is the hybridization between Co 3d and O 2p orbitals at the CFAS/MgO interface. - Highlights: • We achieved perpendicular magnetic anisotropy (PMA) in Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (4.8 nm) film; • L2{sub 1}, B2 and A2 phases coexist in perpendicular magnetic anisotropic Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}; • Magnetic properties have strong dependence on the annealing temperature; • The PMA is induced by the hybridization between Co-3d and O-2p orbitals.

  15. Effects of annealing temperature on microstructure and electromagnetic characteristics of FeSiAl alloy%退火温度对FeSiAl合金微结构及电磁特性的影响

    Institute of Scientific and Technical Information of China (English)

    高峰; 李鹏飞; 王群

    2009-01-01

    对球磨后的FeSiAl合金粉末进行不同温度真空退火,并制备成软磁合金复合材料(SCM).采用SEM、XRD和网络分析仪等分析手段,研究了退火后合金的相组成、超点阵结构有序度、平均晶粒尺寸和1 MHz~1.5 GHz的SCM的复磁导率,随退火温度变化的规律.结果表明:随着退火温度逐渐提高,DO3超点阵结构有序度由0.38增大到0.66、平均晶粒尺寸由36.93 nm增大到71.41 nm、SCM在同频率下的μ′和μ″均逐渐减小.

  16. 扁平化对FeSiAl合金结构及电磁特性的影响%Influence of flattening on the structure and electromagnetic characteristics of FeSiAl alloy

    Institute of Scientific and Technical Information of China (English)

    高峰; 李鹏飞; 王群

    2009-01-01

    通过球磨对气雾化FeSiAl合金粉末进行扁平化,并制备成软磁合金复合材料(SCM).研究球磨时间对合金粉末微观形貌、显微结构以及1 MHz~1 GHz频率范围内SCM的复磁导率的影响.结果表明:随着球磨时间的增加,合金粉末的扁平率由1.18增大到7.01,粒径由50.36 μm减小到33.31 μm,平均晶粒尺寸由79.7 nm减小到49.7 nm,内应变由0.425 2%增大到0.597 4%;对合金粉末进行球磨可以明显提高SCM的μ′和μ″;随着球磨时间增加,SCM在同频率下的μ′和μ″均逐渐增大.

  17. Viscosity and structure evolution of the SiO2-MgO-FeO-CaO-Al2O3 slag in ferronickel smelting process from laterite

    Directory of Open Access Journals (Sweden)

    Lv X.M.

    2017-01-01

    Full Text Available The SiO2 fractions in laterite-nickel ores are quite high, thus certain amount of lime should be used as fluxing material to achieve good fluidity and desulfurization capacity in industrial smelting process. However, this operation leads to an additional cost of lime. In addition, the increase of slag volume decreases the effective furnace volume. To avoid such problem, partial reduction of FeO has been suggested. Therefore, the high SiO2, low MgO and FeO and very little CaO slag is formed, which was less studied in the previous literature. Therefore, the viscosity and slag structure are investigated in the present study through FT-IR and Raman analysis methods. Experimental results show that the slag is a mixture of liquid and solid phases under the experimental temperature. The FT-IR and Raman spectra show that the fractions of the complex polymerization structure decrease significantly with the increase of FeO content and slag basicity, resulting in the decrease of apparent viscosity.

  18. Effect of Al content on the order of phase transition and magnetic entropy change in LaFe{sub 11}Co{sub 0.8}(Si{sub 1−x}Al{sub x}){sub 1.2} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gębara, P., E-mail: pgebara@wip.pcz.pl [Institute of Physics, Częstochowa University of Technology, Al. Armii Krajowej 19, 42-200 Częstochowa (Poland); Pawlik, P. [Institute of Physics, Częstochowa University of Technology, Al. Armii Krajowej 19, 42-200 Częstochowa (Poland); Škorvánek, I. [Institute of Experimental Physics, SAS Watsonowa 47, 043 33 Kosice (Slovakia); Bednarcik, J. [HASYLAB am DESY, Notkestrasse 85, D-22603 Hamburg (Germany); Marcin, J. [Institute of Experimental Physics, SAS Watsonowa 47, 043 33 Kosice (Slovakia); Michalik, Š. [HASYLAB am DESY, Notkestrasse 85, D-22603 Hamburg (Germany); P.J. Safarik University in Kosice, Insitute of Physics, Park Angelinum 9, 041 54 Kosice (Slovakia); Donges, J. [HASYLAB am DESY, Notkestrasse 85, D-22603 Hamburg (Germany); Wysłocki, J.J. [Institute of Physics, Częstochowa University of Technology, Al. Armii Krajowej 19, 42-200 Częstochowa (Poland); Michalski, B. [Faculty of Materials Engineering, Warsaw University of Technology, ul. Wołoska 141, 02-507 Warsaw (Poland)

    2014-12-15

    The comparative studies of the effect of partial substitution of Al by Si on the structure and magnetic entropy change in LaFe{sub 11}Co{sub 0.8}(Si{sub 1−x}Al{sub x}){sub 1.2} alloys produced by arc-melting followed by long time annealing at 1323 K were performed. The X-ray diffraction analysis revealed almost single phase composition of annealed samples. The high intensity synchrotron radiation was used for studying the thermal evolution of lattice constant of the La(Fe,Co,Si){sub 13} phase. Furthermore, calculations of temperature dependences of Landau coefficients were used to reveal changes in the character of phase transformation at around the Curie temperature. - Highlights: • Identification of order of phase transition in LaFe{sub 11.0}Co{sub 0.8}(Si{sub 1−x}Al{sub x}){sub 1.2} where x=0;0.6. • Negative change of lattice parameter near Curie temperature in LaFe{sub 11.0}Co{sub 0.8}Si{sub 1.2}. • Landau theory of phase transitions.

  19. Spin Injection, Transport, and Detection at Room Temperature in a Lateral Spin Transport Device with Co2FeAl0.5Si0.5/n-GaAs Schottky Tunnel Junctions

    Science.gov (United States)

    Saito, Tatsuya; Tezuka, Nobuki; Matsuura, Masashi; Sugimoto, Satoshi

    2013-10-01

    We observed spin-valve signals and Hanle signals in four-terminal nonlocal measurements on a lateral spin transport device with Co2FeAl0.5Si0.5(CFAS)/n-GaAs Schottky tunnel junctions. The estimated spin injection/detection efficiency was 0.06 at 4.2 K, which is larger than those of the devices with Fe and CoFe electrodes [Nature Physics 3 (2007) 197 and Appl. Phys. Lett. 99 (2011) 082108]. The spin diffusion length estimated from Hanle signals was consistent with the gap length dependency of the spin-valve signals. Furthermore, the spin-valve signals were observed at up to 290 K. This is the first demonstration of detecting spin accumulation in semiconductor with full-Heusler alloys electrodes at room temperature.

  20. Liquidus and phase equilibria in CaO-Al2O3-FeOx-SiO2 system under intermediate oxygen partial pressure

    Directory of Open Access Journals (Sweden)

    Wang N.

    2013-01-01

    Full Text Available Phase equilibria of silicate slags relevant to the copper smelting/converting operations have been experimentally studied over a wide range of slag compositions, temperatures and atmospheric conditions. Selected systems are of industrial interest and fill the gaps in fundamental information required to systematically characterise and describe copper slag chemistry. The experimental procedures include equilibration of synthetic slag at high temperatures, rapid quenching of resulting phases, and accurate measurement of phase compositions using electron probe X-ray microanalysis (EPMA. The effects of CaO, Al2O3 and MgO on the phase equilibria of this slag system have been experimentally investigated in the temperature range 1200 to 1300 oC and oxygen partial pressures between 10-5 and 10-9 atm. It was found that spinel and silica are major primary phases in the composition range related to copper smelting/converting slags. In addition, olivine, diopside and pyroxene also appear at certain conditions. The presence of CaO, MgO and Al2O3 in the slag increases the spinel liquidus and decreases the silica liquidus. Liquidus temperatures in silica primary phase field are not sensitive to Po2; Liquidus temperatures in spinel primary phase field increase with increasing Po2. At 1300ºC and low Po2, the spinel (Fe2+,Mg2+O.(Al3+,Fe3+ primary phase field can be replaced by wustite (Fe2+,Mg2+O.

  1. Synthesis and equation of state of post-perovskites in the (Mg,Fe)[subscript 3]Al[subscript 2]Si[subscript 3]O[subscript 12] system

    Energy Technology Data Exchange (ETDEWEB)

    Shieh, Sean R.; Dorfman, Susannah M.; Kubo, Atsushi; Prakapenka, Vitali B.; Duffy, Thomas S. (Princeton); (UC); (UWO)

    2016-08-15

    The formation and properties of the post-perovskite (CaIrO{sub 3}-type) phase were studied in Fe-rich compositions along the pyrope-almandine ((Mg,Fe){sub 3}Al{sub 2}Si{sub 3}O{sub 12}) join. Natural and synthetic garnet starting materials with almandine fractions from 38 to 90 mol% were studied using synchrotron X-ray diffraction in the laser-heated diamond anvil cell. Single-phase post-perovskite could be successfully synthesized from garnet compositions at pressures above 148 GPa and temperatures higher than 1600 K. In some cases, evidence for a minor amount of Al{sub 2}O{sub 3} post-perovskite was observed for Alm38 and Alm54 compositions in the perovskite + post-perovskite two-phase region. Pressure-volume data for the post-perovskite phases collected during decompression show that incorporation of Fe leads to a systematic increase of unit cell volume broadly similar to the variation observed in the (Mg,Fe)SiO{sub 3} system. The presence of Al{sub 2}O{sub 3} increases the stability of perovskite relative to post-perovskite, requiring higher pressures (> 148 GPa) for synthesis of pure post-perovskites. Our data together with those of Tateno et al. (2005) also suggest that in the Al-rich system the presence of Fe has no strong effect on the pressure required to synthesize the pure post-perovskite phase, but the two-phase perovskite and post-perovskite region may be broad and its width dependent on Fe content. Our results suggest that any regions highly enriched in Al{sub 2}O{sub 3} may consist of either the perovskite phase or a mixture of perovskite and post-perovskite phases throughout the entire thickness of the D* region. The observed synthesis pressures (> 148 GPa) for a pure post-perovskite phase are beyond that at the Earth's core-mantle boundary ({approx} 135 GPa).

  2. Preparation and Characterization of Novel Porous Fe-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Jiefeng; HE Yuehui; JIANG Yao; GAO Hanyan; YANG Junsheng; GAO Lin

    2016-01-01

    Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m-1Pa-1s-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the ifltration industries.

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

    Institute of Scientific and Technical Information of China (English)

    Maja VONINA; Joef MEDVED; Tonica BONINA; Franc ZUPANI

    2014-01-01

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

  4. Effects of Al2O3 and MgO on Softening, Melting, and Permeation Properties of CaO-FeO-SiO2 on a Coke Bed

    Science.gov (United States)

    Ueda, Shigeru; Kon, Tatsuya; Miki, Takahiro; Kim, Sun-Joong; Nogami, Hiroshi

    2016-08-01

    In ironmaking, maintaining gas permeability in blast furnace with low coke rate operation is essential to reduce carbon emissions. The high pressure loss in the cohesive zone decreases the gas permeability and affects the productivity of blast furnace. In order to increase the gas permeability in the cohesive zone, the thickness of the cohesive layer should be decreased. For this purpose, increasing softening temperature and decreasing dripping temperature of the iron ore are desired. In this study, softening, melting, and permeation of SiO2-FeO-CaO-Al2O3-MgO on a coke bed were investigated. The oxide sample in a tablet form was heated under CO/CO2 atmosphere, and the shape of the tablet was observed. The softening and melting temperatures of the SiO2-FeO-CaO system changed with the addition of Al2O3 and MgO. Oxide tablets with and without Al2O3 softened below and above the solidus temperature, respectively. The melting temperatures varied with the ratio of CO/CO2 in the gas. The permeation temperature was independent of the melting temperature, but dependent on the wettability.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  6. Interaction of Ta–O and perpendicular magnetic anisotropy of Ta/Pd (0–2.4 nm)/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta structured films

    Energy Technology Data Exchange (ETDEWEB)

    You, C.Y., E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Fu, H.R.; Zhang, X.; Tian, N. [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Wang, P.W. [Material Analysis and Testing Center, Northwest Institute for Non-ferrous Metal Research, Xi’an 710016 (China)

    2015-03-01

    Perpendicular magnetic anisotropy (PMA) was realized by inserting Pd layer into the stack of Ta/Pd (0–2.4 nm)/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta. The realization of PMA is accompanied by the (Co, Fe)–O reduction at Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO interface under annealing. Without inserting Pd layer, the annealed Ta/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO/Ta film presents an in-plane magnetization. Through X-ray photoelectron spectrometry analyzes, it was found that the oxygen was enriched at the interface of Ta/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}. This work clarifies that the inserted Pd layer effectively blocks the diffusion of interfacial oxygen to Ta layer, achieving the beneficial redox reaction at Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO interface to realize PMA. - Highlights: • Perpendicular magnetic anisotropy (PMA) was realized by inserting a Pd layer. • The proper reduction of Co–O and Fe–O occurred at the interface during annealing, improving PMA. • Ta–O interaction is the main reason of the PMA loss without inserting Pd.

  7. Hume-Rothery stabilization mechanism and e/a determination in MI-type Al-Mn, Al-Re, Al-Re-Si, Al-Cu-Fe-Si and Al-Cu-Ru-Si 1/1-1/1-1/1 approximants - a proposal for a new Hume-Rothery electron concentration rule

    Science.gov (United States)

    Mizutani, U.; Inukai, M.; Sato, H.; Zijlstra, E. S.

    2012-05-01

    Full-potential linearized augmented plane wave (FLAPW) band calculations with subsequent FLAPW-Fourier analyses have been performed for five MI-type Al-TM (transition metal)-based 1/1-1/1-1/1 approximants in order to elucidate the origin of a pseudogap from the point of view of the Fermi surface-Brillouin zone (FsBz) interactions. The square of the Fermi diameter ? is determined from the Hume-Rothery plot to be close to 50 without exception in units of ? , where ? is the lattice constant. The FsBz interactions involving several reciprocal lattice vectors are claimed to be responsible for constituting the pseudogap structure across E F. This is referred to as the multi-zone effect. Among them, the ? wave, in which the Fourier coefficients are most evenly and densely distributed across E F, is selected as the critical one satisfying the matching condition ? . The d-states-mediated-splitting appears to be absent in spite of substantial occupations of TM-d states in the valence band. All MI-type approximants studied are found to obey the Hume-Rothery stabilization mechanism. A new Hume-Rothery electron concentration rule linking the number of atoms per unit cell, e/uc, with a critical reciprocal lattice vector ? is found to hold well for structurally complex intermetallic compounds obeying the Hume-Rothery stabilization mechanism.

  8. Fe stable isotope fractionation in modern and ancient hydrothermal Fe-Si deposits

    Science.gov (United States)

    Moeller, K.; Schoenberg, R.; Thorseth, I. H.; Øvreås, L.; Pedersen, R.

    2010-12-01

    -sea sediments and the deposit itself, including abiogenic partial oxidation of hydrothermal Fe(II)aq through mixing with oxygenated seawater, reduction of Fe(III) precipitates by dissimilatory iron reduction (DIR) and re-oxidation by Fe-oxidising bacteria. The Løkken jaspers were postulated to be a combination of Fe-oxyhydroxide precipitation within buoyant and non-buoyant hydrothermal plumes and Si flocculation in a silica-saturated ocean [1]. Observations from a modern basalt-hosted hydrothermal system indicate that Fe(II)aq in a buoyant plume gets fractionated towards heavier isotopic compositions due to precipitation of low-δ56Fe iron sulphides [3]. However, mass balance calculations of plume particles revealed that Fe-oxyhydroxides have δ56Fe values of around -0.2 ‰, thus significantly lighter than the heaviest Løkken signatures of 0.89 ‰. Possible scenarios to explain the Fe isotope compositions of Løkken jaspers and the modern Mohns Ridge Fe-Si deposits will be discussed. [1] Grenne, T. & Slack, J. (2003) Miner Deposita, 38, 625ff. [2] Little, C. et al. (2004) Geomicrobiol J, 21, 415ff. [3] Bennett, S. et al. (2009) Geochim. Cosmochim. Acta., 73, 5619ff.

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

    Science.gov (United States)

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

    2016-04-28

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

  10. Low temperature magnetization behavior in Co{sub 36}Fe{sub 36}Si{sub 3}Al{sub 1}Nb{sub 4}B{sub 20} (at%) nanostructured alloy

    Energy Technology Data Exchange (ETDEWEB)

    Panda, A.K., E-mail: akpanda@nmlindia.or [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Mohanta, Ojaswini [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India); Basumallick, A. [Bengal Engineering and Science University, Shibpur, West Bengal (India); Mitra, A. [Council for Scientific and Industrial Research, National Metallurgical Laboratory, Jamshedpur 831 007 (India)

    2010-12-15

    The investigation addresses low temperature magnetization behavior in Co{sub 36}Fe{sub 36}Si{sub 3}Al{sub 1}Nb{sub 4}B{sub 20} alloy ribbons in their as-spun as well as annealed state. Optimum heat treatment at 875 K led to nanocrystallization whereby bcc-(FeCo)SiAl nanoparticles were dispersed in an amorphous matrix as evidenced from transmission electron microscopy. Low temperature magnetization studies were carried out in the range 77-300 K. Using the method of mathematical fittings, magnetization extrapolated to 0 K was obtained. The dependence of the magnetization with respect to temperature of BT{sup 3/2} was used to determine the Bloch coefficient 'B' and spin wave stiffness constant 'D'. Magnetic softening revealed by lowering in the coercivity in the optimum nanostructured state was also the cause of a drop in the stiffness constant. The range of exchange interaction given by D/T{sub C} was higher in the nanostructured state compared to the as-spun amorphous state. The effect of nanocrystallization and the resulting ferromagnetic coupling was further evidenced by low temperature magnetization studies.

  11. Mossbauer and XRD characterization of the phase transformations in a Fe-Mn-Al-C-Mo-Si-Cu as cast alloy during tribology test

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J. [Universidad Autónoma de Occidente (Colombia); Piamba, J. F. [Universidad del Valle, Departamento Física (Colombia); Sánchez, H. [Universidad del Valle, Escuela de Materiales (Colombia); Alcazar, G. A. Pérez, E-mail: gpgeperez@gmail.com [Universidad del Valle, Departamento Física (Colombia)

    2015-06-15

    In present study Fe-29.0Mn-6Al–0.9C-1.8Mo-1.6Si-0.4Cu (%w) alloy was obtained after melted in an induction furnace, and then molded as an ingot. From the as cast ingot it were cut samples for the different characterization measurements. The microstructure of the as-cast sample is of dendritic type and its XRD pattern was refined with the lines of the austenite, with a big volumetric fraction, and the lines of the martensite, with small volumetric fraction. The Mössbauer spectrum of the sample was fitted with a broad singlet which corresponds to disordered austenite. After the tribology test, its XRD pattern was refined with the lines of two austenite phases, one similar to the previous one and other with bigger lattice parameter. The total volumetric fraction of the austenite is smaller than that obtained for sample without wear. It was added the lines of the martensite phase with bigger volumetric fraction than that of the previous sample. The Mössbauer spectrum of the weared sample was fitted with two paramagnetic sites which correspond to the two Fe austenite phases and a hyperfine magnetic field distribution which is associated to the disordered original martensite and the new one which appears in the surface as a consequence of the wear process. These results show that during wear process the original austenite phase is transformed in martensite and in a new austenite phase. The increases of the martensitic phase improves mechanical properties and wear behavior.

  12. Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in Al-Si alloys

    Directory of Open Access Journals (Sweden)

    Yu-bo Zhang

    2016-09-01

    Full Text Available Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys. The acicular Al3Fe and β-Al5FeSi (or Al9Si2Fe2 are common iron-containing intermetallic compounds (IMCs in conventional structure which have a detrimental impact on the mechanical properties. In this paper, ultrasonic field (USF was applied to modify acicular iron phases in Al-12%Si-2%Fe and Al-2%Fe alloys. The results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic Al3Fe from acicular to blocky and granular without changes in their composition. In the case of Al-Si-Fe alloys, ultrasonic treatment led to both morphological and compositional conversion of the ternary iron IMCs. When the USF was applied, the acicular β-Al9Si2Fe2 was substituted by star-like α-Al12Si2Fe3. The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration. The undercooling induced by the ultrasonic vibration contributes to the nucleation of intermetallics and can explain the transformation effect.

  13. 硅烷偶联剂表面处理后FeSiAl微米片的电磁和微波吸收特性研究%Electromagnetic and microwave absorption properties of surface modified FeSiAl micron-flakes with silane coupling agent

    Institute of Scientific and Technical Information of China (English)

    张永搏; 唐丽云; 徐飞; 位建强; 乔亮; 王涛

    2014-01-01

    FeSiAl 不规则颗粒在酒精溶剂中球磨,制备得到直径为10μm左右厚度为1μm左右的FeSiAl微米片,然后用硅烷偶联剂对微米片表面进行包裹处理。用电子显微镜和 X 射线光谱仪对包裹和未包裹样品做形貌观测和元素分析,并将样品制备成45%(体积分数)的石蜡复合材料,通过矢量网络分析仪测试其在0.1~18 GHz范围内的电磁参数,发现包裹和未包裹样品的复数磁导率曲线基本重合,但包裹后样品的复数介电常数有很明显的下降。微波传输理论计算表明,包裹后样品在L-S波段具有更优越吸波性能。%The irregular FeSiAl particle was used as a raw material for ball milling with alcohol solvent to pro-duce micron-flakes of the diameter and thickness was about 10 μm and 1 μm,and then used silane coupling agent to package the flakes surface.The morphology and the element content of the packaged sample were in-vestigated with SEM and XPS.The frequency-dependent complex permeability of paraffin composites with 45%volume concentration of flakes was measured using the coaxial line method in 0.1-18 GHz frequency range.Af-ter surface modification the complex permittivity of the packaged composite decreased dramatically in the 0.1-5 GHz frequency range,but the permeability wasn’t found obvious change.The calculated microwave re-flectivities indicated that packaged sample had better absorbing performance than unpackaged sample in L-S fre-quency band.

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  15. Influence of Si on Interfacial Combination of SiCp/Al-Mg-Si Composite

    Institute of Scientific and Technical Information of China (English)

    Han Jianmin; Li Ronghua; Li Mingwei; Cui Shihai; Li Weijing; Wang Jinhua

    2004-01-01

    The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite.

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

    Institute of Scientific and Technical Information of China (English)

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin

    2010-01-01

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

  17. Manufacture and properties of an Si- and Al-infiltrated silicon carbide. Herstellung und Eigenschaften eines mit Si- und Al-infiltrierten Siliciumcarbids

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, W.; Hoerhager, S.; Blecha, M.; Wruss, W.; Lux, B. (Technische Univ., Vienna (Austria). Inst. fuer Chemische Technologie Anorganischer Stoffe); Ekstroem, T. (AB Sandvik Hard Materials, Stockholm (Sweden))

    1991-12-01

    Moderate doping of the silicon phase of an SiSiC composite with Al is known to enhance the composite's room-temperature strength. The cause of the strength gain has not yet been investigated in detail. According to the authors' own measurements, the addition of 2.5 wt.% Al improved the strength of the (unalloyed) ceramic material from 330 MPa to 387 MPa, while 5% Al caused a drop in strength to 306 MPa. The unalloyed composite material was found to be contaminated with iron disilicide. Alloying with aluminium induces formation of new phases in the silicon matrix, namely FeSi{sub 1.18}Al{sub 0.84} (2.5% Al in the infiltrant) and FeSi{sub 1.66}Al{sub 1.47} (5% al). At 657 kg/mm{sup 2}, the hardness of the Al-Si-Fe-phase containing 2.5% Al is significantly lower than that of the FeSi{sub 2} phase (1075 kg/mm{sup 2}). The change in strength can be explained by the modified phase composition. (orig.).

  18. Diffusion mechanisms in the Fe3Si alloys

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the possible reasons for the high thermal vacancy concentration and the low migration barriers for the Fe atom diffusion in the stoichiometric D03 structure Fe3Si have been discussed. The high thermal vacancy concentration was attributed to the compression of Fe-Fe atomic pairs and the tension of Fe-Si atomic pairs in Fe75Si25. The deformations (compression or tension) of the atompairs increase the interatomic potentials and thus decrease the enthalpies of vacancy formation. The low migration barriers for the Fe atom diffusion in Fe75Si25 were related to the symmetric property of the triangular barriers. Additionally, it was considered that the Si atoms in Fe3Si could probably migrate via nearest-neighbour jumps without disturbing the long-range order of atomic arrangements, provided that during the diffusion process the residence time on the antistructure sites is very short.

  19. Compression behavior of Fe-Si-H alloys

    Science.gov (United States)

    Tagawa, S.; Ohta, K.; Hirose, K.; Ohishi, Y.

    2015-12-01

    Although the light elements in the Earth's core are still enigmatic, hydrogen has recently been receiving much attention. Planetary formation theory suggested that a large amount of water, much more than is in the oceans, could have been brought to the Earth during its accretion. Hydrogen is a strong siderophile element and could be incorporated into the core as a consequence of a reaction between water and molten iron in a magma ocean [Okuchi, 1997 Science]. Nevertheless, the effect of hydrogen on the property of iron is not well known so far. Here, we have experimentally examined the compression behavior of hcp Fe0.88Si0.12Hx (6.5 wt.% Si) at two different hydrogen concentrations (x = 0.7 and 0.9). Fe0.88Si0.12 foil was loaded into a diamond-anvil cell, and then liquid hydrogen was introduced to a sample chamber below 20 K. Hydrogenation occurred upon thermal annealing below 1500 K at 25-62 GPa, and hcp Fe0.88Si0.12Hx was obtained as a single phase. Unlike the Fe-H alloy, hydrogen did not fully occupy the octahedral sites even under hydrogen-saturated conditions. Two compression curves, one from 25 to 136 GPa, and the other from 62 to 128 GPa, were obtained at room temperature. While the effect of hydrogen on the compressibility of iron has been controversial in earlier experimental studies [Hirao et al., 2004 GRL; Pépin et al., 2014 PRL], our data indicate that the compressibility of Fe0.88Si0.12Hx alloy does not change with changing hydrogen content from x = 0 to 0.9. Such compression behavior observed is consistent with the recent ab initio calculations for hcp Fe-H alloys by Caracas[2015 GRL]. The extrapolation of present data to the outer core pressure and temperature range, assuming thermal expansivity is the same as that for iron and there is no density difference between solid and liquid, shows that the density of Fe0.88Si0.12H0.3 matches the PREM in the whole outer core within 1%.

  20. First-principles study of electronic structures and electro chemical prop erties for Al, Fe and Mg doped Li2MnSiO4%Al,Fe,Mg掺杂Li2MnSiO4的电子结构和电化学性能的第一性原理研究∗

    Institute of Scientific and Technical Information of China (English)

    嘉明珍; 王红艳; 陈元正; 马存良; 王辉

    2015-01-01

    Li2MnSiO4 is one of the potential cathode materials for lithium batteries due to its high capacities, but the poor conductivity hinders its further development. The cycling performance and electrochemical property of Li2MnSiO4 cathode material can be improved by doping metal cation. Twelve structures LixMnyM1−ySiO4 (x=2, 1, 0;y=0.5, 1;M =Al, Fe, Mg) by doping Al, Fe and Mg are constructed in this paper, and their structures, electronic properties and delithiation process are studied by using the density functional theory of first principles within the GGA+U scheme. The best doping site and delithiated structure are found by comparing their energies. The results show that Al-doping is the best way to improve the conductivity and cyclability of the cathode material Li2MnSiO4. The pure Li2MnSiO4 has a low conductivity because of its large band gap (3.41 eV), while Al-doping Li2MnSiO4 crystal has metallic characteristics due to its electron densities of state with up-spin and down-spin cross through the Fermi level. The band gap is also reduced when it is Fe-doped, which improves the conductivity of Li2MnSiO4. Among the delithiated structures LixMnSiO4 (x = 1, 0), Al-doping enhances the structural stability because of the lowest formation energy and its cyclability is improved by reducing the volume change. Within the lithium ion extraction from the Li2MnSiO4 and Li2Mn0.5M0.5SiO4 (M =Al, Fe, Mg), the Mn—O and M—O bonding have much more ionic features, while the covalent bonding feature between Si and O is almost unchanged. And the fully delithiated MnSiO4 and Mn0.5M0.5SiO4 show semic-metallic properties depending on the density of states of configuration. The delithiated voltages for the first Li extraction process decrease when Al and Fe are doped. Therefore the Al-doping in the Li2MnSiO4 is expected to be an effective way to improve the cycling performance and electrochemical property for Li-ion battery cathode material.%硅酸锰锂作为锂离子电池正极

  1. Theoretical investigations of an influence of Ti on electronic structure and magnetic properties of half-metallic Fe2Mn1-xTixSi0.5Al0.5 alloys

    Science.gov (United States)

    Go, Anna

    2015-02-01

    Ab-initio electronic structure calculations are carried out for quinternary Fe2Mn1-xTixSi0.5Al0.5 alloys basing on the density functional theory. When x=0, the alloy is a half-metallic ferromagnet with magnetic moment following the Slater-Pauling rule. Main carrier of magnetism of the alloy is manganese with the magnetic moment of about 2.5 μB. Replacement of Mn by Ti, changes its electronic and magnetic structure. Half-metallicity is present up to Ti concentration x=0.375. However, the further increase of Ti content leads to a strong decrease of electronic spin polarization. When the concentration of Ti increases, total magnetic moment strongly decreases. Fe magnetic moment, in the presence of titanium, changes its orientation into antiparallel in respect to the total magnetic moment and its absolute value increases with increasing Ti content. However, absolute value of Fe magnetic moment does not exceed 0.17 μB. Ti exhibits very weak spin polarization with magnetic moment not higher than 0.05 μB.

  2. EFFECT OF TESTING ENVIRONMENT ON FRACTURING BEHAVIOR OF Fe3Si BASED ALLOY

    Institute of Scientific and Technical Information of China (English)

    J.H. Peng; G.L. Chen

    2003-01-01

    The mechanical behavior of Fe3Si based alloy with B2 structure was studied by tensionand fracture toughness test in various testing media. The fracture strength σb ofFe3Si alloy decreased in the following order: oxygen, air and hydrogen respectively.The fracture toughness in different testing environment showed that KiC in oxygenis 11.5±0.3MPa. m1/2, and is 8.6±0.4MPa. m1/2 in distilled water. The reductionof fracture toughness is contributed to the environmental reaction of Si with water.Addition of Al element in Fe3Si is not beneficial to improve the intrinsic ductility ofFe-14Si-3Al alloy. The scattering phenomenon of fracture strength was found, andexplained by fracture mechanics. It was found by means of SEM that the fracture modechanged from transgranular in oxygen to intergranular in hydrogen gas and distilledwater.

  3. Investigating and engineering spin-orbit torques in heavy metal/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5}/MgO thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Loong, Li Ming; Deorani, Praveen; Qiu, Xuepeng; Yang, Hyunsoo, E-mail: eleyang@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-07-13

    Current-induced spin-orbit torques (SOTs) have the potential to revolutionize magnetization switching technology. Here, we investigate SOT in a heavy metal (HM)/Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (CFAS)/MgO thin film structure with perpendicular magnetic anisotropy (PMA), where the HM is either Pt or Ta. Our results suggest that both the spin Hall effect and the Rashba effect contribute significantly to the effective fields in the Pt underlayer samples. Moreover, after taking the PMA energies into account, current-induced SOT-based switching studies of both the Pt and Ta underlayer samples suggest that the two HM underlayers yield comparable switching efficiency in the HM/CFAS/MgO material system.

  4. Ferromagnetic glass ceramics and glass fibers based on the composition of SiO2-CaO-Al2O3-B2O3-Fe2O3 glass system

    Science.gov (United States)

    Liu, Jianan; Zhu, Chaofeng; Zhang, Meimei; Zhang, Yanfei; Yang, Xuena

    2017-03-01

    Ferromagnetic glass-ceramics and glass fibers were obtained by the melt-method from the glass system SiO2-CaO-Al2O3-B2O3-Fe2O3 without performing any nucleation and crystallization heat treatments. Glass-ceramics and glass fibers were characterized by x-ray diffraction, scanning and transmission electron microscopy, magnetic measurements, and thermal expansion instrument. The influence of alumina content on the spontaneous crystallization of magnetite, magnetism properties and thermal expansion performances in glass were investigated. We examined the crystallization behavior of the glasses and found that the spontaneous crystallization capacity of magnetite and magnetism properties in base glass increases with increasing the content of alumina. The ferromagnetic glass fibers containing magnetite nano-crystals are also obtained.

  5. 冷轧不同微量化学状态Al-Mn-Fe-Si铝合金的等温退火%Isothermal annealing of cold-rolled Al-Mn-Fe-Si alloy with different microchemistry states

    Institute of Scientific and Technical Information of China (English)

    黄科; 李彦军; Knut MARTHINSEN

    2014-01-01

    Microstructural evolution of a cold-rolled Al−Mn−Fe−Si alloy during annealing was studied. Except the as-cast variant, two other different homogenizations were considered, one gave a high density of fine dispersiods providing a considerable Zener drag influencing the softening behavior while the other gave a lower density of coarser dispersoid structure providing a much smaller drag effect. The gradual microstructural evolutions during annealing for the three variants were captured by interrupting annealing at different time. Effects of microchemistry state on recrystallization kinetics, recrystallized grain structure and texture were characterized by EBSD. It is demonstrated that the actual softening kinetics, final microstructure and texture are a result of delicate balance between processing condition and microchemistry state. Strong concurrent precipitation takes place in the case with high concentration of Mn in solid solution, which suppresses nucleation and retards recrystallization and finally leads to grain structure of coarse elongated grains dominated by a P texture component together with a ND-rotated cube component. On the contrary, when solute content of Mn is low and pre-existing dispersoids are relatively coarser, faster recrystallization kinetics is exhibited together with an equiaxed grain structure with mainly cube texture.%通过3种不同热处理工艺使一种Al−Mn−Fe−Si合金获得了不同固溶液和不同尺寸及数量的弥散析出相,包括铸造态,一种富含高密度、细小、弥散相的状态,另外一种状态则仅有少量、相对粗大的弥散相。采用EBSD技术系统研究冷轧后退火过程中微观组织的演变以及初始组织状态对再结晶动力学、再结晶晶粒形貌和织构的影响。结果表明,再结晶动力学、最终微观组织和织构由加工条件和合金的初始组织和固溶度决定。高密度弥散析出相阻止形核,显著阻碍软化过程,最终

  6. Release of Si from silicon, a ferrosilicon (FeSi) alloy and a synthetic silicate mineral in simulated biological media.

    Science.gov (United States)

    Herting, Gunilla; Jiang, Tao; Sjöstedt, Carin; Odnevall Wallinder, Inger

    2014-01-01

    Unique quantitative bioaccessibility data has been generated, and the influence of surface/material and test media characteristics on the elemental release process were assessed for silicon containing materials in specific synthetic body fluids at certain time periods at a fixed loading. The metal release test protocol, elaborated by the KTH team, has previously been used for classification, ranking, and screening of different alloys and metals. Time resolved elemental release of Si, Fe and Al from particles, sized less than 50 µm, of two grades of metallurgical silicon (high purity silicon, SiHG, low purity silicon, SiLG), an alloy (ferrosilicon, FeSi) and a mineral (aluminium silicate, AlSi) has been investigated in synthetic body fluids of varying pH, composition and complexation capacity, simple models of for example dermal contact and digestion scenarios. Individual methods for analysis of released Si (as silicic acid, Si(OH)4) in synthetic body fluids using GF-AAS were developed for each fluid including optimisation of solution pH and graphite furnace parameters. The release of Si from the two metallurgical silicon grades was strongly dependent on both pH and media composition with the highest release in pH neutral media. No similar effect was observed for the FeSi alloy or the aluminium silicate mineral. Surface adsorption of phosphate and lactic acid were believed to hinder the release of Si whereas the presence of citric acid enhanced the release as a result of surface complexation. An increased presence of Al and Fe in the material (low purity metalloid, alloy or mineral) resulted in a reduced release of Si in pH neutral media. The release of Si was enhanced for all materials with Al at their outermost surface in acetic media.

  7. Truncated tetrahedron seed crystals initiating stereoaligned growth of FeSi nanowires.

    Science.gov (United States)

    Kim, Si-in; Yoon, Hana; Seo, Kwanyong; Yoo, Youngdong; Lee, Sungyul; Kim, Bongsoo

    2012-10-23

    We have synthesized epitaxially grown freestanding FeSi nanowires (NWs) on an m-Al(2)O(3) substrate by using a catalyst-free chemical vapor transport method. FeSi NW growth is initiated from FeSi nanocrystals, formed on a substrate in a characteristic shape with a specific orientation. Cross-section TEM analysis of seed crystals reveals the crystallographic structure and hidden geometry of the seeds. Close correlation of geometrical shapes and orientations of the observed nanocrystals with those of as-grown NWs indicates that directional growth of NWs is initiated from the epitaxially formed seed crystals. The diameter of NWs can be controlled by adjusting the composition of Si in a Si/C mixture. The epitaxial growth method for FeSi NWs via seed crystals could be employed to heteroepitaxial growth of other compound NWs.

  8. Current–voltage studies on -FeSi2/Si heterojunction

    Indian Academy of Sciences (India)

    A Datta; S Kal; S Basu

    2000-08-01

    – characteristics of both -FeSi2/n-Si and -FeSi2/p-Si were studied at room temperature. The junctions were formed by depositing Fe on Si selectively followed by thermal annealing and some samples were later treated by pulsed laser. Temperature of thermal annealing and diode area were also varied. – studies on all these samples were done and ideality factors were computed. Results obtained were interpreted.

  9. 流变铸造不同铁含量过共晶Al-Si合金在干摩擦条件下的磨损行为%Dry sliding wear behavior of rheocast hypereutectic Al-Si alloys with different Fe contents

    Institute of Scientific and Technical Information of China (English)

    林冲; 吴树森; 吕书林; 曾劲彪; 安萍

    2016-01-01

    The effect of iron content on wear behavior of hypereutectic Al−17Si−2Cu−1Ni alloy produced by rheocasting process was investigated. The dry sliding wear tests were carried out with a pin-on-disk wear tester. The results show that the wear rate of the rheocast alloy is lower than that of the alloy produced by conventional casting process under the same applied load. The fine particle-likeδ-Al4(Fe,Mn)Si2 and polygonalα-Al15(Fe,Mn)3Si2 phases help to improve the wear resistance of rheocast alloys. As the volume fraction of fine Fe-bearing compounds increases, the wear rate of the rheocast alloy decreases. Moreover, the wear rate of rheocast alloy increases with the increase of applied load from 50 to 200 N. For the rheocast alloy with 3% Fe, oxidation wear is the main mechanism at low applied load (50 N). At higher applied loads, a combination of delamination and oxidation wear is the dominant wear mechanism.%研究铁含量对流变铸造过共晶Al−17Si−2Cu−1Ni合金在干摩擦条件下磨损行为的影响。磨损测试是在销−盘式摩擦磨损试验机上进行的。结果表明,在同等载荷下,流变铸造合金试样比传统重力金属型铸造试样的磨损率小。细小颗粒状δ-Al4(Fe,Mn)Si2相和多边形状α-Al15(Fe,Mn)3Si2相有助于提高流变铸造合金的耐磨性。随着细小富铁相体积分数的增加,流变铸造合金试样的磨损率减小。此外,随着载荷从50增大至200 N,流变铸造合金试样的磨损率增大。对于含3% Fe的流变铸造合金,在低载荷(50 N)时,磨损机制以氧化磨损为主;在高载荷时,磨损机制以氧化磨损和剥层磨损的联合作用为主。

  10. Effect of intensive melt shearing on the formation of Fe-containing intermetallics in LM24 Al-alloy

    OpenAIRE

    2011-01-01

    Fe is one of the inevitable and detrimental impurities in aluminium alloys that degrade the mechanical performance of castings. In the present work, intensive melt shearing has been demonstrated to modify the morphology of Fe-containing intermetallic compounds by promoting the formation of compact α-Al(Fe,Mn)Si at the expense of needle-shaped β-AlFeSi, leading to an improved mechanical properties of LM24 alloy processed by MC-HPDC process. The promotion of the formation of α -Al(Fe, Mn)Si pha...

  11. Low Gilbert damping in Co2FeSi and Fe2CoSi films

    Science.gov (United States)

    Sterwerf, Christian; Paul, Soumalya; Khodadadi, Behrouz; Meinert, Markus; Schmalhorst, Jan-Michael; Buchmeier, Mathias; Mewes, Claudia K. A.; Mewes, Tim; Reiss, Günter

    2016-08-01

    Thin highly textured Fe1+xCo2-xSi (0 ≤ x ≤ 1) films were prepared on MgO (001) substrates by magnetron co-sputtering. Magneto-optic Kerr effect (MOKE) and ferromagnetic resonance (FMR) measurements were used to investigate the composition dependence of the magnetization, the magnetic anisotropy, the gyromagnetic ratio, and the relaxation of the films. Both MOKE and FMR measurements reveal a pronounced fourfold anisotropy for all films. In addition, we found a strong influence of the stoichiometry on the anisotropy as the cubic anisotropy strongly increases with increasing Fe concentration. The gyromagnetic ratio is only weakly dependent on the composition. We find low Gilbert damping parameters for all films with values down to 0.0012 ±0.00010.0007 for Fe1.75Co1.25Si. The effective damping parameter for Co2FeSi is found to be 0.0018 ±0.00040.0034 . We also find a pronounced anisotropic relaxation, which indicates significant contributions of two-magnon scattering processes that is strongest along the easy axes of the films. This makes thin Fe1+xCo2-xSi films ideal materials for the application in spin transfer-torque magnetic RAM (STT-MRAM) devices.

  12. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn{sub 2}, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe); Moessbauerspektroskopische Untersuchung von Struktur und Magnetismus der austauschgekoppelten Schichtsysteme Fe/FeSn{sub 2} und Fe/FeSi/Si und des ionenimplantierten verduennten magnetischen Halbleiters SiC(Fe)

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Frank

    2009-07-07

    In line with this work the structural and magnetic properties of the exchange coupled layered systems Fe/FeSn{sub 2} and Fe/FeSi/Si and of the Fe ion implanted diluted magnetic semiconductor (DMS) SiC(Fe) were investigated. The main measuring method was the isotope selective {sup 57}Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the {sup 57}Fe tracer layer technique, in a temperature range from 4.2 K to 340 K. Further measurement techniques were X-ray diffraction (XRD), electron diffraction (LEED, RHEED), SQUID magnetometry and FMR (Ferromagnetic Resonance). In the first part of this work the properties of thin AF FeSn{sub 2}(001) films and of the exchange-bias system Fe/FeSn{sub 2}(001) on InSb(001) were investigated. With the application of {sup 57}Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (B{sub hf}) of FeSn{sub 2} could be examined. The evaporation of Fe films on the FeSn{sub 2} films produced in the latter ones a high perpendicular spin component at the Fe/FeSn{sub 2} interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore {sup 57}Fe-CEMS provided a correlation between the absolute value of the exchange field vertical stroke He vertical stroke and the amount of magnetic defects within the FeSn{sub 2}. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures T{sub B}{sup *}, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures T{sub B} of the exchange-bias effect, obtained with magnetometry measurements. The second part of this work deals with the indirect exchange coupling within Fe/FeSi/Si/FeSi/Fe multilayers and FeSi diffusion barriers. The goal was to achieve Fe free Si interlayers. The CEMS results show that starting from a thickness of t{sub FeSi}=10-12 A of the

  13. High temperature properties of CrAlN, CrAlSiN and AlCrSiN coatings - Structure and oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Polcar, Tomas, E-mail: polcar@fel.cvut.cz [Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); SEG-CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luis Reis Santos, P-3030 788 Coimbra (Portugal); Cavaleiro, Albano [SEG-CEMUC - Department of Mechanical Engineering, University of Coimbra, Rua Luis Reis Santos, P-3030 788 Coimbra (Portugal)

    2011-09-15

    Highlights: {yields} Deposition and structural analysis of CrAln, CrAlSiN and AlCrSiN coatings. {yields} In-situ XRD analysis at high temperature. {yields} AlCrSiN coating showed the highest oxidation resistance and thermal stability. {yields} CrAlN outperformed CrAlSiN film both in oxidation resistance and thermal stability. - Abstract: CrAlN, CrAlSiN and AlCrSiN coatings were deposited by cathodic arc deposition technique from composite targets. Three targets were used: (i) Cr/Al ratio close to 1, (ii) Cr/Al ratio close to 1 with Si addition, and (iii) Cr/Al ratio close to 1/2 and Si addition. Nitrogen flow was kept constant during the depositions. The Cr/Al ratio of the films, measured by electron probe microanalysis (EPMA), was similar to that of the target and the silicon content was in the range 3-4 at.%. The coatings were deposited onto FeCrAl alloy and WC/Co mirror-polished substrates. To analyze the coating structure, X-ray photoelectron (XPS) and X-ray diffraction (XRD) analysis were used. The evolution of the coating structure up to 1000 deg. C was in situ measured in a XRD apparatus equipped with heating plate. The films oxidation behavior was characterized by thermogravimetric analysis (TGA) at two selected temperatures. The annealed coatings were analyzed by XRD and scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDX). CrAlSiN showed low oxidation resistance being partially oxidized at 800 deg. C. Moreover, the film exhibited low thermal stability, since the cubic nitride phases transformed to hexagonal nitrides at relatively low temperatures. CrAlN oxidation behavior was more promising; nevertheless, AlCrSiN showed excellent thermal stability with cubic nitrides observed even after heating to 1300 deg. C. The oxidation of this film at 900 and 1000 deg. C was negligible.

  14. Wetting of polycrystalline SiC by molten Al and Al-Si alloys

    Science.gov (United States)

    Cong, Xiao-Shuang; Shen, Ping; Wang, Yi; Jiang, Qichuan

    2014-10-01

    The wetting of α-SiC by molten Al and Al-Si alloys was investigated using a dispensed sessile drop method in a high vacuum. In the Al-SiC system, representative wetting stages were identified. The liquid spreading was initially controlled by the deoxidation of the SiC surface and then by the formation of Al4C3 at the interface. The intrinsic contact angle for molten Al on the polycrystalline α-SiC surface was suggested to be lower than 90̊ provided that the oxide films covering the Al and SiC surfaces were removed, i.e., the system is partial wetting in nature. An increase in the Si concentration in liquid Al weakened the interfacial reaction but improved the final wettability. The role of the Si addition on the wetting was presumably attributed to its segregation at the interface and the formation of strong chemical bonds with the SiC surface.

  15. Effect of pre-aging on precipitation behavior of Al- 1.29Mg- 1.22Si-0.68Cu-0.69Mn-0.3Fe-0.2Zn-0.1 Ti alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; CHEN Yang; ZHAO Gang; LIU Chun-ming; ZUO Liang

    2006-01-01

    By means of Vickers-hardness and electrical conductivity measurements, DSC tests and TEM analyses, the effect of different pre-aging treatments on precipitation characteristic of the Al- 1.29Mg- 1.22Si-0.68Cu-0.69Mn-0.3Fe-0.2Fe-0.1 Ti (mass fraction, %) alloy during subsequent artificial aging was investigated. The results indicate that with increasing pre-aging time from 2.5 min to 10 min at 170 ℃, the number of formedβ" nuclei increases, resulting in promoting artificial aging kinetics and enhancing peak hardness. The hardness of pre-aged alloy reduces within lower temperature range of non-isothermal aging and increases in early stage of isothermal aging at 170 ℃. The size and density of clusters in pre-aged samples determine the hardenability in early stage of artificial aging. Pre-aging has dual mechanisms: namely, clusters (β" nuclei) formed by pre-aging can inhibit the precipitation of GP zones during natural aging, and can quicken the precipitation of β" phase in the early stage of subsequent artificial aging.

  16. Moessbauer effect and X-ray distribution function analysis in complex Na{sub 2}O-CaO-ZnO-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Romero, M.; Rincon, J.M.; Musik, S.; Kozhukharov, V.

    1999-05-01

    Moessbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO{sub 2}-CaO-ZnO-Na{sub 2}O-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Isomer shift values of the glasses suggest that Fe{sup 3+} and Fe{sup 2+} are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe{sup +3}/Fe{sup +2} ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distorted when the iron content is greater. X-ray diffraction measurements were carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.

  17. Influence of silicon and atomic order on the magnetic properties of (Fe{sub 80}Al{sub 20}){sub 100}-{sub x}Si{sub x} nanostructured system

    Energy Technology Data Exchange (ETDEWEB)

    Velez, G. Y., E-mail: gyovelca@univalle.edu.co; Perez Alcazar, G. A.; Zamora, Ligia E. [Universidad del Valle, Departamento de Fisica (Colombia); Romero, J. J.; Martinez, A. [Instituto de Magnetismo Aplicado IMA (Spain)

    2010-01-15

    Mechanically alloyed (Fe{sub 80}Al{sub 20}){sub 100-x}Si{sub x} alloys (with x = 0, 10, 15 and 20) were prepared by using a high energy planetary ball mill, with milling times of 12, 24 and 36 h. The structural and magnetic study was conducted by X-rays diffraction and Moessbauer spectrometry. The system is nanostructured and presents only the BCC disordered phase, whose lattice parameter remains constant with milling time, and decreases when the Si content increases. We found that lattice contraction is influenced 39% by the iron substitution and 61% by the aluminum substitution, by silicon atoms. The Moessbauer spectra and their respective hyperfine magnetic field distributions show that for every milling time used here, the ferromagnetism decreases when x increases. For samples with x {>=} 15 a paramagnetic component appears. From the shape of the magnetic field distributions we stated that the larger ferromagnetic phase observed in the samples alloyed during 24 and 36 h is a consequence of the structural disorder induced by mechanical alloying.

  18. Thermal Properties of Al-50%Si Alloys

    Institute of Scientific and Technical Information of China (English)

    Akio Nishimoto; Katsuya Akamatsu; Kazuyoshi Nakao; Kazuo Ichii

    2004-01-01

    In order to prepare a hypereutectic Al-Si alloy with low coefficients of thermal expansion (CTE), Al-50was produced by powder metallurgy (P/M) and ingot metallurgy (I/M). P/M specimen was prepared by mechanical alloying(MA) and pulsed electric-current sintering (PECS). The microstructures of specimens were characterized by optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Vickers microhardness and CTE measurements were performed. The grains in the P/M specimen were refined with increasing MA time. Primary Si and eutectic Si in the I/M specimen were remarkably refined by adding minute amounts of Sr. The CTE of P/M and I/M specimens were estimated as 7.8×10-6 and 10.7×10-6, respectively. These values were as same as a CTE of Al2O3 ceramics.

  19. Mechanical properties and electronic structures of Fe-Al intermetallic

    Science.gov (United States)

    Liu, YaHui; Chong, XiaoYu; Jiang, YeHua; Zhou, Rong; Feng, Jing

    2017-02-01

    Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe3Al, FeAl, FeAl2, Fe2Al5 and FeAl3) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe2Al5 has the lowest formation enthalpy, which shows the Fe2Al5 is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young's modulus and anisotropic index. Fe3Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong's modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

  20. Environmental embrittlement of intermetallic compounds in Fe-Al alloys

    Institute of Scientific and Technical Information of China (English)

    张建民; 张瑞林; S.H.YU; 余瑞璜

    1996-01-01

    First,it is proposed that hydrogen atoms occupy the interstitial sites in Fe3Al and FeAl.Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe3Al and FeAl containing hydrogen atoms.From the analyses it is found that the states of metal atoms will change,in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys,which will result in the decrease of local metallicity in Fe3Al and FeAl.Meanwhile,it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form.As a conclusion,these factors result in the environmental embrittlement of Fe3Al and FeAl.

  1. A Sulfide Capacity Prediction Model of CaO-SiO2-MgO-FeO-MnO-Al2O3 Slags during the LF Refining Process Based on the Ion and Molecule Coexistence Theory

    Science.gov (United States)

    Yang, Xue-Min; Zhang, Meng; Shi, Cheng-Bin; Chai, Guo-Ming; Zhang, Jian

    2012-04-01

    A sulfide capacity prediction model of CaO-SiO2-MgO-FeO-MnO-Al2O3 ladle furnace (LF) refining slags has been developed based on the ion and molecule coexistence theory (IMCT). The predicted sulfide capacity of the LF refining slags has better accuracy than the measured sulfide capacity of the slags at the middle and final stages during the LF refining process. Increasing slag binary basicity, optical basicity, and the Mannesmann index can lead to an increase of the predicted sulfide capacity for the LF refining slags as well as to an increase of the sulfur distribution ratio between the slags and molten steel at the middle and final stages during the LF refining process. The calculated equilibrium mole numbers, mass action concentrations of structural units or ion couples, rather than mass percentages of components, are recommended to represent the slag composition for correlating with the sulfide capacity of the slags. The developed sulfide capacity IMCT model can calculate not only the total sulfide capacity of the slags but also the respective sulfide capacity of free CaO, MgO, FeO, and MnO in the slags. The comprehensive contribution of the combined ion couples (Ca2+ + O2-) and (Mn2+ + O2-) on the desulfurization reactions accounts for 96.23 pct; meanwhile, the average contribution of the ion couple (Fe2+ + O2-) and (Mg2+ + O2-) only has a negligible contribution as 3.13 pct and 0.25 pct during the LF refining process, respectively. The oxygen activity of bulk molten steel in LF is controlled by the [Al]-[O] equilibrium, and the oxygen activity of molten steel at the slag-metal interface is controlled by the (FeO)-[O] equilibrium. The ratio of the oxygen activity of molten steel at the slag-metal interface to the oxygen activity of bulk molten steel will decrease from 37 to 5 at the initial stage, and further decrease from 28 to 4 at the middle stage, but will maintain at a reliable constant as 5 to 14 at the final stage during the LF refining process. The

  2. Ab-initio study of electronic structure and magnetic properties of half-metallic Fe{sub 2}Mn{sub 1−x}V{sub x}Si{sub 0.5}Al{sub 0.5} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Go, Anna, E-mail: annago@alpha.uwb.edu.pl

    2014-11-15

    Ab-initio electronic structure calculations are carried out for quinternary Fe{sub 2}Mn{sub 1−x}V{sub x}Si{sub 0.5}Al{sub 0.5} alloys. When x=0 the alloy is half-metallic ferromagnet, with magnetic moment following the Slater–Pauling rule. Replacement of Mn by V, changes its electronic and magnetic structure. V-doped alloys exhibit half-metallic behavior for x≤0.25. However, even for higher V concentrations, electronic spin polarization is still very high, what makes the alloys interesting for spintronic applications. - Graphical abstract: Densities of states of Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} and magnetic moments of Fe{sub 2}Mn{sub 1−x}V{sub x}Si{sub 0.5}Al{sub 0.5}. - Highlights: • Fe{sub 2}MnSi{sub 0.5}Al{sub 0.5} is a half-metallic ferromagnet with a minority band gap of 0.49 eV. • Half-metallic band gap is very stable against the change of the lattice parameter. • Half-metallic band gap is obtained for Fe{sub 2}Mn{sub 1−x}V{sub x}Si{sub 0.5}Al{sub 0.5} for x≤0.25. • Electronic spin polarization is very high and equal to at least 95% for x≤0.625. • The main carrier of magnetism of the compound is manganese.

  3. Properties of porous FeAlO/FeAl ceramic matrix composite influenced by mechanical activation of FeAl powder

    Indian Academy of Sciences (India)

    V Usoltsev; S Tikhov; A Salanov; V Sadykov; G Golubkova; O Lomovskii

    2013-12-01

    Porous ceramic matrix composites FeAlO/FeAl with incorporated metal inclusions (cermets) were synthesized by pressureless method, which includes hydrothermal treatment of mechanically alloyed FeAl powder followed by calcination. Their main structural, textural and mechanical features are described. Variation of FeAl powder alloying time results in non-monotonous changes of the porosity and mechanical strength. Details of the cermet microstructure and its relation to the mechanical properties are discussed.

  4. Reactions between monolayer Fe and Si(001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, M.; Kobayashi, N.; Hayashi, N. [Electrotechnical Lab., Tsukuba, Ibaraki (Japan)

    1997-03-01

    Reactions between 1.5 monolayer(ML) Fe deposited on Si(001)-2x1 and -dihydride surfaces were studied in situ by reflection high-energy electron diffraction and time-of-flight ion scattering spectrometry with the use of 25 keV H ions. The reactions between Fe and Si which were successively deposited on Si(001)-dihydride surface were also studied. After the room temperature deposition Fe reacted with Si(001)-2x1 substrate resulting in the formation of polycrystalline Fe5Si3. By annealing to 560-650degC composite heteroepitaxial layer of both type A and type B {beta}-FeSi2 was formed. On the dihydride surface polycrystalline Fe was observed after 1.5ML Fe deposition at room temperature, and reaction between Fe and Si(001)-dihydride surface is not likely at room temperature. We observed 3D rough surface when we deposited only Fe layer on the dihydride surface and annealed above 700degC. The hydrogen termination of Si(001) surface prevents the deposited Fe from diffusing into the substrate below 500degC, however the annealing above 710degC leads to the diffusion. We obtained 2D ordered surface, which showed 3x3 RHEED pattern as referenced to the primitive unreconstructed Si(001) surface net, when we deposited 2.5ML Fe and 5.8ML Si successively onto Si(001)-dihydride surface and annealed to 470degC. (author)

  5. Evaluation of photovoltaic properties of nanocrystalline-FeSi2/Si heterojunctions

    Science.gov (United States)

    Shaban, Mahmoud; Bayoumi, Amr M.; Farouk, Doaa; Saleh, Mohamed B.; Yoshitake, Tsuyoshi

    2016-09-01

    In this paper, an application of nanocrystalline iron disilicide (NC-FeSi2) combined with nanocrystalline-Si (NC-Si) in a heterostructured solar cell is introduced and numerically evaluated in detail. The proposed cell structure is studied based on an experimental investigation of photovoltaic properties of NC-FeSi2/crystalline-Si heterojunctions, composed of unintentionally-doped NC-FeSi2 thin film grown on Si substrate. Photoresponse measurement of NC-FeSi2/crystalline-Si heterojunction confirmed ability of NC-FeSi2 to absorb NIR light and to generate photocarriers. However, collection of these carriers was not so efficient and a radical improvement in design of the device is required. Therefore, a modified device structure, comprising of NC-FeSi2 layer sandwiched between two heavily-doped p- and n-type NC-Si, is suggested and numerically evaluated. Simulation results showed that the proposed structure would exhibit a relatively high conversion efficiency of 25%, due to an improvement in collection efficiency of photogenerated carriers in the NC-FeSi2 and NC-Si layers. To attain such efficiency, defect densities in NC-FeSi2 and NC-Si layers should be kept less than 1014 and 1016 cm-3 eV-1, respectively. Remarkable optical and electrical properties of NC-FeSi2, employed in the proposed structure, facilitate improving device quantum efficiency spectrum providing significant spectrum extension into the near-infrared region beyond Si bandgap.

  6. Airborne Emissions from Si/FeSi Production

    Science.gov (United States)

    Kero, Ida; Grådahl, Svend; Tranell, Gabriella

    2016-10-01

    The management of airborne emissions from silicon and ferrosilicon production is, in many ways, similar to the management of airborne emissions from other metallurgical industries, but certain challenges are highly branch-specific, for example the dust types generated and the management of NO X emissions by furnace design and operation. A major difficulty in the mission to reduce emissions is that information about emission types and sources as well as abatement and measurement methods is often scarce, incomplete and scattered. The sheer diversity and complexity of the subject presents a hurdle, especially for new professionals in the field. This article focuses on the airborne emissions from Si and FeSi production, including greenhouse gases, nitrogen oxides, airborne particulate matter also known as dust, polyaromatic hydrocarbons and heavy metals. The aim is to summarize current knowledge in a state-of-the-art overview intended to introduce fresh industry engineers and academic researchers to the technological aspects relevant to the reduction of airborne emissions.

  7. Airborne Emissions from Si/FeSi Production

    Science.gov (United States)

    Kero, Ida; Grådahl, Svend; Tranell, Gabriella

    2017-02-01

    The management of airborne emissions from silicon and ferrosilicon production is, in many ways, similar to the management of airborne emissions from other metallurgical industries, but certain challenges are highly branch-specific, for example the dust types generated and the management of NO X emissions by furnace design and operation. A major difficulty in the mission to reduce emissions is that information about emission types and sources as well as abatement and measurement methods is often scarce, incomplete and scattered. The sheer diversity and complexity of the subject presents a hurdle, especially for new professionals in the field. This article focuses on the airborne emissions from Si and FeSi production, including greenhouse gases, nitrogen oxides, airborne particulate matter also known as dust, polyaromatic hydrocarbons and heavy metals. The aim is to summarize current knowledge in a state-of-the-art overview intended to introduce fresh industry engineers and academic researchers to the technological aspects relevant to the reduction of airborne emissions.

  8. Giant Magneto-Impedance Effect in Sandwiched FeSiB/Cu/FeSiB Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yong; YANG Chun-Sheng; YU Jin-Qiang; ZHAO Xiao-Lin; MAO Hai-Ping

    2000-01-01

    Giant magneto-impedance (GMI) effect has been realized in the sandwiched FeSiB/Cu/FeSiB films. With magnetic field Ha and ac current applied along the longitudinal direction of the sample, the GMI ratio increases with the increasing Ha, reaching a positive maximum, value, and then decreases to negative values with further increase of magnetic field. Field dependence of the GMI ratio also indicates that the magnetic field corresponding to the maximum GMI ratio is different for various frequencies. The positive maximum GMI ratio is 17.2% for Ha=1600 A/m and frequency of 3 MHz. In addition, the films display a large negative GMI ratio with a magnetic field applied along the transverse direction and the value of the GMI ratio is about -13.4% for Ha=5600A/m and frequency of 3 MHz.

  9. ELECTROLYSIS OF SWINE MANURE EFFLUENTS USING THREE DIFFERENT ELECTRODES Fe-Fe, Al-Al AND Fe-Al

    Directory of Open Access Journals (Sweden)

    S. Rahman

    2014-01-01

    Full Text Available Swine effluent with high organic strength need to be treated to make it suitable for applying to crop/pasture fields, or discharging to any waterways. Electrocoagulation is a relatively simpler and cheaper technique over biological and chemical treatment methods currently used to treat high-strength industrial and municipal wastewater. The performance of an electrocoagulation system mainly depends on the pH, Electrical Conductivity (EC of the medium, Chemical Oxygen Demand (COD loading rates and catalytic activity of the electrodes used. In this research, a study was conducted to compare the pollutant removal efficiencies of three electrodes (Fe-Fe, Al-Al and Fe-Al with three electric current levels (500, 1000 and 2000 mA while treating swine manure effluents. The electrochemical cell consisted of two parallel rectangular plates (90×25×1.5 mm of Iron (Fe-Fe, Aluminum (Al-Al and Iron-Aluminum (Fe-Al, later on described as hybrid electrodes; immersed in a beaker with 550 mL swine effluents and powered by a Direct Current (DC supply. All studies were conducted in batches at room temperature. In general, removal efficiencies were increased with increasing current densities and electrolysis times for electrodes evaluated. Aluminum electrodes outperformed iron and hybrid (iron-aluminum electrodes in removing Total Phosphorus (TP at all current density levels tested. Overall, use of hybrid electrodes resulted in better COD removal. For the same treatment times (1200 s at higher current density (21 mA cm-2, hybrid electrodes removed about 100% COD, which are about 1.9 and 1.3 times higher than those of aluminum and iron electrodes, respectively. Iron electrodes showed the highest removal efficiency (85% for Total Organic Carbon (TOC at 21 mA cm-2 current density and 1200 s treatment time. Overall, lower Specific Electrical Energy Consumptions (SEECs per kg of Pollutants (TP, COD and TOC were estimated for the aluminum

  10. Large magnetization and high Curie temperature in highly disordered nanoscale Fe2CrAl thin films

    Science.gov (United States)

    Dulal, Rajendra P.; Dahal, Bishnu R.; Forbes, Andrew; Pegg, Ian L.; Philip, John

    2017-02-01

    We have successfully grown nanoscale Fe2CrAl thin films on polished Si/SiO2 substrates using an ultra-high vacuum deposition with a base pressure of 9×10-10 Torr. The thickness of thin films ranges from 30 to 100 nm. These films exhibit cubic crystal structure with lattice disorder and display ferromagnetic behavior. The Curie temperature is greater than 400 K, which is much higher than that reported for bulk Fe2CrAl. The magnetic moments of the films varies from 2.5 to 2.8 μB per formula unit, which is larger than the reported bulk values. Thus, the disordered nanoscale Fe2CrAl films exhibit strong Fe-Fe exchange interactions through Fe-Cr-Fe and Fe-Al-Fe layers, resulting in both a large magnetization and a high Curie temperature.

  11. Microstructure characterization of fluidized bed nitrided Fe–Si and Fe–Si–Al foils

    Indian Academy of Sciences (India)

    H Atmani; O Thoumire

    2002-06-01

    This work deals with the structural modifications of FeSi and FeSiAl foils when subjected to a thermochemical nitriding treatment (TNT) performed in a fluidized-bed laboratory furnace. The investigations on the nitrided samples were carried out by optical and SEM microscopic observations, X-ray diffraction and Mössbauer spectroscopy. Both the compound and diffusion layers were investigated.

  12. Magnetron-sputter epitaxy of {beta}-FeSi{sub 2}(220)/Si(111) and {beta}-FeSi{sub 2}(431)/Si(001) thin films at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hongfei; Tan Chengcheh; Chi Dongzhi [Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

    2012-07-15

    {beta}-FeSi{sub 2} thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 Degree-Sign C. On Si(111), the growth is consistent with the commonly observed orientation of [001]{beta}-FeSi{sub 2}(220)//[1-10]Si(111) having three variants, in-plane rotated 120 Degree-Sign with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]{beta}-FeSi{sub 2}(431)//[110]Si(001) with four variants, which is hitherto unknown for growing {beta}-FeSi{sub 2}. Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between {beta}-FeSi{sub 2} grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of {beta}-FeSi{sub 2}/Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of {beta}-FeSi{sub 2}(431)/Si(001) is larger than that on the surface of {beta}-FeSi{sub 2}(220)/Si(111).

  13. Effect of B compounds and Sr on Fe-rich intermetallics in secondary Al-Si alloy%硼化物和锶对再生Al-Si合金中富铁相的影响

    Institute of Scientific and Technical Information of China (English)

    杨承志; 龙思远; 王朋; 杨怀德; 黄彦彦

    2016-01-01

    为了研究硼化物(KBF4)和锶(Sr)对再生Al-Si合金中富铁相的影响,分别采用X射线荧光光谱分析仪(XRF)对试样进行成分分析,应用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)对试样显微组织进行形貌观察和相成分分析.结果表明,KBF4不能起到降铁作用,但促使β-Fe相向初生α-Fe相转变,当B加入量达到0.75%时,初生α-Fe相周围出现了汉字状α-Fe相;Sr会促使β-Fe相向汉字状α-Fe相转变,当Sr加入量为0.3%时,β-Fe相几乎消失,同时,Sr对针状β-Fe相有溶解碎裂作用.

  14. 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.)

  15. 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.

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

    NARCIS (Netherlands)

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

    2007-01-01

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

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  18. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  19. Diffusion and electrical behavior of Al implanted into capped Si

    Energy Technology Data Exchange (ETDEWEB)

    Scandurra, A. (Consorzio Catania Ricerche, Catania (Italy)); Galvagno, G. (Istituto di Metodologie e Tecnologie per la Microelettronica-CNR, Catania (Italy)); Raineri, V. (Univ. di Catania (Italy). Dipartimento di Fisica); Frisina, F. (ST-Microelectronics, Catania (Italy)); Torrisi, A. (Univ. di Catania (Italy). Dipartimento di Scienze Chimiche)

    1993-07-01

    The diffusion and the electrical behavior of Al implanted in the dose of 1 x 10[sup 13] to 5 x 10[sup 15] cm[sup [minus]2] at 300 keV in capped and uncapped Si is investigated. The Al-based precipitates which are formed when Al concentration exceeds its solid solubility in Si are electrically inactive. The out-diffusion phenomenon that is always present in uncapped samples reduces the Al dose diffused into Si substrate. A study on the electrical activity of Al implanted in Si through SiO[sub 2], Si[sub 3]N[sub 4], and Si[sub 3]N[sub 4]/SiO[sub 2] capping films also is presented. In these capped samples Al segregation in SiO[sub 2] layer occurs. The electrically active doses are small and comparable to that of uncapped samples. The authors studied the diffusivity of Al in bulk SiO[sub 2] and Si[sub 3]N[sub 4] at 1,200 C. The fast Al diffusion through SiO[sub 2] thin layers is driven by a chemical reaction between Al and SiO[sub 2] starting from the SiO[sub 2]/Si interface.

  20. Effect of Si addition on AC and DC magnetic properties of (Fe-P)-Si alloy

    Science.gov (United States)

    Gautam, Ravi; Prabhu, D.; Chandrasekaran, V.; Gopalan, R.; Sundararajan, G.

    2016-05-01

    We report a new (Fe-P)-Si based alloy with relatively high induction (1.8-1.9 T), low coercivity (step heat-treatment process and ii) Si addition enhancing the resistivity of the α-Fe matrix phase. As the alloy processing is by conventional wrought metallurgy method, it has the potential for large scale production.

  1. Localized Corrosion Behavior of Al-Si-Mg Alloys Used for Fabrication of Aluminum Matrix Composites

    Science.gov (United States)

    Pech-Canul, M. A.; Giridharagopal, R.; Pech-Canul, M. I.; Coral-Escobar, E. E.

    2013-12-01

    The relationship between microstructure and localized corrosion behavior in neutral aerated chloride solutions was investigated with SEM/EDAX, conventional electrochemical techniques, and with scanning Kelvin probe force microscopy (SKPFM) for two custom-made alloys with Si/Mg molar ratios of 0.12 and 0.49. In this order, Al3Fe, Al3Mg2, and Mg2Si intermetallics were identified in the first alloy and Al(FeMn)Si and Mg2Si particles in the second one. Anodic polarization curves and corrosion morphology showed that the alloy with higher Si/Mg molar ratio exhibited a better corrosion performance and evidence was shown that it had a more corrosion-resistant passive film. The corrosion process for both alloys in aerated 0.1 M NaCl solutions was localized around the Fe-rich intermetallics. They acted as local cathodes and produced dissolution of the aluminum matrix surrounding such particles. Mg2Si and Al3Mg2 exhibited anodic behavior. SKPFM was successfully used to map the Volta potential distribution of main intermetallics. The localized corrosion behavior was correlated with a large Volta potential difference between the Fe-rich intermetallics and the matrix. After immersion in the chloride solution, such Volta potential difference decreased.

  2. Compression of Fe-Si-H alloys to core pressures

    Science.gov (United States)

    Tagawa, Shoh; Ohta, Kenji; Hirose, Kei; Kato, Chie; Ohishi, Yasuo

    2016-04-01

    We examined the compression behavior of hexagonal-close-packed (hcp) (Fe0.88Si0.12)1H0.61 and (Fe0.88Si0.12)1H0.79 (in atomic ratio) alloys up to 138 GPa in a diamond anvil cell (DAC). While contradicting experimental results were previously reported on the compression curve of double-hcp (dhcp) FeHx (x ≈ 1), our data show that the compressibility of hcp Fe0.88Si0.12Hx alloys is very similar to those of hcp Fe and Fe0.88Si0.12, indicating that the incorporation of hydrogen into iron does not change its compression behavior remarkably. The present experiments suggest that the inner core may contain up to 0.47 wt % hydrogen (FeH0.26) if temperature is 5000 K. The calculated density profile of Fe0.88Si0.12H0.17 alloy containing 0.32 wt % hydrogen in addition to geochemically required 6.5 wt % silicon matches the seismological observations of the outer core, supporting that hydrogen is an important core light element.

  3. Catalytic Methane Decomposition over Fe-Al2O3

    KAUST Repository

    Zhou, Lu

    2016-05-09

    The presence of a Fe-FeAl2O4 structure over an Fe-Al2O3 catalysts is demonstrated to be vital for the catalytic methane decomposition (CMD) activity. After H2 reduction at 750°C, Fe-Al2O3 prepared by means of a fusion method, containing 86.5wt% FeAl2O4 and 13.5wt% Fe0, showed a stable CMD activity at 750°C for as long as 10h. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Study of aluminum nitride precipitation in Fe- 3%Si steel

    Directory of Open Access Journals (Sweden)

    F.L. Alcântara

    2013-01-01

    Full Text Available For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese sulphides and aluminium nitride delay normal grain growth during primary recrystallization, causing preferential growth of grains with Goss orientation during secondary recrystallization. The sulphides precipitate during the hot rolling process. The aluminium nitride particles are formed during hot rolling and the hot band annealing process. In this work AlN precipitation during hot deformation of a high permeability grain oriented 3%Si steel is examined. In the study, transfer bar samples were submitted to controlled heating, compression and cooling treatments in order to simulate a reversible hot rolling finishing. The samples were analyzed using the transmission electron microscope (TEM in order to identify the precipitates and characterize size distribution. Precipitate extraction by dissolution method and analyses by inductively coupled plasma optical emission spectrometry (ICP-OES were used to quantify the precipitation. The results allowed to describe the precipitation kinetics by a precipitation-time-temperature (PTT diagram for AlN formation during hot rolling.

  5. Atomic data from the iron project. 3: Rate coefficients for electron impact excitation of boron-like ions: Ne VI, Mg VIII, Al IX, Si X, S XII, Ar XIV, Ca XVI and Fe XXII

    Science.gov (United States)

    Zhang, Hong Lin; Graziani, Mark; Pradhan, Anil K.

    1994-01-01

    Collison strengths and maxwellian averaged rate coefficients have been calculated for the 105 transitions among all 15 fine structure levels of the 8 LS terms 2s(sup 2) 2 P(P-2(sup 0 sub 1/, 3/2)), 2s2p(sup 2)(P-4(sub 1/2,3/2,5/2), D-2(sub 3/2, 5/2), S-2(sub 1/2), P-2(sub 1/2, 3/2)), 2p(sup 3)(S-4(sup 0)(sub 3/2), D-2(sup 0 sub 3/2, 5/2), P-2(sup 0 sub 1/2, 3/2)) in highly- charged B-like Ne, Mg, Al, Si, S, Ar, Ca and Fe. Rate coefficients have been tabulated at a wide range of temperatures, depending on the ion charge and abundance in plasma sources. Earlier work for O IV has also been extended to include the high temperature range. A brief discussion of the calculations, sample results, and comparison with earlier works is also given. While much of the new data should be applicable to UV spectral diagnostics, the new rates for the important ground state fine structure transition P-2(sup 0 sub 1/2)-P-2(sup 0 sub 3/2) should result in significant revision of the IR cooling rates in plasmas where B-like ions are prominent constituents, since the new rate coefficients are generally higher by several factors compared with the older data.

  6. Optically stimulated luminescence response to ionizing radiation of red bricks (SiO{sub 2}, Al{sub 2}O{sub 3} an Fe{sub 2}O{sub 3}) used as building materials

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, G.; Golzarri, J. I.; Santiago, P. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000 Mexico D. F. (Mexico); Bogard, J. S. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge TN 37831-6426 (United States)]. e-mail: espinosa@fisica.unam.mx

    2008-02-15

    Quartz is the most common mineral in our environment. It is found in granite, hydrothermal veins and volcanic rocks, as well as in sedimentary deposits derived from such solid materials. These sediments are also made into building materials, such as bricks and pottery. Thus the potential use of a dose reconstruction technique based on quartz grains is enormous, whether as a dating tool in archaeology and quaternary geology, or in nuclear accident dosimetry. This work describes the Optically Stimulated Luminescence (OSL) response of red brick to ionizing radiation. The bricks, from the state of Puebla, Mexico, represent another class of materials that can be used in retrospective dosimetry following nuclear or radiological incidents. The chemical composition of fifteen bricks (three samples from five different brick factories) was determined, using energy dispersive spectroscopy, be primarily SiO{sub 2}, Al{sub 2}0{sub 3} and Fe{sub 2}O{sub 3} and is believed to be representative for this common building material. Individual aliquots from these bricks were powdered in agate mortars and thermally annealed. Replicate samples of the aliquots were then irradiated with beta particles from a sealed source of {sup 9}0Sr/{sup 9}0Y. The OSL response was measured with a Daybreak Model 2200 High-Capacity OSL Reader System. We present here for this material the characteristic OSL response to beta particles; the reproducibility of the OSL response; the linearity of the response in the dose range 0.47 Gy to 47 Gy; and the fading characteristics. (Author)

  7. Mechanical alloying of Fe-Mn and Fe-Mn-Si

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The ball milling of Fe-24Mn and Fe-24Mn-6Si mixed powders has been performed by the high energy ball milling technique.By employing X-ray diffraction and Moessbauer measurements.The ccmposition evolution during the milling process has been investigated.The results indicate the formation of paramagnetic Fe-Mn or Fe-Mn-Si alloys with a metastable fcc phase as final products.which imply that the Fe and Mn proceed a co-diffusion meenanism through the surface of fragmented powders.The thermal stability and composition evolution of the as-milled alloys were discussed comparing with the bulk alloy,.

  8. ELECTRONIC STRUCTURE OF CLUSTER ASSEMBLED Al12C (Si) SOLID

    Institute of Scientific and Technical Information of China (English)

    QUAN HONG-JUN; GONG XIN-GAO

    2000-01-01

    The electronic structures of the cluster-assembled solid Al12C (Si) are studied by the ab initio method. We find that Al12C (Si) can solidify into a van der Waals solid. The electronic band structures show very weak dispersion. The main features in the electronic structure of cluster are retained in the solid, and an energy gap up to about 1.5 eV is observed for Al12C and Al12Si solids.

  9. Investigation on The Properties of Fe-Si3N4 Bonded SiC Composite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; FENG Di; PENG Dayan

    2005-01-01

    The mechanical properties of pressureless sintering Fe-Si3N4 bonded SiC and Si3 N4 bonded SiC with same manufacture process have been compared in this paper.The oxidizing mechanism of Fe-Si3 N4 bonded SiC ceramic matrix composite has been investigated especially through TG-DSC (thermo gravimetric analysis-differential scanning calorimeter) experiment. During oxidation procedure the main reaction is the oxidation of SiC and Si3N4, SiO2 which form protecting film to prevent further oxidizing. And residual iron in the samples become Fe2 O3 and Fe3O4, the oxidation kinetics at 1100 ~ 1300℃ of re-Si3 N4 bonded SiC has been studied especially. The weight gain per unit area at initial stage changes according to beeline rule, in the middle according to conic, and in the last oxidation period follows parabola rule.

  10. Evidence for a Fe3+-rich pyrolitic lower mantle from (Al,Fe)-bearing bridgmanite elasticity data

    Science.gov (United States)

    Kurnosov, A.; Marquardt, H.; Frost, D. J.; Ballaran, T. Boffa; Ziberna, L.

    2017-03-01

    The chemical composition of Earth’s lower mantle can be constrained by combining seismological observations with mineral physics elasticity measurements. However, the lack of laboratory data for Earth’s most abundant mineral, (Mg,Fe,Al)(Al,Fe,Si)O3 bridgmanite (also known as silicate perovskite), has hampered any conclusive result. Here we report single-crystal elasticity data on (Al,Fe)-bearing bridgmanite (Mg0.9Fe0.1Si0.9Al0.1)O3 measured using high-pressure Brillouin spectroscopy and X-ray diffraction. Our measurements show that the elastic behaviour of (Al,Fe)-bearing bridgmanite is markedly different from the behaviour of the MgSiO3 endmember. We use our data to model seismic wave velocities in the top portion of the lower mantle, assuming a pyrolitic mantle composition and accounting for depth-dependent changes in iron partitioning between bridgmanite and ferropericlase. We find excellent agreement between our mineral physics predictions and the seismic Preliminary Reference Earth Model down to at least 1,200 kilometres depth, indicating chemical homogeneity of the upper and shallow lower mantle. A high Fe3+/Fe2+ ratio of about two in shallow-lower-mantle bridgmanite is required to match seismic data, implying the presence of metallic iron in an isochemical mantle. Our calculated velocities are in increasingly poor agreement with those of the lower mantle at depths greater than 1,200 kilometres, indicating either a change in bridgmanite cation ordering or a decrease in the ferric iron content of the lower mantle.

  11. Rapid solidification of undercooled Al-Cu-Si eutectic alloys

    Institute of Scientific and Technical Information of China (English)

    RUAN Ying; WEI BingBo

    2009-01-01

    Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation.In this work,rapid solidification of an undercooled liquid Al,80.4Cu,13.6Si,6 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating.The re-lationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt.The maximum undercooling is 147 K (0.18 TE).The undercooled ternary eutectic is composed of α(Al) solid solution,(Si) semiconductor and β(CuAl,2) intermetallic compound.In the (Al+Si+θ) ternary eutectic,(Si) faceted phase grows independently,while (Al) and θ non-faceted phases grow coopera-tively in the lamellar mode.When undercooling is small,only (Al) solid solution forms as the leading phase.Once undercooling exceeds 73 K,(Si) phase nucleates firstly and grows as the primary phase.The alloy microstructure consists of primary (Al) dendrite,(Al+9) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling,while at large undercooling primary (Si) block,(Al+θ) pseudo-binary eutectic and (Al+Si+θ) ternary eutectic coexist.As undercooling increases,the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases.

  12. Catalystlike behavior of Si adatoms in the growth of monolayer Al film on Si(111).

    Science.gov (United States)

    Teng, Jing; Zhang, Lixin; Jiang, Ying; Guo, Jiandong; Guo, Qinlin; Wang, Enge; Ebert, Philipp; Sakurai, T; Wu, Kehui

    2010-07-07

    The formation mechanism of monolayer Al(111)1x1 film on the Si(111) radical3x radical3-Al substrate was studied by scanning tunneling microscopy and first-principles calculations. We found that the Si adatoms on the radical3x radical3-Al substrate play important roles in the growth process. The growth of Al-1x1 islands is mediated by the formation and decomposition of SiAl(2) clusters. Based on experiments and theoretical simulations we propose a model where free Si atoms exhibit a catalystlike behavior by capturing and releasing Al atoms during the Al film growth.

  13. Measurements of Al concentration in the primary Si crystals from the rheocast Al-15.5 wt% Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G.H.; Lee, J.C.; Lee, H.I. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Lee, J.I. [Chungju National Univ. (Korea, Republic of). Dept. of Materials Science and Engineering

    1997-10-01

    The purpose of the present study is to investigate the distribution of Al in the primary crystal of Si in rheocast hypereutectic Al-Si alloy. Lattice parameters of primary Si crystals were determined using relative positions of the higher order Laue zone (HOLZ) lines recorded from the CBED patterns. The measured lattice parameters were then converted to the Al concentrations to compare with EPMA measurements for the accurate determination of solute concentration profile in the primary Si and to understand the role of solute redistribution on the microstructural change in hypereutectic Al-Si alloy during rheocasting.

  14. Stabilization of itinerant (band) magnetism in FeAl by Ga substitution for Al

    Energy Technology Data Exchange (ETDEWEB)

    Papaconstantopoulos, D. A.; Mazin, I. I.; Hathaway, K. B.

    2001-06-01

    Band structure calculations of FeGa{sub 1{minus}x}Al{sub x} have been performed, to further investigate the stability of ferromagnetism in FeAl. The Stoner parameter increases by about 20% at the FeGa end. This is also confirmed by our spin-polarized calculations. We conclude that Ga substitution for Al is likely to stabilize the elusive (or illusive) ferromagnetic state in FeAl. {copyright} 2001 American Institute of Physics.

  15. Laser clad AlSiCuNi functionally graded coatings

    NARCIS (Netherlands)

    Pei, Yutao; de Hosson, J.T.M.; Brebbia, CA

    2001-01-01

    This paper presents an exploration of laser clad AlSiCuNi-alloy FGCs on cast Al-alloy substrates. SEM microstructure observations indicate that, besides Si primary particles, hard Al3Ni2 compounds also exhibits a continuous increase in both particle sizes and volume fractions from the bottom to the

  16. Electron Structure and Microwave Absorbing Ability of Flaky FeSiAI Powders

    Institute of Scientific and Technical Information of China (English)

    T.D.Zhou; D.F.Liang; L.J.Deng; D.C.Luan

    2011-01-01

    Soft magnetic metallic materials have been widely used for absorbing electromagnetic wave. Flaky Fe86-tSitAl14 (t=9, 11, 14 and 16) alloys powders were prepared from melt-quenched ribbons by annealing and milling. In a previous report we discussed the order-disordered structure of this alloys. In this article, we studied their electron structure. Covalence electron numbers of (111) and (100) plane increase with increasing Si content but Bohr magneton decreases. Complex permittivity and complex permeability are both decreased with increasing Si content t. The lowest value of reflectivity among the four alloys is originated from Fe70Si14Al14. The peak values of reflectivity are all lower than -10 dB, and the absorbing frequency range (R<-10 dB) increases from 1 to 2 GHz when t reaches 16.

  17. Sound velocities of Fe and Fe-Si alloy in the Earth's core.

    Science.gov (United States)

    Mao, Zhu; Lin, Jung-Fu; Liu, Jin; Alatas, Ahmet; Gao, Lili; Zhao, Jiyong; Mao, Ho-Kwang

    2012-06-26

    Compressional wave velocity-density (V(P)--ρ) relations of candidate Fe alloys at relevant pressure-temperature conditions of the Earth's core are critically needed to evaluate the composition, seismic signatures, and geodynamics of the planet's remotest region. Specifically, comparison between seismic V(P)--ρ profiles of the core and candidate Fe alloys provides first-order information on the amount and type of potential light elements--including H, C, O, Si, and/or S-needed to compensate the density deficit of the core. To address this issue, here we have surveyed and analyzed the literature results in conjunction with newly measured V(P)--ρ results of hexagonal closest-packed (hcp) Fe and hcp-Fe(0.85)Si(0.15) alloy using in situ high-energy resolution inelastic X-ray scattering and X-ray diffraction. The nature of the Fe-Si alloy where Si is readily soluble in Fe represents an ideal solid-solution case to better understand the light-element alloying effects. Our results show that high temperature significantly decreases the V(P) of hcp-Fe at high pressures, and the Fe-Si alloy exhibits similar high-pressure V(P)--ρ behavior to hcp-Fe via a constant density offset. These V(P)--ρ data at a given temperature can be better described by an empirical power-law function with a concave behavior at higher densities than with a linear approximation. Our new datasets, together with literature results, allow us to build new V(P)--ρ models of Fe alloys in order to determine the chemical composition of the core. Our models show that the V(P)--ρ profile of Fe with 8 wt % Si at 6,000 K matches well with the Preliminary Reference Earth Model of the inner core.

  18. Mechanical alloying of Mo-Si-Fe powders

    Institute of Scientific and Technical Information of China (English)

    曹昱; 易丹青; 张松

    2002-01-01

    Mechanical milling behavior of Mo-Si-Fe powders was investigated u sing XRD, SEM and TEM techniques. The mixtures of elemental molybdenum (>99%), s ilicon (>99%) and iron (>98%) powders with a stoichiometry of Mo5-xFe xSi3 (x=0.5, 1, 2) were milled in a planetary mill for up to 195 h. For all three powder mixt ures, high-energy milling of 60h led to formation of the Mo(Fe, Si) supers aturated solid solution (Moss); and to a remarkable expansion of the solub ility of Fe, Si in molybdenum. The transformation of Moss to an amorphous phase was identified after longer time milling. In the milling process, the grain size of Mo (Fe, Si) decreased gradually and the internal stress increased linearly. After 40 h milling, the grain size was reduced to about 11 nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195 h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100 nm.

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

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xi-ya

    2004-01-01

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

  20. Glass Forming Ability and Magnetic Property of Fe74Al4Sn2(PSiB)20 Amorphous Alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei-fei; ZHOU Shao-xiong

    2004-01-01

    Amorphous ribbons of Fe74Al4Sn2(PSiB)20 alloy have been synthesized by melt spinning and axial design method. The thermal properties of the amorphous ribbons have been measured by differential scanning calorimeter (DSC). The DSC results show that the Fe74Al4Sn2P12Si4B4 amorphous alloy has relatively wider supercooled liquid region with a temperature interval of 40.38 K (ΔTx=Tx-Tg). The alloys with a higher phosphorous content in the metalloid element composition triangle of Fe74Al4Sn2(PSiB)20 have high glass forming ability. The amorphous alloys also show good magnetic properties in which Fe74Al4Sn2P6.67Si6.67B6.67 alloy has a large maximum permeability (μm), Fe78Al4Sn2P3Si3B10 alloy exhibits a high square ratio (Br/B10) and Fe74Al4Sn2P4Si12B4 shows a low core loss (P0.5/1.3T). High glass forming ability and good magnetic properties make Fe74Al4Sn2(PSiB)20 amorphous alloys valuable in future research.

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  2. Thermal annealing and magnetic anisotropy of NiFe thin films on n{sup +}-Si for spintronic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q.H. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Huang, R. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Wang, L.S. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Wu, Z.G., E-mail: zgwu@lzu.edu.cn [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, C., E-mail: lich@xmu.edu.cn [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Luo, Q. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Zuo, S.Y. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Li, J. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, People’s Republic of China (China); Peng, D.L. [Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Han, G.L. [Gansu Key Laboratory of Sensor and Sensor Technology, Institute of Sensor Technology, Gansu Academy of Science, Lanzhou 730000 (China); Yan, P.X. [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2015-11-15

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO{sub 2} dielectric layer and n{sup +}-Si directly by sputtering deposition, and treated by conventional furnace annealing and/or high vacuum magnetic field annealing were investigated. It was found that thermal annealing at 250 °C improved the crystalline quality and reduced surface roughness of the NiFe films, thus enhancing its saturation magnetization intensity. The 100 nm thick NiFe films had too large coercive force and saturation magnetization intensity in vertical direction to meet the requirements of Hanle curve detection. While, 30 nm thick NiFe films showed paramagnetic hysteresis loops in vertical direction, and the magnetization intensity of the sample after annealing at 250 °C for 30 min was less than 2% to the parallel when the external magnetic field was given between ±10 Oe. This was preferred to Hanle curve detection. The thin HfO{sub 2} dielectric layer between metal and Si partially suppressed the diffusion of Ni in NiFe into Si substrate and formation of NiSi, greatly enhancing the saturation magnetization intensity of the Al/NiFe/HfO{sub 2}/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO{sub 2}/Si structure, from the point view of magnetic electrodes, would be suitable for spin injection and detection applications. - Highlights: • The saturation magnetization intensity of NiFe thin-film was enhanced by thermal annealing. • A paramagnetic hysteresis loop of NiFe thin-film was observed in vertical direction. • The thin HfO{sub 2} dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si.

  3. Electrical and Magnetic Properties of FeSi2 Nanowires

    Institute of Scientific and Technical Information of China (English)

    PENG Zu-Lin; S. Liang

    2008-01-01

    We report the characterization of serf-assembled epitaxially grown FeSi2 nanowires (NWs) in terms of electrical and magnetic properties. NWs grown by reactive deposition epitaxy (RDE) on silicon (110) show dimensions of 1Onm×5nm, and several micrometres in length. By using conductive-AFM (c-AFM), electron transport properties of one single NW is measured, resistivity of a single crystalline FeSi2 NW is estimated to be 225 μΩ·cm.Using superconducting quantum interference device (SQUID), we measure a magnetic moment of 0.3±0.1 Bohr magneton per iron atom for these FeSi2 NWs.

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

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

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

  5. AlMnFeSi合金退火过程中的微观组织及力学性能的演变%Evolution in microstructure and mechanical properties during back-annealing of AlMnFeSi alloy

    Institute of Scientific and Technical Information of China (English)

    王宁; Jarl Erik FLAT(Φ)Y; 李彦军; Knut MARTHINSEN

    2012-01-01

    An Al-Mn-Fe-Si model alloy was subjected to two homogenization treatments,to achieve materials with different levels of Mn in solid solution and dispersoid densities,followed by cold rolling and back-annealing.Characterization of homogenization and deformation structures with respect to the effect of different microchemistries and strains on the structures was performed.Time-temperature-transformation (TTT) diagram with respect to precipitation and recrystallisation as a basis for analysis of the degree of concurrent precipitation was established.The TTT-diagram shows a strong effect of Mn concentration in solid solution and dispersoid density on the softening behavior.Recrystallization which finishes without the effect of concurrent precipitation results in an even,fine and equiaxed grain structure.Precipitation prior to or during recrystallization (concurrent) does retard the softening kinetics and leads to a coarse grain structure.However,the effect also depends on the duration of recrystallization and amount of precipitation.Recrystallization proceeding over a long time combined with a large amount of concurrent precipitation has a strong effect,otherwise the effect will be limited.Pre-existing fine and dense dispersoids (mean size 0.1 μm) before back-annealing do also lead to a coarse grain structure after recrystallization no matter whether additional concurrent precipitation occurs.%通过2种不同的均匀化热处理及随后的冷轧,使一种3xxx系模型合金获得不同尺寸和分布的弥散析出相,并使铝基体含有不同含量的Mn.系统研究不同均匀化热处理组织和冷轧变形量对退火过程中模型合金的回复与再结晶行为的影响.根据实验结果,绘制出弥散析出相和再结晶过程的相互作用时间-温度-转变曲线(TTT).TTT曲线显示固溶体中Mn的含量和弥散析出相的颗粒密度对软化行为有强烈的影响.在再结晶退火过程中或再结晶退火之前析出的高密度、细

  6. Room temperature luminescence and ferromagnetism of AlN:Fe

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-06-01

    Full Text Available AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV and 598 nm (2.07 eV are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  7. Semisolid casting with ultrasonically melt-treated billets of Al-7mass%Si alloys

    Directory of Open Access Journals (Sweden)

    Yoshiki Tsunekawa

    2012-02-01

    Full Text Available The demand for high performance cast aluminum alloy components is often disturbed by increasing impurity elements, such as iron accumulated from recycled scraps. It is strongly required that coarse plate-like iron compound of モ-Al5FeSi turns into harmless form without the need for applying refining additives or expensive virgin ingots. The microstructural modification of Al-7mass%Si alloy billets with different iron contents was examined by applying ultrasonic vibration during the solidification. Ultrasonically melt-treated billets were thixocast right after induction heating up to the semisolid temperature of 583 ìC, the microstructure and tensile properties were evaluated in the thixocast components. Globular primary メ-Al is required to fill up a thin cavity in thixocasting, so that the microstructural modification by ultrasonic melt-treatment was firstly confirmed in the billets. With ultrasonic melt-treatment in the temperature range of 630 ìC to 605 ìC, the primary メ-Al transforms itself from dendrite into fine globular in morphology. The coarse plate-like モ-Al5FeSi compound becomes markedly finer compared with those in non-treated billets. Semisolid soaking up to 583 ìC, does not appreciably affect the size of モ-Al5FeSi compounds; however, it affects the solid primary メ-Al morphology to be more globular, which is convenient for thixocasting. After thixocasting with preheated billets, eutectic silicon plates are extremely refined due to the rapid solidification arising from low casting temperature. The tensile strength of thixocast samples with different iron contents does not change much even at 2mass% of iron, when thixocast with ultrasonically melt-treated billets. However, thixocast Al-7mass%Si-2mass%Fe alloy with non-treated billets exhibits an inferior strength of 80 MPa, compared with 180 MPa with ultrasonically melt-treated billets. The elongation is also improved by about a factor of two in thixocastings with

  8. Preparation technique of SiCp reinforced Al matrix composite

    Institute of Scientific and Technical Information of China (English)

    HAO Bin; CUI Hua; YU Zhi-yong; TAO Kai; YANG Bin; ZHANG Ji-shan

    2006-01-01

    A new preparation technique-"block dispersal and cast" method is introduced, and three kinds of powd.er mixing methods, vertical, horizontal and inclining styles, are compared. The results demonstrate that the inclining style is the best way to mix powders. The Al and nano SiC powders are pressed into blocks, dipped into molten Al, stirred into mold so that SiC/Al matrix composites can be obtained at last. The microstructure of SiC particle reinforced Al matrix composite prepared by "block dispersal and cast" method have been studied using scanning electron microscopy (SEM). Phase analysis has also been conducted by means of X-ray diffraction (XRD). The results show that nano SiC particles can be dispersed uniformly in Al matrix. Thus, it is feasible to prepare SiC particle reinforced Al matrix composites by this method.

  9. Activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag and their application to the recycling of Ni-Co-Fe-based end-of-life superalloys via remelting

    Science.gov (United States)

    Lu, Xin; Miki, Takahiro; Nagasaka, Tetsuya

    2017-01-01

    To design optimal pyrometallurgical processes for nickel and cobalt recycling, and more particularly for the end-of-life process of Ni-Co-Fe-based end-of-life (EoL) superalloys, knowledge of their activity coefficients in slags is essential. In this study, the activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag, a candidate slag used for the EoL superalloy remelting process, were measured using gas/slag/metal equilibrium experiments. These activity coefficients were then used to consider the recycling efficiency of nickel and cobalt by remelting EoL superalloys using CaO-Al2O3-SiO2 slag. The activity coefficients of NiO and CoO in CaO-Al2O3-SiO2 slag both show a positive deviation from Raoult's law, with values that vary from 1 to 5 depending on the change in basicity. The activity coefficients of NiO and CoO peak in the slag with a composition near B = (%CaO)/(%SiO2) = 1, where B is the basicity. We observed that controlling the slag composition at approximately B = 1 effectively reduces the cobalt and nickel oxidation losses and promotes the oxidation removal of iron during the remelting process of EoL superalloys.

  10. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong

    2009-01-01

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

  12. GMI in FeCuNbSiB/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Correa, M.A. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil)]. E-mail: mmacorrea@gmail.com; Viegas, A.D.C. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Silva, R.B. da [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Andrade, A.M.H. de [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Fisicas, 22290-180, Rio de Janeiro, RJ (Brazil)

    2006-10-01

    Very high magnetoimpedance (MI) measured at frequencies up to 1.8 GHz in single and multilayered thin films with composition Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} and (Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9}+Cu) are reported. The magnetic properties of both systems are also compared. MI ratio as high as 300% for the multilayered samples were obtained.

  13. Magnetic properties of nanocrystalline Fe-Cu-Si-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, Y; Ohta, M, E-mail: yoshihito_yoshizawa@hitachi-metals.co.j [Advanced Electronics Research Laboratory, Hitachi Metals, Ltd., 5200 Mikajiri, Kumagaya, Saitama 360-0843 (Japan)

    2009-01-01

    Recently, nanocrystalline Fe-Cu-B and Fe-Cu-Si-B soft magnetic alloys with high saturation magnetic flux density more than 1.8 T and low coercivity of about 6 A m{sup -1} were developed by annealing melt-quenched alloys containing 1.3 -1.5 at % Cu and 0 - 7 at % Si. In this work, the magnetic properties of annealed Fe{sub 77.5-x}Cu{sub x}Si{sub 15.5}B{sub 7} alloys with high Si content prepared by melt spinning are reported. The appropriate Cu content in this alloy system shifted to Cu content higher than that of the reported Fe-Cu-Si-B alloys with high B{sub s}. The annealed alloy with x = 2.0 showed the H{sub c} of about 10 A m{sup -1}, the B{sub 8000} of 1.47 T, and low magnetostriction of +4.8 x 10{sup -6}.

  14. Abiologic silicon isotope fractionation between aqueous Si and Fe(III)-Si gel in simulated Archean seawater: Implications for Si isotope records in Precambrian sedimentary rocks

    Science.gov (United States)

    Zheng, Xin-Yuan; Beard, Brian L.; Reddy, Thiruchelvi R.; Roden, Eric E.; Johnson, Clark M.

    2016-08-01

    Precambrian Si-rich sedimentary rocks, including cherts and banded iron formations (BIFs), record a >7‰ spread in 30Si/28Si ratios (δ30Si values), yet interpretation of this large variability has been hindered by the paucity of data on Si isotope exchange kinetics and equilibrium fractionation factors in systems that are pertinent to Precambrian marine conditions. Using the three-isotope method and an enriched 29Si tracer, a series of experiments were conducted to constrain Si isotope exchange kinetics and fractionation factors between amorphous Fe(III)-Si gel, a likely precursor to Precambrian jaspers and BIFs, and aqueous Si in artificial Archean seawater under anoxic conditions. Experiments were conducted at room temperature, and in the presence and absence of aqueous Fe(II) (Fe(II)aq). Results of this study demonstrate that Si solubility is significantly lower for Fe-Si gel than that of amorphous Si, indicating that seawater Si concentrations in the Precambrian may have been lower than previous estimates. The experiments reached ˜70-90% Si isotope exchange after a period of 53-126 days, and the highest extents of exchange were obtained where Fe(II)aq was present, suggesting that Fe(II)-Fe(III) electron-transfer and atom-exchange reactions catalyze Si isotope exchange through breakage of Fe-Si bonds. All experiments except one showed little change in the instantaneous solid-aqueous Si isotope fractionation factor with time, allowing extraction of equilibrium Si isotope fractionation factors through extrapolation to 100% isotope exchange. The equilibrium 30Si/28Si fractionation between Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -2.30 ± 0.25‰ (2σ) in the absence of Fe(II)aq. In the case where Fe(II)aq was present, which resulted in addition of ˜10% Fe(II) in the final solid, creating a mixed Fe(II)-Fe(III) Si gel, the equilibrium fractionation between Fe(II)-Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -3.23 ± 0.37‰ (2σ). Equilibrium

  15. A thermodynamic description of the Si-rich Si-Fe system

    Institute of Scientific and Technical Information of China (English)

    Kai TANG; Merete Tangstad

    2012-01-01

    Phase equilibria in the Si-rich domain of the Si-Fe system have been reassessed based on the recent DTA experimental results.Thermodynamic properties of liquid phase have been reassessed using the associated solution model.The properties of DIAMOND_A4 mixture phase have been added in order to evaluate the phase equilibria for the pure silicon materials.The assessed system is able to reproduce the experimental values in the whole composition range of the Si-Fe system.

  16. Electronic properties of Co{sub 2}FeSi investigated by X-ray magnetic linear dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Emmel, M. [Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55128 Mainz (Germany); Alfonsov, A. [IFW Dresden, Institute for Solid State Research, D-01069 Dresden (Germany); Legut, D. [VSB - Technical University of Ostrava, 17. Listopadu 15, CZ-70833 Ostrava (Czech Republic); Kehlberger, A.; Vilanova, E. [Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55128 Mainz (Germany); Krug, I.P. [Peter Grünberg Institut PGI-6, Forschungszentrum Jülich, D-52425 Jülich (Germany); Gottlob, D.M. [Peter Grünberg Institut PGI-6, Forschungszentrum Jülich, D-52425 Jülich (Germany); Fakultät für Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), D-47048 Duisburg (Germany); Belesi, M. [IFW Dresden, Institute for Solid State Research, D-01069 Dresden (Germany); Büchner, B. [IFW Dresden, Institute for Solid State Research, D-01069 Dresden (Germany); Institut für Physik, TU Dresden, D-01062 Dresden (Germany); Kläui, M. [Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55128 Mainz (Germany); Oppeneer, P.M. [Department of Physics and Astronomy, Uppsala University, P. O. Box 516, S-751 20 Uppsala (Sweden); Wurmehl, S. [IFW Dresden, Institute for Solid State Research, D-01069 Dresden (Germany); Institut für Physik, TU Dresden, D-01062 Dresden (Germany); and others

    2014-11-15

    We present experimental XMLD spectra measured on epitaxial (001)-oriented thin Co{sub 2}FeSi films, which are rich in features and depend sensitively on the degree of atomic order and interdiffusion from capping layers. Al- and Cr-capped films with different degrees of atomic order were prepared by DC magnetron sputtering by varying the deposition temperatures. The local structural properties of the film samples were additionally investigated by nuclear magnetic resonance (NMR) measurements. The XMLD spectra of the different samples show clear and uniform trends at the L{sub 3,2} edges. The Al-capped samples show similar behavior as previous measured XMLD spectra of Co{sub 2}FeSi{sub 0.6}Al{sub 0.4}. Thus, we assume that during deposition Al atoms are being implanted into the subsurface of Co{sub 2}FeSi. Such an interdiffusion is not observed for the corresponding Cr-capped films, which makes Cr the material of choice for capping Co{sub 2}FeSi films. We report stronger XMLD intensities at the L{sub 3,2} Co and Fe egdes for films with a higher saturation magnetization. Additionally, we compare the spectra with ab initio predictions and obtain a reasonably good agreement. Furthermore, we were able to detect an XMCD signal at the Si L-edge, indicating the presence of a magnetic moment at the Si atoms. - Highlights: • Co{sub 2}FeSi thin films with different degree ordering were grown by DC sputtering. • The films were structurally investigated by NMR, XMLD and XMCD. • We see a relation between the saturation magnetization and the XMLD strength. • We notice an intermixing of the Al capping with the film material. • We detect a magnetic moment at the Si atom probed with XMCD.

  17. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    A K Khanra; S Patra; M M Godkhindi

    2006-06-01

    Electrical discharge machining (EDM) studies on reactive sintered FeAl were carried out with different process parameters. The metal removal rate and tool removal rate were found to increase with the applied pulse on-time. The surface roughness of machined surface also changed with the applied pulse on-time. XRD analysis of machined surface of sintered FeAl showed the formation of Fe3C phase during the EDM process. The debris analysis was used to identify the material removal mechanism occurring during the EDM of sintered FeAl.

  18. EXAFS study of ion beam mixed Fe/Al multilayers

    CERN Document Server

    Arcon, I; Zalar, A; Kodre, A; Jagielski, J

    2003-01-01

    Composition and structure of Fe/Al multilayer coatings after ion beam mixing at different temperatures are studied. Samples were prepared by consecutive sputter deposition of Fe and Al on well-polished silicon substrate. The samples were ion beam mixed with 330 keV Ar ions at the dose of 3x10 sup 1 sup 5 ions/cm sup 2 in the temperature range between room temperature and 400 deg. C. AES depth profiles showed that mixing between Fe and Al layers started at 100 deg. C and was complete at 400 deg. C. Fe K-edge EXAFS, however, reveals that Fe bcc metallic phase is still present at all temperatures. The amount of an additional Fe-Al phase is about 20% up to 300 deg. C, increasing to 50% at 400 deg. C.

  19. Magnetic and mechanical properties of FeSi alloys with high Si content

    Institute of Scientific and Technical Information of China (English)

    LU Feng-shuang; QIAO Liang; BI Xiao-fang

    2006-01-01

    The chemical vapor(CVD) deposition-diffusion method was applied to prepare FeSi alloys with high silicon content up to 6.5%. In spite of various deposition and post-annealing, the sample remains α-Fe bcc structure. The cross section of the composition was analyzed to evaluate the Si content and distribution before and after annealing. The results show that the soft magnetic properties are improved by increasing the silicon content. For the samples containing about 6.5% Si, the coercivity decreases to 60 from 237.3 A/m of the original. It is also obtained that, in addition to the Si content, Si distribution has a large influence on the core loss due to the effect of resistivity. The micro-hardnesses were also evaluated along the cross-section after various annealings.

  20. Newly developed Ti-Nb-Zr-Ta-Si-Fe biomedical beta titanium alloys with increased strength and enhanced biocompatibility.

    Science.gov (United States)

    Kopova, Ivana; Stráský, Josef; Harcuba, Petr; Landa, Michal; Janeček, Miloš; Bačákova, Lucie

    2016-03-01

    Beta titanium alloys are promising materials for load-bearing orthopaedic implants due to their excellent corrosion resistance and biocompatibility, low elastic modulus and moderate strength. Metastable beta-Ti alloys can be hardened via precipitation of the alpha phase; however, this has an adverse effect on the elastic modulus. Small amounts of Fe (0-2 wt.%) and Si (0-1 wt.%) were added to Ti-35Nb-7Zr-6Ta (TNZT) biocompatible alloy to increase its strength in beta solution treated condition. Fe and Si additions were shown to cause a significant increase in tensile strength and also in the elastic modulus (from 65 GPa to 85 GPa). However, the elastic modulus of TNZT alloy with Fe and Si additions is still much lower than that of widely used Ti-6Al-4V alloy (115 GPa), and thus closer to that of the bone (10-30 GPa). Si decreases the elongation to failure, whereas Fe increases the uniform elongation thanks to increased work hardening. Primary human osteoblasts cultivated for 21 days on TNZT with 0.5Si+2Fe (wt.%) reached a significantly higher cell population density and significantly higher collagen I production than cells cultured on the standard Ti-6Al-4V alloy. In conclusion, the Ti-35Nb-7Zr-6Ta-2Fe-0.5Si alloy proves to be the best combination of elastic modulus, strength and also biological properties, which makes it a viable candidate for use in load-bearing implants.

  1. Protected Fe valence in quasi-two-dimensional α-FeSi2

    Science.gov (United States)

    Miiller, W.; Tomczak, J. M.; Simonson, J. W.; Smith, G.; Kotliar, G.; Aronson, M. C.

    2015-05-01

    We report the first comprehensive study of the high temperature form (α-phase) of iron disilicide. Measurements of the magnetic susceptibility, magnetization, heat capacity and resistivity were performed on well characterized single crystals. With a nominal iron d6 configuration and a quasi-two-dimensional crystal structure that strongly resembles that of LiFeAs, α-FeSi2 is a potential candidate for unconventional superconductivity. Akin to LiFeAs, α-FeSi2 does not develop any magnetic order and we confirm its metallic state down to the lowest temperatures (T = 1.8 K). However, our experiments reveal that paramagnetism and electronic correlation effects in α-FeSi2 are considerably weaker than in the pnictides. Band theory calculations yield small Sommerfeld coefficients of the electronic specific heat γ = Ce/T that are in excellent agreement with experiment. Additionally, realistic many-body calculations further corroborate that quasi-particle mass enhancements are only modest in α-FeSi2. Remarkably, we find that the natural tendency to vacancy formation in the iron sublattice has little influence on the iron valence and the density of states at the Fermi level. Moreover, Mn doping does not significantly change the electronic state of the Fe ion. This suggests that the iron valence is protected against hole doping and indeed the substitution of Co for Fe causes a rigid-band like response of the electronic properties. As a key difference from the pnictides, we identify the smaller inter-iron layer spacing, which causes the active orbitals near the Fermi level to be of a different symmetry in α-FeSi2. This change in orbital character might be responsible for the lack of superconductivity in this system, providing constraints on pairing theories in the iron based pnictides and chalcogenides.

  2. The high-pressure behavior of an Al- and Fe-rich natural orthopyroxene

    DEFF Research Database (Denmark)

    Nestola, F.; Boffa Ballaran, T.; Balic Zunic, Tonci

    2008-01-01

    A single crystal of a natural orthopyroxene with composition M2[Fe2+0.818Mg0.156Ca0.010Mn0.016]M1[Fe2+0.081 Mg0.767Al0.084Fe3+0.068]TA[Si]TB[Si0.848Al0.152]O6 and space group Pbca (sample S95) was investigated at high pressure by X-ray diffraction using a diamond-anvil cell up to 9.56 GPa. No phase...... complete intensity data were collected at 0, 0.16, 1.72, 3.95, 8.03, and 9.56 GPa. The results confirm previous conclusions regarding the compressional mechanism in orthopyroxenes. At lower pressures, compression is mostly connected to a decrease in volume of the two M-coordination octahedra, accompanied...

  3. Thermoelectric Properties of Epitaxial β-FeSi2 Thin Films on Si(111) and Approach for Their Enhancement

    Science.gov (United States)

    Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Okuhata, Ryo; Ishibe, Takafumi; Watanabe, Kentaro; Suzuki, Takeyuki; Fujita, Takeshi; Sawano, Kentarou; Nakamura, Yoshiaki

    2016-10-01

    We have investigated the intrinsic thermoelectric properties of epitaxial β-FeSi2 thin films and the impact of phosphorus (P) doping. Epitaxial β-FeSi2 thin films with single phase were grown on Si(111) substrates by two different techniques in an ultrahigh-vacuum molecular beam epitaxy (MBE) system: solid-phase epitaxy (SPE), where iron silicide films formed by codeposition of Fe and Si at room temperature were recrystallized by annealing at 530°C to form epitaxial β-FeSi2 thin films on Si(111) substrates, and MBE of β-FeSi2 thin films on epitaxial β-FeSi2 templates formed on Si(111) by reactive deposition epitaxy (RDE) at 530°C (RDE + MBE). Epitaxial SPE thin films based on codeposition had a flatter surface and more abrupt β-FeSi2/Si(111) interface than epitaxial RDE + MBE thin films. We investigated the intrinsic thermoelectric properties of the epitaxial β-FeSi2 thin films on Si(111), revealing lower thermal conductivity and higher electrical conductivity compared with bulk β-FeSi2. We also investigated the impact of doping on the Seebeck coefficient of bulk and thin-film β-FeSi2. A route to enhance the thermoelectric performance of β-FeSi2 is proposed, based on (1) fabrication of thin-film structures for high electrical conductivity and low thermal conductivity, and (2) proper choice of doping for high Seebeck coefficient.

  4. Magnetic and magnetostrictive properties of amorphous TbFe/FeAl multilayer thin film

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; MI Yiming; QIAN Shiqiang; ZHOU Xiying

    2008-01-01

    Exchange coupling multilayer thin films, which combined giant magnetostriction and soft magnetic properties, were of growing interest for applications. The TbFe/FeAl multilayer thin films were prepared by dc magnetron sputtering onto glass substrates. The microstructure, magnetic, and magnetostrictive properties of TbFe/FeAl multilayer thin film was investigated at different annealing temperatures. The results indicated that the soft magnetic and magnetostrictive properties for TbFe/FeAl multilayer thin film compared with TbFe single layer film were obviously improved. In comparison with the intrinsic coercivity JHc of 59.2 kA/m for TbFe single layer film, the intrinsic coercivity JHc for TbFe/FeAl multilayer thin films rapidly dropped to 29.6 kA/m. After optimal annealing (350 ℃×60 min), magnetic properties of Hs=96 kA/m and JHc=16 kA/m were obtained, and magnetostrictive coefficient could reach to 574×10-6 under an external magnetic field of 400 kA·m-1 for the TbFe/FeAl multilayer thin film.

  5. Preparation of SiO2-Protecting Metallic Fe Nanoparticle/SiO2 Composite Spheres for Biomedical Application

    Directory of Open Access Journals (Sweden)

    Pin-Wei Hsieh

    2015-11-01

    Full Text Available Functionalized Fe nanoparticles (NPs have played an important role in biomedical applications. In this study, metallic Fe NPs were deposited on SiO2 spheres to form a Fe/SiO2 composite. To protect the Fe from oxidation, a thin SiO2 layer was coated on the Fe/SiO2 spheres thereafter. The size and morphology of the SiO2@Fe/SiO2 composite spheres were examined by transmission electron microscopy (TEM. The iron form and its content and magnetic properties were examined by X-ray diffraction (XRD, inductively-coupled plasma mass spectrometry (ICP-MS and a superconducting quantum interference device (SQUID. The biocompatibility of the SiO2@Fe/SiO2 composite spheres was examined by Cell Counting Kit-8 (CCK-8 and lactate dehydrogenase (LDH tests. The intracellular distribution of the SiO2@Fe/SiO2 composite spheres was observed using TEM. XRD analysis revealed the formation of metallic iron on the surface of the SiO2 spheres. According to the ICP-MS and SQUID results, using 0.375 M FeCl3·6H2O for Fe NPs synthesis resulted in the highest iron content and magnetization of the SiO2@Fe/SiO2 spheres. Using a dye loading experiment, a slow release of a fluorescence dye from SiO2@Fe/SiO2 composite spheres was confirmed. The SiO2@Fe/SiO2 composite spheres co-cultured with L929 cells exhibit biocompatibility at concentrations <16.25 µg/mL. The TEM images show that the SiO2@Fe/SiO2 composite spheres were uptaken into the cytoplasm and retained in the endosome. The above results demonstrate that the SiO2@Fe/SiO2 composite spheres could be used as a multi-functional agent, such as a magnetic resonance imaging (MRI contrast agent or drug carriers in biomedical applications.

  6. Formation of β-FeSi 2 thin films by partially ionized vapor deposition

    Science.gov (United States)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

  7. Growth and magnetic properties of epitaxial Fe4N films on insulators possessing lattice spacing close to Si(001) plane

    Science.gov (United States)

    Ito, Keita; Higashikozono, Soma; Takata, Fumiya; Gushi, Toshiki; Toko, Kaoru; Suemasu, Takashi

    2016-12-01

    We grew ferromagnetic Fe4N films by molecular beam epitaxy on MgO(001), MgAl2O4(MAO)(001), SrTiO3(STO)(001), and CaF2(001) substrates, possessing the lattice spacing close to Si(001) plane. Highly oriented epitaxial growth was confirmed for the Fe4N films on the MgO, MAO, and STO by reflection high-energy electron diffraction and x-ray diffractions. The degree of orientation of the Fe4N film on the STO was the best among these samples. This was attributed to the smallest lattice mismatch of -2.8% between Fe4N(001) and STO(001). On the other hand, crystallinity of the Fe4N film on the CaF2(001) substrate was poor due to a very large lattice mismatch of -30% between Fe4N(001) and CaF2(001) arising from the unexpected epitaxial relationship as Fe4N(001)[100] || CaF2(001)[100]. The saturation magnetization of the Fe4N films was approximately 1200 emu/cm3 at room temperature for all the samples, and the magnetization easy axis was in-plane Fe4N[100]. We consider that STO is the suitable buffer layer for the growth of Fe4N on Si(001), hence to realize the Si-based spintronics devices using highly spin-polarized Fe4N.

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

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

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

  9. Theoretical investigations of an influence of Ti on electronic structure and magnetic properties of half-metallic Fe{sub 2}Mn{sub 1−x}Ti{sub x}Si{sub 0.5}Al{sub 0.5} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Go, Anna, E-mail: annago@alpha.uwb.edu.pl

    2015-02-01

    Ab-initio electronic structure calculations are carried out for quinternary Fe{sub 2}Mn{sub 1−x}Ti{sub x}Si{sub 0.5}Al{sub 0.5} alloys basing on the density functional theory. When x=0, the alloy is a half-metallic ferromagnet with magnetic moment following the Slater–Pauling rule. Main carrier of magnetism of the alloy is manganese with the magnetic moment of about 2.5 μ{sub B}. Replacement of Mn by Ti, changes its electronic and magnetic structure. Half-metallicity is present up to Ti concentration x=0.375. However, the further increase of Ti content leads to a strong decrease of electronic spin polarization. When the concentration of Ti increases, total magnetic moment strongly decreases. Fe magnetic moment, in the presence of titanium, changes its orientation into antiparallel in respect to the total magnetic moment and its absolute value increases with increasing Ti content. However, absolute value of Fe magnetic moment does not exceed 0.17 μ{sub B}. Ti exhibits very weak spin polarization with magnetic moment not higher than 0.05 μ{sub B}. - Highlights: • Half-metallic band gap is obtained for Fe{sub 2}Mn{sub 1−x}Ti{sub x}Si{sub 0.5}Al{sub 0.5} for x≤0.375. • The further increase of Ti content leads to a strong decrease of polarization ratio. • The main carrier of magnetism of the compound is manganese. • Total magnetic moment decreases almost linearly with increasing Ti content.

  10. Al/Fe isomorphic substitution versus Fe{sub 2}O{sub 3} clusters formation in Fe-doped aluminosilicate nanotubes (imogolite)

    Energy Technology Data Exchange (ETDEWEB)

    Shafia, Ehsan [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy); Esposito, Serena [Università degli Studi di Cassino e del Lazio Meridionale, Department of Civil and Mechanical Engineering (Italy); Manzoli, Maela; Chiesa, Mario [Università di Torino, Dipartimento di Chimica and Centro Interdipartimentale NIS (Italy); Tiberto, Paola [Electromagnetism, I.N.Ri.M. (Italy); Barrera, Gabriele [Università di Torino, Dipartimento di Chimica and Centro Interdipartimentale NIS (Italy); Menard, Gabriel [Harvard University, Department of Chemistry and Chemical Biology (United States); Allia, Paolo, E-mail: paolo.allia@polito.it [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy); Freyria, Francesca S. [Massachusetts Institute of Technology, Department of Chemistry (United States); Garrone, Edoardo; Bonelli, Barbara, E-mail: barbara.bonelli@polito.it [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy)

    2015-08-15

    Textural, magnetic and spectroscopic properties are reported of Fe-doped aluminosilicate nanotubes (NTs) of the imogolite type, IMO, with nominal composition (OH){sub 3}Al{sub 2−x}Fe{sub x}O{sub 3}SiOH (x = 0, 0.025, 0.050). Samples were obtained by either direct synthesis (Fe-0.025-IMO, Fe-0.050-IMO) or post-synthesis loading (Fe-L-IMO). The Fe content was either 1.4 wt% (both Fe-0.050-IMO and Fe-L-IMO) or 0.7 wt% (Fe-0.025-IMO). Textural properties were characterized by High-Resolution Transmission Electron Microscopy, X-ray diffraction and N{sub 2} adsorption/desorption isotherms at 77 K. The presence of different iron species was studied by magnetic moment measurements and three spectroscopies: Mössbauer, UV–Vis and electron paramagnetic resonance, respectively. Fe{sup 3+}/Al{sup 3+} isomorphic substitution (IS) at octahedral sites at the external surface of NTs is the main process occurring by direct synthesis at low Fe loadings, giving rise to the formation of isolated high-spin Fe{sup 3+} sites. Higher loadings give rise, besides IS, to the formation of Fe{sub 2}O{sub 3} clusters. IS occurs up to a limit of Al/Fe atomic ratio of ca. 60 (corresponding to x = 0.032). A fraction of the magnetism related to NCs is pinned by the surface anisotropy; also, clusters are magnetically interacting with each other. Post-synthesis loading leads to a system rather close to that obtained by direct synthesis, involving both IS and cluster formations. Slightly larger clusters than with direct synthesis samples, however, are formed. The occurrence of IS indicates a facile cleavage/sealing of Al–O–Al bonds: this opens the possibility to exchange Al{sup 3+} ions in pre-formed IMO NTs, a much simpler procedure compared with direct synthesis.

  11. The Effect of Si Morphology on Machinability of Al-Si Alloys

    Directory of Open Access Journals (Sweden)

    Muhammet Uludağ

    2015-12-01

    Full Text Available Many of the cast parts require some sort of machining like milling, drilling to be used as a finished product. In order to improve the wear properties of Al alloys, Si is added. The solubility of Si in Al is quite low and it has a crystallite type structure. It behaves as particulate metal matrix composite which makes it an attractive element. Thus, the wear and machinability properties of these type of alloys depend on the morphology of Si in the matrix. In this work, Sr was added to alter the morphology of Si in Al-7Si and Al-12Si. Cylindrical shaped samples were cast and machinability characteristics of Sr addition was studied. The relationship between microstructure and machinability was evaluated.

  12. 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.

  13. Origin of Fe3+ in Fe-containing, Al-free Mantle Silicate Perovskite

    CERN Document Server

    Xu, Shenzhen; Morgan, Dane

    2016-01-01

    We have studied the ferrous (Fe2+) and ferric (Fe3+) iron concentrations in Al-free Fe containing Mg-silicate perovskite (Mg-Pv) at pressure (P), temperature (T), and oxygen fugacity (fO2) conditions related to the lower mantle using a thermodynamic model based on ab-initio calculations. We consider the oxidation reaction and the charge disproportionation reaction, both of which can produce Fe3+ in Mg-Pv. The model shows qualitatively good agreement with available experimental data on Fe3+/{\\Sigma}Fe ({\\Sigma}Fe = total Fe in system), spin transitions, and equations of state. We predict that under lower-mantle conditions Fe3+/{\\Sigma}Fe determined by the charge disproportionation is estimated to be 0.01-0.07 in Al-free Mg-Pv, suggesting that low Al Mg-Pv in the uppermost pyrolitic mantle (where majoritic garnet contains most of the Al) and in the harzburgitic heterogeneities throughout the lower mantle contains very little Fe3+. We find that the volume reduction by the spin transition of the B-site Fe3+ leads...

  14. Fe-Si system: a potential major component of the Earth's core

    Science.gov (United States)

    Caracas, R.; Verstraete, M.; Fischer, R. A.; Campbell, A. J.

    2013-12-01

    We investigate Silicon in the Earth's core using first-principles calculations. Specifically we look at the phase diagram of the Fe-Si system, the solubility limits of Si into hcp Fe, and the effect of Si on the thermal and electrical conductivities of iron. We consider several Fe hcp supercells and replace some of the Fe atoms with Si in different amounts and configurations. In this way we mimic the dissolution of silicon into hcp and take into account a realistic solid solution. Silicon slightly increases the specific volume of iron, but the differences levels out at high pressures. We show that the density and seismic profiles of the core can be easily matched by Fe-Si alloys with small amounts of Si. Further phonon analysis suggests that stoichiometric Fe3Si is dynamically unstable at high pressure. This results in decomposition into Si-bearing hcp Fe and Fe-bearing B2 FeSi. Then we follow the evolution of the Fe-FeSi immiscibility gap as a function of pressure. Finally we compute the electrical and thermal conductivities of Si-bearing hcp iron at inner core conditions. We obtain that a relatively small amount of Si decreases the conductivity of iron. Based on these considerations we conclude that Si can be the preferred light element of the Earth's core.

  15. Positive magnetoresistance in Co40Fe40B20/SiO2/Si heterostructure

    KAUST Repository

    Zhang, Y.

    2016-07-20

    Current-perpendicular-to-plane electronic transport properties and magnetoresistance of amorphous Co40Fe40B20/SiO2/Si heterostructures are investigated systematically. A backward diode-like rectifying behavior was observed due to the formation of a Schottky barrier between Co40Fe40B20 and Si. The junction resistance shows a metal-insulator transition with decreasing temperature in both the forward and reverse ranges. A large positive magnetoresistance (MR) of ∼2300% appears at 200 K. The positive MR can be attributed to the magnetic-field-controlled impact ionization process of carriers. MR shows a temperature-peak-type character under a constant bias current, which is related to the spin-dependent barrier in the Si near the interface. © CopyrightEPLA, 2016.

  16. Fabric cutting application of FeAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Sklad, S.P. [Univ. of Virginia, Charlottesville, VA (United States); Deevi, S.C. [Philip Morris U.S.A., Richmond, VA (United States); Shih, H.R. [Jackson State Univ., MS (United States)

    1998-11-01

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60), and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel.

  17. MICROSTRUCTURES AND OXIDATION RESISTANCE OF Fe3Al WELD OVERLAY

    Institute of Scientific and Technical Information of China (English)

    X.G.Min; X.Q.Yu; Y.S.Sun; J.R.Sun

    2001-01-01

    Using the Fe3Al electrode through manual arc surfacing (MAS),Fe3Al coatings havebeen deposited on the stainless steel substrate.The microstructures,hardness andoxidation resistance of the weld overlay have been investigated.The results show thatcrack-free overlays can be obtained when pre-heating of the substrate at 500℃ andpostweld heat treatment at 700℃ were used.Elements of Al,Cr,Ni etc.transferredbetween the substrate and the overlay,but this does not influence the microhardnessof the substrate and the Fe3Al overlay.Oxidation tests show that the Fe3Al overlayshave excellent oxidation resistance in comparison with the stainless steel substrate at800℃ and 900℃.

  18. All-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayers fabricated by Sn-induced low-temperature epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, M.; Ikawa, M.; Arima, K.; Yamada, S.; Kanashima, T.; Hamaya, K., E-mail: hamaya@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531 (Japan)

    2016-01-28

    We demonstrate low-temperature growth of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co{sub 2}FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co{sub 2}FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a T{sub G} of 250 °C. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co{sub 2}FeSi/Ge/Co{sub 2}FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.

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

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

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

  20. SPIN-DEPENDENT TUNNELING MAGNETORESISTANCE IN Fe-O/AlOx/Fe-O FILMS

    Institute of Scientific and Technical Information of China (English)

    L.Q. Pan; H. Qiu; F.P. Wang; P. Wu; Y. Tian; S. Luo

    2002-01-01

    Fe-O/AlOx/Fe-O tunnel junctions were prepared by reactive magnetron sputteringunder mixed working gas Ar+2%O2. The insulating AlOx layer of 1-2nm thicknesswas sputtered directly from Al2O3 target. Electrode layers were made of 80at.% ironand 20at.% oxygen. Bottom Fe-O electrode deposited on glass substrate annealedat 473K at the pressure of 3× 10-4Pa for an hour shows disparate crystalline grainstructure, lower electrical resistance and coercivity compared to the as-deposited topelectrode. Only crystalline structrure of α-Fe is observed in both electrodes. Largetunnel magnetoresistance in large Fe-O/AlOx/Fe-O junctions of 1cm2 is observed atroom temperature and the Ⅰ-Ⅴ characteristic curve of the junction shows that thebarrier of the junction is of high quality.

  1. Site occupancy of Fe in ternary Ni75-Fe+Al25- alloys

    Indian Academy of Sciences (India)

    B Annie D'Santhoshini; S N Kaul

    2003-03-01

    The results of a detailed structural and magnetic study clearly indicate that regardless of the thermal history of the samples, Fe has a strong preference for the Ni sites in Ni-poor (non-stoichiometric) Ni75Al25 alloys. Fe substitution has a profound effect on the nature of magnetism in Ni75Al25.

  2. Anelasticity in Fe-Al-Cr alloys at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, I.S., E-mail: i.golovin@misis.ru [Physics of Metals Department, National University ' Moscow Institute of Steel and Alloys' , Moscow (Russian Federation); Physics of Metals Department and Materials Science, Tula State University, Tula (Russian Federation); Riviere, A. [LMPM-UMR CNRS 6617, ENSMA, F-86961 Futuroscope Chasseneuil Cedex (France)

    2009-09-15

    Several (Fe,Cr){sub 3}Al alloys with Cr content from 3 to 25% have been studied in the temperature range from 680 to 930 K using isothermal frequency dependent tests (from 10{sup -4} to 10{sup 2} Hz). Three relaxation peaks were observed in this range. The Zener relaxation (P1 peak) caused by reorientation of pairs of substitute atoms in Fe is observed in all studied alloys and used to evaluate the activation parameters of substitute atom jumps in Fe. Activation parameters of the Zener peak in Fe-26Al-Cr depend not too much on Cr content (H = 275-290 kJ/mol, {tau}{sub 0} = 10{sup -19} to 10{sup -20} s), while the relaxation strength increases with the increase in Al + Cr content. The second internal friction peak (P2) at higher temperatures with similar activation energies but higher {tau}{sub 0} (10{sup -17} to 10{sup -19} s) is observed only in Cr containing alloys but not in Fe-25Al binary alloy. Most probably this peak is controlled by dislocations motion in Fe-26Al-Cr alloys. The third peak, denoted as P3 (H = 428 kJ/mol, {tau}{sub 0} = 10{sup -25} s), was observed only in the Fe-25Al-25Cr alloy and was classified as a grain boundary peak.

  3. Phase relations in the Fe-FeSi system at high pressures and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Rebecca A.; Campbell, Andrew J.; Reaman, Daniel M.; Miller, Noah A.; Heinz, Dion L.; Dera, Przymyslaw; Prakapenka, Vitali B. (UC); (Maryland)

    2016-07-29

    The Earth's core is comprised mostly of iron and nickel, but it also contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is important to understand the high pressure, high temperature properties and behavior of alloys in the Fe–FeSi system, such as their phase diagrams. We determined melting temperatures and subsolidus phase relations of Fe–9 wt% Si and stoichiometric FeSi using synchrotron X-ray diffraction at high pressures and temperatures, up to ~200 GPa and ~145 GPa, respectively. Combining this data with that of previous studies, we generated phase diagrams in pressure–temperature, temperature–composition, and pressure–composition space. We find the B2 crystal structure in Fe–9Si where previous studies reported the less ordered bcc structure, and a shallower slope for the hcp+B2 to fcc+B2 boundary than previously reported. In stoichiometric FeSi, we report a wide B2+B20 two-phase field, with complete conversion to the B2 structure at ~42 GPa. The minimum temperature of an Fe–Si outer core is 4380 K, based on the eutectic melting point of Fe–9Si, and silicon is shown to be less efficient at depressing the melting point of iron at core conditions than oxygen or sulfur. At the highest pressures reached, only the hcp and B2 structures are seen in the Fe–FeSi system. We predict that alloys containing more than ~4–8 wt% silicon will convert to an hcp+B2 mixture and later to the hcp structure with increasing pressure, and that an iron–silicon alloy in the Earth's inner core would most likely be a mixture of hcp and B2 phases.

  4. Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

    Indian Academy of Sciences (India)

    K C Barick; D Bahadur

    2006-11-01

    The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 spheres have been prepared by an in situ reaction using different molar ratios of Fe3+/Fe2+ (50–200%). It has been observed that morphology of the assembly and properties of these hybrid materials composed of SiO2 as core and Fe3O4 nanoparticles as shell depend on the molar ratio of Fe3+/Fe2+.

  5. Magnetic properties, morphology and interfaces of (Fe/Si){sub n} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bartolomé, J., E-mail: barto@unizar.es [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Badía-Romano, L. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Rubín, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Ciencia de Materiales e Ingeniería Metalúrgica, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Bartolomé, F. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Varnakov, S.N.; Ovchinnikov, S.G. [Kirensky Institute of Physics SB of RAS, 660036 Krasnoyarsk (Russian Federation); Bürgler, D.E. [Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany)

    2016-02-15

    A systematic study of the iron–silicon interfaces formed upon preparation of (Fe/Si) multilayers has been performed by the combination of modern and powerful techniques. Samples were prepared by molecular beam epitaxy under ultrahigh vacuum onto Si wafers or single crystalline Ag(100) buffer layers grown on GaAs(100). The morphology of these films and their interfaces was studied by a combination of scanning transmission electron microscopy, X-ray reflectivity, angle resolved X-ray photoelectron spectroscopy and hard X-ray photoelectron spectroscopy. The Si-on-Fe interface thickness and roughness were determined to be 1.4(1) nm and 0.6(1) nm, respectively. Moreover, determination of the stable phases formed at both Fe-on-Si and Si-on-Fe interfaces was performed using conversion electron Mössbauer spectroscopy on multilayers with well separated Si-on-Fe and Fe-on-Si interfaces. It is shown that while a fraction of Fe remains as α-Fe, the rest has reacted with Si, forming the paramagnetic FeSi phase and a ferromagnetic Fe rich silicide. We conclude that there is an identical paramagnetic c-Fe{sub 1−x}Si silicide sublayer in both Si-on-Fe and Fe-on-Si interfaces, whereas an asymmetry is revealed in the composition of the ferromagnetic silicide sublayer. - Highlights: • The Si-on-Fe interface has a thickness of 1.4 nm and a roughness of 0.6 nm. • The para- c-Fe{sub 1-x}Si and the ferromagnetic Fe{sub 1−x}Si{sub x} form the interfaces. • c-Fe{sub 1−x}Si is symmetric and Fe{sub 1−x}Si{sub x} is asymmetric in Si/Fe and Fe/Si interfaces. • (Fe/Si){sub 3} multilayers conserve their integrity just till T≈450 K. • Irreversible chemical transformations take place at high temperature.

  6. Microstructural effects of phosphorus on pressure die cast Al-12Si components

    Directory of Open Access Journals (Sweden)

    Suárez-Peña, B.

    2007-10-01

    Full Text Available The refinement of cuboidal silicon in eutectic Al-Si alloys by phosphorus additions used to manufacture pressure die cast components was studied. The results show that the addition of phosphorus in the form of AlFeP mother alloy before process degassing, leads to the best refinement of the size of the Si-cuboids phase, among several phosphorus additions analysed in the present research.

    Se ha estudiado el afino del silicio cuboidal en aleaciones eutécticas Al-Si por acción del fósforo, en piezas obtenidas mediante la técnica de fundición a presión. Tras la adición de fósforo en pruebas industriales, en las que dicho elemento se incorpora al baño con diversas composiciones, los mejores resultados se obtienen con la adición de la aleación madre AlFeP, previa al desgasificado industrial.

  7. The Effect of Plasma Spraying on the Microstructure and Aging Kinetics of the Al-Si Matrix Alloy and Al-Si/SiC Composites

    Science.gov (United States)

    Altunpak, Yahya; Akbulut, Hatem; Üstel, Fatih

    2010-02-01

    The Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.

  8. Microstructures and Properties of Ti-Coated SiCp Reinforced Al-Si Alloy Composites

    Science.gov (United States)

    Feng, Yan; Ren, Junpeng; Dong, Cuige; Wang, Richu

    2016-12-01

    A double-layer structure of Ti coating was plated on the surface of SiC particles using a diffusion method in a vacuum reactor, which is a new method to fabricate a Ti-coating layer on the SiC particles. The phase structure of Ti coating on the surface of SiC particles was composed inside of Ti5Si3 and outside of TiC investigated by x-ray diffraction. The Ti5Si3 and TiC double-layer structure realizes the tight chemical bonding between SiC particles and the Ti coating, and significantly promotes the wettability between the aluminum matrix and the Ti-coated SiC particles. The Ti-coated SiCp-reinforced Al-Si composites are prepared by a powder metallurgy method, and express excellent relative densities, desirable mechanical properties and frictional wear resistance.

  9. Microstructural evolution and creep of Fe-Al-Ta alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prokopcakova, Petra; Svec, Martin [Technical University of Liberec (Czech Republic). Dept. of Material Science; Palm, Martin [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany). Structure and Nano-/Micromechanics of Materials

    2016-05-15

    The microstructural evolution in Fe-Al-Ta alloys containing 23 - 31 at.% Al and 1.5 - 2.2 at.% Ta has been studied in the temperature range 650 - 750 C by annealing for 1, 10, 100 and 1 000 h. The experiments confirm that in this temperature range the precipitation of the stable hexagonal C14 Laves phase is preceded by formation of coherent, metastable L2{sub 1} Heusler phase precipitates within the Fe-Al matrix. However, precipitates of C14 are observed after much shorter annealing times than previously assumed. Creep strength increases substantially with increasing Al content of the alloys because the solid solubility for Ta in the Fe-Al matrix increases with increasing Al content and solid-solution hardening contributes substantially to the observed high creep strength. It may therefore be that the microstructural changes during creep have no noticeable effect on creep strength.

  10. Removal of C and SiC from Si and FeSi during ladle refining and solidification

    Energy Technology Data Exchange (ETDEWEB)

    Klevan, Ole Svein

    1997-12-31

    The utilization of solar energy by means of solar cells requires the Si to be very pure. The purity of Si is important for other applications as well. This thesis mainly studies the total removal of carbon from silicon and ferrosilicon. The decarburization includes removal of SiC particles by stirring and during casting in addition to reduction of dissolved carbon by gas purging. It was found that for three commercial qualities of FeSi75, Refined, Gransil, and Standard lumpy, the refined quality is lowest in carbon, followed by Gransil and Standard. A decarburization model was developed that shows the carbon removal by oxidation of dissolved carbon to be a slow process at atmospheric pressure. Gas stirring experiments have shown that silicon carbide particles are removed by transfer to the ladle wall. The casting method of ferrosilicon has a strong influence on the final total carbon content in the commercial alloy. Shipped refined FeSi contains about 100 ppm total carbon, while the molten alloy contains roughly 200 ppm. The total carbon out of the FeSi-furnace is about 1000 ppm. It is suggested that low values of carbon could be obtained on an industrial scale by injection of silica combined with the use of vacuum. Also, the casting system could be designed to give low carbon in part of the product. 122 refs., 50 figs., 24 tabs.

  11. Microstructure of reactive sintered Al bonded Si3N4-SiC ceramics

    Institute of Scientific and Technical Information of China (English)

    CUI Chong; WANG Yuan-ting; JIANG Jin-guo; CHEN Guang; SUN Qiang-jin

    2006-01-01

    Aluminium nitride-silicon nitride-silicon carbide (AlN-Si3N4-SiC) composite ceramics were prepared to increase the bending strength and improve the phase structure of Si3N4-based ceramics. The ceramics were made by reactive sintering in N2 atmosphere at 1 360 ℃, using Al as sintering additive. The phase composing of ceramics was identified with an X-ray diffractometer and the microstructure of the materials was studied by scanning electron microscopy. The results indicate that the phase structure is affected remarkably and the interface modality is changed. The interface between Si3N4 and SiC becomes blurry and that between SiC and AlN matches more better at the same time. But the liquid-phase appears during the reactive sintering along with the addition of Al by which the melting point of Si is decreased. The appearance of liquid Si decreases the bending strength of the ceramics. Lower temperature nitrification technic was introduced to avoid the appearance of liquid-phase Si. The optimum addition of Al was investigated by XRD and SEM analysis in order to obtain the maximal bending strength of materials.

  12. Synthesis and characterization of Fe{sub 3}Si/SiO{sub 2} structures for spintronics

    Energy Technology Data Exchange (ETDEWEB)

    Mantovan, R.; Georgieva, M.; Fanciulli, M. [Laboratorio Nazionale MDM CNR-INFM, Agrate Brianza (Italy); Goikhman, A.; Barantcev, N.; Lebedinskii, Yu.; Zenkevich, A. [Moscow Engineering Physics Institute, Moscow (Russian Federation)

    2008-08-15

    The Fe{sub 3}Si thin film is a good candidate as ferromagnetic electrode in spintronics devices due to its high spin polarization and high Curie temperature. The use of Fe{sub 3}Si in contact with a thin SiO{sub 2} barrier can have various applications in practical devices, such as magnetic tunnel junctions. We report on the synthesis of Fe{sub 3}Si/SiO{sub 2} structures, in one vacuum cycle, by pulsed laser deposition and glow-discharge plasma oxidation followed by vacuum annealing. The structural and morphological characterization of the Fe{sub 3}Si/SiO{sub 2} stacks is performed by in-situ X-ray photoelectron spectroscopy and with atomic force microscopy. Using a {sup 57}Fe tracer layer, conversion electron Moessbauer spectroscopy is performed at the Fe{sub 3}Si/SiO{sub 2} interface, proving the formation of a ferromagnetic phase with no paramagnetic inclusions. Our experimental results indicate that the Fe{sub 3}Si/SiO{sub 2} stack is a promising system for application in spintronics devices. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. The influence of the iron content on the reductive decomposition of A{sub 3−x}Fe{sub x}Al{sub 2}Si{sub 3}O{sub 12} garnets (A = Mg, Mn; 0.47 ≤ x ≤ 2.85)

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio, Claudia, E-mail: claudia.aparicio@upol.cz; Filip, Jan, E-mail: claudia.aparicio@upol.cz; Mashlan, Miroslav, E-mail: claudia.aparicio@upol.cz; Zboril, Radek, E-mail: claudia.aparicio@upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

    2014-10-27

    Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 °C (heating rate of 10 °C/min) under atmosphere of forming gas (10% of H{sub 2} in N{sub 2}). Crystallochemical formula of the studied garnet was calculated as {sup VIII}(A{sub 3−x}Fe{sub x}{sup 2+}){sup VI}(Al,Fe{sup 3+}){sub 2}Si{sub 3}O{sub 12}, where the amount of Fe{sup 3+} in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ≤ x ≤ 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 °C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp{sub 80}Alm{sub 20}). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 μm) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

  14. Simulation of Nano Si and Al Wires Growth on Si(1O0) Surface

    Institute of Scientific and Technical Information of China (English)

    吴锋民; 黄辉; 吴自勤

    2000-01-01

    Growth of nano Si and Al wires on the Si(100) surfaces is investigated by computer simulation, including the anisotropic diffusion and the anisotropic sticking. The diffusion rates along and across the substrate dimer rows are different, so are the sticking probabilities of an adatom, at the end sites of existing islands or the side sites. Both one-dimensional wires of Si and Al are perpendicular to the dimer rows of the substrate, though the diffusion of Si adatoms is contrary to that of Al adatoms, i.e. Si adatoms diffuse faster along the dimer rows while Al adatoms faster across the dimer rows. The simulation results also show that the shape anisotropy of islands is due to the sticking anisotropy rather than the diffusion anisotropy,which is in agreement with the experiments.

  15. Morphological development and oxidation of elongated {beta}-SiAlON material

    Energy Technology Data Exchange (ETDEWEB)

    Hou Xinmei, E-mail: houxinmei@ustb.edu.c [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of Ecological and Recycle Metallurgy, Ministry of Education, Beijing 100083 (China); Yue Changsheng [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Singh, Ankit Kumar [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Department of Ceramic Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005 (India); Zhang Mei; Chou Kuo-Chih [Department of Physical Chemistry, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2011-06-15

    Research highlights: {yields} Single phase {beta}-SiAlON whiskers and ribbons with z value of 1.6 have been prepared. {yields} The oxidation of the {beta}-SiAlON whiskers and ribbons in air has been investigated. {yields} A new kinetic theory has been used to deal with the experimental results with a good agreement. {yields} The characteristic oxidation time has been introduced for measuring the oxidation resistance. - Abstract: Elongated {beta}-SiAlON whiskers and ribbons have been synthesized at 1700 K under flowing nitrogen atmosphere. A series of experiments have been performed using thermogravimetry (TG) and thermal field emission scanning electron microscope (FE-SEM) to investigate its oxidation resistance. The results showed that the synthesized {beta}-SiAlON material possessed good oxidation resistance and the shape can be well kept up to 1373 K. Chou's model has been used to investigate the oxidation kinetics, from which it was concluded that {beta}-SiAlON in shape of ribbons has better oxidation resistance than that in shape of whisker from the view point of a new index of the characteristic oxidation time.

  16. Charge storage in β-FeSi{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Theis, Jens; Küpper, Sebastian; Lorke, Axel [Fakultät für Physik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany); Bywalez, Robert; Wiggers, Hartmut [Institut für Verbrennung und Gasdynamik and CENIDE, Universität Duisburg-Essen, D-47048 Duisburg (Germany)

    2015-02-07

    We report on the observation of a surprisingly high specific capacitance of β-FeSi{sub 2} nanoparticle layers. Lateral, interdigitated capacitor structures were fabricated on thermally grown silicon dioxide and covered with β-FeSi{sub 2} particles by drop or spin casting. The β-FeSi{sub 2}-nanoparticles, with crystallite sizes in the range of 10–30 nm, were fabricated by gas phase synthesis in a hot wall reactor. Compared to the bare electrodes, the nanoparticle-coated samples exhibit a 3–4 orders of magnitude increased capacitance. Time-resolved current voltage measurements show that for short times (seconds to minutes), the material is capable of storing up to 1 As/g at voltages of around 1 V. The devices are robust and exhibit long-term stability under ambient conditions. The specific capacitance is highest for a saturated relative humidity, while for a relative humidity below 40% the capacitance is almost indistinguishable from a nanoparticle-free reference sample. The devices work without the need of a fluid phase, the charge storing material is abundant and cost effective, and the sample design is easy to fabricate.

  17. Transport and magnetic properties of Fe3Si epitaxial films

    Science.gov (United States)

    Vinzelberg, H.; Schumann, J.; Elefant, D.; Arushanov, E.; Schmidt, O. G.

    2008-11-01

    The paper presents resistivity and magnetization measurements on nearly stoichiometric Fe3Si films epitaxially grown on GaAs substrates by electron-beam evaporation in an ultrahigh vacuum chamber. In the low-temperature resistivity a T3 term was found in all samples. A term like that is known to describe the anomalous single-magnon scattering processes in half-metallic materials and confirms so for our samples the hypothesis of half-metallic ferromagnetism in Fe3Si. The films show an anisotropic magnetoresistance in low magnetic fields. In high magnetic fields a negative longitudinal and transverse magnetoresistance (MR) has been observed linearly depending on the field strength. In the vicinity of 200 K the MR shows maximum absolute values up to 1.5% at magnetic fields of about 8 T. From the magnetization measurements a magnetic moment of 0.86μB/atom was obtained, which is close to that of bulk Fe3Si.

  18. Study on Liquid Structure of Iron-Rich Fe-Si Alloy

    Institute of Scientific and Technical Information of China (English)

    TENG Xin-ying; LIU Han-lian; WANG Huan-rong; YE Yi-fu

    2003-01-01

    The liquid structure of iron-rich Fe-Si alloys (the silicon content is 22, 32, 34, 50 at%, respectively) was studied by high temperature θ-θ diffractometer at 1 550 ℃. The results show that the coordination number of atoms decreases with increasing silicon content. A visible pre-peak was observed in the structure factor of Fe-Si alloys, especially for the liquid Fe78Si22 and Fe68Si32 alloys. The special study was given on the liquid structure of Fe68Si32 alloy at temperature from 1 250 to 1 550 ℃. A distinct pre-peak was found at scattering vector Q=15.5 nm-1 in the structure factor. That means there are ordered D03 structure clusters in the liquid Fe68Si32 alloy. The correlation between silicon atoms in the Fe3Si compounds leads to the pre-peak in the structure factor.

  19. From interstellar abundances to grain composition: the major dust constituents Mg, Si and Fe

    CERN Document Server

    Voshchinnikov, N V

    2010-01-01

    We analyse observational correlations for three elements entering into the composition of interstellar silicate and oxide grains. Using current solar abundances (Asplund et al. 2009), we convert the gas-phase abundances into dust-phase abundances for 196 sightlines. We deduce a sharp difference in abundances for sightlines located at low ($|b|30\\degr$) galactic latitudes. For high-latitude stars the ratios Mg/Si and Fe/Si in dust are close to 1.5. For disk stars they are reduced to ${\\rm Mg/Si} \\sim 1.2$ and ${\\rm Fe/Si} \\sim 1.05$. The derived numbers indicate that 1) the dust grains cannot be the mixture of silicates with olivine and pyroxene composition only and some amount of magnesium or iron (or both) should be in another population and 2) the destruction of Mg-rich grains in the warm medium is more effective than of Fe-rich grains. We reveal a decrease of dust-phase abundances and correspondingly an increase of gas-phase abundances with distance $D$ for stars with $D\\ga 400$\\,pc. We attribute this fact...

  20. Microstructural investigation of Sr-modified Al-15 wt%Si alloys in the range from micrometer to atomic scale

    Energy Technology Data Exchange (ETDEWEB)

    Timpel, M., E-mail: melanie.timpel@helmholtz-berlin.de [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Vinod Kumar, G.S.; Banhart, J. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Technische Universitaet Berlin, Werkstoffwissenschaften und -Technologien, Hardenbergstr. 36, 10623 Berlin (Germany)

    2011-05-15

    Strontium-modified Al-15 wt%Si casting alloys were investigated after 5 and 60 min of melt holding. The eutectic microstructures were studied using complementary methods at different length scales: focused ion beam-energy selective backscattered tomography, transmission electron microscopy and 3D atom probe. Whereas the samples after 5 min of melt holding show that the structure of eutectic Si changes into a fine fibrous morphology, the increase of prolonged melt holding (60 min) leads to the loss of Sr within the alloy with an evolution of an unmodified eutectic microstructure displaying coarse interconnected Si plates. Strontium was found at the Al/Si eutectic interfaces on the side of the eutectic Al region, measured by 3D atom probe. The new results obtained using 3D atom probe shed light on the location of Sr within the Al-Si eutectic microstructure. -- Research highlights: {yields} Microstructural investigation of Sr-modified Al-15 wt%Si alloy after 5 and 60 min of melt holding using 3D microscopy techniques. {yields} FIB-EsB tomography: Fibrous eutectic modification of Si after 5 min of melt holding; unmodified eutectic microstructure after 60 min of melt holding. {yields} Structural and chemical analysis of Fe-rich intermetallic phases using TEM: Fe-rich {alpha}-phases are present in the eutectic microstructure after 60 min of melt holding; no Fe rich {alpha}-phases are observed within the modified fibrous network after 5 min of melt holding. {yields} 3D-AP analysis of specimens containing A/Si eutectic interfaces: enrichment of Sr is found at the Al/Si interface on the side of the eutectic Al region.

  1. Crystal structure and electronic properties of the new compounds, U 6Fe 16Si 7 and its interstitial carbide U 6Fe 16Si 7C

    Science.gov (United States)

    Berthebaud, D.; Tougait, O.; Potel, M.; Lopes, E. B.; Gonçalves, A. P.; Noël, H.

    2007-10-01

    The new compounds U6Fe16Si7 and U6Fe16Si7C were prepared by arc-melting and subsequent annealing at 1500 °C. Single-crystal X-ray diffraction showed that they crystallize in the cubic space group Fm3¯m (No. 225), with unit-cell parameters at room temperature a=11.7206(5) Å for U6Fe16Si7 and a=11.7814(2) Å for U6Fe16Si7C. Their crystal structures correspond to ordered variants of the Th6Mn23 type. U6Fe16Si7 adopts the Mg6Cu16Si7 structure type, whereas U6Fe16Si7C crystallizes with a novel "filled" quaternary variant. The inserted carbon is located in octahedral cages formed by six U atoms, with U-U interatomic distances of 3.509(1) Å. Insertion of carbon in the structure of U6Fe16Si7 has a direct influence on the U-Fe and Fe-Fe interatomic distances. The electronic properties of both compounds were investigated by means of DC susceptibility, electrical resistivity and thermopower. U6Fe16Si7 is a Pauli paramagnet. Its electrical resistivity and thermopower point out that it cannot be classified as a simple metal. The magnetic susceptibility of U 6Fe 16Si 7C is best described over the temperature range 100-300 K by using a modified Curie-Weiss law with an effective magnetic moment of 2.3(2) μB/U, a paramagnetic Weiss temperature, θp=57(2) K and a temperature-independent term χ0=0.057(1) emu/mol. Both the electrical resistivity and thermopower reveal metallic behavior.

  2. CaAl 12Si 4O 27, a New High-Pressure Phase Containing Al 6O 19 Clusters

    Science.gov (United States)

    Grey, I. E.; Madsen, I. C.; Hibberson, W. O.; O'Neill, H. St. C.

    2000-09-01

    CaAl12Si4O27, a new high-pressure phase in the CaO-Al2O3-SiO2 system, was prepared at 1550°C and 14 GPa. It has trigonal symmetry, P-3, with a=7.223(1) and c=8.614(3) Å. Its structure was solved using crystal chemistry principles and refined using the Rietveld method applied to powder X-ray diffraction data, Rwp=6.1%, RB=2.7%. The structure is a new type based on a close-packed anion lattice with a mixed layer stacking sequence ABACA≡(hc)2 and with Ca atoms ordered in one-seventh of the anion sites in alternate c-stacked layers. The Si atoms are ordered in both octahedral and tetrahedral sites while the Al atoms are ordered in two independent octahedral sites. Octahedral edge-shared clusters, Al6O19, occur in the structure, interconnected within the close-packed layers by corner-linking to SiO4 tetrahedra. The clusters are also connected by corner-sharing to nine-member rings of edge-shared Al- and Si-centered octahedra in adjacent layers. The new phase has structural features in common with the barium titanium ferrite of similar composition, BaFe11Ti3O23, as well as with the mineral simpsonite, Al4Ta3O13(OH), and alkali metal niobates which contain Nb6O19 clusters.

  3. GIANT MAGNETO-IMPEDANCE OF PATTERNED FeSiB/Cu/FeSiB TRI-LAYER FILMS

    Institute of Scientific and Technical Information of China (English)

    X.H. Mao; Y. Zhou; M.S. Wu; B.C. Cai

    2003-01-01

    Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patterned FeSiB/Cu/FeSiB tri-layer films with the change of external magnetic field and frequency were studied at the same time. The change of the impedance of the films with the external magnetic fieldand frequency was shown. Comparing the longitudinal and transverse effect, the transverse effect has a larger linear range from zero magnetic field to a quite large magnetic field at all frequencies, and the change still were not saturated until the external magnetic field reached 1.2×104A/m, which illustrated that the films can be utilized to detect larger magnetic fields than now presented GMI sensors.

  4. Recycling of Al-Si die casting scraps for solar Si feedstock

    Science.gov (United States)

    Seo, Kum-Hee; Jeon, Je-Beom; Youn, Ji-Won; Kim, Suk Jun; Kim, Ki-Young

    2016-05-01

    Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3 N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al-30 wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells.

  5. An Assessment of the Al- Fe- N System

    Science.gov (United States)

    Hillert, Mats; Jonsson, Stefan

    1992-11-01

    The thermodynamic properties of the Al-Fe-N system are assessed, taking various types of information into account. For solid AIN, a description very similar to that given by JANAF is found to yield reasonable predictions for the solubility of A1N in face-centered cubic (fcc) Fe and in liquid Fe. An ionic two-sublattice model is applied to the liquid phase, containing two N species, N-3 and N0 The melting point of A1N is taken as 3068 K, and a required gas pressure of 9.75 bar is predicted. A sublimation point of 2690 K at 1 bar is also predicted. A plot of the liquidus surfaces in the Fe-rich end of the Al-Fe-N system is presented.

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

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

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

  7. Structure and optical properties of aSiAl and aSiAlHx magnetron sputtered thin films

    Directory of Open Access Journals (Sweden)

    Annett Thøgersen

    2016-03-01

    Full Text Available Thin films of homogeneous mixture of amorphous silicon and aluminum were produced with magnetron sputtering using 2-phase Al–Si targets. The films exhibited variable compositions, with and without the presence of hydrogen, aSi1−xAlx and aSi1−xAlxHy. The structure and optical properties of the films were investigated using transmission electron microscopy, X-ray photoelectron spectroscopy, UV-VisNIR spectrometry, ellipsometry, and atomistic modeling. We studied the effect of alloying aSi with Al (within the range 0–25 at. % on the optical band gap, refractive index, transmission, and absorption. Alloying aSi with Al resulted in a non-transparent film with a low band gap (1 eV. Variations of the Al and hydrogen content allowed for tuning of the optoelectronic properties. The films are stable up to a temperature of 300 °C. At this temperature, we observed Al induced crystallization of the amorphous silicon and the presence of large Al particles in a crystalline Si matrix.

  8. TEM analysis of (Ni,Fe)Si{sub 2} precipitates in Si

    Energy Technology Data Exchange (ETDEWEB)

    Langkau, Sabine; Wagner, Gerald; Kloess, Gert [Institute of Mineralogy, Crystallography and Materials Science, Leipzig University, Scharnhorststr. 20, 04275 Leipzig (Germany); Heuer, Matthias [CaliSolar GmbH, Magnusstr. 11, 12489 Berlin (Germany)

    2010-08-15

    The present article provides evidence that Fe impurity atoms in silicon can be gathered by NiSi{sub 2} precipitates at temperatures near RT via solid-state diffusion. Mixtures of silicon and silicide grains, resulting from annealing at 800-900 C, were analysed. High supersaturation (about 10{sup 19}-10{sup 20} atoms/cm{sup 3}) of metal impurities in Si was achieved locally by incorporation of nickel and iron atoms from silicide grains into silicon grains during ion milling for TEM specimen preparation. Consequently, particles with local densities of 10{sup 13}-10{sup 14} precipitates/cm{sup 3} and average volumes of 10{sup -18}-10{sup -16} cm{sup 3} formed via diffusion and precipitation. Precipitates with an irregular octahedra shape and platelet-like habit were found at dislocations. Less frequently, precipitates with a regular octahedra shape were observed in undisturbed matrix. HRTEM images and SAD patterns demonstrate that all precipitates have NiSi{sub 2} structure. Ni contents were detected for all precipitates by EDX analysis, but accumulated amounts of Fe could only be proven for some precipitates at dislocations. Quantitative EDX-analysis revealed Fe/(Fe + Ni) ratios between 16 and 30 at% for these ternary precipitates. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

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

    Institute of Scientific and Technical Information of China (English)

    许志武; 闫久春; 吕世雄; 杨士勤

    2004-01-01

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

  10. Five-Fold Branched Si Particles in Laser Clad AlSi Functionally Graded Materials

    NARCIS (Netherlands)

    Pei, Y.T.; Hosson, J.Th.M. De

    2001-01-01

    Many five-fold branched Si particles (Sip) were observed in Al–40 wt% Si functionally graded materials produced by a single-step laser cladding process on cast Al-alloy substrate. In this paper the five-fold twinning and growth features of Sip are scrutinized with orientation imaging microscopy and

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

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-04-01

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

  12. United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

    Institute of Scientific and Technical Information of China (English)

    韩延峰; 刘相法; 王海梅; 王振卿; 边秀房; 张均艳

    2003-01-01

    The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated. It is foundthat excellent modification effect can be obtained by the addition of this new type of A1-P master alloy into Al-24Simelt and the average primary Si grain size is decreased below 47 μm from original 225 μm. It is also found that theTiC particles in the melt coming from Al8Ti2C can improve the modification effect of the Al-P master alloy. Whenthe content of TiC particles in the Al-24Si melt is 0.03 %, the improvement reaches the maximum and keeps steadywith increasing content of TiC particles. Modification effect occurs at 50 min after the addition of the Al-P master al-loy and TiC particles, and keeps stable with prolonging holding time.

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  14. Microdistortion behavior of Al alloy reinforced by SiCp

    Institute of Scientific and Technical Information of China (English)

    LI Duo-sheng; ZUO Dun-wen; ZHOU Xian-liang; HUA Xiao-zhen; CHEN Rong-fa; ZHAO Li-gang

    2007-01-01

    Al alloy reinforced with SiCp was fabricated by the method of pressureless infiltration. The effects of factors such as SiCp size, volume fraction, matrix material and heat treatment process on microdistortion behavior of Al alloy were investigated. The results show that microdistortion decreases along with lessening of SiCp size and increasing of SiCp volume fraction. Matrix material has influence on the microdistortion behavior, and solution-aging can improve the microdistortion behavior. Stress and residual strain related to microdistortion behavior were simulated by FEM. It is found that the distribution of strain and stress is not symmetrical; residual strain and stress at interface are higher than those at the other places; at the sharp-angled area of a particle, matrix has the highest strain and stress where plastic distortion is caused at first; the microdistortion and stress far from the interface are smaller.

  15. Property measurements on spray formed Si-Al alloys

    Institute of Scientific and Technical Information of China (English)

    WEI Yan-guang; XIONG Bai-qing; ZHANG Yong-an; LIU Hong-wei; WANG Feng; ZHU Bao-hong

    2007-01-01

    A novel Si-Al alloy was prepared by spray forming process for electronic packaging. Property measurements on spray-formed Si-Al alloys after hot pressing were carried out. The results indicate that the alloys (Si-(30%-40%)Al) have advantageous physical and mechanical characteristics, including low coefficient of thermal expansion (6.9×10-6-8.7×10-6/K), high thermal conductivity (118-127 W/(m·K)), low density (2.421×103-2.465×103 kg/m3), high ultimate flexural strength (180-220 MPa) and Brinell hardness (162-261). The alloys are easy to machine to tight tolerances using standard machine tools and they can be electroplated with gold finishes and soldered with Sn-Pb alloy without any difficulty.

  16. 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

  17. Torsion impedance of CoFeSiB amorphous wires

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, M.L. E-mail: grande@pinon.ccu.uniovi.es; Prida, V.M.; Hernando, B.; Tejedor, M.; Vazquez, M

    2002-08-01

    In this work we report some results concerning the torsion impedance of amorphous Co{sub 68.1}Fe{sub 4.4}Si{sub 12.5}B{sub 15} wires in the as-cast state, and after a stress annealing treatment. The influence of the drive current amplitude and frequency is also studied for these samples. A sensitivity to the applied torsion up to 17.6%/rad m is obtained for the annealed wire. The magnetoimpedance response of both types of samples gives evidence to the difference in their domain structure.

  18. Magnetotunable left-handed FeSiB ferromagnetic microwires.

    Science.gov (United States)

    Labrador, Alberto; Gómez-Polo, Cristina; Pérez-Landazábal, José Ignacio; Zablotskii, Vitalii; Ederra, Iñigo; Gonzalo, Ramón; Badini-Confalonieri, Giovanni; Vázquez, Manuel

    2010-07-01

    The magnetotunable left-handed characteristics of Fe(77.5)Si(12.5)B(10) glass-coated ferromagnetic microwires are analyzed in array and single microwire configuration, employing a rectangular waveguide working in X band. While the negative permeability is ascribed to the natural ferromagnetic resonance (NFMR) of the highly and positive magnetostrictive microwire, the negative permittivity features of the medium are attributed to the interaction of the microwires with the metallic rectangular waveguide. The dependence of the NFMR frequency on the applied external magnetic field enables the design of magnetotunable left-handed systems with wide-frequency band.

  19. Characterization of β-FeSi II films as a novel solar cell semiconductor

    Science.gov (United States)

    Fukuzawa, Yasuhiro; Ootsuka, Teruhisa; Otogawa, Naotaka; Abe, Hironori; Nakayama, Yasuhiko; Makita, Yunosuke

    2006-04-01

    β-FeSi II is an attractive semiconductor owing to its extremely high optical absorption coefficient (α>10 5 cm -1), and is expected to be an ideal semiconductor as a thin film solar cell. For solar cell use, to prepare high quality β-FeSi II films holding a desired Fe/Si ratio, we chose two methods; one is a molecular beam epitaxy (MBE) method in which Fe and Si were evaporated by using normal Knudsen cells, and occasionally by e-gun for Si. Another one is the facing-target sputtering (FTS) method in which deposition of β-FeSi II films is made on Si substrate that is placed out of gas plasma cloud. In both methods to obtain β-FeSi II films with a tuned Fe/Si ratio, Fe/Si super lattice was fabricated by varying Fe and Si deposition thickness. Results showed significant in- and out-diffusion of host Fe and Si atoms at the interface of Si substrates into β-FeSi II layers. It was experimentally demonstrated that this diffusion can be suppressed by the formation of template layer between the epitaxial β-FeSi II layer and the substrate. The template layer was prepared by reactive deposition epitaxy (RDE) method. By fixing the Fe/Si ratio as precisely as possible at 1/2, systematic doping experiments of acceptor (Ga and B) and donor (As) impurities into β-FeSi II were carried out. Systematical changes of electron and hole carrier concentration in these samples along variation of incorporated impurities were observed through Hall effect measurements. Residual carrier concentrations can be ascribed to not only the remaining undesired impurities contained in source materials but also to a variety of point defects mainly produced by the uncontrolled stoichiometry. A preliminary structure of n-β-FeSi II/p-Si used as a solar cell indicated a conversion efficiency of 3.7%.

  20. Crystal structural refinement for NdAlSi

    Institute of Scientific and Technical Information of China (English)

    HE Wei; ZHANG Jiliang; ZENG Lingmin; ZHUANG Yinghong

    2006-01-01

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

  1. Interfacial reaction between the oxidized SiC particles and Al-Mg alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The interfacial reactions of oxidized SiC particles reinforced Al-Mg matrix composites were investigated by the field emission-scanning electron microscopy (FE- SEM), TEM and X-ray diffraction. It was found that the nanoscale MgO forms initially due to the interfacial reaction, then whether it reacts with molten Al continuously or not depends on the content of Mg in the matrix and its covering densification at the surface of particles. When there is not enough Mg in the matrix for the formation of dense MgO layer, MgO will transform into MgAl2O4 crystal owing to the continuous reaction with SiO2 and molten Al. When dense MgO layer forms at the surface of the particles due to the affluence of Mg for the initial reaction, it will protect the inner SiC from the attack of molten Al. However, the reaction products of both MgO and MgAl2O4 are thermo-stable phases at the surface of the particles under high temperature. The results clarify the interfacial reaction route and they are of great value to the control of the interfacial reactions and their interfacial design of the composites.

  2. About the mechanical stability of MnFe(P,Si,B) giant-magnetocaloric materials

    Energy Technology Data Exchange (ETDEWEB)

    Guillou, F., E-mail: f.guillou@tudelft.nl [FAME, Faculty of Applied Sciences, TU Delft, Mekelweg 15, 2629 JB Delft (Netherlands); Yibole, H.; Dijk, N.H. van [FAME, Faculty of Applied Sciences, TU Delft, Mekelweg 15, 2629 JB Delft (Netherlands); Zhang, L. [BASF Netherlands B.V., Strijkviertel 67, 3454 PK De Meern (Netherlands); Hardy, V. [CRISMAT, Ensicaen, UMR 6508 CNRS, 6 B" d Maréchal Juin, 14050 Caen Cedex (France); Brück, E. [FAME, Faculty of Applied Sciences, TU Delft, Mekelweg 15, 2629 JB Delft (Netherlands)

    2014-12-25

    Highlights: • Electrical resistivity and hardness show an evolution at T{sub C} with thermal cycling. • Degradation depends on the (c/a) lattice discontinuity at the transition. • Boron substituted materials present an improved mechanical stability. - Abstract: Due to its ability to control the latent heat and the hysteresis (thermal or magnetic) at the first-order transition (FOT) without deteriorating the saturation magnetisation, boron substitution in MnFe(P,Si) materials has recently been reported to be an ideal parameter to reach promising magnetocaloric performances: ΔS ≈ 10 Jkg{sup −1} K{sup −1} and cyclic ΔT of 2.6 K (and more) at a moderate magnetic field of ΔB = 1 T. Additionally, an interesting aspect for applications is the improvement of the mechanical stability in B doped materials compared to the pristine MnFe(P,Si) compounds. These improved mechanical properties were initially supported by naked-eye inspection and the observation of a constant ΔT during a few thousands of magnetic cycles. (Guillou et al., 2014) Here, the evolution upon cycling of MnFe(P,Si,B) materials is studied in a more quantitative and systematic manner. For that purpose transformation temperatures, electrical resistivity, micro-hardness and the microstructure are tracked as a function of the thermal cycling across the FOT for three prototypical compositions in the MnFe(P,Si,B) system. It turns out this set of data confirms the initial finding that B substitution has a positive effect on the mechanical stability. The origin of this improvement is discussed, in particular in respect to the lattice parameter discontinuities at the phase transition.

  3. Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowustite in a shocked Martian meteorite.

    Science.gov (United States)

    Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo

    2011-04-12

    We report evidence for the natural dissociation of olivine in a shergottite at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa(34-41)) adjacent to or entrained in the shock melt vein and melt pockets of Martian meteorite olivine-phyric shergottite Dar al Gani 735 dissociated into (Mg,Fe)SiO(3) perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO(3) Pv and Mw have 50-100 nm in diameter, and lamellar (Mg,Fe)SiO(3) Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, K(Pv/Mw) = [FeO/MgO]/[FeO/MgO](Mw), between (Mg,Fe)SiO(3) Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700 °C at least.

  4. Transmission electron microscopy study on ion-beam-synthesized amorphous Fe-Si thin layers

    Science.gov (United States)

    Naito, Muneyuki; Ishimaru, Manabu; Hirotsu, Yoshihiko; Valdez, James A.; Sickafus, Kurt E.

    2005-12-01

    Ion-beam-synthesized amorphous Fe-Si thin layers have been characterized using transmission electron microscopy (TEM) in combination with imaging plate techniques. Si single crystals with a (111) orientation were irradiated with 120keV Fe+ ions to a fluence of 4.0×1017cm-2 at cryogenic temperature (120K). Cross-sectional TEM observations indicated the formation of an amorphous bilayer on the topmost layer of the Si substrate. It was found that the upper layer is an amorphous Fe-Si with the composition, in terms of atomic ratio, of Fe /Si ˜1/2, while the lower one is an amorphous Si. Atomic pair-distribution functions extracted from microbeam electron diffraction patterns revealed that the nature of short-range order in amorphous Fe-Si thin layer can be well described by the atomic arrangements of crystalline iron silicides.

  5. Ab initio studies on the adsorption and implantation of Al and Fe to nitride materials

    Energy Technology Data Exchange (ETDEWEB)

    Riedl, H., E-mail: helmut.riedl@tuwien.ac.at [Christian Doppler Laboratory for Application Oriented Coating Development at the Institute of Materials Science and Technology, TU Wien, A-1040 Wien (Austria); Zálešák, J. [Erich Schmid Institute for Materials Science, Austria Academy of Science, A-8700 Leoben (Austria); Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Arndt, M. [Oerlikon Balzers, Oerlikon Surface Solutions AG, LI-9496 Balzers (Liechtenstein); Polcik, P. [Plansee Composite Materials GmbH, D-86983 Lechbruck am See (Germany); Holec, D. [Christian Doppler Laboratory for Application Oriented Coating Development at the Institute of Materials Science and Technology, TU Wien, A-1040 Wien (Austria); Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Mayrhofer, P. H. [Christian Doppler Laboratory for Application Oriented Coating Development at the Institute of Materials Science and Technology, TU Wien, A-1040 Wien (Austria); Institute of Materials Science and Technology, TU Wien, A-1040 Vienna (Austria)

    2015-09-28

    The formation of transfer material products on coated cutting and forming tools is a major failure mechanism leading to various sorts of wear. To describe the atomistic processes behind the formation of transfer materials, we use ab initio to study the adsorption energy as well as the implantation barrier of Al and Fe atoms for (001)-oriented surfaces of TiN, Ti{sub 0.50}Al{sub 0.50}N, Ti{sub 0.90}Si{sub 0.10}N, CrN, and Cr{sub 0.90}Si{sub 0.10}N. The interactions between additional atoms and nitride-surfaces are described for pure adhesion, considering no additional stresses, and for the implantation barrier. The latter, we simplified to the stress required to implant Al and Fe into sub-surface regions of the nitride material. The adsorption energies exhibit pronounced extrema at high-symmetry positions and are generally highest at nitrogen sites. Here, the binary nitrides are comparable to their ternary counterparts and the average adhesive energy is higher (more negative) on CrN than TiN based systems. Contrary, the implantation barrier for Al and Fe atoms is higher for the ternary systems Ti{sub 0.50}Al{sub 0.50}N, Ti{sub 0.90}Si{sub 0.10}N, and Cr{sub 0.90}Si{sub 0.10}N than for their binary counterparts TiN and CrN. Based on our results, we can conclude that TiN based systems outperform CrN based systems with respect to pure adhesion, while the Si-containing ternaries exhibit higher implantation barriers for Al and Fe atoms. The data obtained are important to understand the atomistic interaction of metal atoms with nitride-based materials, which is valid not just for machining operations but also for any combination such as interfaces between coatings and substrates or multilayer and phase arrangements themselves.

  6. Modelling grain growth in the presence of Zener drag: application for Fe-3% Si

    Science.gov (United States)

    Maazi, N.; Rouag, N.

    2001-09-01

    The presence of AlN and MnS inhibitors in Fe-3%Si sheets, grade Hi-B, permits the development of Goss texture by the sudden and rapid growth of small grains possessing a {110} orientation. This behaviour is not in good agreement with the classical laws of secondary recrystallization. In the present study, first the minimum critical radius of the grain which is susceptible to growth is determined in relation to orientation and grain size neighbourhood. Moreover, the necessity to define a maximum critical radius for the neighbourhood is established. Consideration of these two radii permits the exploration of possible growth sequences for small grains.

  7. On the structural and magnetic properties of R{sub 2}Fe{sub 17-x}(A,T){sub x} (R=rare earth; A=Al, Si, Ga; T=transition metal) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rama Rao, K.V.S. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Ehrenberg, H.; Fuess, H. [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Markandeyulu, G.; Murthy, V.S. [Dept. of Physics, Indian Inst. of Tech. Madras, Chennai (India); Varadaraju, U.V.; Venkatesan, M. [Indian Inst. of Tech., Madras (India). Materials Science Research Centre; Suresh, K.G. [Indian Inst. of Tech., Bombay (India). Dept. of Physics; Schmidt, P.C. [Technische Univ. Darmstadt (Germany). Inst. fuer Physikalische Chemie

    2002-02-16

    R{sub 2}Fe{sub 17} (R = rare earth) intermetallic compounds constitute one of the most important classes of materials identified as high-energy permanent magnet materials. They crystallize either in the rhombohedral Th{sub 2}Zn{sub 17} structure (for light R) or in the hexagonal Th{sub 2}Ni{sub 17} structure (for heavy R). In this article, we discuss the variations in the lattice parameters (unit cell volume), site occupancies and Curie temperature when non-transition and transition metals are substituted for Fe in R{sub 2}Fe{sub 17} compounds. (orig.)

  8. Fabric cutting application of FeAl-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Sklad, S.P. [University of Virginia, Charlottesville, VA 22905 (United States); Deevi, S.C. [Research, Development, and Engineering Center, Philip Morris USA, Richmond, VA 23234 (United States); Shih, H.-R. [Jackson State University, 1400 J.R. Lynch Street, Jackson, MS 39217 (United States)

    1998-12-31

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60) and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel. (orig.) 18 refs.

  9. Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al with low carbon steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Yin Yansheng; Ma Haijun

    2005-02-01

    The distribution of elements near the Fe3Al/Q235 diffusion bonding interface was computed by the diffusion equation as well as measured by means of EPMA. The results indicated close agreement between the two for iron and aluminium. Diffusion coefficient in the interface transition zone is larger than that in the Fe3Al and Q235 steel at the same temperature, which is favourable to elemental diffusion. The diffusion distance near the Fe3Al/Q235 interface increased with increasing heating temperature, , and the holding time, . The relation between the width of the interface transition zone, , and the holding time, , conformed to parabolic growth law: 2 = 4.8 × 104 exp(– 133/RT) ( – 0). The width of the interface transition zone does not increase significantly for holding times beyond 60 min.

  10. Preparation of SiCp/Al2O3-Al Composites by Directed Metal Oxidation

    Institute of Scientific and Technical Information of China (English)

    LIN Ying; YANG Hai-bo; WANG Fen; ZHU Jian-feng

    2006-01-01

    SiCp/Al2O3-Al composites were synthesized by means of direct metal oxidation method. The composition and microstructures of the composites were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and metallurgical microscope. The effects of technical parameters on the properties of the product were analyzed. The results indicate that the composite possesses a dense microstructure, composed of three interpenetrated phases. Of them, SiO2 layer prohibits the powdering of the composites; Mg promotes the wetting and infiltration of the system and Si restricts the interfacial reaction while improving the wetting ability between reinforcement and matrix.

  11. Mullite/SiAlON/alumina composites by infiltration processing

    Energy Technology Data Exchange (ETDEWEB)

    Albano, M.P.; Scian, A.N. [Centro de Tecnologia de Recursos Minerales y Ceramica, Buenos Aires (Argentina)

    1997-01-01

    The formation of mullite/SiAlON/alumina composites was studied by infiltrating a SiAlON/alumina-base composite with two different solutions, followed by thermal treatment. The base composite was prepared from a mixture of tabular Al{sub 2}O{sub 3} grains, fume SiO{sub 2}, and aluminum powders. The mixture was pressed into test bars and nitrided in a nitrogen-gas (N{sub 2}) atmosphere at 1,480 C. The infiltrants were prehydrolyzed ethyl polysilicate solution and ethyl polysilicate-aluminum nitrate solution. The composites were infiltrated under vacuum, cured at 100 C, and precalcined in air at 700 C. This infiltration process was repeated several times to produce bars that had been subjected to multiple infiltrations, then the bars were calcined in a N{sub 2} atmosphere at 1,480 C to obtain mullite/SiAlON/alumina composites. The infiltration process increased the percentage of nitrogenous crystalline and mullite phases in the matrix; therefore, a decrease of the composite microporosity was observed. The infiltration increased the mechanical strength of the composites. Of the two composites, the one produced using prehydrolyzed ethyl polysilicate as the infiltrant had a higher mechanical strength, before and after being subjected to a severe thermal shock.

  12. Microstructure and Hot Oxidation Resistance of SiMo Ductile Cast Irons Containing Si-Mo-Al

    Science.gov (United States)

    Ibrahim, Mervat M.; Nofal, Adel; Mourad, M. M.

    2016-12-01

    SiMo ductile cast irons are used as high-temperature materials in automotive components, because they are microstructurally stable at high operating temperatures. The effect of different amounts of Si and Mo as well as the addition of 3 wt pct Al on the microstructure, high-temperature oxidation, and mechanical properties of SiMo ductile cast iron was studied. Dilatometric measurements of SiMo ductile iron exhibited obvious differences in the transformation temperature A 1 due to presence of Al and the increase of Si. The microstructure of the SiMo alloys without Al addition showed outstanding nodularity and uniform nodule distribution. However, by adding 3 wt pct Al to low Si-SiMo ductile iron, some compacted graphite was observed. The results of oxidation experiments indicated that high Si-SiMo ductile iron containing 4 and 4.9 wt pct Si had superior resistance to lower Si-SiMo and SiMo ductile iron containing 3 wt pct Al. The results showed also that with increasing Si up to 4.9 wt pct or by replacing a part of Si with 3 wt pct Al, tensile strength increased while elongation and impact toughness decreased.

  13. Structure and magnetocaloric effect in melt-spun La(Fe,Si)13 and MnFePGe compounds

    Institute of Scientific and Technical Information of China (English)

    YAN Aru

    2006-01-01

    The magnetocaloric properties of melt-spun La(Fe,Si) 13 and MnFePGe compounds were investigated. Very large value of magnetic entropy change |ΔS|=31 and 35.4J·(kg·K)-1 under 5 T were obtained at 201 K in LaFe11.8Si1.2 melt-spun ribbons and at around 317 K in Mn1.1Fe0.9P0.76Ge0.24 melt-spun ribbons, respectively. The large magnetocaloric effect results from a more homogenous element distribution related to the very high cooling rate during melt-spinning. The excellent MCE properties, the low materials cost and the accelerated aging regime make the melt-spun-type La(Fe,Si)13 and MnFePGe materials an excellent candidate for magnetic refrigerant applications.

  14. Directional alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayer with high anisotropy field above 500 Oe.

    Science.gov (United States)

    Hirata, Ken-Ichiro; Gomi, Shunsuke; Nakagawa, Shigeki

    2011-03-01

    In-plane magnetic anisotropy and crystal structure of FeCoB layer on Si/NiFe/Ru underlayer were investigated by using X-Ray Diffraction (XRD) measurement. A pole-figure measurement of XRD showed directionally tilted alignment of FeCo crystallites in Si/NiFe/Ru/FeCoB multilayered film with high in-plane anisotropy field H(k) but no directional alignment was found in FeCoB single layered film. The higher H(k) appeared in the Si/NiFe/Ru/FeCoB multilayered configuration with the thicker FeCoB layer. Since Ru crystallites in a multiunderlayer configuration exhibited no directional alignment, the surface structure of underlayer should be no main reason for the directional alignment of FeCo crystallites deposited on it. The dependence of hickness of FeCoB layer in Si/NiFe/Ru/FeCoB film on H(k) indicated that the in-plane magnetic anisotropy is caused by not only the structure of Ru underlayer but also oblique incidence effect of sputtered particles, which is attained in configuration of Facing Targets Sputtering (FTS) system. From these experimental results, remarkably high H(k) of 540 Oe was obtained.

  15. Influence of Al-Si Master Alloy on Microstructure and Property of Al-Mg-Si Alloy%Al-Si中间合金对Al-Mg-Si系合金组织性能的影响

    Institute of Scientific and Technical Information of China (English)

    张建新; 高爱华

    2011-01-01

    The effects of Al-Si master alloy on microstructure and property of Al-Mg-Si system alloy were studied, and the mechanism of Si in influencing the microstructure and property of the alloy was discussed.The results indicate that Al-Si master alloy with 18% Si can refine the microstmcture of cast aluminum alloy and improve the mechanical properties.The corrosion resistance of Al-Mg-Si system alloy decreases with the increase of Si content in Al-Si master alloy, the corrosion resistance significantly decreases when more than 18%Si in Al-Si master alloy.The tensile strength of Al-Mg-Si system alloy improves with the increase of Si content in Al-Si master alloy, the tensile strength declines when Si content is above 20 %.%研究了Al-Si中间合金对Al-Mg-Si系铝合金组织性能的影响,并分析了Si的作用机理.结果表明:含18%Si的Al-Si中间合金对合金的铸态组织作用效果较好,并能合理改善材料的力学性能;随Al-Si中间合金中Si含量的增加,Al-Mg-Si系合金的耐腐蚀性下降,Si含量高于18%后下降显著;Al-Si中间合金中Si含量的增加,能提高Al-Mg-Si系合金的抗拉强度,Si含量高于20%后其抗拉强度开始下降.

  16. A nano-Si/FeSi2Ti hetero-structure with structural stability for highly reversible lithium storage

    Science.gov (United States)

    Jo, Mi Ru; Heo, Yoon-Uk; Lee, Yoon Cheol; Kang, Yong-Mook

    2013-12-01

    A nano-Si/FeSi2Ti hetero-structure has been synthesized for highly reversible Li-ion batteries by using a simple melt-spinning method. We demonstrate that this composite has a very peculiar core/shell structure in which the FeSi2Ti alloy plays various pivotal roles as a mechanically supporting backbone and as an electronic pathway for the active Si attached to its surface, and is responsible for the altered electrochemical reactions with relatively small volume expansion routes. The FeSi2Ti matrix significantly contributes to not only the stabilization of cyclic retention, but also the enhancement of conductivity, as well as a high rate capability unprecedented in research on Si-based anodes. This achievement demonstrates the potency of this novel hybrid design for electrode materials for energy storage.A nano-Si/FeSi2Ti hetero-structure has been synthesized for highly reversible Li-ion batteries by using a simple melt-spinning method. We demonstrate that this composite has a very peculiar core/shell structure in which the FeSi2Ti alloy plays various pivotal roles as a mechanically supporting backbone and as an electronic pathway for the active Si attached to its surface, and is responsible for the altered electrochemical reactions with relatively small volume expansion routes. The FeSi2Ti matrix significantly contributes to not only the stabilization of cyclic retention, but also the enhancement of conductivity, as well as a high rate capability unprecedented in research on Si-based anodes. This achievement demonstrates the potency of this novel hybrid design for electrode materials for energy storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04954j

  17. CARACTERIZACIÓN TÉRMICA Y ESPECTROSCÓPICA DE ARCILLAS PILARIZADAS CON SOLUCIONES POLIHIDROXOCATIÓNICAS DE Al, Ce, Fe.

    Directory of Open Access Journals (Sweden)

    José Carriazo

    2009-04-01

    Full Text Available Este trabajo presenta la caracterización por espectroscopía infrarroja (IR, análisis termogravimétrico (TGA, análisis térmico diferencial (DTA y espectroscopía de resonancia magnética nuclear  (RMN de 29Si y RMN de 27Al de un conjunto de arcillas pilarizadas con soluciones polihidroxocatiónicas de Al, Al-Fe, Al-Ce o Al-Ce-Fe. Los análisis de TGA-DTA indican un efecto térmico favorable (mayor estabilidad térmica con la adición de Ce, Fe o Ce-Fe. Los resultados de IR y de RMN de 29Si revelan una probable formación de enlace entre el pilar de alúmina y la capa tetraédrica de SiO4 de la arcilla, mientras que la RMN de 27Al no muestra evidencias de reemplazo isomórfico de Fe o Ce en los pilares de alúmina incorporados. Igualmente y por IR, no se observan diferencias estructurales entre los sólidos pilarizados con Al y los pilarizados con Al-Ce, indicando que el cerio posiblemente se incorpora de manera independiente al pilar de alúmina.  

  18. Optical investigations of AlSi-SiC composites subjected to laser CO 2 annealing

    Science.gov (United States)

    Jaglarz, Janusz; Grabowski, Andrzej

    2010-10-01

    The optical study of the AlSi/SiC composite materials before and after laser annealing has been performed. They concerned total and diffuse reflectance measurements obtained by the means of integrating sphere in the spectral range 250-2500 nm, measurements of intensity of scattered light as a function of scattering angle ( BRDF method) and ellipsometric measurements performed in the range 190-1700 nm. For determination of optical constants, the Kramers-Krönig dispersion relation has been applied. Obtained results had great differences of optical properties alloys before and after laser annealing. For investigated composites roughness and correlation lengths of studied surfaces have been determined. Moreover, optical measurements allowed concluding the light scattering being a result of interaction of light with surface topography and material scattering appeared due to variation of optical constants on surfaces of AlSi/SiC composites.

  19. Enhancement of the Si p-n diode NIR photoresponse by embedding β-FeSi2 nanocrystallites

    Science.gov (United States)

    Shevlyagin, A. V.; Goroshko, D. L.; Chusovitin, E. A.; Galkin, K. N.; Galkin, N. G.; Gutakovskii, A. K.

    2015-10-01

    By using solid phase epitaxy of thin Fe films and molecular beam epitaxy of Si, a p+-Si/p-Si/β-FeSi2 nanocrystallites/n-Si(111) diode structure was fabricated. Transmission electron microscopy data confirmed a well-defined multilayered structure with embedded nanocrystallites of two typical sizes: 3-4 and 15-20 nm, and almost coherent epitaxy of the nanocrystallites with the Si matrix. The diode at zero bias conditions exhibited a current responsivity of 1.7 mA/W, an external quantum efficiency of about 0.2%, and a specific detectivity of 1.2 × 109 cm × Hz1/2/W at a wavelength of 1300 nm at room temperature. In the avalanche mode, the responsivity reached up to 20 mA/W (2% in terms of efficiency) with a value of avalanche gain equal to 5. The data obtained indicate that embedding of β-FeSi2 nanocrystallites into the depletion region of the Si p-n junction results in expansion of the spectral sensitivity up to 1600 nm and an increase of the photoresponse by more than two orders of magnitude in comparison with a conventional Si p-n junction. Thereby, fabricated structure combines advantage of the silicon photodiode functionality and simplicity with near infrared light detection capability of β-FeSi2.

  20. Comparison of the microstructure and magnetic properties of strontium hexaferrite films deposited on Al2O3(0001), Si(100)/Pt(111) and Si(100) substrates by pulsed laser technique

    Science.gov (United States)

    Masoudpanah, S. M.; Seyyed Ebrahimi, S. A.; Ong, C. K.

    2014-01-01

    Strontium hexaferrite SrFe12O19 (SrM) films have been deposited on Al2O3(0001), Si(100)/Pt(111) and Si(100) substrates. The (001) oriented SrFe12O19 films deposited on the Al2O3(0001) and Si(100)/Pt(111) substrates have been confirmed by X-ray diffraction patterns. Higher coercivity in perpendicular direction rather than in-plane direction of the SrM/Al2O3(0001) and SrM/Pt(111) films showed that the films had perpendicular magnetic anisotropy. The (001) orientation and similar microstructure and magnetic properties of the SrM/Al2O3(0001) and SrM/Pt(111) films show the Al2O3(0001) substrate can be replaced by the Si(100)/Pt(111) substrate.

  1. Corrosion of Mechanically Alloyed Nanostructured FeAl Intermetallic Powders

    Directory of Open Access Journals (Sweden)

    A. Torres-Islas

    2012-01-01

    Full Text Available The corrosion behavior of the Fe40Al60 nanostructured intermetallic composition was studied using electrochemical impedance spectroscopy (EIS and linear polarization resistance (LPR techniques with an innovative electrochemical cell arrangement. The Fe40Al60 (% at intermetallic composition was obtained by mechanical alloying using elemental powders of Fe (99.99% and Al (99.99%. All electrochemical testing was carried out in Fe40Al60 particles that were in water with different pH values. Temperature and test time were also varied. The experimental data was analyzed as an indicator of the monitoring of the particle corrosion current density icorr. Different oxide types that were formed at surface particle were found. These oxides promote two types of surface corrosion mechanisms: (i diffusion and (ii charge transfer mechanisms, which are a function of icorr behavior of the solution, pH, temperature, and test time. The intermetallic was characterized before and after each test by transmission electron microscopy. Furthermore, the results show that at the surface particles uniform corrosion takes place. These results confirm that it is possible to sense the nanoparticle corrosion behavior by EIS and LPR conventional electrochemical techniques.

  2. 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

    formation of more stable UAl3 within the diffusion layer [14]. In addition, Si will not notably influence the reactor neutronics due to its low absorption cross section for thermal neutrons of σabs = 0.24 barn. Aluminum has σabs = 0.23 barn.Williams [28], Bierlein [29], Green [30] and de Luca [31] showed the first time in the 1950s that alloying Aluminum with some Silicon reduces the Uranium-Aluminum diffusion kinetics in can-type fuel elements. However, up to now uncertainties remained about the most promising Si concentration and the involved mechanisms.Ground powder - possibility 4 - introduces a high density of defects like dislocations, oxide layers and impurities into UMo grains. Fuel prepared with this kind of powder exhibits a larger porosity. It may also be combined with an AlSi matrix. As a consequence, the degree of swelling due to high-burn up is reduced compared to fuel with atomized powder [5,6,25].This study focuses on the metallurgical characterization of as-fabricated samples prepared with ground UMo and UMoX (X = Ti, Nb, Pt) powders and atomized UMo powder. The influence of some Si into the Al matrix and the presence of oxide layers on the UMo is discussed. Details of the differences of samples with ground UMo from atomized UMo will be discussed.The examined samples originate from non-irradiated spare fuel plates from the IRIS-TUM irradiation campaign [5,6]. The samples containing ground UMoX powders and atomized UMo powders with Si addition into the matrix have been produced for this study [32]. Powder mixing: The UMo powder is mixed with Al powder. Compact production: UMo-Al powder is poured into a mould and undergoes compaction under large force. Plate-processing: An AlFeNi frame is placed on an AlFeNi plate and the UMo-Al compact is placed into the frame. Afterwards it is covered with a second AlFeNi plate. This assembly is hot-rolled to reduce the total thickness to 1.4 mm. Subsequently, a blister test (1-2 h at 400-450 °C) ensures that the

  3. Quick preparation and thermal transport properties of nanostructured β-FeSi2 bulk material

    Institute of Scientific and Technical Information of China (English)

    Li Han; Tang Xin-Feng; Cao Wei-Qiang; Zhang Qing-Jie

    2009-01-01

    This paper reports that the nanostructured β-FeSi2 bulk materials are prepared by a new synthesis process by combining melt spinning (MS) and subsequent spark plasma sintering (SPS). It investigates the influence of linear speed of the rolling copper wheel, injection pressure and SPS regime on microstructure and phase composition of the rapidly solidified ribbons after MS and bulk production respectively, and discusses the effects of the microstructure on Sis2 and ε-FeSi) in the rapidly solidified ribbons;thermal transport properties. There are two crystalline phases (α-Fe the crystal grains become smaller when the cooling rate increases (the 20 nm minimum crystal of ε-FeSi is obtained). Having been sintered for 1 min above 1123K and annealed for 5min at 923K, the single-phase nanostructured β- FeSi2 bulk materials with 200-500 nm grain size and 98% relative density are obtained. The microstructure of β-FeSi2has great effect on thermal transport properties. With decreasing sintering temperature, the grain size decreases, the thermal conductivity of β-FeSi2is reduced remarkably. The thermal conductivity of β-FeSi decreases notably (reduced 72% at room temperature) in comparison with the β-FeSi2prepared by traditional casting method.

  4. Development of ODS-Fe{sub 3}Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; McKamey, C.G. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    The overall goal of this program is to develop an oxide dispersion-strengthened (ODS) version of Fe{sub 3}Al that has sufficient creep strength and resistance to oxidation at temperatures in the range 1000 to 1200 C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The main areas being addressed are: (a) alloy processing to achieve the desired alloy grain size and shape, and (b) optimization of the oxidation behavior to provide increased service life compared to semi-commercial ODS-FeCrAl alloys intended for the same applications. The recent studies have focused on mechanically-alloyed powder from a commercial alloy vendor. These starting alloy powders were very clean in terms of oxygen content compared to ORNL-produced powders, but contained similar levels of carbon picked up during the milling process. The specific environment used in milling the powder appears to exert a considerable influence on the post-consolidation recrystallization behavior of the alloy. A milling environment which produced powder particles having a high surface carbon content resulted in a consolidated alloy which readily recrystallized, whereas powder with a low surface carbon level after milling resulted in no recrystallization even at 1380 C. A feature of these alloys was the appearance of voids or porosity after the recrystallization anneal, as had been found with ORNL-produced alloys. Adjustment of the recrystallization parameters did not reveal any range of conditions where recrystallization could be accomplished without the formation of voids. Initial creep tests of specimens of the recrystallized alloys indicated a significant increase in creep strength compared to cast or wrought Fe{sub 3}Al, but the specimens failed prematurely by a mechanism that involved brittle fracture of one of the two grains in the test cross section, followed by ductile fracture of the remaining grain. The reasons for this behavior are not yet understood. The

  5. Study of microstructure and magnetic properties of L10 FePt/SiO2 thin films

    Directory of Open Access Journals (Sweden)

    Giannopoulos G.

    2014-07-01

    Full Text Available Achieving magnetic recording densities in excess of 1Tbit/in2 requires not only perpendicular media with anisotropies larger than 7 MJ/m3, making FePt alloys an ideal choice, but also a narrow distribution below 10 nm for a reduced S/N ratio. Such grain size reduction and shape control are crucial parameters for high density magnetic recording, along with high thermal stability. Previous work has shown that the L10 FePt grain size can be controlled by alloying FePt with materials such as C, Ag, and insulators such as AlOx, MgO. Au and Al2O3 also act to segregate and magnetically decouple the FePt grains. Better results were obtained with C with respect to the uniformity of grains and SiO2 with respect to the shape. We present our results on co-sputtering FePt with C or SiO2 (up to 30 vol % on MgO (001 single crystal substrates at 350 and 500 oC. With C or SiO2 addition we achieved grain size reduction, shape control and isolated structure formation, producing continuous films with high uniformity and a narrow grain size distribution. These additions thus allow us to simultaneously control the coercivity and the S/N ratio. We also will report structural and microstructural properties.

  6. Fabrication Of Al 2024/SiC Nanocomposite with Al and Cu Pure Coatings

    Directory of Open Access Journals (Sweden)

    P. Melali

    2015-06-01

    Full Text Available Composites find an important place as new advanced materials in last decades; those especially produced with nanoparticles reinforcements, attracts researchers and a number of researches were executed on this topic. In this study, Al-base 2024 alloy composites reinforced with SiC nanoparticles were fabricated and the effects of two different coating materials were investigated. Coatings were pure Al and Cu powder with constant grain particle size. The results show that the Al coating has impacts on grain size and the interface layer between reinforcement and matrix. The mechanism of formation of interface layer between SiC nanoparticles and the Al-base 2024 matrix with reinforced with Cu coated SiC particles is quite different.

  7. Study of the Al-Si-X system by different cooling rates and heat treatment

    Directory of Open Access Journals (Sweden)

    Miguel Angel Suarez

    2012-10-01

    Full Text Available The solidification behavior of the Al-12.6% Si (A1, the hypereutectic Al-20%Si (A2 and the Al-20%Si-1.5% Fe-0.5%Mn (A3 (in wt. (% alloys, at different cooling rates is reported and discussed. The cooling rates ranged between 0.93 °C/s and 190 °C/s when cast in sand and copper wedge-shaped molds, respectively. A spheroidization heat treatment was carried out to the alloys in the as-cast condition at 540 °C for 11 hours and quench in water with a subsequent heat treatment at 170 °C for 5 hours with the purpose of improving the mechanical properties. The samples were characterized by optical microscopy, scanning electron microscopy and mechanically by tensile test, in order to evaluate the response of the heat treatment on the different starting microstructures and mechanical properties. It was found that alloys cooled at rates greater than 10.8 °C/s had a smaller particle size and better distribution, also showed a greater response to spheroidization heat treatment of all silicon (Si phases. The spheroidization heat treatment caused an increase in the ultimate tensile stress (UTS and elongation when compared with the alloys in the as-cast condition. The highest UTS value of 174 MPa was obtained for the (A1 alloy.

  8. Influence of the permeability of networked primary Si on the ejection of hypereutectic Al-Si melts by centrifugation

    Science.gov (United States)

    Youn, Ji Won; Jeon, Je-Beom; Park, Jin Man; Seo, Seok Yong; Lim, Jeon Taik; Kim, Suk Jun; Kim, Ki Young

    2017-02-01

    The separation of high purity Si for solar cells from Al-Si alloy melt in the mushy zone was investigated using an advanced centrifugal technique. The efficiency of separating Si, based on the weight ratio of separated Si to Si in alloy melt, was maximized by optimizing the permeability of a porous structure of Si (Si foam.) For the optimization of the permeability, two fundamental microstructure variables, size and the solid fraction of primary Si platelets, were controlled by adjusting the Si content in the melts and the rotation start temperature, respectively. The best separation efficiency (48.3% with 3N purity) was achieved when Si content in melt was 24% and the solid fraction was 8.7%. The melt with 23% Si led to a higher separation efficiency (69.8%) for a solid fraction of 10.4%, but Al sandwiched between the Si platelets resulted in a decrease in the purity to 2N.

  9. Production of Al-Si-SiCp cast composites by injection of low-energy ball-milled Al-SiCp powder into the melt

    Science.gov (United States)

    Ghahremanian, Mohsen; Niroumand, Behzad; Panjepour, Masoud

    2012-02-01

    Al-7wt%Si-10wt%SiCp composite with uniformly distributed reinforcement particles with the average size of about 3 microns was produced by a special compocasting method in which the reinforcement was injected into the melt in the form of particulate Al-SiCp composite powder instead of SiCp. The effects of the reinforcement addition form, the solid fraction of primary alpha-aluminum particles at pouring, and stirring speed on the incorporation of reinforcement particles into the matrix were investigated. Injection of particulate Al-SiCp composite led to improved incorporation and dispersion and reduced size of SiCp. Casting from the semisolid state significantly improved the incorporation of SiCp into the matrix. The optimal solid fraction of primary alpha-aluminum particles to achieve a reasonable combination of reinforcement incorporation and fluidity of the composite slurry was recognized to be about 0.1. The incorporation of SiCp was improved by increasing the stirring speed up to 500 rpm and then gradually decreased.

  10. Corrosion performance of Fe-Cr-Al and Fe aluminide alloys in complex gas environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K. [Argonne National Lab., IL (United States); Johnson, R.N. [Pacific Northwest Lab., Richland, WA (United States)

    1995-05-01

    Alumina-forming structural alloys can offer superior resistance to corrosion in the presence of sulfur-containing environments, which are prevalent in coal-fired fossil energy systems. Further, Fe aluminides are being developed for use as structural materials and/or cladding alloys in these systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve their engineering ductility. In addition, surface coatings of Fe aluminide are being developed to impart corrosion resistance to structural alloys. This paper describes results from an ongoing program that is evaluating the corrosion performance of alumina-forming structural alloys, Fe-Al and Fe aluminide bulk alloys, and Fe aluminide coatings in environments typical of coal-gasification and combustion atmospheres. Experiments were conducted at 650-1000{degrees}C in simulated oxygen/sulfur gas mixtures. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HCl-containing gases. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales and to determine the modes of corrosion degradation that occur in the materials when they are exposed to S/Cl-containing gaseous environments.

  11. Formation and stability of Al-Nd and Al-Nd-Fe metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Battezzati, Livio (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy)); Baricco, Marcello (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy)); Antonione, Carlo (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy))

    1994-07-01

    Partially amorphous Al[sub 91]Nd[sub 9] and Al[sub 86]Nd[sub 9]Fe[sub 5] ribbons were prepared by melt spinning. Metastable crystalline phases were found in both alloys. Complete amorphization of Al[sub 86]Nd[sub 9]Fe[sub 5] was also achieved. Crystallization was monitored by differential scanning calorimetry (DSC). It occurs in two stages at 440 and 510 K for Al[sub 91]Nd[sub 9]. Al[sub 86]Nd[sub 9]Fe[sub 5] presented a eutectic crystallization at 550 K. Microscopy observations, combined with Johnson-Mehl-Avrami (JMA) analyses performed in isothermal DSC traces, showed that Al[sub 91]Nd[sub 9] transforms via growth on pre-existing crystals. Al[sub 86]Nd[sub 9]Fe[sub 5] transformed via heterogeneous nucleation on sites unevenly distributed through the ribbon. The fitting of isothermal peaks by means of the JMA equation was less satisfactory. The limits of this approach are discussed. ((orig.))

  12. Optimization of Electrical Discharge Machining Characteristics of SiCp/LM25 Al Composites Using Goal Programming

    Institute of Scientific and Technical Information of China (English)

    R.Karthikeyan; S. Raju; R.S.Naagarazan; B. C. Pai

    2001-01-01

    In the present study an effort has been made to optimize the machining conditions for electric discharge machining of LM25 Al (7 Si, 0.33 Mg, 0.3 Mn, 0.5 Fe, 0.1 Cu, 0.1 Ni,.2 Ti) reinforced with green bonded SiC particles with approximate size of 25 μm. Polynomial models were developed for the various EDM characteristics such as metal removal rate, tool wear rate and surface roughness in terms of the process parameters such as volume fraction of SiC, current and pulse time. The models were used to optimize the EDM characteristics using nonlinear goal programming.

  13. Morphology ofα-Si3N4 in Fe-Si3N4 prepared via flash combustion

    Institute of Scientific and Technical Information of China (English)

    Bin Li; Jun-hong Chen; Jin-dong Su; Ming-wei Yan; Jia-lin Sun; Yong Li

    2015-01-01

    The state and formation mechanism ofα-Si3N4 in Fe–Si3N4 prepared by flash combustion were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate thatα-Si3N4 crystals exist only in the Fe–Si3N4 dense areas. When FeSi75 particles react with N2, which generates substantial heat, a large number of Si solid particles evaporate. The prod-uct between Si gas and N2 is a mixture ofα-Si3N4 andβ-Si3N4. At the later stage of the flash combustion process,α-Si3N4 crystals dissolve and reprecipitate asβ-Si3N4 and theβ-Si3N4 crystals grow outward from the dense areas in the product pool. As the temperature decreases, the α-Si3N4 crystals cool before transforming into β-Si3N4 crystals in the dense areas of Fe–Si3N4. The phase composition of flash-combustion-synthesized Fe–Si3N4 is controllable through manipulation of the gas-phase reaction in the early stage and theα→βtrans-formation in the later stage.

  14. Study of Microwave Absorbing Performances of Nanometer Fe-Al Solid solution

    Institute of Scientific and Technical Information of China (English)

    Xiaohui Wang; Xiaoping Liang; Shaobo Xin

    2006-01-01

    In this paper, Fe-Al solid solution was prepared by mechanical alloying technology, and Fe-Al powder was dispersed into unsaturated polyester (UP) with different contents as absorber to form mixture Fe-Al-UP. The results indicate that the alloying process is almost accomplished and most of the particles are nanometer. Meanwhile, the microwave absorbability of Fe-Al-UP samples in frequency from 0.3 MHz to 1.5 GHz was studied. The results indicate that the more the absorber, the better the absorbing property. The absorbing property of Fe-50Al-UP was slightly higher than Fe-28Al-UP.

  15. Mechanical milling of Fe3O4/SiO2: Formation of an amorphous Fe(II)-Si-O-containing phase

    DEFF Research Database (Denmark)

    Koch, C.B.; Jiang, Jianzhong; Mørup, Steen

    1999-01-01

    The product of ball milling of magnetite and amorphous silica (40 mole% Fe3O4 in SiO2) for an extended period of time (800 h) in a closed vial, has been investigated by Mossbauer spectroscopy, X-ray diffraction and infrared spectroscopy. It is found that the milling induces extensive reduction...... of Fe(III). The material constitutes a mixture of ultrafine Fe-rich spinel particles (magnetite/maghemite) and ail amorphous Fe(II)-containing silicate with a magnetic transition temperature of approximately 25 K. The amorphous phase has a rather high Fe content and is distinctly differenct from...

  16. Properties of magnetocaloric La(Fe,Co,Si)13 produced by powder metallurgy

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl; Kuhn, Luise Theil; Bahl, Christian Robert Haffenden;

    2010-01-01

    We present a comprehensive study of the magnetocaloric materials series La(Fe1−xCox)11.9Si1.1 with 0.055......We present a comprehensive study of the magnetocaloric materials series La(Fe1−xCox)11.9Si1.1 with 0.055...

  17. Infrared spectroscopic study of phonons coupled to charge excitations in FeSi

    NARCIS (Netherlands)

    Damascelli, A.; Schulte, K. Van der; Marel, D. van der; Menovsky, A. A.

    1997-01-01

    From an investigation of the optical conductivity of FeSi single crystals using Fourier-transform infrared spectroscopy in the frequency range from 30 to 20 000 cm-l we conclude that the transverse effective charge of the Fe and Si ions is approximately 4e. Of the five optical phonons that are allow

  18. Short-range Ferromagnetism in Alloy Ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    DEFF Research Database (Denmark)

    Thanh, P. Q.; Hoa, N. Q.; Chau, N.;

    2014-01-01

    We have studied the magnetic properties of two amorphous alloy ribbons Fe72Cr6Si4Nb5B12Ag1 (FCSNB-Ag) and Fe72Cr6Si4Nb5B12Cu1 (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization (M) measurements for various temperatures (T) and magnetic fields (H) indicate that ferromagnetic...

  19. Development of Si3N4/Al composite by pressureless melt infiltration

    Institute of Scientific and Technical Information of China (English)

    Akhtar Farid; GUO Shi-ju

    2006-01-01

    Pressureless infiltration process to synthesize Si3N4/Al composite was investigated. Al-2%Mg alloy was infiltrated into Si3N4 and Si3N4 containing 10% Al2O3 preforms in the atmosphere of nitrogen. It is possible to infiltrate Al-2%Mg alloy in Si3N4 and Si3N4 containing 10% Al2O3 preforms. The growth of the dense composite of useful thickness was facilitated by the presence of magnesium powder at the interface and by flowing nitrogen. During infiltration Si3N4 reacted with aluminium to form Si and AlN,the growth of composite was found to proceed in two ways, depending on the Al2O3 content in the initial preform. Firstly, preform without Al2O3 content gives rise to AlN, Al3.27Si0.47 and Al type phases after infiltration. Secondly, perform with 10% Al2O3 content gives rise to AlN-Al2O3 solid solution phase (AlON), MgAl2O4, Al and Si type phases. AlON phase was only present in composite,containing 10% Al2O3 in the Si3N4 preforms before infiltration.

  20. Giant electric field control of magnetism and narrow ferromagnetic resonance linewidth in FeCoSiB/Si/SiO2/PMN-PT multiferroic heterostructures

    Science.gov (United States)

    Gao, Y.; Wang, X.; Xie, L.; Hu, Z.; Lin, H.; Zhou, Z.; Nan, T.; Yang, X.; Howe, B. M.; Jones, J. G.; Brown, G. J.; Sun, N. X.

    2016-06-01

    It has been challenging to achieve combined strong magnetoelectric coupling and narrow ferromagnetic resonance (FMR) linewidth in multiferroic heterostructures. Electric field induced large effective field of 175 Oe and narrow FMR linewidth of 40 Oe were observed in FeCoSiB/Si/SiO2/PMN-PT heterostructures with substrate clamping effect minimized through removing the Si substrate. As a comparison, FeCoSiB/PMN-PT heterostructures with FeCoSiB film directly deposited on PMN-PT showed a comparable voltage induced effective magnetic field but a significantly larger FMR linewidth of 283 Oe. These multiferroic heterostructures exhibiting combined giant magnetoelectric coupling and narrow ferromagnetic resonance linewidth offer great opportunities for integrated voltage tunable RF magnetic devices.

  1. Precipitation Sequence of a SiC Particle Reinforced Al-Mg-Si Alloy Composite

    Science.gov (United States)

    Shen, Rujuan; Wang, Yihan; Guo, Baisong; Song, Min

    2016-10-01

    In this study, the precipitation sequence of a 5 vol.% SiC particles reinforced Al-1.12 wt.%Mg-0.77 wt.%Si alloy composite fabricated by traditional powder metallurgy method was investigated by transmission electron microscopy and hardness measurements. The results indicated that the addition of SiC reinforcements not only suppresses the initial aging stage but also influences the subsequent precipitates. The precipitation sequence of the composite aged at 175 °C can be described as: Guinier-Preston (G.P.) zone → β″ → β' → B', which was confirmed by high-resolution transmission electron microscopy. This work might provide the guidance for the design and fabrication of hardenable automobile body sheet by Al-based composites with enhanced mechanical properties.

  2. Precipitation Sequence of a SiC Particle Reinforced Al-Mg-Si Alloy Composite

    Science.gov (United States)

    Shen, Rujuan; Wang, Yihan; Guo, Baisong; Song, Min

    2016-11-01

    In this study, the precipitation sequence of a 5 vol.% SiC particles reinforced Al-1.12 wt.%Mg-0.77 wt.%Si alloy composite fabricated by traditional powder metallurgy method was investigated by transmission electron microscopy and hardness measurements. The results indicated that the addition of SiC reinforcements not only suppresses the initial aging stage but also influences the subsequent precipitates. The precipitation sequence of the composite aged at 175 °C can be described as: Guinier-Preston (G.P.) zone → β″ → β' → B', which was confirmed by high-resolution transmission electron microscopy. This work might provide the guidance for the design and fabrication of hardenable automobile body sheet by Al-based composites with enhanced mechanical properties.

  3. Microstructures of worn surface and wear debris of as-cast Al-17Si-xLa alloys under unlubricated conditions

    Institute of Scientific and Technical Information of China (English)

    易宏坤; 张荻; 范同祥; 吕维洁

    2003-01-01

    The tribological characteristics of hypereutectic Al-17Si-xLa alloys against heat-treated GCr15 bearing steel under unlubricated conditions were investigated using a block-on-ring type wear testing apparatus in air at room temperature. Microstructures and chemical compositions of worn surface and wear debris were characterized by means of SEM with EDS and XRD patterns. XRD results show that wear behaviors of Al-17Si-xLa alloys are similar and the typical worn surface is characterized by smooth region and crater region. The mechanically mixed layer (MML) and the wear debris are very similar in microstructures and chemical compositions, both containing the fine equiaxed aggregates and large plates and blocks from the both sliding counterparts (α(Al) and α-Fe) and some reaction products (ternary oxides, I.e. Al-Fe-O and Fe-Si-O).

  4. Effect of Si on the reversibility of stress-induced martensite in Fe-Mn-Si shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stanford, N. [Centre for Material and Fibre Innovation, Deakin University, Geelong, Victoria 3217 (Australia); Dunne, D.P., E-mail: druce_dunne@uow.edu.au [Faculty of Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2010-12-15

    Fe-Mn-Si is a well-characterized ternary shape memory alloy. Research on this alloy has consistently shown that the addition of 5-6 wt.% Si is desirable to enhance the reversibility of stress-induced martensite vis-a-vis shape memory. This paper examines the effect of Si on the morphology and the crystallography of the martensite in the Fe-Mn-Si system. It is concluded that the addition of Si increases the c/a ratio of the martensite, reduces the transformation volume change and decreases the atomic spacing difference between the parallel close-packed directions in the austenite-martensite interface (habit) plane. It is proposed that, in addition to austenite strengthening, Si enhances reversibility by reducing the volume change and the interfacial atomic mismatch between the martensite and the austenite. Although shape memory is improved, transformation reversibility remains limited by the necessary misfit dislocations that accommodate the atomic spacing differences in the interface.

  5. Wettability of AlSi5Mg on Spodumene

    Science.gov (United States)

    Fankhänel, Beate; Stelter, Michael; Voigt, Claudia; Aneziris, Christos G.

    2015-02-01

    The development of new filters for the aluminum industry requires investigations on the wettability of aluminum and its alloys on novel filter materials. The requested filter effects require not only an adequate wetting but also information about the interaction between the filter material and the metal. In the present work the wettability of an AlSi5Mg alloy on spodumene (LiAl[Si2O6]) containing substrates is investigated using the sessile drop technique. These measurements were carried out at 1223 K (950 °C) under vacuum. The spodumene-based substrates showed a completely different wetting behavior compared with an alumina substrate. The contact angel reduced more quickly and leveled out at a lower value (75 ± 2 deg) than in case of a pure alumina substrate (90 ± 1 deg). The reason for this behavior is a reaction between the LiAl(Si2O6) and the alloy droplet which supported deoxidation and formed a silica-rich reaction layer at the droplet/substrate interface.

  6. Effect of Mg on microstructures and properties of Al-Mg-Si-Cu aluminium alloys for automotive body sheets

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; SONG Wen-ju; ZHAO Gang; LIU Chun-ming; ZUO Liang

    2005-01-01

    The effects of variation of Mg content on microstructures,the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy,optical metallographic analysis,tensile and Ericsson tests.The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si,with an increment of Mg content,the strength enhances,the specific elongation and Erisson values of alloys decrease,and the number of Mg2 Si constituent increases and that of Al(MnFe)Si type constituents reduces.Al-MgSi-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint bake cycle (I.e.artificial aging at 170 ℃ for 30 min immediately after the solution treatment and quenching).Suitable Mg content should be controlled in the range of 0.8% and 1.2 % (mass fraction).

  7. Evolution of Intermetallics, Dispersoids, and Elevated Temperature Properties at Various Fe Contents in Al-Mn-Mg 3004 Alloys

    Science.gov (United States)

    Liu, K.; Chen, X.-G.

    2016-12-01

    Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight, and low-cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys have been found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high-temperature properties of 3004 alloys has been investigated. Results show that the dominant intermetallic changes from α-Al(MnFe)Si at 0.1 wt pct Fe to Al6(MnFe) at both 0.3 and 0.6 wt pct Fe. In the Fe range of 0.1-0.6 wt pct studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of yield strength and creep resistance at 573 K (300 °C) is obtained in the 0.3 wt pct Fe alloy with the finest size and highest volume fraction of dispersoids. The superior properties obtained at 573 K (300 °C) make 3004 alloys more promising for high-temperature applications. The relationship between the Fe content and the dispersoid precipitation as well as the materials properties has been discussed.

  8. The structure of rapidly solidified Al- Fe- Cr alloys

    Science.gov (United States)

    Yearim, R.; Shechtman, D.

    1982-11-01

    Four aluminum alloys, designed for use at elevated temperatures, were studied. The alloys were supersaturated with iron and chromium, and one of them contained small amounts of Ti, V, and Zr. The starting materials were alloy powders made by the RSR (Rapid Solidification Rate) centrifugal atomization process. Extrusion bars were made from the four powders. The as-extruded microstructure and the microstructure of the alloys after annealing at 482 °C were investigated by optical and transmission electron microscopy and by X-ray diffraction. The microstructure consists of equiaxed grains of aluminum matrix and two types of precipitates, namely, Al3(Fe ,Cr) and a metastable phase, Al6(Fe,Cr). The precipitates were different in their shape, size, distribution, and location within the grains.

  9. Effects of AlMnCa and AlMnFe Alloys on Deoxidization of Low Carbon and Low Silicon Aluminum Killed Steels

    Institute of Scientific and Technical Information of China (English)

    ZHAN Dong-ping; ZHANG Hui-shu; JIANG Zhou-hua

    2008-01-01

    To confirm the effects of AlMnCa and AIMnFe alloys on the deoxidization and modification of Al2O3 inclu-sions, experiments of 4-heat low carbon and low silicon aluminum killed steels deoxidized by AlMnCa and AlMnFe alloys were done in a MoSi2 furnace at 1 873 K. It is found that the 1# A1MnCa alloy has the best ability of deoxidi-zation and modification of Al2 O3 inclusions than 2# A1MnCa and A1MnFe alloys. Steel A deoxidized by 1# AlMnCa alloy has the lowest total oxygen content in the terminal steel, which is 37 × 10-6. Most of the inclusions in the steel deoxidized by 1# AIMnCa alloy are spherical CaO-containing compound inclusions, and 89. 1% of them are smaller than 10 μm. The diameter of the inclusion bigger than 50 μm is not found in the final steels deoxidized by AlMnCa alloys. Whereas, for the steels deoxidized by AlMnFe alloys, most inclusions in the terminal steel are Al2O3 or Al2O3-MnO inclusions, and a few of them are spherical, and only 76. 8% of them are smaller than 10 μm. Some in-clusions bigger than 50 μm are found in the steel D deoxidized by AlMnFe alloy.

  10. Effect of heat treatment on microstructure and interface of SiC particle reinforced 2124 Al matrix composite

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-15

    The microstructure and interface between metal matrix and ceramic reinforcement of a composite play an important role in improving its properties. In the present investigation, the interface and intermetallic compound present in the samples were characterized to understand structural stability at an elevated temperature. Aluminum based 2124 alloy with 10 wt.% silicon carbide (SiC) particle reinforced composite was prepared through vortex method and the solid ingot was deformed by hot rolling for better particle distribution. Heat treatment of the composite was carried out at 575 °C with varying holding time from 1 to 48 h followed by water quenching. In this study, the microstructure and interface of the SiC particle reinforced Al based composites have been studied using optical microscopy, scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), electron probe micro-analyzer (EPMA) associated with wavelength dispersive spectroscopy (WDS) and transmission electron microscopy (TEM) to identify the precipitate and intermetallic phases that are formed during heat treatment. The SiC particles are uniformly distributed in the aluminum matrix. The microstructure analyses of Al–SiC composite after heat treatment reveal that a wide range of dispersed phases are formed at grain boundary and surrounding the SiC particles. The energy dispersive X-ray spectroscopy and wavelength dispersive spectroscopy analyses confirm that finely dispersed phases are CuAl{sub 2} and CuMgAl{sub 2} intermetallic and large spherical phases are Fe{sub 2}SiAl{sub 8} or Al{sub 15}(Fe,Mn){sub 3}Si. It is also observed that a continuous layer enriched with Cu and Mg of thickness 50–80 nm is formed at the interface in between Al and SiC particles. EDS analysis also confirms that Cu and Mg are segregated at the interface of the composite while no carbide is identified at the interface. - Highlights: • The composite was successfully heat treated at 575°C for 1

  11. Microstructures and magnetic properties of [SiO2/FePt]5/Ag thin films

    Institute of Scientific and Technical Information of China (English)

    FAN Jiu-ping; XU Xiao-hong; JIANG Feng-xian; TIAN Bao-qiang; WU Hai-shun

    2008-01-01

    [SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO2/FePt]5/Ag films are changed into L10 and (111) mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controllingSiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 (0. 6nm)/FePt (3 nm)]5/Ag (50 nm) films and highly (001)-oriented films can be obtained in the [SiO2 (2 nm)/FePt (3 nm)]5/Ag (50 nm) films.

  12. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Ma Haijun

    2005-02-01

    Microstructure at the diffusion bonding interface between Fe3Al and steel including Q235 low carbon steel and Cr18–Ni8 stainless steel was analysed and compared by means of scanning electron microscopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe3Al/steel diffusion bonding interface was discussed. The experimental results indicate that it is favourable for the diffusion of Cr and Ni at the interface to accelerate combination of Fe3Al and steel during bonding. Therefore, the width of Fe3Al/Cr18–Ni8 interface transition zone is more than that of Fe3Al/Q235. And Fe3Al dislocation couples with different distances, even dislocation net occurs at the Fe3Al/Cr18–Ni8 interface because of the dispersive distribution of Cr and Ni in Fe3Al phase.

  13. Fine structure at the diffusion welded interface of Fe3Al/Q235 dissimilar materials

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Wu Huiqiang

    2001-12-01

    The interface of Fe3Al/Q235 dissimilar materials joint, which was made by vacuum diffusion welding, combines excellently. There are Fe3Al, FeAl phases and -Fe (Al) solid solution at the interface of Fe3Al/Q235. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe3Al with DO3 type body centred cubic (bcc) structure to -Fe (Al) solid solution with B2 type bcc structure. All phases are present in sub-grain structure level and there is no obvious brittle phases or micro-defects such as pores and cracks at the interface of Fe3Al/Q235 diffusion joint.

  14. Phase, microstructure, and magnetocaloric effect of the large disc LaFe11.6Si1.4 alloy

    Institute of Scientific and Technical Information of China (English)

    陈湘; 陈云贵; 肖定全; 唐永柏

    2015-01-01

    The large disc LaFe11.6Si1.4 alloy, which was prepared by medium-frequency induction furnace, was annealed at 1503 K for different time. The main phases were 1:13 phase in the edge parts of the large discs alloy;the impurity phases includedα-Fe phase, LaFeSi phase, and even very small amount of La5Si3 phase. The amounts of impurity phases reduced with increasing in annealing time. The magnetic properties in the edge parts of the large discs LaFe11.6Si1.4 alloy were investigated. The magnetic susceptibility had an abrupt change at Curie temperature (TC) as the magnetization in M-T curves. The alloys had almost the same TC (191 K), the mag-netocaloric effect (MCE) and relative cooling power (RCP) increased with increasing in annealing time. In addition, for the same al-loy, the magnetic hysteresis decreased with the increase in temperature.

  15. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

  16. Concentration dependent structural parameters of liquid Al-Fe alloys

    Science.gov (United States)

    Lalnuntluanga, C.; Mishra, Raj Kumar

    2016-10-01

    Square well potential is perturbed over Lebowtiz solution of hard sphere mixtures to determine direct correlation function,C(0) ij(r) in repulsive and attractive regions under Mean Spherical Model Approximation [1]. Obtained direct correlation functions were employed to derive partial structure factors and then total structure factor, S(k) in liquid Al-Fe alloy at different atomic percent of Al. Fourier transform of partial and total structure factors gives partial and total radial distribution functions, g(r) from which partial and total coordination numbers and the partial nearest-neighbor distances were computed.

  17. Influence of n$^{+}$ and p$^{+}$ doping on the lattice sites of implanted Fe in Si

    CERN Document Server

    Silva, Daniel José; Correia, João Guilherme; Araújo, João Pedro

    2013-01-01

    We report on the lattice location of implanted $^{59}$Fe in n$^{+}$ and p$^{+}$ type Si by means of emission channeling. We found clear evidence that the preferred lattice location of Fe changes with the doping of the material. While in n$^{+}$ type Si Fe prefers displaced bond-centered (BC) sites for annealing temperatures up to 600°C, changing to ideal substitutional sites above 700°C, in p$^{+}$ type Si, Fe prefers to be in displaced tetrahedral interstitial positions after all annealing steps. The dominant lattice sites of Fe in n$^{+}$ type Si therefore seem to be well characterized for all annealing temperatures by the incorporation of Fe into vacancy-related complexes, either into single vacancies which leads to Fe on ideal substitutional sites, or multiple vacancies, which leads to its incorporation near BC sites. In contrast, in p$^{+}$ type Si, the major fraction of Fe is clearly interstitial (near-T or ideal T) for all annealing temperatures. The formation and possible lattice sites of Fe in FeB...

  18. High-temperature ab initio calculations on FeSi and NiSi at conditions relevant to small planetary cores

    Science.gov (United States)

    Wann, E. T. H.; Vočadlo, L.; Wood, I. G.

    2017-02-01

    The Fe-Ni-Si system is potentially a very important component of terrestrial planetary cores. However, at present, even the behaviour of the FeSi and NiSi end members is poorly understood, especially at low to moderate pressures—the data for FeSi are contradictory and NiSi has been little studied. For FeSi, there is general agreement that there is a phase transition from the ɛ-FeSi to the CsCl structure with increasing pressure, but, in experiments, there is disagreement as to the position and slope of the phase boundary and the range of coexistence of the two phases. In this paper we have used ab initio lattice dynamics calculations to determine the phase boundary between the ɛ-FeSi and CsCl structures as a function of pressure and temperature in both FeSi and NiSi. For FeSi, we find that the transition pressure at zero Kelvin is 11 GPa and that the boundary between the ɛ-FeSi and CsCl phases varies little with temperature, having a slight negative Clapeyron slope, going from 11 GPa at 300 K to 3 GPa at 2000 K. For NiSi, there is much greater variation of the transition pressure with temperature, with a much shallower negative Clapeyron slope, going from 156 GPa at 300 K to 94 GPa at 2000 K.

  19. Origin of the broad three-terminal Hanle signals in Fe/SiO{sub 2}/Si tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Shoichi; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakane, Ryosho [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Institute for Innovation in International Engineering Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-07-20

    Lorentzian-shaped broader three-terminal Hanle (B-3TH) signals are observed in Fe/SiO{sub 2}/Si tunnel junction devices at 6–300 K. We propose a spin conducting model, which explains all the characteristics of our experimental results, such as field angle dependence and bias dependence of the B-3TH signals, as well as experimental results reported by other groups. It was found that the shape of the B-3TH signals is determined by the spin depolarization at the Fe/SiO{sub 2} interface caused by local magnetic fields, unlike the conventional understanding. The shape of the B-3TH signals, including narrower and inverted Hanle signals, reflects the magnetic order of an ultrathin paramagnetic layer formed at the Fe/SiO{sub 2} interface. Our model provides a unified explanation of the B-3TH signals observed in three-terminal Hanle measurements.

  20. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  1. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Wilkening, D. [Columbia Falls Aluminum Co., 2000 Aluminum Dr., Columbia Falls, MT 59912 (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., P.O. Box 1071, Anaconda, MT 59711 (United States)

    1998-12-31

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{sup TM} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast. (orig.) 18 refs.

  2. Spontaneous magnetostriction of Y2Fe16Al compound

    Institute of Scientific and Technical Information of China (English)

    Hao Yan-Ming; Zhao Miao; Zhou Yan

    2005-01-01

    The structure and magnetic properties of Y2Fe16Al compound have been investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe16Al compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Y2Fe16Al compound in the temperature range from 332 to 438K by x-ray dilatometry. The coefficient of the average thermal expansion is α = -3.4 × 10-5K-1. The spontaneous magnetostrictive deformations from 293 to 427K have been calculated based on the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 5.4× 10-3 to near zero with temperature increasing from 293 to 427K,the spontaneous linear magnetostrictive deformation λc along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane in the same temperature range except near 427K.

  3. Analysis of the High Conversion Efficiencies β-FeSi2 and BaSi2 n-i-p Thin Film Solar Cells

    OpenAIRE

    Jung-Sheng Huang; Kuan-Wei Lee; Yu-Hsiang Tseng

    2014-01-01

    Both β-FeSi2 and BaSi2 are silicides and have large absorption coefficients; thus they are very promising Si-based new materials for solar cell applications. In this paper, the dc I-V characteristics of n-Si/i-βFeSi2/p-Si and n-Si/i-BaSi2/p-Si thin film solar cells are investigated by solving the charge transport equations with optical generations. The diffusion current densities of free electron and hole are calculated first. Then the drift current density in the depletion regions is obtaine...

  4. Simulation and Optimization of β-FeSi2(n)/a-Si(i)/c-Si(p)/μc-Si(p+) Heterojunction Solar Cells%β-FeSi2(n)/a-Si(i)/c-Si(p)/μc-Si(p+)异质结太阳能电池的模拟与优化

    Institute of Scientific and Technical Information of China (English)

    刘振芳; 刘淑平; 聂慧军

    2016-01-01

    运用AFORS-HET软件对β-FeSi2(n)/a-Si(i)/c-Si(p)/μc-Si(p+)HIT型异质结太阳能电池的性能进行了模拟,并对各层参数进行了优化.模拟结果表明,在FeSi2(n)/c-si(p)结构上加上本征层和背场,能显著地提高电池的性能.加入缺陷并优化各项参数后,电池的最后参数为VoC=647.7 mV,JSC=42.29 mA·cm-2,FF=75.32%,EFF=20.63%,β-FeSi2(n)/c-Si(p)太阳能电池的效率提高了2.3%.

  5. A comparative wear study on Al-Li and Al-Li/SiC composite

    Science.gov (United States)

    Okumus, S. Cem; Karslioglu, Ramazan; Akbulut, Hatem

    2013-12-01

    Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al2O3 ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms-1 and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.

  6. Fe- and Cr-correlated defects in monocrystalline Si:Ga and electrical properties of multicrystalline Si:P; Fe- und Cr-korrelierte Defekte in einkristallinem Si:Ga und elektrische Eigenschaften von multikristallinem Si:P

    Energy Technology Data Exchange (ETDEWEB)

    Beljakowa, S.

    2005-12-05

    Presently silicon (Si)-based solar cells are in general made of boron (B)-doped material. An alternative to B-doped Si is the doping with gallium (Ga) or phosphorus (P). In the framework of this thesis, electrical (Deep Level Transient Spectroscopy (DLTS), Minority Carrier Transient Spectroscopy (MCTS), resistivity topography) and optical (microwave-detected photoconductance decay ({mu}-PCD)) methods are applied to investigate the electrical properties of FeGa- and CrGa-pairs in monocrystalline Si and of P-doped EFG (edge defined film fed growth)-Si. (orig.)

  7. Microstructure and Wear Behavior Of as Cast Al-25mg2si-2cu-2ni Alloy

    Directory of Open Access Journals (Sweden)

    1Geetanjali.S.Guggari ,

    2015-09-01

    Full Text Available The remarkable feature of the Aluminium is its low density and ability to withstand corrosion effect due to phenomenon of passivation. Structural components made from Aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The oxides and sulphate are useful compounds of Aluminium based on its weight. In this work, an attempt has been made to utilize the combined effect of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg2Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys.

  8. Elasticity of AlFeO(3) and FeAlO(3) perovskite and post-perovskite from first-principles calculations

    OpenAIRE

    Caracas, Razvan

    2010-01-01

    International audience; We use state-of-the-art ab initio calculations based on the generalized gradient approximation of the density functional theory in the planar augmented wavefunction formalism to determine the elastic constants tensor of perovskite and post-perovskite with formulas AlFeO(3) and FeAlO(3) in which Fe or Al respectively occupy only octahedral sites, for the stable magnetic configurations. The phase transition between perovskite and post-perovskite is associated with a site...

  9. Influence of Melt Superheat, Sr Modifier, and Al-5Ti-1B Grain Refiner on Microstructural Evolution of Secondary Al-Si-Cu Alloys

    Science.gov (United States)

    Rakhmonov, Jovid; Timelli, Giulio; Bonollo, Franco

    2016-11-01

    The role of impurity elements and melt superheat on the efficiency of Sr modification, grain refinement with Al-Ti-B and the precipitation behavior of intermetallic phases in a secondary Al-7Si-3Cu-0.3Mg alloy were investigated. Metallographic and thermal analysis techniques were used to quantitatively examine the macro- and microstructural changes occurring with modifier and grain refiner additions at various pouring temperatures. The results indicate how the Sr modification and grain refinement with Al-Ti-B can be effective enough despite the presence of impurity elements in the material and the variation of pouring temperature. A slight poisonous effect of impurities, in particular, Zr and V, in the grain refinement efficiency can be eventually induced due to their action in promoting the formation of primary AlSiTi compounds. Moreover, grain refiner addition exerted a pronounced influence on the precipitation sequence of Fe-rich phases. The TiB2 particles appeared to promote the formation of Al5FeSi during solidification by acting as a favorable nucleation site.

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

    Science.gov (United States)

    de La Peña, J. L.; Pech-Canul, M. I.

    2008-06-01

    The wetting behavior of Al Si Mg alloys on Si3N4/Si substrates has been investigated using the sessile drop technique. Based on a Taguchi experiment design, the effect of the following processing parameters on the contact angle (θ) and surface tension (σLV) was studied: processing time and temperature, atmosphere (Ar and N2), substrate surface condition (with and without a silicon wafer), as well as the Mg and Si contents in the aluminium alloy. In nitrogen, non-wetting conditions prevail during the isothermal events while in argon a remarkable non-wetting to wetting transition leads to contact angles θ as low as 11±3° and a liquid surface tension σLV of 33± 10×10-5 kJ/m2. According to the multiple analysis of variance (Manova), the optimum conditions for minimizing the values of θ and σLV are as follows: temperature of 1100 °C, processing time of 90 min, argon atmosphere, no use of a silicon wafer, and the use of the Al-18% Mg-1% Si alloy. A verification test conducted under the optimized conditions resulted in a contact angle of θ=9±3° and a surface tension of σLV=29± 9×10-5 kJ/m2, both indicative of excellent wetting.

  11. Structural study on nickel doped Li{sub 2}FeSiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Jaén, Juan A., E-mail: juan.jaen@up.ac.pa [Universidad de Panamá, Departamento de Química Física, CITEN, Edificio de Laboratorios Científicos-VIP (Panama); Jiménez, Miguel [Universidad de Panamá, Departamento de Física (Panama); Flores, Eibar [Universidad de Panamá, Escuela de Física (Panama); Muñoz, Alcides [Universidad de Panamá, Departamento de Física (Panama); Tabares, Jesús A.; Pérez Alcázar, Germán A. [Universidad del Valle, Departamento de Física (Colombia)

    2015-06-15

    The effect of nickel doping on the structure of Li{sub 2}FeSiO{sub 4} is examined by X-ray diffraction, Mössbauer spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometer, and magnetization measurements. Both, the pristine and nickel doped Li{sub 2}FeSiO{sub 4}, crystallize in a monoclinic structure with (P2{sub 1}/n) symmetry. Their lattice parameters are similar, which suggests that Ni{sup 2+} doesn’t destroy the lattice structure. Some small amounts of Fe{sup 3+} impurity phases and unreacted Li{sub 2}SiO{sub 3} are detected. Samples doped with more than 10 mol% contain some magnetic impurity of Fe-Ni alloy. Magnetic measurements indicated that Li{sub 2}FeSiO{sub 4} is paramagnetic and becomes antiferromagnetic below 23 K. Nickel dopant does not modify the paramagnetic nature of this material.

  12. High Curie temperature of Ce-Fe-Si compounds with ThMn12 structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, C; Pinkerton, FE; Herbst, JF

    2015-01-15

    We report the discovery of ternary CeFe(12-x)Si(x)compounds possessing the ThMn12 structure. The samples were prepared by melt spinning followed by annealing. In contrast to other known Ce Fe-based binary and ternary compounds, CeFe12-xSix compounds exhibit exceptionally high Curie temperatures whose values increase with added Si substitution. The highest T. = 583 K in CeFe10Si2 rivals that of the well-established Nd2Fe14B compound. We ascribe the T-c behavior to a combination of Si-induced 3d band structure changes and partial Ce3+ stabilization. (C) 2014 Published by Elsevier Ltd.

  13. Preparation and mechanical properties of Fe3Al/Al2O3 nano-/micro-composite

    Institute of Scientific and Technical Information of China (English)

    尹衍升; 龚红宇; 范润华; 王昕; 谭训彦

    2003-01-01

    Al2O3 matrix composites reinforced with Fe3 Al nano-particles were fabricated by hot processing at 1 450-1 600℃.The effect of Fe3Al content on the densification,mechanical properties and microstructure of the composites was investigated.The results show that some elongated Al2 O3 grains are observed.Fe3 Al particles are mainly situated at grain boundaries of the matrix while smaller particles are trapped within the alumina grains.The addition of Fe3 Al nanoparticles improves the mechanical properties of alumina.The maximum strength and toughness of the Fe3Al/Al2O3 nanocomposites are 832 Mpa and 7.96 Mpa·m1/2,respectively.

  14. Wear resistance of TiAlSiN thin coatings.

    Science.gov (United States)

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

    2012-12-01

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

  15. Novel Fe@C-TiO2 and Fe@C-SiO2 water-dispersible magnetic nanocomposites

    Science.gov (United States)

    Fleaca, Claudiu Teodor; Dumitrache, Florian; Morjan, Ion; Alexandrescu, Rodica; Luculescu, Catalin; Niculescu, Ana; Vasile, Eugeniu; Kuncser, Victor

    2013-08-01

    We report the synthesis of novel nanocomposites based on Fe@C nanoparticles obtained from Fe(CO)5 and C2H4/H2 by laser pyrolysis technique using a three nozzles injector. The αFe-FexCy@C particles (below 24 nm diameter) were first functionalized with hydrophilic groups using Na carboxymethylcellulose. Oxidic precursors (Si(OC2H5)4 or Ti(OC2H5)4) dissolved in ethanol were mixed with ethanolic suspensions of hydrophilized Fe@C nanoparticles using strong ultrasonication, then with water (at different pH values) and finally the Fe-containing composites were recovered by magnetic separation. The SiO2 and TiO2-coated powders were characterized by XRD, FT-IR and TEM techniques and their magnetic hysteresis curves were recorded at different temperatures. Both composites contain submicron aggregates of Fe@C nanoparticles embedded in/surrounded by a disordered porous oxidic matrix/shell. Near superparamagnetic behavior and room temperature and 26 A m2/kg (for Fe@C/SiO2) or 57 A m2/kg (for Fe@C/TiO2) saturation magnetization values were recorded and a blocking temperature around 500 K was extrapolated.

  16. Diffraction at GaAs/Fe3Si core/shell nanowires: The formation of nanofacets

    Science.gov (United States)

    Jenichen, B.; Hanke, M.; Hilse, M.; Herfort, J.; Trampert, A.; Erwin, S. C.

    2016-05-01

    GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111) substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe3Si shells exhibit nanofacets. These facets consist of well pronounced Fe3Si{111} planes. Density functional theory reveals that the Si-terminated Fe3Si{111} surface has the lowest energy in agreement with the experimental findings. We can analyze the x-ray diffuse scattering and diffraction of the ensemble of nanowires avoiding the signal of the substrate and poly-crystalline films located between the wires. Fe3Si nanofacets cause streaks in the x-ray reciprocal space map rotated by an azimuthal angle of 30° compared with those of bare GaAs nanowires. In the corresponding TEM micrograph the facets are revealed only if the incident electron beam is oriented along [1 1 ¯ 0] in accordance with the x-ray results. Additional maxima in the x-ray scans indicate the onset of chemical reactions between Fe3Si shells and GaAs cores occurring at increased growth temperatures.

  17. Influence of hydrogenation and mechanical grinding on the structural and ferromagnetic properties of GdFeSi

    Energy Technology Data Exchange (ETDEWEB)

    Chevalier, Bernard; Duttine, Mathieu; Wattiaux, Alain [Universite de Bordeaux, CNRS ICMCB, Pessac (France)

    2016-08-01

    Hydrogen insertion into GdFeSi induces (i) a structural transition from a tetragonal CeFeSi-type to a tetragonal ZrCuSiAs-type, (ii) an anisotropic expansion of the unit cell parameters because the a parameter decreases, whereas the c parameter increases, and (iii) a decrease in Curie temperature from 121 to 20 K. On the contrary, an amorphous ferromagnet (T{sub C} = 65 K) is obtained by mechanical grinding of GdFeSi. The three compounds (GdFeSi, GdFeSiH, and amorphous GdFeSi) were investigated by {sup 57}Fe Moessbauer spectroscopy. At 4.2 K, this study has revealed that the magnetically ordered Gd substructure produces a small transferred hyperfine magnetic field at the {sup 57}Fe nucleus.

  18. Effects of Si Content and the Addition Amount of Al-3B Master Alloy on the Solidification Structures of Hypoeutectic Al-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Effects of Si content and the addition amount of Al-3B master alloy on the solidification structures of hypoeutectic Al-Si alloys were studied. The addition amounts of the master alloy were 0.2%, 0.4%, 0.7% and 1% (mass fraction, so as the follows), respectively. The Si content of Al-Si binary alloys investigated varied from 1% to 11%. The observation of macrostructures of non-refined samples showed that 3% Si constitutes a transition point at which the minimum grain size can be obtained. It was also found that Al-3B master alloy can shift the transition point towards a higher Si value when its addition amount increases, making this point appear at 4%, 5% and 6% Si as its addition amount increases up to 0.4%, 0.7% and 1%, respectively.

  19. Determination of Ba, Sr, Fe, Al and Si Elements in Baryte Sample with Wavelength Dispersive X-ray Fluorescence Spectrometry%X射线荧光光谱法测定重晶石中的钡、锶、铁、铝、硅

    Institute of Scientific and Technical Information of China (English)

    刘益锋; 田琼; 杨树洁; 吕善胜; 林海; 刘中勇

    2013-01-01

    采用偏硼酸锂和四硼酸锂混合熔剂熔融法制样,波长色散X射线荧光光谱法测定重晶石中钡、锶、铁、铝、硅。采用理论α系数和经验系数相结合的方法校正元素间的基体效应。测定重晶石试样各组分的相对标准偏差(RSD,n=12)均小于5.5%,结果与化学分析法吻合。%A method has been developed for direct determination of Ba, Sr, Fe, Al and Si elements in baryte samples using fusion method by Axios PW4400 XRF spectrometer. The matrix effect was corrected by theoretical alpha coefficients and empirical coefficients. The precision (RSD, n=12) of the method is less than 5.5%for major elements and other elements.

  20. Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hu, Xunxiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-30

    The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

  1. Synthesis of SiC/Al Co-Continuous Composite by Spontaneous Melt Infiltration

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@Investigation has been made on the process of synthesizing SiC/Al co-continuous composite by spontaneous melt infiltration. It is found that nitrogen atmosphere is an indispensable factor for spontaneous infiltration of melt Al into SiC preform with continuous porosity. The critical temperature for spontaneous infiltration occurrence can be lowered and spontaneous infiltration rate increased by doping a small amount of Mg into the Al alloy. Adding fine SiO2 powders into the ceramic preform can play the similar role as Mg-doping by increasing wetting through the chemical reaction of 3SiO2+4Al=2Al2O3+3Si at the infiltration front. Infiltration rate can also be increased by Si-doping to lower the viscosity of the molten Al alloy. In addition, sufficient Si content in the molten Al is also indispensable to avoid the formation of Al4C in the synthesized composite.

  2. First-principles study on Al4Sr as the heterogeneous nucleus of Mg2Si

    Science.gov (United States)

    Xia, Zhi; Li, Ke

    2016-12-01

    The interfacial structure, electronic structure, work of adhesion and interfacial energy of the Al4Sr(100)/Mg2Si(100) interface have been studied with first-principles calculations to clarify the heterogeneous nucleation potential of the Al4Sr particle for a primary Mg2Si phase. Eight models of the Al4Sr(100)/Mg2Si(100) interface with OT and HCP stacking were adopted for the interfacial model geometries. The results show that the Al-Mg terminations of HCP and Al-Si terminations of OT stacking, with lower interfacial spacing and higher interfacial adhesion, are the most favorable structures after relaxation. Al-Mg- and Al-Si-terminated interfaces, with a lower interfacial distance, form chemical bonds more easily. Metallic bonds are formed near the Al-Mg-terminated interface, while the Al-Si-terminated interface exhibits predominantly covalent bond characteristics. Moreover, the calculated interfacial energies of both terminations are negative in conditions involving excess Mg atoms. The interfacial energies of Al-Si are lower than those of Al-Mg termination, indicating that the Al-Si-terminated interface is more stable. From thermodynamic analysis, we discover that the Al4Sr particle can be an effective heterogeneous nucleation substrate for Mg2Si in a Mg-Al-Si alloy melt.

  3. Phase Transformations in Low-Fe Alloys of the Al-Cu-Fe System

    Institute of Scientific and Technical Information of China (English)

    Liming Zhang

    2004-01-01

    Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20 -50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatures by means of different thermal analysis, magnetothermal analysis, scanning electron microscopy, electron probe analysis and powder X-ray diffraction. Representative phase transformations categorized as polymorphic, discontinuous precipitation,quasi-binary eutectoid, and ternary transitional U-type phase transformation are presented. These phase transformations were found to have a common feature which consumes the β phase and appears the φ phase. A schematic diagram was proposed to demonstrate the transition processes with decreasing temperature.

  4. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyong June [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  5. Foaming behaviour of Al-Si-Cu-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A. [Kongju National University (Korea). Dept. of Mechanical Engineering; Cho, S.S. [Chungnam National University, Daejeon (Korea). School of Materials Engineering; Lee, H.J. [Hanbat National University, Daejeon (Korea). Dept. of Building Service Engineering

    2004-12-15

    The powder metallurgical route was utilised to obtain the Al-5Si-4Cu-4Mg (alloy 544) and Al-3Si-2Cu-2Mg (alloy 322) foams. Various steps such as centrifugal atomisation, mixing alloy powder and foaming agent (1 wt-%TiH{sub 2}), cold compaction of mixture, hot extrusion and foaming in a preheated furnace were performed. Foaming behaviour of the alloys was investigated by digital microscopy, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) mapping in this study. It was found that alloy 544 takes a shorter period of time to initiate pore nucleation than alloy 322. Alloy 544 had a higher pore growth rate than alloy 322 at the same pre-set furnace temperature. In both alloys, crack-like pore nucleation occurred between aluminium alloy powders elongated in a direction parallel to the extrusion direction. Both alloys showed the same foaming sequence of crack-like pore nucleation, spherical pore growth, coalescence of neighbouring pores and collapse of pores adjacent to the free surface of specimen. The time required to start pore nucleation decreased with the increase of foaming temperature. The cell walls of both alloys consisted of {alpha}-Al phase and eutectic phase. (author)

  6. Electrical performance of multilayer MoS2 transistors on high-κ Al2O3 coated Si substrates

    Directory of Open Access Journals (Sweden)

    Tao Li

    2015-05-01

    Full Text Available The electrical performance of MoS2 can be engineered by introducing high-κ dielectrics, while the interactions between high-κ dielectrics and MoS2 need to be studied. In this study, multilayer MoS2 field-effect transistors (FETs with a back-gated configuration were fabricated on high-κ Al2O3 coated Si substrates. Compared with MoS2 FETs on SiO2, the field-effect mobility (μFE and subthreshold swing (SS were remarkably improved in MoS2/Al2O3/Si. The improved μFE was thought to result from the dielectric screening effect from high-κ Al2O3. When a HfO2 passivation layer was introduced on the top of MoS2/Al2O3/Si, the field-effect mobility was further enhanced, which was thought to be concerned with the decreased contact resistance between the metal and MoS2. Meanwhile, the interface trap density increased from 2.4×1012 eV−1cm−2 to 6.3×1012 eV−1cm−2. The increase of the off-state current and the negative shift of the threshold voltage may be related to the increase of interface traps.

  7. Transformation reversibility in Fe-Mn-Si shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzaki, K. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.; Natsume, Y. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.; Maki, T. [Kyoto Univ. (Japan). Dept. of Mater. Sci. and Eng.

    1995-12-01

    The change of the surface relief associated with stress-induced epsilon martensite before and after the reverse transformation in an Fe-33%Mn-6%Si alloy (Ms=264K) has been investigated. The permanent strain of a 2.7% tensile-strained specimen was 1.1% after the reverse transformation. In this specimen, a large part of surface relief still remained after heating to 623K (above Af). When five training cycles of 2.5% straining at room temperature and heating at 623K were applied, the permanent strain became negligible and the surface relief vanished well. TEM observations showed that usual permament slip deformation hardly occurred in the interior of an austenite grain in a 3.8% tensile-strained specimen where the permanent strain after the reversion was 2%. These results indicate that the permanent strain in the shape memory behavior is mainly attributed to the lack of transformation reversibility, i.e., the lack of reversible movement of Shockley partial dislocations. The conditions for the reversibility were discussed and the importance of the back stress formed by the forward transformation was pointed out. The effects of traning were also briefly discussed. (orig.).

  8. Magnetoresistance of rolled-up Fe3Si nanomembranes

    Science.gov (United States)

    Schumann, J.; Lisunov, K. G.; Escoffier, W.; Raquet, B.; Broto, J. M.; Arushanov, E.; Mönch, I.; Makarov, D.; Deneke, C.; Schmidt, O. G.

    2012-06-01

    Magnetotransport of individual rolled-up Fe3Si nanomembranes is investigated in a broad temperature range from 4.2 K up to 300 K in pulsed magnetic fields up to 55 T. The observed magnetoresistance (MR) has the following pronounced features: (i) MR is negative in the investigated intervals of temperature and magnetic field; (ii) its magnitude increases linearly with the magnetic field in a low-field region and reveals a gradual trend to saturation when the magnetic field increases; (iii) the MR effect becomes more pronounced with increasing temperature. These dependences of MR on the magnetic field and temperature are in line with predictions of the spin-disorder model of the spin-flip s-d interaction assisted with creation or annihilation of magnons, which is expected above a certain critical temperature. Comparison of the MR features in rolled-up and planar samples reveals a substantial increase of the critical temperature in the rolled-up tube, which is attributed to a new geometry and internal strain arising in the rolled-up nanomembranes, influencing the electronic and magnetic properties of the material.

  9. Effects of ion irradiation on structural and magnetic properties of Fe/Si multilayers prepared by helicon plasma sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Purwanto, Setyo E-mail: setyofzm@batan.go.id; Sakamoto, I. E-mail: isao-sakamoto@aist.go.jp; Koike, M.; Tanoue, H.; Honda, S

    2003-05-01

    Helicon plasma sputtering has been used to prepare Fe/Si MLs with an Fe layer thickness around t{sub Fe}=2-5 nm for a Si spacer fixed at the thickness of t{sub Si}=1 and 1.5 nm. Present study found that the Fe/Si MLs of the Si spacer thickness at t{sub Si}=1 nm exhibit antiferromagnetic nature, but the other Fe/Si MLs are ferromagnetic. The maximum value of magnetoresistance (MR) ratio in Fe/Si MLs appears at t{sub Fe}=3 nm, t{sub Si}=1 nm and is about 0.22%. We performed 400 keV Ar ion irradiation to investigate the behavior of magnetic properties in Fe/Si MLs. The magnetization measurements of Fe/Si MLs after 400 keV Ar ion irradiation show the degradation of antiferromagnetic behavior and the values of MR ratio after ion irradiation decrease. X-ray diffraction (XRD) patterns indicate that the peak intensity of a satellite peak originated in superlattice structure does not change within the range of ion dose used. These results imply that the interface structures after ion irradiation become rough although the superlattice structures remain. Therefore, we consider that the change of MR properties in Fe/Si MLs by 400 keV Ar ion irradiation is due to the thickness dependence of Si layers like metallic superlattice structures.

  10. Massive Si Phase and Its Growth Mechanism in Al-Si Casting Alloy

    Institute of Scientific and Technical Information of China (English)

    Hengcheng LIAO; Guoxiong SUN

    2004-01-01

    Optical microscope and scanning electron microscope were used to observe the microstructure of the Al-11.6%Si and Al-11.6%Si-0.4%Mg alloys and the morphology of the massive silicon particles. It is found that the massive silicon phase, observed in the unfully modified alloys with 0.010%Sr, disappears completely in the alloys fully modified with 0.020%Sr. The serrations and reentrant edges shown in the massive silicon particles with the conventional casting indicate that the TPRE mechanism plays an important role in the growth of the massive silicon phase. The ripples and steps suggest that the "lateral microscopic growth" may be another operating mechanism.

  11. Electrochemical properties of Si/(FeSiB) anode materials prepared by high-energy mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ho Tak; Loka, Chadrasekhar [Department of Advanced Materials Engineering, Kongju National University, Cheonan City 330-717 (Korea, Republic of); Lee, Kee-Sun, E-mail: kslee@kongju.ac.kr [Department of Advanced Materials Engineering, Kongju National University, Cheonan City 330-717 (Korea, Republic of); Cho, Jong Soo; Lee, Sang Han [Research Institute, MK electronics, Yongin City 449-821 (Korea, Republic of)

    2013-12-01

    Highlights: • Si-embedded in less-active FeSiB nano-composite structures synthesized. • Capacity of Si anode is 540 mAh g{sup −1} and 533 mAh g{sup −1} after the 3rd and 50th cycle. • The nano-composite exhibited 99% efficiency until the 50th cycle. • Cracks or voids in coin cells are rarely observed during cycling. • Elastic recoverable energy range of FeSiB is 2.96 times higher than Si. -- Abstract: Nano-structured composite with overall atomic composition Si{sub 60}/(FeSiB){sub 40} has been synthesized by high-energy mechanical milling (HEMM) for Lithium-ion rechargeable batteries as anode material. Crystal structure, microstructure, electrochemical properties, elastic modulus and Vickers hardness (H{sub V}) have been observed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), electrochemical test and nano-indentation test. With increasing milling time from 6 to 10 h, we observed a relatively homogeneous structure comprised of nano-crystalline active silicon (Si) embedded in less active FeSiB matrix phase. Electrochemical properties of 10 h milled nano-composite powder offers low capacity fade, high coulombic efficiency from 3rd cycle (540 mAh g{sup −1}) to until 102nd cycle (495 mAh g{sup −1}). The coulombic efficiencies of both 6 and 10 h milled powders are 98% and 99%, respectively. Coin cell cross sections of 6 and 10 h milled powders showed evidence for the void formation during lithiation and delithiation. Nano-indentation results exhibited that the amorphous FeSiB flakes have 2.96 times higher recoverable energy than Si. Resultant composite powders showed high irreversible capacity and stable lithiation and delithiation due to the reduced particle size, increased surface area and the highly elastic FeSiB matrix phase. Research reveals that the obtained nano-composite can be a promising candidate for lithium-ion rechargeable batteries.

  12. Effects of high magnetic field on modification of Al-Si alloy

    Institute of Scientific and Technical Information of China (English)

    LIAN Feng; QI Feng; LI Ting-ju; HU Guo-bing

    2005-01-01

    Effects of high magnetic field on modification of Al-6 %Si hypoeutectic alloy, Ak-12.6%Si eutectic alloy and Al-18 % Si hypereutectic alloy were studied. For the Al-6 % Si alloy, it is found that the sample modified by Na salt does not lose efficacy after remelting under high magnetic field. For the Al-12.6%Si alloy, if the sample modi fied by Na-salt is kept at the temperature of modification reaction, high magnetic field can postpone the effective time of the modification. For Al-18%Si alloy modified by P-salt, the primary Si in solidified structure concentrates at the edge of the sample and eutectic Si appears in the center of the sample under the condition without high magnetic field, while the primary Si distributes evenly in the sample when the high magnetic field is imposed. It is thought that the high magnetic field restrains the convection of the melt.

  13. Perpendicular magnetic anisotropy of Au/FePt thin films grown on Si substrates

    CERN Document Server

    Lee, Y W; Kim, C O

    1999-01-01

    FePt thin films show in plane magnetism with a very large coercive force when they are deposited on lattice-mismatched substrates, such as glass or Si In our research, FePt alloy thin films were deposited, using the coevaporation method, on a Au buffer layer which was evaporated onto a Si substrate at 500 .deg. C. The magnetic easy axis of the FePt film changed from the in-plane direction to the normal direction of the film. Therefore, it can be said that a Au buffer layer can enhance the perpendicular magnetic anisotropy of a FePt thin film on a lattice-mismatched substrate.

  14. Study of Physical Properties of SiCw/Al Composites During Unloaded Thermal Cycling

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin-ming; TIAN zhi-gang; CHENG hua; ZHU Xiao-gang; CHEN Wen-li

    2004-01-01

    The thermal expansion coefficient of SiCw/Al composites squeeze cast during unloaded thermal cycling was determined and analyzed. The study had shown that the thermal expansion coefficient of SiCw/Al composites reduced greatly with temperature raising. The thermal expansion coefficient of artificial ageing treatment SiCw/Al composites during unloaded thermal cycling reduced gradually, while the thermal expansion coefficient of squeezing SiCw/Al composites increased gradually. In addition, the thermal expansion coefficient of SiCw/Al composites reduced drastically with fiber fraction increasing.

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

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  16. Coherent inelastic scattering in Si and TiAl.

    Science.gov (United States)

    Moodie, Alexander F; Colson, Tobias A; Whitfield, Harold J

    2004-11-01

    An image filter has been used to test a simple model describing the dynamical scattering of electrons that have suffered multiple interactions with plasmons. Semi-quantitative agreement is observed in both Si and TiAl under quasi two-beam conditions. In the latter material it is shown that the classical Hirsch, Howie, Whelan analysis of contrast due to dislocations can be carried out in images produced by electrons that have suffered as many as five interactions with plasmons and at thicknesses at which the unfiltered and zero loss images show no contrast.

  17. Coherent inelastic scattering in Si and TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Moodie, Alexander F. [Department of Applied Physics, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia)]. E-mail: alexander.moodie@rmit.edu.au; Colson, Tobias A. [Department of Applied Physics, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia); Whitfield, Harold J. [Department of Applied Physics, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia)

    2004-11-15

    An image filter has been used to test a simple model describing the dynamical scattering of electrons that have suffered multiple interactions with plasmons. Semi-quantitative agreement is observed in both Si and TiAl under quasi two-beam conditions. In the latter material it is shown that the classical Hirsch, Howie, Whelan analysis of contrast due to dislocations can be carried out in images produced by electrons that have suffered as many as five interactions with plasmons and at thicknesses at which the unfiltered and zero loss images show no contrast.

  18. Microwave synthesis of Li2FeSiO4 cathode materials for lithium-ion batteries

    Institute of Scientific and Technical Information of China (English)

    Zhong Dong Peng; Yan Bing Cao; Guo Rong Hu; Ke Du; Xu Guang Gao; Zheng Wei Xiao

    2009-01-01

    A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-type Li2FeSiO4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700 ℃ in 12 min. And the obtained Li2FeSiO4 materials show better electrochemical performance and microstructure than those of Li2FeSiO4 sample by the conventional solid-state reaction.

  19. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification; Analisis elemental del intermetalico Al-Fe preparado por solidificacion rapida

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  20. Al{sub 2}O{sub 3} nanoparticles induced simultaneous refinement and modification of primary and eutectic Si particles in hypereutectic Al-20Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hongseok; Konishi, Hiromi [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Li Xiaochun, E-mail: xcli@engr.wisc.edu [Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Size of primary Si particles decreased by 80% after addition of Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Eutectic Si particles were also simultaneously modified by Al{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer Morphology of eutectic Si changed from large thin plate into coralline-like shape. Black-Right-Pointing-Pointer The ductility of hypereutectic Al-20Si alloy was enhanced by 365%. - Abstract: It is well known that the mechanical properties of hypereutectic Al-Si alloys are affected by the size, volume fraction, and distribution of primary and eutectic Si particles. However, it is very difficult to simultaneously refine and modify Si particles in hypereutectic Al-Si alloys by conventional means. This study investigates an effect of nanoparticles on Si particles during solidification in hypereutectic Al-Si alloys. Various contents of {gamma}-Al{sub 2}O{sub 3} nanoparticles were added in hypereutectic Al-20Si alloy melt and further dispersed through an ultrasonic cavitation based technique. The cast hypereutectic Al-20Si alloy with the nanoparticle addition showed a significant enhancement in both strengths and ductility. The ductility of the cast hypereutectic Al-20Si alloy was increased from 0.37% to 1.72% with an addition of 0.5 wt% {gamma}-Al{sub 2}O{sub 3} nanoparticles. Yield strength and ultimate tensile strength of the nanocomposite also showed an improvement of about 6% and 26%, respectively. Study suggests that {gamma}-Al{sub 2}O{sub 3} nanoparticles effectively induced simultaneous refinement of primary Si and modification of eutectic Si, resulting in superior ductility enhancement that is much higher than that conventional methods can offer. Microstructural analysis with optical and scanning electron microscope (SEM) revealed that the primary Si particles were refined from large star shapes with small features to polygon or blocky shapes with smooth edges and corners

  1. Moessbauer study of Fe[sub 3-x]Cr[sub x]Si alloys with DO[sub 3]-type ordering. [Fe-Cr-Si

    Energy Technology Data Exchange (ETDEWEB)

    Satula, D.; Szymanski, K.; Dobrzynski, L.; Waliszewski, J. (Faculty of Physics, Warsaw Univ. Branch, Bialystok (Poland))

    1993-02-01

    The influence of chromium atoms substituting for iron in the Fe[sub 3-x]Cr[sub x]Si alloys with DO[sub 3]-type ordering is investigated by Moessbauer spectroscopy at room temperature. Using the correlation between local hyperfine magnetic field and magnetic moments observed for Fe[sub 3]Si it is inferred that the magnetic moment of iron in Fe[sub 3-x]Cr[sub x]Si decreases linearly with x for both (A,C) and B sites. A few models intended to describe an influence of Cr on local hyperfine fields are tested. It is found that the local hyperfine magnetic field depends primarily on the chemical composition of the nearest neighbour shell. The isomer shift and magnetic hyperfine field show no substantial dependence on the alloy composition. Chromium atoms occupy, unexpectedly, both B and (A, C) sites, although the B sites are preferentially occupied. (orig.).

  2. One-step electrolytic preparation of Si-Fe alloys as anodes for lithium ion batteries

    Science.gov (United States)

    Wang, Hailong; Sun, Diankun; Song, Qiqi; Xie, Wenqi; Jiang, Xu; Zhang, Bo

    2016-06-01

    One-step electrolytic formation of uniform crystalline Si-Fe alloy particles was successfully demonstrated in direct electro-reduction of solid mixed oxides of SiO2 and Fe2O3 in molten CaCl2 at 900∘C. Upon constant voltage electrolysis of solid mixed oxides at 2.8V between solid oxide cathode and graphite anode for 5h, electrolytic Si-Fe with the same Si/Fe stoichimetry of the precursory oxides was generated. The firstly generated Fe could function as depolarizers to enhance reduction rate of SiO2, resulting in the enhanced reduction kinetics to the electrolysis of individual SiO2. When evaluated as anode for lithium ion batteries, the prepared SiFe electrode showed a reversible lithium storage capacity as high as 470mAh g-1 after 100 cycles at 200mA g-1, promising application in high-performance lithium ion batteries.

  3. Diffraction at GaAs/Fe3Si core/shell nanowires: The formation of nanofacets

    Directory of Open Access Journals (Sweden)

    B. Jenichen

    2016-05-01

    Full Text Available GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111 substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe3Si shells exhibit nanofacets. These facets consist of well pronounced Fe3Si{111} planes. Density functional theory reveals that the Si–terminated Fe3Si{111} surface has the lowest energy in agreement with the experimental findings. We can analyze the x-ray diffuse scattering and diffraction of the ensemble of nanowires avoiding the signal of the substrate and poly-crystalline films located between the wires. Fe3Si nanofacets cause streaks in the x-ray reciprocal space map rotated by an azimuthal angle of 30° compared with those of bare GaAs nanowires. In the corresponding TEM micrograph the facets are revealed only if the incident electron beam is oriented along [1 1 ¯ 0] in accordance with the x-ray results. Additional maxima in the x-ray scans indicate the onset of chemical reactions between Fe3Si shells and GaAs cores occurring at increased growth temperatures.

  4. Obtenção in situ do compósito alfa-SiAlON-SiC In situ preparation of alpha-SiAlON-SiC composite

    Directory of Open Access Journals (Sweden)

    C. Santos

    2005-12-01

    Full Text Available O objetivo desse trabalho foi a preparação in situ do compósito alfa-SiAlON-SiC com desenvolvimento de solução sólida de nitreto de silício (SiAlON durante a sinterização, utilizando o óxido misto de ítrio e terras raras (CRE2O3, fabricado na FAENQUIL, como estabilizador da fase alfa-Si3N4. Uma fração de 20% em volume da mistura AlN-CRE2O3, na proporção 9:1 (mol%, foi misturada a 80% em volume de Si3N4. A essa mistura (Si3N4-AlN-CRE2O3, foram adicionadas quantidades variadas de beta-SiC (entre 0 e 20 peso%. As misturas de pós foram moídas e, em seguida, compactadas por prensagem uniaxial e, subseqüente prensagem isostática a frio. Os compactos foram submetidos a sinterização a 1950 0C por 1 h e sob pressão de 1 MPa de N2. As amostras sinterizadas foram caracterizadas quanto às fases presentes, transformação Si3N4-SiAlON e aspectos microestruturais. Os resultados revelaram alfa-SiAlON e beta-SiC como únicas fases cristalinas. Além disso, não houve cristalização parcial da fase intergranular remanescente, e observou-se que variadas adições de SiC não interferiram na solubilidade e conseqüente formação de alfa-SiAlON, porém o crescimento de grãos alongados de alfa' é inibido em função da adição de quantidades maiores de SiC.The objective of this work is to obtain in situ alpha-SiAlON-SiC composites, by silicon nitride solid solution development, during sintering, using rare earth and yttrium oxide mixture (CRE3O3 as stabilizer of the alpha-Si3N4 phase. A fraction of 20 vol.% of AlN-CRE2O3 mixture was mixed to 80 vol.% of Si3N4. Different contents of beta-SiC powders were mixed to the Si3N4-AlN-CRE2O3 powder mixture. The powder mixtures were milled and compacted by uniaxial and cold isostatic pressing. The green bodies were sintered at 1950 °C during 1 h under 1 MPa of N2 pressure. The sintered samples were characterized by X-ray diffraction and scanning electron microscopy, in order to assess the

  5. Si and Fe depletion in Galactic star-forming regions observed by the Spitzer Space Telescope

    CERN Document Server

    Okada, Yoko; Miyata, Takashi; Okamoto, Yoshiko K; Sakon, Itsuki; Shibai, Hiroshi; Takahashi, Hidenori

    2008-01-01

    We report the results of the mid-infrared spectroscopy of 14 Galactic star-forming regions with the high-resolution modules of the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. We detected [SiII] 35um, [FeII] 26um, and [FeIII] 23um as well as [SIII] 33um and H2 S(0) 28um emission lines. Using the intensity of [NII] 122um or 205um and [OI] 146um or 63um reported by previous observations in four regions, we derived the ionic abundance Si+/N+ and Fe+/N+ in the ionized gas and Si+/O0 and Fe+/O0 in the photodissociation gas. For all the targets, we derived the ionic abundance of Si+/S2+ and Fe2+/S2+ for the ionized gas. Based on photodissociation and HII region models the gas-phase Si and Fe abundance are suggested to be 3-100% and <8% of the solar abundance, respectively, for the ionized gas and 16-100% and 2-22% of the solar abundance, respectively, for the photodissociation region gas. Since the [FeII] 26um and [FeIII] 23um emissions are weak, the high sensitivity of the IRS enables to de...

  6. {sup 57}Fe Moessbauer effect in R{sub 2}Fe{sub 13.6}Si{sub 3.4} (R=U, Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A.V. [Institute of Physics, Academy of Sciences, Na Slovance 2, 18221 Prague (Czech Republic)]. E-mail: andreev@mag.mff.cuni.cz; Niznansky, D. [Department of Inorganic Chemistry, Faculty of Natural Sciences, Charles University, Albertov 6, 12843 Prague (Czech Republic); Joint Laboratory of Moessbauer Spectrometry, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, Prague (Czech Republic); Homma, Y. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8578 (Japan); Onodera, H. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8578 (Japan); Shiokawa, Y. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8578 (Japan); Satoh, I. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8578 (Japan)

    2005-12-01

    From a comparative analysis of {sup 57}Fe Moessbauer spectra of U{sub 2}Fe{sub 13.6}Si{sub 3.4} and Lu{sub 2}Fe{sub 13.6}Si{sub 3.4}, the contributions from the Fe and U sublattices to the total magnetic moment of U{sub 2}Fe{sub 13.6}Si{sub 3.4} are estimated to be M {sub Fe}=1.33{mu} {sub B} and M {sub U}=2.6{mu} {sub B}.

  7. Analysis Si/Al ratio in zeolites type FAU by laser induced breakdown spectroscopy (LIBS)

    Science.gov (United States)

    Contreras, W. A.; Cabanzo, R.; Mejía-Ospino, E.

    2011-01-01

    In this work, Laser Induced Breakdown Spectroscopy (LIBS) is used to determine the Si/Al ratio of Zeolite type Y. The catalytic activity of zeolite is strongly dependent of the Si/Al ratio. We have used Si lines in the spectral region between 245-265 nm to determine temperature of the plasma generated on pelletized sample of zeolite, and stoichiometry relation between Si and Al.

  8. Effect on thickness of Al layer in poly-crystalline Si thin films using aluminum(Al) induced crystallization method.

    Science.gov (United States)

    Jeong, Chaehwan; Na, Hyeon Sik; Lee, Suk Ho

    2011-02-01

    The polycrystalline silicon (poly-Si) thin films were prepared by aluminum induced crystallization. Aluminum (Al) and amorphous silicon (a-Si) layers were deposited using DC sputtering and plasma enhanced chemical vapor deposition method, respectively. For the whole process Al properties of bi-layers can be one of the important factors. In this paper we investigated the structural and electrical properties of poly-crystalline Si thin films with a variation of Al thickness through simple annealing process. All samples showed the polycrystalline phase corresponding to (111), (311) and (400) orientation. Process time, defined as the time required to reach 95% of crystalline fraction, was within 60 min and Al(200 nm)/a-Si(400 nm) structure of bi-layer showed the fast response for the poly-Si films. The conditions with a variation of Al thickness were executed in preparing the continuous poly-Si films for solar cell application.

  9. Tribological properties of high velocity arc sprayed Fe-Al based composite coatings at elevated temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; ZHANG Shu; XU Wei-pu; ZU Zi-xin; XU Bin-shi

    2004-01-01

    Fe-Al based intermetallic composite coatings were in-situ synthesized using Fe-Al/Cr3C2 or Fe-Al/WC cored wires and high velocity are spraying (HVAS) technology. The tribological properties of the Fe-Al based intermetallic composite coatings were investigated using a ball-on-disc tribotester from room temperature to 650 ℃. The results show that the coatings have relatively high bond strength and micro-hardness. The tribological properties of Fe-Al/Cr3C2 and Fe-Al/WC composite coatings were further analyzed and compared. Low and stable wear rates of the Fe-Al based intermetallic composite coatings were indicated from room temperature to 650 ℃. The excellent wear resistance of the composite coatings in high temperature was discussed.

  10. Comparison of the microstructure and magnetic properties of strontium hexaferrite films deposited on Al{sub 2}O{sub 3}(0001), Si(100)/Pt(111) and Si(100) substrates by pulsed laser technique

    Energy Technology Data Exchange (ETDEWEB)

    Masoudpanah, S.M. [Center of Excellence for Magnetic Materials, School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); School of Materials Science and Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Seyyed Ebrahimi, S.A., E-mail: saseyyed@ut.ac.ir [Center of Excellence for Magnetic Materials, School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Ong, C.K. [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2014-01-15

    Strontium hexaferrite SrFe{sub 12}O{sub 19} (SrM) films have been deposited on Al{sub 2}O{sub 3}(0001), Si(100)/Pt(111) and Si(100) substrates. The (001) oriented SrFe{sub 12}O{sub 19} films deposited on the Al{sub 2}O{sub 3}(0001) and Si(100)/Pt(111) substrates have been confirmed by X-ray diffraction patterns. Higher coercivity in perpendicular direction rather than in-plane direction of the SrM/Al{sub 2}O{sub 3}(0001) and SrM/Pt(111) films showed that the films had perpendicular magnetic anisotropy. The (001) orientation and similar microstructure and magnetic properties of the SrM/Al{sub 2}O{sub 3}(0001) and SrM/Pt(111) films show the Al{sub 2}O{sub 3}(0001) substrate can be replaced by the Si(100)/Pt(111) substrate. - Highlights: • The SrFe{sub 12}O{sub 19} film deposited on different Si(100), Si(100)/Pt(111) and Al{sub 2}O{sub 3}(0001) substrates by PLD. • The SrM/Pt(111) and SrM/Al{sub 2}O{sub 3}(0001) films showed the c-axis perpendicular orientation. • The SrM/Al{sub 2}O{sub 3}(0001) films exhibited more perpendicular magnetic anisotropy than SrM/Pt(111) films. • The Al{sub 2}O{sub 3}(0001) substrate can be replaced by the Si(100)/Pt(111) substrate.

  11. Effect of aging treatment on mechanical properties of (SiCw+SiCp)/2024Al hybrid nanocomposites

    Institute of Scientific and Technical Information of China (English)

    GENG Lin; ZHANG Xue-nan; WANG Gui-song; ZHENG Zhen-zhu; XU Bin

    2006-01-01

    2024Al based composites reinforced by a hybrid of SiC whisker and SiC nanoparticle were fabricated by a squeeze casting route. In the (SiCw+SiCp)/Al composites, the volume fraction of SiC whisker is 20% and that of SiC nanoparticle is 2%, 5% and 7%,respectively. The as cast composites were solution treated followed by aging treatment. The experimental results show that the SiC nanoparticles are more effective in improving the hardness and tensile strength of the composites than SiC whiskers. The hardening kinetics of the composites is enhanced by reinforcements addition and the peak aging time is 4-5 h. The hardness of all the hybrid composite decreases at the initial aging stage, suggesting that dislocation recovery softening process coexists with precipitation hardening. DSC study shows that the GP zone formation of the hybrid composites is suppressed.

  12. Zener Relaxation Peak in an Fe-Cr-Al Alloy

    Institute of Scientific and Technical Information of China (English)

    周正存; 程和法; 宫晨利; 魏健宁; 韩福生

    2002-01-01

    We have studied the temperature spectra of internal friction and relative dynamic modulus of the Fe-(25 wt%)Cr-(5wt%)Al alloy with different grain sizes. It is found that a peak appears in the internal friction versus temperature plot at about 550°C. The peak is of a stable relaxation and is reversible, which occurs not only during heating but also during cooling. Its activation energy is 2.5 (± 0.15) eV in terms of the Arrhenius relation. In addition, the peak is not obvious in specimens with a smaller grain size. It is suggested that the peak originates from Zener relaxation.

  13. Modifying bentonite with Al-fe from concentrated clay suspensions

    Directory of Open Access Journals (Sweden)

    Sonia Moreno

    2010-04-01

    Full Text Available This article reports modifying a Colombian bentonite with an Al-Fe mixture from 10% and 50% p/p clay suspensions as well as dry materal, using water or acetone as dispersal phase. The solids thus obtained were characterised using atomic abdorption, residual cationic interchange ability and x-ray diffraction. Catalytic activity was evaluated regarding phenol oxidation reaction with hydrogen peroxide in diluted aqueous medium. The results indicated that solids prepared in concentraded suspension presented structural, textural and catalytic propierties comparable with modified solids in diluted suspension (2% weight.

  14. Initial stages of Zr-Fe-Si alloy formation on Zr(0001) surface

    Science.gov (United States)

    Horáková, Kateřina; Cichoň, Stanislav; Lančok, Ján; Sajdl, Petr; Cháb, Vladimír

    2017-03-01

    We studied initial stages of Fe and Si atoms interaction with the Zr(0001) surface. Fe and Si were deposited in-situ on the clean Zr surface up to coverage of one monolayer. Chemical state of Zr as a function of annealing temperature and the surface composition was investigated. Characteristic (1×1) LEED (Low Energy Electron Diffraction) pattern of the clean Zr surface becomes significantly modified when Fe and Si are deposited and annealed at 400 °C. The arrangement of new spots of the pattern corresponds to the (2√3×2√3)R30° structure, stable up to annealing at 750 °C. Changes in the electronic structure were identified from the images of equi-energy cuts of the k-space covering the entire Brillouin zone. The results imply that hydrogen, typically present in the clean surface, was eliminated either by annealing or upon the deposition of Fe and Si.

  15. Chemical hydrogenation of La(Fe,Si) family of intermetallic compounds

    Science.gov (United States)

    Wlodarczyk, P.; Polak, M.; Hawelek, L.; Kowalczyk, M.; Hreczka, M.; Kolano-Burian, A.

    2016-11-01

    In the present work, the chemical hydrogenation process of La(Fe,Si)13 compounds has been shown. It was found, that the La(Fe,Si) compound can be easily saturated with hydrogen by performing reaction with 0.6 M hydrochloric acid (HCl) for 2 h. After reaction, the heat treatment process is necessary to make hydrogenated powder homogenous. For the LaFe11.8Si1.2 micronized (induction up to 2T. The adiabatic temperature change is equal to 3 K in magnetic field change 0-1.7T at 335 K, while magnetic entropy change is equal 13 J/kg*K at 2T. The structural homogeneity of initial and hydrogenated powders was validated by powder X-ray diffraction method. The amount of hydrogen in the hydrogenated compounds was evaluated using thermogravimetry method (4 H atoms per formula unit LaFe11.8Si1.2).

  16. High-pressure crystal structure investigation of synthetic Fe2SiO4 spinel

    DEFF Research Database (Denmark)

    Nestola, F.; Balic Zunic, Tonci; Koch-Müller, M.;

    2011-01-01

    The crystal structure of Fe2SiO4 spinel at room temperature was investigated at seven different pressures by X-ray diffraction, using a diamond anvil cell to examine the influence of Fe substitution on ringwoodite behaviour at high pressure. The results compared with those of a pure Mg endmember...... show that the substitution of Fe into the spinel structure causes only small changes in the compression rate of coordination polyhedra and the distortion of the octahedron. The data show that the compression rate for the octahedron and tetrahedron in (Mg,Fe)2SiO4 can be considered statistically equal...... for FeO6 and MgO6, as well as for SiO4 in both the endmembers. This shows why almost identical bulk moduli are reported along the solid solution in recent literature....

  17. Separation of primary Si and impurity boron removal from Al-30%Si-10%Sn melt under a traveling magnetic ifeld

    Institute of Scientific and Technical Information of China (English)

    Jin-ling Sun; Qing-chuan Zou; Jin-chuan Jie; Ting-ju Li

    2016-01-01

    Separation of primary Si phase and removal of boron in the primary Si phase during the solidiifcation process of the Al-30%Si-10%Sn melt under a traveling magnetic field (TMF) were investigated. The results showed that the agglomeration layer of the primary Si can be formed in the periphery of the ingot while the inner microstructures mainly consist of the eutectic α-Al+Si and β-Sn phases. The intense melt lfow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is ifrst precipitated close to the inner wal of crucible with a relatively lower temperature, resulting in the remarkable segregation of the primary Si phase. The content of impurity B in the primary Si phase can be removed effectively with an increase in magnetic lfux intensity. The results of electron probe microanalysis (EPMA) clearly indicated that the average intensity of the B Ka line in theα-Al phase region of Al-Si-Sn aloy is higher in the case of solidiifcation under TMF than that of normal solidiifcation condition, suggesting that the electromagnetic stirring can promote the B removal from the primary Si phase.

  18. Preparation of iron aluminate (FeAl2O4) nanoparticles from FeAl2O4 hollow particles fabricated by using a spray pyrolysis process

    Science.gov (United States)

    Yun, Jaecheol; Kim, Yangdo; Park, Dahee; Yun, Jung-Yeul

    2015-05-01

    Iron aluminate (FeAl2O4) hollow particles with a spinel structure were synthesized by using a spray pyrolysis process. FeAl2O4 hollow particles were formed at a reaction temperature of 900 °C at a flow rate of 40 L/min as a result of the rapid solvent evaporation and decomposition gases from the droplets in the spray solution prepared from metal salts and organic reagents. FeAl2O4 hollow particles were fabricated at a reaction temperature of 900 °C with a flow rate of 40 L/min. The FeAl2O4 hollow particles were heat treated for 3 hours at 600 °C in a 5% H2/Ar atmosphere to form the crystal particles. Subsequently, FeAl2O4 nanoparticles were fabricated from the FeAl2O4 hollow particles by using the wet milling process. After milling for 60 minutes, transmission electron microscopy revealed the FeAl2O4 particles to have a mean size of approximately 50 nm. The FeAl2O4 nanoparticles were fabricated successfully by using a two-step process, spray pyrolysis and wet milling.

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

    Science.gov (United States)

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

    2016-06-01

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

  20. MICROSTRUCTURAL ANALYSIS OF Al-Mg-Si-Zn ALLOY

    Directory of Open Access Journals (Sweden)

    SERGIO VALADEZ

    2010-01-01

    Full Text Available En un esfuerzo por desarrollar una nueva aleación con aplicación estructural, se ha desarrollado una aleación base Aluminio aleada con magnesio, silicio y zinc. La investigación pretende correlacionar la microestructura y con el tratamiento térmico. La aleación AlMgSiZn, fue elegida para ese propósito debido a la presencia de precipitados tanto en la matriz del aAl, como en los límites de grano, los cuales permiten una excelente relación entre la dureza y la resistencia mecánica. En lo que respecta a la microestructura, esta fue caracterizada bajo condición de colada y después de ser tratada térmicamente por envejecimiento. Este tratamiento fue realizado en dos etapas, la primera a 450ºC durante 3 horas que corresponde al tratamiento de homogeneización: y la segunda al proceso de envejecimiento artificial llevado a cabo a 160ºC durante 1hr. Los resultados indican la presencia de dendritas de aAl, además un eutéctico binario y partículas de Mg7Zn3 adentro de las regiones interdendríticas. El eutéctico y las partículas fueron modificados por el tratamiento de envejecido. Las observaciones realizadas con el microscopio electrónico de transmisión en especímenes con y sin tratamientos térmicos, demostraron una distribución uniforme de precipitados con diversas morfologías, tales como cúbico, esférico y plaqueta: para la matriz de aAl, los cuales no fueron detectados durante las observaciones en el microscopio electrónico de barrido.

  1. Role of Si in Improving the Shape Recovery of FeMnSiCrNi Shape Memory Alloys

    Science.gov (United States)

    Maji, Bikas C.; Krishnan, Madangopal; Gouthama; Ray, R. K.

    2011-08-01

    The effect of Si addition on the microstructure and shape recovery of FeMnSiCrNi shape memory alloys has been studied. The microstructural observations revealed that in these alloys the microstructure remains single-phase austenite ( γ) up to 6 pct Si and, beyond that, becomes two-phase γ + δ ferrite. The Fe5Ni3Si2 type intermetallic phase starts appearing in the microstructure after 7 pct Si and makes these alloys brittle. Silicon addition does not affect the transformation temperature and mechanical properties of the γ phase until 6 pct, though the amount of shape recovery is observed to increase monotonically. Alloys having more than 6 pct Si show poor recovery due to the formation of δ-ferrite. The shape memory effect (SME) in these alloys is essentially due to the γ to stress-induced ɛ martensite transformation, and the extent of recovery is proportional to the amount of stress-induced ɛ martensite. Alloys containing less than 4 pct and more than 6 pct Si exhibit poor recovery due to the formation of stress-induced α' martensite through γ- ɛ- α' transformation and the large volume fraction of δ-ferrite, respectively. Silicon addition decreases the stacking fault energy (SFE) and the shear modulus of these alloys and results in easy nucleation of stress-induced ɛ martensite; consequently, the amount of shape recovery is enhanced. The amount of athermal ɛ martensite formed during cooling is also observed to decrease with the increase in Si.

  2. Local environment analysis of Fe ions in BaMgSiO4

    Science.gov (United States)

    Kase, Junya; Shingaki, Yoshihiro; Inaba, Yuta; Meguro, Kazune; Murata, Hidenobu; Okajima, Toshihiro; Yamamoto, Tomoyuki

    2016-08-01

    Polycrystalline Fe-doped BaMgSiO4 is synthesized by the conventional solid state reaction method, which shows strong photochromism. Photochromic property of the synthesized specimens is investigated by measuring the diffuse reflectance spectrum. Local environment of doped Fe ions in BaMgSiO4 has been studied by the analysis of the X-ray absorption near-edge structure (XANES) spectrum with the aid of the first-principles calculations.

  3. Novel La(Fe,Si){sub 13}/Cu composites for magnetic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, Julia; Hannemann, Ullrich; Ryan, Mary P. [Department of Materials, Imperial College London, London, SW7 2AZ (United Kingdom); Cohen, Lesley F. [Department of Physics, Imperial College London, London, SW7 2AZ (United Kingdom)

    2012-11-15

    An approach to engineering magnetic refrigerant materials with defined thermal transport properties is demonstrated using the example of high magnetocaloric performance La-Fe-Si alloys. A tunability of up to 300% of the thermal conductivity can be achieved in composites consisting of a La(Fe,Si){sub 13} compound and Cu prepared by electroless copper plating without compromising the magnitude of the magnetocaloric effect. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Thermomagnetic behaviour and compositional irreversibility on (Fe/Si){sub 3} multilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Badía-Romano, L., E-mail: lbadia@unizar.es [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Rubín, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Ciencia de Materiales e Ingeniería Metalúrgica, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Magén, C. [Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, E-50018 Zaragoza (Spain); Fundación ARAID, E-50004 Zaragoza (Spain); Bartolomé, F. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Sesé, J.; Ibarra, M.R. [Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, E-50018 Zaragoza (Spain); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); and others

    2014-09-01

    This work presents the correlation between the morphology and magnetic properties of (Fe/Si){sub 3} multilayers with different Fe layer thicknesses and fixed Si spacer thickness in a broad temperature range (5Fe/Ag deposited on a GaAs(001) substrate. Transmission electron microscopy reveals good epitaxial growth and phase transformations in the c-FeSi phase formed during deposition as well as upon subsequent annealing of the sample up to 800 K. Remanence to saturation magnetization M{sub R}/M{sub S} ratios and saturation fields are related to several types of interlayer exchange coupling. 90°-coupling and a superposition of 90° and antiferromagnetic interlayer exchange coupling are found depending on the Fe layer thickness. Magnetization curves were investigated as a function of temperature by in situ annealing. They show an irreversible thermal process as temperature increases from 300 to 450 K that is correlated to the formation of a ferromagnetic silicide phase. At higher temperature this phase transforms into a paramagnetic Fe–Si phase. - Highlights: • A thermomagnetic study on (Fe/Si){sub 3} multilayers is performed by in situ annealing. • We assess on the Fe layer thickness dependence, while the Si spacer is fixed. • 90° and AF interlayer exchange couplings are found depending on the Fe thickness. • We report an irreversible thermal process, correlated to chemical transformations. • The integrity of these (Fe/Si){sub 3} films is conserved just till T≈410K.

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

    Institute of Scientific and Technical Information of China (English)

    GU Wan-li

    2006-01-01

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

  6. Fracture of Fe-3wt.% Si single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prahl, J. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Machova, A. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Landa, M. [Institute of Thermomechanics, Academy of Sciences of the Czech Republic, Dolejskova 5, 182 00 Prague 8 (Czech Republic); Hausild, P. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic)], E-mail: Petr.Hausild@fjfi.cvut.cz; Karlik, M. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Spielmannova, A. [Czech Technical University in Prague, Department of Materials, Trojanova 13, 120 00 Prague 2 (Czech Republic); Clavel, M. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France); Haghi-Ashtiani, P. [Ecole Centrale Paris, LMSS-Mat, CNRS UMR 8579, Grande Voie des Vignes, 92295 Chatenay-Malabry (France)

    2007-07-25

    The ductile to brittle transition in {alpha}-iron was studied on four oriented single crystals of a Fe-3wt.% Si alloy using tensile tests of flat-notched specimens, scanning and transmission electron microscopy. The experimental results are compared with molecular dynamic simulations. Single-edge notched specimens were loaded in tension at room temperature, the crack propagated in a (001) plane and in the [1-bar10] direction. The crosshead speed was changed in the range from 0.1 to 5.0mm/min. Under the lowest loading rate, a plastic zone was formed at the notch tip, faster loading lead to brittle fracture. Fractographic analysis of one specimen ruptured at 1mm/min loading showed flat cleavage facets and tongues formed by the interaction of the principal crack with deformation twins. Besides the tongues, the fracture surface of the second sample ruptured at the same loading rate exhibited signs of plastic deformation. In the first specimen, transmission electron microscopy in the vicinity of the fracture surface confirmed deformation twinning and a very low dislocation density. In the second specimen, deformation twinning was assisted by slip of dislocations in the <111> {l_brace}112{r_brace} slip system. Molecular dynamics simulations confirmed that the crack growth has a more brittle character with increasing loading rates. At a slower loading rate, the crack growth is more difficult since it is impeded by emission of shielding dislocations from the crack tip in the <111> {l_brace}112{r_brace} slip system. Twin formation at the crack front was detected in simulations with edge cracks.

  7. Seismic parameters of hcp-Fe alloyed with Ni and Si in the Earth's inner core

    Science.gov (United States)

    Liu, Jin; Lin, Jung-Fu; Alatas, Ahmet; Hu, Michael Y.; Zhao, Jiyong; Dubrovinsky, Leonid

    2016-02-01

    Iron alloyed with Ni and Si has been suggested to be a major component of the Earth's inner core. High-pressure results on the combined alloying effects of Ni and Si on seismic parameters of iron are thus essential for establishing satisfactory geophysical and geochemical models of the region. Here we have investigated the compressional (VP) and shear (Vs) wave velocity-density (ρ) relations, Poisson's ratio (ν), and seismic heterogeneity ratios (dlnρ/dlnVP, dlnρ/dlnVS, and dlnVP/dlnVS) of hcp-Fe and hcp-Fe86.8Ni8.6Si4.6 alloy up to 206 GPa and 136 GPa, respectively, using multiple complementary techniques. Compared with the literature velocity values for hcp-Fe and Fe-Ni-Si alloys, our results show that the combined addition of 9.0 wt % Ni and 2.3 wt % Si slightly increases the VP but significantly decreases the VS of hcp-Fe at a given density relevant to the inner core. Such distinct alloying effects on velocities of hcp-Fe produce a high ν of about 0.40 for the alloy at inner core densities, which is approximately 20% higher than that for hcp-Fe. Analysis of the literature high P-T results on VP and VS of Fe alloyed with light elements shows that high temperature can further enhance the ν of hcp-Fe alloyed with Ni and Si. Most significantly, the derived seismic heterogeneity ratios of this hcp alloy present a better match with global seismic observations. Our results provide a multifactored geophysical constraint on the compositional model of the inner core which is consistent with silicon being a major light element alloyed with Fe and 5 wt % Ni.

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

    Directory of Open Access Journals (Sweden)

    J. Śleziona

    2006-04-01

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

  9. Y-SiAlON/BaSi2Al2O8复合陶瓷的微观结构与力学性能%Microstructure and Mechanical Properties of Y-SiAlON/BaSi2Al2O8 Composite Ceramics

    Institute of Scientific and Technical Information of China (English)

    吕建华; 叶枫; 刘春凤; 刘利盟; 黄玉东; 周玉

    2012-01-01

    以 α-Si3N4粉、Al2O3粉、AlN 粉、Y2O3粉和 BaSi2Al2O8(BAS)粉为原料,采用热压烧结技术制备 Y-SiAlON/BAS 复合陶瓷,研究了 BAS 含量对复合陶瓷相组成、微观结构及力学性能的影响。结果表明:所制备的材料均接近完全致密(致密度〉99%),且生成了长棒状 SiAlON 晶粒,随 BAS添加量增加,α-SiAlON 含量减少,β-SiAlON 含量增加,材料硬度急剧下降,断裂韧性和弹性模量略有降低,添加 10% (质量分数)BAS 的 Y-SiAlON陶瓷具有最高的抗弯强度(775.5MPa)。长棒状 SiAlON 晶粒的拔出及裂纹偏转是 Y-SiAlON/BAS 复合陶瓷的主要增韧机制。%Y-SiAlON/BaSi2Al2O8 (BAS) composite ceramics were prepared via a hot-press sintering method using the powders of α-Si3N4, Al2O3, AlN, Y2O3 and BAS as raw materials. The effect of BAS content on phase composition, microstructure and mechani- cal properties was investigated. The results reveal that all the materials are fully densified (relative density 〉 99%), and are composed of the elongated SiAlON grains. The amount of α-SiAlON decreased and the amount of β-SiAlON increased with increasing the BAS content, resulting in a drastic decrease in the hardness and slight decreases in the fracture toughness and elastic module. The Y-SiAlON/10% (in mass)BAS composite ceramics possessed a flexural strength of 775.5 MPa. The pull-out of elongated SiAION grain and the crack deflection both are the main self-toughness mechanisms for Y-SiAlON/BAS composite ceramics.

  10. A thermomechanical process to make iron aluminide (FeAl) sheet

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, M.R.; Deevi, S.C. [Philip Morris Research Center, Richmond, VA (United States); Sikka, V.K. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37387 (United States); Scorey, C.R. [Ametek Specialty Metals Division, Wallingford, CT 06492 (United States)

    1998-12-31

    An innovative combination of roll compaction, and thermomechanical processing allowed manufacture of FeAl alloy intermetallic sheets with 24 wt.% Al content. Green sheets of FeAl were obtained by roll compaction of water atomized FeAl powder with a polymeric binder. Roll compacted green sheets were de-bindered and partially sintered prior to cold rolling through tungsten carbide rolls. Cold rolling decreased the thickness, reduced the level of porosity and work-hardened the sheets. Several intermediate annealings at or above 1100 C were found to be necessary to relieve the work hardening stresses prior to rolling the sheets to a final thickness of 0.20 mm. The annealing temperatures were chosen to be at or above 1100 C to allow concurrent sintering of FeAl necessary for the densification of FeAl sheets. Thermomechanical processing of cold rolled sheets allowed commercial manufacture of FeAl intermetallic sheets without the necessity of hot rolling of a cast FeAl ingot. Fully dense sheets possess fine grain microstructure with an average grain size of 20 {mu}m. The electrical resistivities of FeAl sheets can be varied from 140 to 155 {mu}{Omega} cm{sup -1}, and the high resistivities make them ideally suited for resistive heating applications. Mechanical properties of FeAl sheets are comparable to the properties of hot extruded FeAl alloys. (orig.) 26 refs.

  11. Disorder in Al-li-cu and Al-mn-si icosahedral alloys.

    Science.gov (United States)

    Heiney, P A; Bancel, P A; Horn, P M; Jordan, J L; Laplaca, S; Angilello, J; Gayle, F W

    1987-10-30

    Faceted dendrites of icosahedral AL(6)Li(3)Cu have been studied by high-resolution x-ray scattering. The samples display long-range icosahedral symmetry both in their diffraction patterns and in their macroscopic morphology. Despite the appearance of well-defined facets, the samples have a high degree of atomic disorder. The Bragg peaks have symmetry-dependent shapes and widths that scale linearly with G perpendicular (phason momentum). The peak widths are surprisingly similar to those found in icosahedral Al-Mn-Si alloys in both their absolute magnitude and their dependence on G perpendicular. The origin of these features in models for the icosahedral phase is discussed.

  12. Role of Al2O3 fiber in eutectic Al-Si alloy composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of Al2O3 fiber on wear characteristics of eutectic Al-Si alloy composites were studied using a pin-on-disk tester under dry sliding condition. The results show that the Al2O3 fiber can make matrix grain be fine, specially the eutectic Si be finer and prevent the plastic flow of matrix and prohibit the crack propagation in the wear layer, thereby it can remarkably improve the mechanical property and the wear resistance of the MMCs. Since Al2O3 fiber plays a role of certain framework in protecting the matrix against crash, it can eliminate the severe wear of MMCs with higher φf of fiber from the beginning of test. At mild stage, when φf is in the range of 8%~10%, the wear rates are the lowest. With increasing φf of Al2O3 fiber, the wear mechanism of MMCs can be transformed from adhesive delamination to brittle breakaway.

  13. Preparation of continuous Si-Fe-C-O functional ceramic fibers

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new polymer named polyferrocarbosilane(PFCS) was prepared from polydimethylsilane and ferrocene. The spinnability of this polymer can be tailored by controlling the content of ferrocene in the polymer. The prepared polymer was spun into a continuous polymer fiber that was subsequently cured in air and heat-treated finally in N2 up to 1 350 ℃ for conversion into Si-Fe-C-O fibers. The resulted Si-Fe-C-O fibers display low specific resistance and magnetic property due to the existence of Fe,which also reduces the specific resistance significantly to 10-2 Ω·cm at room temperature when the amount of ferrocene in feed is as low as 3.0% (mass fraction). The resulted Si-Fe-C-O fibers, with C/Si molar ratio of about 1.3 and the maximum Fe content of about 2.0% (mole fraction), are composed of β-SiC and small amount of Fe3Si-like crystalline and have an average tensile strength of about 2.0 GPa.

  14. Effects of residual stress and dislocation on tensile deformation behavior of SiCw/Al composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By means of XRD, Instron electronic tensile machine and TEM, the dislocation states and strengthening mechanisms of SiC whisker reinforced pure aluminum matrix composites were studied with different annealing treatment processes and matrixes. The results showed that the strengthening mechanisms of SiCw/p-Al composite and SiCw/6061Al composites are different. For the SiCw/p-Al composite, the thermal residual stress plays more important role in strengthening than the high density dislocations in matrix; for the SiCw/6061Al composite, the dislocation strengthening and precipitation are main strengthening factors.

  15. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    Science.gov (United States)

    Kumar, Santosh; Deepika; Tripathi, Malvika; Vaibhav, Pratyush; Kumar, Aman; Kumar, Ritesh; Choudhary, R. J.; Phase, D. M.

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn0.97Al0.03O, Zn0.95Fe0.05O and Zn0.92Al0.03Fe0.05O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments.

  16. Al-Induced Crystallization Growth of Si Films by Inductively Coupled Plasma Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; WANG Jin-Xiao; YIN Min; GAO Ping-Qi; HE De-Yan

    2006-01-01

    Polycrystalline Si (poly-Si) films are in situ grown on Al-coated glass substrates by inductively coupled plasma chemical vapour deposition at a temperature as low as 350 C. Compared to the traditional annealing crystallization of amorphous Si/Al-layer structures, no layer exchange is observed and the resultant poly-Si film is much thicker than Al layer. By analysing the depth profiles of the elemental composition, no remains of Al atoms are detected in Si layer within the limit (< 0.01 at. %) of the used evaluations. It is indicated that the poly-Si material obtained by Al-induced crystallization growth has more potential applications than that prepared by annealing the amorphous Si/Al-layer structures.

  17. Distribution of Si, Fe, and Ni in the Intracluster Medium of the Coma Cluster

    CERN Document Server

    Matsushita, Kyoko; Sakuma, Eri; Sato, Kosuke

    2012-01-01

    We studied the distributions of Si, Fe, and Ni in the intracluster medium (ICM) of the Coma cluster, one of the largest clusters in the nearby universe, using XMM-Newton data up to 0.5 r180 and Suzaku data of the central region up to 0.16 r180. Using the flux ratios of Ly alpha of H-like Si and 7.8 keV blend to K alpha of He-like Fe, the abundance ratios of Si to Fe and Ni to Fe of the ICM were derived using APEC model v2.0.1. The Si/Fe ratio in the ICM of the Coma cluster shows no radial gradient. The emission weighted averages of the Si/Fe ratio in the ICM within 0.0--0.2 r180, 0.2--0.5 r180, and 0.0--0.5 r180 are 0.97 +- 0.11, 1.05 +- 0.36 and 0.99 +- 0.13, respectively, in solar units using the solar abundance of Lodders (2003). These values are close to those of smaller clusters and groups of galaxies. Using the Suzaku data of the central region, the derived Ni/Fe ratio of the ICM is 0.6--1.5 in solar units, according to the same solar abundance table. The systematic difference in the derived abundance r...

  18. Enhanced microwave absorption of Fe nanoflakes after coating with SiO{sub 2} nanoshell

    Energy Technology Data Exchange (ETDEWEB)

    Yan Longgang; Wang Jianbo; Han Xianghua; Ren Yong; Liu Qingfang; Li Fashen, E-mail: wangjb@lzu.edu.cn [Institute of Applied Magnetics, Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2010-03-05

    Fe nanoflakes were prepared by the ball-milling technique, and then were coated with 20 nm-thick SiO{sub 2} to prepare Fe/SiO{sub 2} core-shell nanoflakes. Compared with the uncoated Fe nanoflakes, the permittivity of Fe/SiO{sub 2} nanoflakes decreases dramatically, while the permeability decreases slightly. Consequently, reflection losses exceeding - 20 dB of Fe/SiO{sub 2} nanoflakes are obtained in the frequency range of 3.8-7.3 GHz for absorber thicknesses of 2.2-3.6 mm, while the reflection loss of uncoated Fe nanoflakes almost cannot reach - 10 dB in the same thickness range. The enhanced microwave absorption of Fe/SiO{sub 2} nanoflakes can be attributed to the combination of the proper electromagnetic impedance match due to the decrease of permittivity and large magnetic loss due to strong and broadband natural resonance. The key to the combination is the coexistence of the nanoshell microstructure and the nanoflake morphology.

  19. Solid-state {sup 27}Al and {sup 29}Si NMR investigations on Si-substituted hydrogarnets

    Energy Technology Data Exchange (ETDEWEB)

    Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Pena, P. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)]. E-mail: ppena@icv.csic.es; Aza, A.H. de [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, CSIC, Serrano Galvache, 4, 28033 Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain); Sanz, J. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

    2007-02-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} hydrates prepared by a reaction in the presence of D{sub 2}O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by {sup 29}Si and {sup 27}Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The {sup 29}Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} was followed by {sup 27}Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.

  20. Electrical investigation of the Al/porous Si/p{sup +}-Si heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, A. [Universite de Sousse, Laboratoire Energie-Materiaux, Ecole Superieure des Sciences et de la Technologie, Rue Lamine Abessi 4011, Hammam Sousse (Tunisia); Jomni, S. [Laboratoire Materiaux, Organisation et Proprietes, Faculte des Sciences de Tunis (Tunisia); Hannachi, R. [Universite de Sousse, Laboratoire Energie-Materiaux, Ecole Superieure des Sciences et de la Technologie, Rue Lamine Abessi 4011, Hammam Sousse (Tunisia); Laboratoire Materiaux, Organisation et Proprietes, Faculte des Sciences de Tunis (Tunisia); Universite de Sousse, Equipe de recherche caracterisations optoelectronique et spectroscopique des materiaux et nanomateriaux pour les telecommunications et capteurs, ISITCOM 4011, Hammam Sousse (Tunisia); and others

    2013-01-15

    Porous silicon based Al/porous Si/p{sup +}-Si heterojunction with porous silicon layer was fabricated on low-resistivity crystalline silicon substrate by electrochemical anodisation. Measurements of the current-voltage I(V) characteristics and capacitance-voltage C(V) at various frequencies were used for the investigation of the electrical properties of this heterojunction. The forward bias I(V) dependencies exhibited a high value of the quality factor close to 7. This was attributed to the existence of interfacial layer and interface states which cause the forward I(V) characteristic not to obey the ideal Schottky diode characteristic. Therefore, it was demonstrated that the current has a square root dependence on the forward bias and it was governed by the Richardson-Schottky conduction mechanism. Furthermore, an ideality factor near the unity has been obtained in the reverse current and the I(V) characteristics were governed by the porous Si/Si heterojunction. The C(V) measurement was performed at different frequencies and revealed that the capacitance behavior was typical of material with interface states. The density of interface states was found to vary from 2 Multiplication-Sign 10{sup 10} eV{sup -1}cm{sup -2} to 1.1 Multiplication-Sign 10{sup 11} eV{sup -1}cm{sup -2} as a function of the interface states energy level position in the band gap of the porous silicon.

  1. Influence of the doping on the lattice sites of Fe in Si

    CERN Document Server

    Silva, Daniel; Wahl, Ulrich; Martins Correia, Joao; Esteves De Araujo, Araujo Joao Pedro

    2014-01-01

    We report on the lattice location and thermal stability of Fe in n+- and p+-type silicon. By means of emission channeling we have observed Fe on ideal substitutional sites, sites located in between bond-centered (BC) and substitutional sites, and sites displaced from tetrahedral towards anti-bonding sites. Here, we focus our analysis on the identification of Fe displaced 0.4-0.6 Å from BC sites and the influence of the doping on the stability of these sites. Fe on near-BC sites is found to be more thermally stable in n+-type Si than in low doped or p+-type Si, and seems to be related to multiple vacancy defects. We suggest that the complexes which trap Fe near BC sites, as well as the formation of substitutional Fe, may play a crucial role in P-diffusion gettering.

  2. Investigation of the 600 C isothermal section of the Fe-Al-Ce ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huiyun; Yin, Fucheng [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Li, Zhi [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Xiangtan Univ., Hunan (China). Key Laboratory of Key Film Materials and Application for Equipment (Hunan province); Ji, Li [South China University of Technology, Guangdong (China). School of Materials Science and Engineering

    2017-01-15

    The isothermal section of the Fe-Al-Ce system at 600 C was determined by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray powder diffraction. Twenty three-phase regions were confirmed experimentally, and two three-phase regions could be deduced in this section. Five ternary compounds, i. e., τ{sub 1}, τ{sub 2}, τ{sub 3}, τ{sub 5}, and τ{sub 6}, exist at 600 C. The Fe{sub 2}Ce phase contains 6.6 at.% Al in the Fe-Al-Ce system. The Fe solubility in α-Al, αAl{sub 11}Ce{sub 3}, αAl{sub 3}Ce, Al{sub 2}Ce, AlCe, and AlCe{sub 3} is approximately 1.7 at.%, 1.1 at.%, 1.2 at.%, 1.3 at.%, 5.8 at.%, and 0.1 at.%, respectively, and the solubility of Ce in α-Al, FeAl{sub 3}, Fe{sub 2}Al{sub 5}, FeAl{sub 2}, and FeAl is approximately 0.1 at.%, 1.2 at.%, 1.9 at.%, 0.9 at.%, and 3.7 at.%, respectively.

  3. Reaction behavior of trace oxygen during combustion of falling FeSi75 powder in a nitrogen flow

    Science.gov (United States)

    Li, Bin; Chen, Jun-hong; Jiang, Peng; Yan, Ming-wei; Sun, Jia-lin; Li, Yong

    2016-08-01

    To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si3N4 sample was heat-treated to remove SiO2. The samples before and after the treatment were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the formation mechanism of SiO2 was investigated. The results show that SiO2 in the Fe-Si3N4 is mainly located on the surface or around the Si3N4 particles in dense areas, existing in both crystalline and amorphous states; when the FeSi75 particles, which are less than 0.074 mm in size, fell in up-flowing hot N2 stream, trace oxygen in the N2 stream did not significantly hinder the nitridation of FeSi75 particles as it was consumed by the surface oxidation of the generated Si3N4 particles to form SiO2. At the reaction zone, the oxidation of Si3N4 particles decreased the oxygen partial pressure in the N2 stream and greatly reduced the opportunity for FeSi75 particles to be oxidized into SiO2; by virtue of the SiO2 film developed on the surface, the Si3N4 particles adhered to each other and formed dense areas in the material.

  4. Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

    Indian Academy of Sciences (India)

    Li Yajiang; Wang Juan; Zhang Yonglan; X Holly

    2002-12-01

    The fine structure in the Fe–Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe–Al alloy layer of the new aluminized steel mainly composed of Fe3Al, FeAl and -Fe (Al) solid solution. There was no brittle phase containing higher aluminum content, such as FeAl3 (59.18% Al) and Fe2Al7 (62.93% Al). The tiny cracks and embrittlement, formerly caused by these brittle phases in the conventional aluminum-coated steel, were effectively eliminated. There was no microscopic defect (such as tiny cracks, pores or loose layer) in the coating. This is favourable to resist high temperature oxidation and corrosion of the aluminized steel.

  5. Pressureless infiltration processing and thermal properties of SiCp/Al composites with high SiC particle content

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xian-liang; ZOU Ai-hua; HUA Xiao-zhen; ZHANG Jian-yun; RAO You-hai

    2006-01-01

    SiCp/1060A1, SiCp/ZL101, SiCp/ZL102 composites with SiCp volume fraction of 55% were fabricated by pressureless infiltration. The microstructure was examined and thermal properties were characterized for SiCp/Al composites. The results show that the composites are dense and macroscopically homogeneous. With the increase of temperature, the mean linear coefficient of thermal expansion(CTE) at 25-200 ℃ of the composites increases and ranges from 7.23×10-6 to 10.4×10-6 K-1, but thermal conductivity declines gradually at the same time. With the increase of Si content in the Al matrix, CTE of the composites declines and thermal conductivity also declines but not linearly, when Si content is up to 7%, the average thermal conductivity is 140.4 W/(m.K), which is close to that of the SiCp/1060Al composite (144.6 W/(m.K)). While Si content is 11.7%, the average thermal CTE and improving thermal conductivity of the composites. Compared with conventional thermal management materials, SiCp/Al composites are potential candidate materials for advanced electronic packaging due to their tailorable thermo-physical properties.

  6. Numerical modelling of microstructure forming process for Al-Al3Fe eutectic alloy

    Institute of Scientific and Technical Information of China (English)

    李荣德; 周振平

    2003-01-01

    A self-adjusting model was presented on the basis of the effect of temperature gradient on eutectic growth and a curved solid/liquid interface. Finite differential method was adopted to solve the model. The average lamellar spacing of the Al-Al3Fe eutectic alloy and the content fields ahead of the solidifying interface under different growth rates were calculated. Directional solidification experiments were carried out in order to prove the modification of the modeling. The experimental results are in relatively good agreement with the calculations.

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

    Institute of Scientific and Technical Information of China (English)

    亓效刚; 王玉厚; 边秀房

    2000-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ahmed M. Nabawy

    2016-05-01

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

  9. Stable iron isotope fractionation between aqueous Fe(II) and model Archean ocean Fe-Si coprecipitates and implications for iron isotope variations in the ancient rock record

    Science.gov (United States)

    Wu, Lingling; Percak-Dennett, Elizabeth M.; Beard, Brian L.; Roden, Eric E.; Johnson, Clark M.

    2012-05-01

    Iron isotope fractionation between aqueous Fe(II) (Fe(II)aq) and two amorphous Fe(III) oxide-Si coprecipitates was investigated in an aqueous medium that simulated Archean marine conditions, including saturated amorphous silica, low sulfate, and zero dissolved oxygen. The equilibrium isotope fractionation (in 56Fe/54Fe) between Fe(II)aq and Fe(III)-Si coprecipitates at circum-neutral pH, as inferred by the three-isotope method, was -3.51 ± 0.20 (2σ)‰ and -3.99 ± 0.17 (2σ)‰ for coprecipitates that had Fe:Si molar ratios of 1:2 and 1:3, respectively. These results, when combined with earlier work, indicate that the equilibrium isotope fractionation factor between Fe(II)aq and Fe(III)-Si coprecipitates changes as a function of Fe:Si ratio of the solid. Isotopic fractionation was least negative when Fe:Si = 1:1 and most negative when Fe:Si = 1:3. This change corresponds with changes in the local structure of iron, as revealed by prior spectroscopic studies. The kinetics of isotopic exchange was controlled by movement of Fe(II) and Si, where sorption of Fe(II) from aqueous to solid phase facilitated atom exchange, but sorption of Si hindered isotopic exchange through blockage of reactive surface sites. Although Fe(II)-Fe(III) isotopic exchange rates were a function of solid and solution compositions in the current study, in all cases they were much higher than that determined in previous studies of aqueous Fe(III) and ferrihydrite interaction, highlighting the importance of electron exchange in promoting Fe atom exchange. When compared to analogous microbial reduction experiments of overlapping Fe(II) to Fe(III) ratios, isotopic exchange rates were faster in the biological experiments, likely due to promotion of atom exchange by the solid-phase Fe(II) produced in the biological experiments. These results provide constraints for interpreting the relatively large range of Fe isotope compositions in Precambrian marine sedimentary rocks, and highlight important

  10. Si-FeOOH催化臭氧氧化降解活性艳红MX-5B的效能研究%Catalytic ozonation of active red MX-5B in water with Si-FeOOH

    Institute of Scientific and Technical Information of China (English)

    周康; 霍明昕; 汪小雄; 姜成春

    2013-01-01

    通过共沉淀的方法在羟基氧化铁(FeOOH)合成过程中掺入硅(Si)来制备硅羟基氧化铁(Si-FeOOH)催化剂,比较其与FeOOH在物理强度等方面的差异,同时研究Si-FeOOH催化臭氧氧化降解活性艳红的效能、推断反应机理、考察各种因素对脱色率的影响.结果表明:相对于FeOOH,Si-FeOOH的物理强度有所提高,在水溶液中不易破碎;Si-FeOOH催化臭氧氧化降解活性艳红效果显著,比单独臭氧氧化的脱色率有较大提高;催化过程遵循自由基反应机理;脱色率随着臭氧浓度的增加而升高,在应用Si-FeOOH催化臭氧对染料脱色时存在最佳催化剂投量;Si-FeOOH在中性条件下其催化活性显著,催化剂性能稳定,可重复利用.%In this study, Si was added into FeOOH to prepare Si-FeOOH, and the physical intensity and other properties of Si-FeOOH and FeOOH were compared. The influencing factors of Si-FeOOH-catalyzed ozone on red MX-5B degradation were studied, and the reaction mechanism and the efficiency of decolorization ratio were investigated. The result indicated that, compared with FeOOH, Si-FeOOH had higher physical intensity and was not likely to be crushed in water solution. The iron dissolution was effectively prevented because of the addition of Si, and the effect of Si-FeOOH-catalyzed ozone on red MX-5B degradation was obvious. The decolorization ratio of Si-FeOOH was improved, and the catalytic process followed free radical reaction mechanism. The decolorization ratios increased in response to the increased ozone concentration, whereas the dosage of the catalyst existed an optimum value. Si-FeOOH had a distinct catalytic activity under the neutral condition. The capability of the catalyst was stable, and the catalyst can he recycled and reused.

  11. Simulation Study of Al-1Mn/Al-10Si Circular Clad Ingots Prepared by Direct Chill Casting

    Science.gov (United States)

    Wu, Li; Kang, Huijun; Chen, Zongning; Fu, Ying; Wang, Tongmin

    2016-02-01

    A modified direct chill casting process based on Novelis FusionTM Technology co-casting process was used recently to prepare Al-1Mn/Al-10Si circular clad ingots. In the current study, a comprehensive simulation model was developed to investigate the direct chill casting process for preparing the Al-1Mn/Al-10Si circular clad ingots, and a parametric study and experimental research of the direct chill casting process was conducted to explore potential success and failure casting conditions. The simulation results revealed the bonding mechanism of the Al-1Mn/Al-10Si interface in the direct chill casting process and identified the effect of certain parameters on casting performance. The results indicated that the effect of casting speed and Al-1Mn casting temperature on the variations of the minimum solid fraction of Al-1Mn at the interface is stronger than that of cooling water flow rate in inner mold, while Al-10Si casting temperature is the weakest of the four casting parameters. The corresponding experimental results verified that Al-1Mn/Al-10Si circular clad ingot with acceptable metallurgical bonding can be successfully prepared by direct chill casting process under the proper casting parameters. The thickness of diffusion zone is about 40 μm, and the fractured position in tensile test was located in the Al-1Mn alloy side which indicated the strength of the interfacial region is higher than that of Al-1Mn alloy.

  12. Zener relaxation in ordered and disordered Fe-(22-28%)Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, I.S. [Institute for Materials, Technical University of Braunschweig, Langer Kamp 8, Braunschweig D-38106 (Germany)]. E-mail: i.golovin@tu-bs.de; Riviere, A. [LMPM ENSMA, UMR CNRS 6617, F-86961 Futuroscope Chasseneuil Cedex (France)

    2006-12-20

    The Zener relaxation in three Fe-Al alloys with 22, 26 and 28 at.% Al has been studied by isothermal measurements of elastic-energy-dissipation as a function of vibrating frequency in the range from 10{sup -4} to 10{sup 2} Hz. The activation energy of the Zener relaxation has been determined as follows (in kJ/mol): 238 in Fe-22Al of the disordered bcc (A2) structure, 270 in Fe-22Al of the D0{sub 3} + A2, two phase structure, 235 in Fe-26Al of the B2 ordered structure, 286 in Fe-26Al of the D0{sub 3} ordered structure, and 276 in Fe-28Al-3Cr at temperature close to the D0{sub 3} {r_reversible} B2 transition.

  13. Structure and wear behavior of AlCrSiN-based coatings

    Science.gov (United States)

    Chen, Yun; Du, Hao; Chen, Ming; Yang, Jun; Xiong, Ji; Zhao, Haibo

    2016-05-01

    AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC-Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N2 mixtures. Al0.6Cr0.4, Al0.6Cr0.3Si0.1, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiNx peak were formed in the AlCrSiN/MexN coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H3/E2 ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  14. Pressureless infiltration of Si3N4 preforms with an