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Sample records for al si fe

  1. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

  2. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    Energy Technology Data Exchange (ETDEWEB)

    Gueneau, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. des Procedes d`Enrichissement]|[Paris-11 Univ., 91 - Orsay (France)]|[Compagnie de Produits Chimiques et Electrometallurgiques Pechiney, 74 - Passy-Chedde (France). Lab. Graphitation; Servant, C. [Paris-11 Univ., 91 - Orsay (France); Ansara, I. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Grenoble (France)

    1994-12-31

    The substitutions of Al <-> Si, Fe <-> Mn and Fe <-> Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil`s model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs.

  3. Assessment of the al corner of the ternary Al-Fe-Si system

    OpenAIRE

    Eleno, Luiz; Vezelý, Josef; Sundman, Bo; Cieslar, Miroslav; Lacaze, Jacques

    2010-01-01

    The present work provides a review of the information available on the Al-rich corner of the Al-Fe-Si system as well as a CALPHAD type assessment making use of the COST 507 database as a starting point. The description of the intermetallic compounds has been modified to account for substitution of Al and Si in the ternary Al-Fe-Si system and to take new experimental information into account.

  4. New orthorhombic phase in U-Fe-Al-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Zenou, V.Y. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Nuclear Research Center - Negev, P.O. Box 9001, Beer-Sheva 84190 (Israel); Ezersky, V.; Meshi, L.; Fuks, D. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Talianker, M., E-mail: mital@bgu.ac.il [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2011-01-12

    Research highlights: > In this paper we report on the results of structure investigation of a new quaternary phase observed in U-Fe-Al-Si system. > The composition of this phase is: U-18.6 at% Fe-29.2 at% Al-32.6 at% Si. > This phase is orthorhombic and its symmetry can be described by the Immm space group. > The unit cell parameters of the new phase are: a = 12.241 A, b = 18.362 A and c = 4.066 A. > Structural investigations were performed using electron microscopy, X-ray powder diffraction, conventional and convergent beam electron diffraction techniques. - Abstract: A new quaternary phase with the approximate composition U-18.6 at%Fe-29.2 at%Al-32.6 at%Si was observed in U-Fe-Al-Si system. The crystal structure of this phase was investigated by electron diffraction and X-ray powder diffraction techniques. It has an orthorhombic unit cell with lattice parameters a = 12.241 A, b = 18.362 A and c = 4.066 A and can be described by the Immm space group.

  5. New orthorhombic phase in U-Fe-Al-Si system

    International Nuclear Information System (INIS)

    Research highlights: → In this paper we report on the results of structure investigation of a new quaternary phase observed in U-Fe-Al-Si system. → The composition of this phase is: U-18.6 at% Fe-29.2 at% Al-32.6 at% Si. → This phase is orthorhombic and its symmetry can be described by the Immm space group. → The unit cell parameters of the new phase are: a = 12.241 A, b = 18.362 A and c = 4.066 A. → Structural investigations were performed using electron microscopy, X-ray powder diffraction, conventional and convergent beam electron diffraction techniques. - Abstract: A new quaternary phase with the approximate composition U-18.6 at%Fe-29.2 at%Al-32.6 at%Si was observed in U-Fe-Al-Si system. The crystal structure of this phase was investigated by electron diffraction and X-ray powder diffraction techniques. It has an orthorhombic unit cell with lattice parameters a = 12.241 A, b = 18.362 A and c = 4.066 A and can be described by the Immm space group.

  6. Thermodynamic assessment of the aluminum corner of the Al-Fe-Mn-Si system

    OpenAIRE

    Lacaze, Jacques; Eleno, Luiz; Sundman, Bo

    2010-01-01

    A new assessment of the aluminum corner of the quaternary Al-Fe-Mn-Si system has been made that extends beyond the COST-507 database. This assessment makes use of a recent, improved description of the ternary Al-Fe-Si system. In the present work, modeling of the Al-rich corner of the quaternary Al-Fe-Mn-Si system has been carried out by introducing Fe solubility into the so-called alpha-AlMnSi and beta-AlMnSi phases of the Al-Mn-Si system. A critical review of the data available on the quater...

  7. Thermodynamic Assessment of the Aluminum Corner of the Al-Fe-Mn-Si System

    Science.gov (United States)

    Lacaze, Jacques; Eleno, Luiz; Sundman, Bo

    2010-09-01

    A new assessment of the aluminum corner of the quaternary Al-Fe-Mn-Si system has been made that extends beyond the COST-507 database. This assessment makes use of a recent, improved description of the ternary Al-Fe-Si system. In the present work, modeling of the Al-rich corner of the quaternary Al-Fe-Mn-Si system has been carried out by introducing Fe solubility into the so-called alpha-AlMnSi and beta-AlMnSi phases of the Al-Mn-Si system. A critical review of the data available on the quaternary system is presented and used for the extension of the description of these ternary phases into the quaternary Al-Fe-Mn-Si.

  8. Precipitation of Fe and Si in cold rolled Al-Fe-Si sheet during annealing

    International Nuclear Information System (INIS)

    The aim of this present work is to make clear the precipitation behavior of Fe and Si in cold rolled commercial pure aluminum sheet during annealing, especially on the phases and on the effects of prior cold rolling

  9. 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.

  10. Addition of iron for the removal of the β-AlFeSi intermetallic by refining of α-AlFeSi phase in an Al-7.5Si-3.6Cu alloy

    International Nuclear Information System (INIS)

    Addition of iron into the molten metal for the removal of the β-AlFeSi intermetallic by refining of α-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 α-AlFeSi and β-AlFeSi phases. This phenomenon was confirmed with calculations made by Thermo-CalcTM 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 α-AlFeSi and removal of β-AlFeSi phases can be improved. Final results showed an improvement in mechanical properties by removal and refining of β-AlFeSi and α-AlFeSi phases, respectively. This study shows a new method of removal of β-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 μm.

  11. Growth of Fe2Al5 phase on pure iron hot-dipped in Al-Mg-Si alloy melt with Fe in solution

    International Nuclear Information System (INIS)

    We have examined the growth and morphology of the Fe-Al alloy layer (Fe2Al5-η and FeAl3-θ phases) on pure Fe sheets hot-dipped at 750°C in an Al-8.2Mg-4.8Si-Fe (wt.%) and Al-Fe alloy melts which are saturated with Fe where the effect of Fe dissolution from the solid Fe can be eliminated. In both the Al-Mg-Si-Fe and Al-Fe melts, the total thickness of Fe sheets increased during the dipping, indicating that the diffusion of Al from the melt side is dominant in the growth of the Fe-Al alloy layer. The growth rate constant of the η phase layer in the both melts was close to 0.5 while the growth rate in the Al-Mg-Si-Fe alloy melt was approximately one order of magnitude slower than that in the Al-Fe melt. The θ phase layer appeared continuous in the Al-Mg-Si-Fe alloy melt, whereas the layer was discontinuous in the Al-Fe melt. The sluggish growth of the η phase layer in the Al-Mg-Si-Fe alloy melt is discussed. (author)

  12. Al-Si-Cu-Fe Alloys -relationship between the spacing of dendritic branches and the size of the intermetallic phase Beta-Al5FeSi

    International Nuclear Information System (INIS)

    This work analyzes the effect of copper on the morphological parameters that the Fe-rich intermetallic phases acquire in Al-Si-Cu alloys. Alloys with Cu content of 1% and 3% were studied and in both cases the percentages of Fe used were 0.7%. The sheet sizes of β-Al5FeSi were measured for the different experimental conditions using an image analysis system. Results obtained until now indicate that for lower percentages of Cu, the size of the intermetallic phase of Fe (β-Al5FeSi) decreases, because the inter dendritic canals become smaller. Based on these results, a correlation was made of the effect that the modification of the dendritic arm spacing, DAS, as a result of the presence of Cu, has on the binary eutectic reactions (Liq1 →Alp + β-Al5FeSi + Liq2) and ternary eutectic (Liq1→Alp + β-Al5FeSi + Si +Liq2) which promote the presence of the + β-Al5FeSi phase (CW)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

  14. INTERFACIAL SOLID STATE REACTIONS OF Si3N4/Fe AND Si3N4/Fe3Al COUPLES%Si3N4/Fe,Si3N4/Fe3Al界面的固相反应

    Institute of Scientific and Technical Information of China (English)

    高建杰; 汤文明; 吴玉程; 郑治祥

    2009-01-01

    After Si3N4/Fe, Si3N4/Fe3Al couples had been heat treated at 1150 ℃ for 10h in Ar atmosphere, the morphologies, phases, microstructures and elemental distributions in the reaction zones of the couples were studied using a scanning electron microscope with an energy disperse spectroscopy analyzer and X-ray diffraction. The results show that there is a reaction zone about 120 μm thick on the Si3N4/Fe interface by solid state reaction. The reaction zone is composed of Fe(Si) solid solution, in which many small pores are distributed uniformly. The Fe content in the reaction zone gradually increases from the Si3N4 surface to the Fe surface, and the Si content of the reaction zone is 5% in mole. The thickness of the interfacial reaction zone formed by the Si3N4/Fe3Al solid state reaction is about 3 μm. The reaction zone is composed of FeAl, Fe(Al, Si) solid solution and AlgFeSi3, and in which the Al content is higher than in Fe3Al. The chemical compatibility of the Si3N4/Fe3Al system sample is much higher than that of the Si3N4/Fe system.%用扫描电子显微镜、电子能谱仪、X射线衍射等研究了在Ar气氛中,经1150℃,10h等温热处理后,Si3N4/Fe,Si3N4/Fe3Al平而偶界面固相反应区的形貌、成分分布、显微结构及相组成.结果表明:Si3N4/Fe界面固相反应形成约120μn厚的反应区,Fe含量从Si3N4侧到Fe侧逐渐增加,反应区中的Si成分约为5%(原子分数),反应区主要由Fe(Si)固溶体构成,其中均匀地分御着细小的孔洞:Si3NdFe3Al界面固相反应形成约3μm厚的反应区,反应区具有比Fe3Al高得多的Al含量,反应区由FeAl,Fc(Al,Si)固溶体及三元化合物AlgFeSi3构成.Si3NdFe3Al具有比Si3N4/Fe高得多的 界面化学相容性.

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

    International Nuclear Information System (INIS)

    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 (Fe1) increases to about 14.3% while of the other site (Fe2) 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

  16. 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.

  17. Structural and magnetic properties of (Al, Fe)-codoped SiC

    International Nuclear Information System (INIS)

    In this study, as a first attempt, we choose Al and transition metals (TMs), Fe, as codoping atoms to synthesize (Al, TM)-codoped SiC. X-ray diffraction and Raman analysis showed that a series of single-phase codoped 4H-SiC samples were obtained and no trace of any other impurity phases, such as Fe3Si and polytypes of other types of SiC, was found. Measurement of magnetic properties showed that codoping by Al and Fe elements changed the original glassy ferromagnetism (FM) features in Al-doped SiC and induced a robust room temperature FM order that gradually dominated (Al, Fe)-codoped 4H-SiC with increase in Fe content. The contribution of Al elements to the magnetic properties of (Al, Fe)-codoped 4H-SiC can be neglected and the magnetic origin should be ascribed to be induced by Fe doping. The only major role of Al is to stabilize the codoped crystal structure as 4H- single phase. As the first investigation on (Al, TM)-codoped SiC, this study opens a new pathway to obtain TM-doped SiC-based diluted magnetic semiconductors with a high Tc via the codoping strategy.

  18. 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.

    2016-04-01

    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.

  19. 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.

  20. EFFECT OF Si CONTENT ON ORDERING DEGREE AND ELECTROMAGNETIC CHARACTERISTICS IN FeSiAl ALLOYS

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

    FeSiAl alloys ribbons synthesized by melt-quench were annealed in vacuum at 873 K for 60 min. The flaky powders were prepared by milling the annealed ribbons for 70 h. After milling, the powders were heat treated at 573 K for 90 min. The ordering degree of the powders lattice structure was analyzed by X-ray diffraction (XRD).The measurement of specific saturation magnetization was carried out by vibrating samples magnetometer (VSM). Complex permittivity and complex permeability in the frequency band of 0.5-18 GHz were measured with the vector network analyzer. The ordering degree of the superlattice structure increased from 0.27 to 0.49. Complex permittivity and complex permeability decreased with increasing Si content. After ordering, the specific saturation magnetization decreased from 134.2 to 85.0 A.m2.kg-1.For use in anti-EMI material, the total contents of Si and Al in FeSiAl alloys should be controlled at a low level.

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-15

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

  3. EBSD study of crystallographic identification of Fe-Al-Si intermetallic phases in Al-Si coating on Cr-Mo steel

    International Nuclear Information System (INIS)

    5Cr-0.5Mo steel was coated by hot-dipping in a molten Al-10 wt.% Si bath at 700 deg. C for 10, 60, 120 or 180 s. The identification of the phases in the Fe-Al-Si intermetallic phases formed in the aluminide layers during hot-dipping was carried out by using a combination of scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The EDS results show a τ5(H)-Al7Fe2Si phase, which exhibited 2 distinct morphologies, small particles widely dispersed and a continuous layer. Also revealed by EDS were τ6-Al4FeSi and τ4-Al3FeSi2 phases, which showed plate-shaped morphology, in an Al-Si topcoat. However, the XRD results show the intermetallic phases in the aluminide layer were composed of outer cubic τ5(C)-Al7(Fe,Cr)2Si and inner hexagonal τ5(H)-Al7Fe2Si. EBSPs and mapping functions in EBSD helped to clarify the confused phase identifications yielded by EDS and XRD. In this way, the small intermetallic particles and the continuous intermetallic layer were identified as cubic τ5(C)-Al7(Fe,Cr)2Si and hexagonal τ5(H)-Al7Fe2Si, respectively, and the plate-shaped intermetallic phase was identified as monoclinic τ6-Al4FeSi and tetragonal τ4-Al3FeSi2 with the same metallographic morphology. EBSD proved to be a very effective technique for local phase identification of aluminide layers with complicated multiphase morphologies.

  4. 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.

  5. First-principles study of the electronic and magnetic properties of Fe2MnAl, Fe2MnSi and Fe2MnSi0.5Al0.5

    International Nuclear Information System (INIS)

    In this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler compounds Fe2MnAl, Fe2MnSi and alloy Fe2MnSi0.5Al0.5 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 Fe2MnAl, Fe2MnSi indicate half-metallic behavior with vanishing electronic density of states for minority spin at the Fermi level, which yields perfect spin polarization while for Fe2MnSi0.5Al0.5 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 Fe2MnAl, Fe2MnSi and Fe2MnSi0.5Al0.5 are studied • Our calculated lattice constants and spin magnetic moments are in good agreement with the available theoretical and experimental data • Fe2MnAl, Fe2MnSi are half-metals and Fe2MnSi0.5Al0.5 nearly half-metals

  6. Magnetic properties of ultrasoft-nanocomposite FeAlSiBNbCu alloys

    International Nuclear Information System (INIS)

    The effects of up to 10 at% substitution of Fe by Al on the microstructure and DC and AC magnetic properties of nanocrystalline FeSiBCuNb alloy ribbon are summarised and analysed. The minimum DC Hc developed during annealing decreases by 40% for 2 at% Al (to 0.3 A/m) and remains roughly constant for larger Al contents. The largest peak value of μ0.4 at 50 Hz also corresponds to 2 at% Al. The best frequency response for μ0.4 occurs for 6 at% Al while there was no improvement in AC power loss behaviour over the 0% Al alloy. The improvements in DC Hc and AC μ0.4 are ascribed to a reduction in K1 of the Fe-Si-based nanocrystallites by the introduction of Al

  7. 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

  8. NUCLEATION BEHAVIOR OF Al8Fe4Nd PHASE IN RAPIDLY SOLIDIFIED AI-Fe-V-Si-Nd ALLOY

    Institute of Scientific and Technical Information of China (English)

    H. Pang; Z.H. Jin; J.N. Deng; M.G. Zeng

    2002-01-01

    The microstructure of Al-Fe- V-Si-Nd alloy prepared by rapid solidification (RS) pro-cessing was studied by X-ray diffraction (XRD), transmission electron microscopy(TEM) and high resolution electron microscopy (HREM). The phase selection of thealloy during solidification and the nucleation behavior of Al8Fe4Nd phase were ana-lyzed witinin the framework of time-dependent nucleation theory. The incubation timefor Al8Fe4Nd phase was found shorter and the nucleation rate higher than those ofα-Al. The results indicate the nucleation of Al8Fe4Nd phase is heterogeneous and thedispersoids of Al8Fe4Nd form as primary particles from the liquid, which is consistentwith experimental observation.

  9. Electrical resistivity of nanocrystals in Fe-Al-Ga-P-B-Si-Cu alloy

    International Nuclear Information System (INIS)

    In new supercooled Fe74Al4Ga2P11B4Si4Cu1 alloy the 10 nm size α-Fe(Si) nanocrystals are precipitated. Thermal stability is analyzed by the electron transport and magnetization measurements. Temperature variation of electrical resistivity of nanocrystals is determined and discussed for alloys with different initial crystalline fraction. Possible mechanism inhibiting the grain growth is presented

  10. Electronic structure and soft magnetic properties of Se/FeSiAl (110) films

    Science.gov (United States)

    Schwindt, V. Cardoso; Ardenghi, J. S.; Bechthold, P.; Juan, A.; Batic, B. Setina; Jenko, M.; González, E. A.; Jasen, P. V.

    2015-11-01

    The Se adsorption at different coverages on DO3 FeSiAl(110) surface is studied using density functional theory (DFT). Se adsorption is favorable in almost all surface high-symmetry sites, except for the bridge site formed by Fe-Si atoms. The most stable is a hollow site formed by four Fe atoms with adsorption energy of -5.30 eV. When the coverages increase, the energies decrease in the case of hollow sites. The surface present a reconstruction after Se adsorption, being the most important at 1/2 ML. The local magnetic moment for Fe atoms increase for the type A (all nearst neighbours (nn) are Fe atoms) and decrease for the type B (nn are Fe, Si and Al atoms). The most affected metal orbitals are Fe 4s and 4p. In the case of the hollow site the surface Fe-Fe bond is weakened after Se adsorption. A Fe-Se bond is developed at all coverages in both sites being the most important on top (dFe-Se = 2.23 Å, OP: 0.774 at 1/4 ML). The first and second layer Fe-Fe bond increase at 1/4 ML and decrease at 1/2 and 1 ML. Small Se-Se bonding interaction appear at 1/2 ML and increase noticeable for 1 ML. For the top site, the Se-Se bond appears at all coverage. The Fe-Fe surface bonds also decrease its strength with respect to the clean surface at all coverage. The first and second layer Fe-Fe bond increase at all coverage.

  11. Thermoelectric properties of Fe and Al double substituted MnSiγ (γ~1.73)

    Science.gov (United States)

    Barczak, S. A.; Downie, R. A.; Popuri, S. R.; Decourt, R.; Pollet, M.; Bos, J. W. G.

    2015-07-01

    Two series of Fe and Al double substituted MnSiγ 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 Mn1-xFexSi1.75-xAlx series while the second Mn1-xFexSi1.75-1.75xAl2x series follows the pseudo-binary between MnSi1.75 and FeAl2. 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 ~1×1021 holes cm-3 from variable temperature Seebeck measurements. The substituted samples have lower electrical resistivities (ρ300 K=2-5 mΩ cm) due to an improved microstructure. This leads to increased thermoelectric power factors (largest S2/ρ=1.95 mW m-1 K-2) compared to MnSiγ. The thermal conductivity for the Mn0.95Fe0.05Si1.66Al0.1 sample is 2.7 W m-1 K-1 between 300 and 800 K, and is comparable to literature data for the parent material.

  12. Structure and magnetic behaviour of Fe-Cu-Nb-Si-B-Al alloys

    International Nuclear Information System (INIS)

    Fe was substituted by Al up to 7 at% in Finemet. After annealing at 550 deg. C all samples were nanocrystalline, with more or less ordered α-Fe(Si,Al) grains; the DO3-like ordering was the most dominant in samples with 5 and 7 at% of Al. In as-quenched state Al decreased linearly the magnetization, but up to 3 at% enhanced the Curie temperature of the alloy. The Curie temperature of the crystalline phase and the magnetization in annealed samples abruptly decreased, when there was more than 5 at% of Al in the alloy

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

    OpenAIRE

    Umezawa, Osamu

    2005-01-01

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

  14. Thermoelectric properties of Fe and Al double substituted MnSiγ (γ~1.73)

    International Nuclear Information System (INIS)

    Two series of Fe and Al double substituted MnSiγ 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 Mn1−xFexSi1.75−xAlx series while the second Mn1−xFexSi1.75–1.75xAl2x series follows the pseudo-binary between MnSi1.75 and FeAl2. 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 ~1×1021 holes cm−3 from variable temperature Seebeck measurements. The substituted samples have lower electrical resistivities (ρ300 K=2–5 mΩ cm) due to an improved microstructure. This leads to increased thermoelectric power factors (largest S2/ρ=1.95 mW m−1 K−2) compared to MnSiγ. The thermal conductivity for the Mn0.95Fe0.05Si1.66Al0.1 sample is 2.7 W m−1 K−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 MnSiγ (γ~1.73) have been investigated. - Highlights: • Up to 7% Al can be substituted in MnSiγ when co-doped with Fe. • Improved microstructure and reduced electrical resistivities for Al substituted samples. • Largest power factor 1.95 mW m−1 K−2 and best estimated ZT=0.5

  15. 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.

  16. Influence of Grain-Refiner Addition on the Morphology of Fe-Bearing Intermetallics in a Semi-Solid Processed Al-Mg-Si Alloy

    Science.gov (United States)

    Smith, Tahsina; O'Reilly, Keyna; Kumar, Sundaram; Stone, Ian

    2013-11-01

    The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α c-AlFeSi and β-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes β-AlFeSi formation. β-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α c-AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner.

  17. 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

  18. 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.

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

    OpenAIRE

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

    1999-01-01

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

  20. Refinement of the crystal structure π-Al9FeMg3Si5

    International Nuclear Information System (INIS)

    The crystal structure of the quaternary so-called π-phase, which was originally solved from photographic single crystal data, has been refined from single crystal automatic four circle counter data. Single crystals were obtained from the residue of a slowly cooled melt of nominal composition (in at %) Al74.1Fe0.5Mg8.4Si17.0, which was dissolved in butanol. The composition of the π-phase crystal was Al9Fe1Mg3.5Si5.0. The π-phase crystallizes in a unique structure type (Al9FeMg3Si5-type) with the noncentrosymmetric hexagonal space group P anti 62m-D33h, No. 189. The lattice parameters obtained from a Gandolfi camera were a=0.6625(2) nm and c=0.7910(4) nm, Z=1. For 366 reflections (parallel F0 parallel ≥3σ) the residual values are R= sum (parallel ΔF parallel / sum parallel F0 parallel)=0.064, Rw=0.075. Whereas previous structure determinations claimed full atom order, the present refinement clearly indicates that the crystal structure is partially ordered with a random distribution of 0.94 Al+0.06 Mg in the 6i-sites. Furthermore, whilst lattice and atom parameter essentially correspond to the values derived earlier, the new composition as a result of the refinement (Al8.7Fe1Mg3.3Si5) is in close agreement with the experimental composition Al9FeMg3.5Si5. (orig.)

  1. High-quality Co2FeSi0.5Al0.5/Si heterostructures for spin injection in silicon spintronic devices

    International Nuclear Information System (INIS)

    For high-performance spin injectors in silicon (Si)-based spintronic applications, we have explored the growth technique of quaternary Co-based Heusler-compound Co2FeSi0.5Al0.5 on Si(111) by using low-temperature molecular beam epitaxy (LTMBE). In our previous study, Al co-deposition induced an interfacial reaction between Co2FeSi1−xAlx and Si. Here, we dramatically improve the Co2FeSi0.5Al0.5/Si heterostructures by introducing a nonstoichiometric LTMBE technique. Atomically smooth Co2FeSi0.5Al0.5/Si heterointerfaces and L21-ordered Co2FeSi0.5Al0.5 films are simultaneously achieved. Even in as-grown conditions, the magnetic properties of the Co2FeSi0.5Al0.5 layers are nearly equivalent to those of the heat-treated ones reported on MgO. This study gives important knowledge to realize the optimized highly spin-polarized ferromagnet/Si heterointerfaces for next-generation Si-based spintronic devices. - Highlights: • Atomically smooth Co2FeSi0.5Al0.5/Si heterointerfaces were achieved. • Room-temperature grown Co2FeSi0.5Al0.5 film formed an L21-ordered structure. • Relatively high magnetic moment of the grown Co2FeSi0.5Al0.5 layer was obtained

  2. Si Nano-crystallites embedded in Cu-Al-Fe matrix as an anode for Li secondary batteries

    International Nuclear Information System (INIS)

    Si nanocrystallites embedded in Cu-Al-Fe matrix were developed using arc melting followed by a rapid quenching method which could produce a large scale at one time. Si nanocrystallites of approximately 100 nm were dispersed in matrix composed of Al4Cu9 and AlFe phases. To identify the reaction mechanism, the ex situ XRD and HRTEM analyses were employed. Only Si reacted with Li forming a Li15Si4 phase as the final product while the Al4Cu9 and AlFe phases acted as inactive matrix during the first discharge. The Si/Cu-Al-Fe composite showed a good cycle performance with 836 mAh g−1 over 50 cycles. This indicated that inactive matrices not only endured the stress caused by volume expansion of Li-Si alloy but also provided a good electron path as a conductor

  3. Determination of Si, Al and Fe in atmospheric particulate material by 14-MeV neutron activation analysis

    International Nuclear Information System (INIS)

    Concentrations of Si, Al and Fe were determined in atmospheric particulate material using 14 MeV neutron activation analysis, at the levels at which they normally exist. Enrichment factor and the importance of Al and Fe as being normalizing elements were discussed. Concentrations of Si, Al and Fe were found to be 20.8+-3.6, 7.20+-1.5 and 2.68 +-0.91 μg/m3 respectively

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

    Energy Technology Data Exchange (ETDEWEB)

    Prichard, P.D.

    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 (D{sub 84} < 32 {micro}m). 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 {micro}m. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 {micro}m to 104 {micro}m. 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 {alpha} + DO{sub 3} structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  5. Optical properties of heusler alloys Co2FeSi, Co2FeAl, Co2CrAl, and Co2CrGa

    Science.gov (United States)

    Shreder, E. I.; Svyazhin, A. D.; Belozerova, K. A.

    2013-11-01

    The results of an investigation of optical properties and the calculations of the electronic structure of Co2FeSi, Co2FeAl, Co2CrAl, and Co2CrGa Heusler alloys are presented. The main focus of our attention is the study of the spectral dependence of the real part (ɛ1) and imaginary part (ɛ2) of the dielectric constant in the range of wavelengths λ = 0.3-13 μm using the ellipsometric method. An anomalous behavior of the optical conductivity σ(ω) has been found in the infrared range in the Co2CrAl and Co2CrGa alloys, which differs substantially from that in the Co2FeSi and Co2FeAl alloys. The results obtained are discussed based on the calculations of the electronic structure.

  6. Tunnel magnetoresistance in textured Co2FeAl/MgO/CoFe magnetic tunnel junctions on a Si/SiO2 amorphous substrate

    Science.gov (United States)

    Wen, Zhenchao; Sukegawa, Hiroaki; Mitani, Seiji; Inomata, Koichiro

    2011-05-01

    Magnetic tunnel junctions with B2-ordered Co2FeAl full Heusler alloy as a ferromagnetic electrode were fabricated by sputtering on thermally oxidized Si/SiO2 amorphous substrates. A Co2FeAl/MgO/Co50Fe50 structure showed a highly (001)-textured structure and the tunneling magnetoresistance (TMR) ratio of 166% at room temperature and 252% at 48 K were achieved. The temperature dependence of TMR can be fitted with spin wave excitation model, and the bias voltage dependence of differential conductance demonstrated that the high TMR was mainly contributed by coherent tunneling. This work suggests the B2-Co2FeAl is one of the promising candidates for practical spintronic applications.

  7. Effect of nitrogenation on magnetism for Y2Fe17-x(SiAl)x

    International Nuclear Information System (INIS)

    The magnetic moment (μ) of the host compounds Y2Fe17-xMx (M=Si, Si0.7Al0.3, Al) decreases gradually with x irrespective of M and of the unit cell volume. After that, μ decreases steeply with x. μ increases about 15% after nitrogenation. μ of nitrides decreases with x which is similar to that of the host compounds. However, the range of x, where μ 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.))

  8. Importance of magnetic effects on structural properties in Al- and Si- substituted laves phases Fe2Nb and Fe2W

    International Nuclear Information System (INIS)

    Laves phases are promising candidates for the design of new steels with superior mechanical strength. Here we study systematically thermodynamic, structural and magnetic properties in Al- and Si- substituted Laves phase compounds Fe2Nb and Fe2W using first-principles density functional methods. Spin polarized calculations predict that substituting Al atoms for Fe atoms in Fe2Nb is energetically more favorable than substituting Al atoms for Nb atoms. Furthermore, they show that this leads to a significant increase of the lattice constant along the a axis. To investigate the effects of magnetism, non-magnetic calculations are carried out for the same Fe-Nb-Al compounds. Our results show that the inclusion of magnetism is crucial to accurately reproduce experimental data. Based on this insight, theoretical predictions for ternary alloys Fe-Nb-Si, Fe-W-Al and Fe-W-Si are presented.

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

    International Nuclear Information System (INIS)

    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 D03 ordered Fe3Al. 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

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

    Science.gov (United States)

    Fabrizi, A.; Timelli, G.

    2016-03-01

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

  11. 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.

  12. Thermodynamics of oxygen solutions in Fe-40% Ni-15% Cr melts containing Mn, Si, Ti, Al

    International Nuclear Information System (INIS)

    Thermodynamic analysis and experimental studied are performed for oxygen solutions in Fe-40% Ni-15% Cr melts where Mn, Si, Ti, Al are used as reducing agents. It is revealed that in the alloys studied the affinity of reducing agents to oxygen essentially lower than in liquid iron, nickel and Fe-40% Ni alloy. This is explained by the fact that the oxygen activity in melts noticeably decreases due to a high chromium content whereas the activity of reducing elements increases in a rather less degree. The agreement between analytical and experimental results confirms the validity of the calculation technique

  13. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    International Nuclear Information System (INIS)

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation

  14. Assessment of Post-eutectic Reactions in Multicomponent Al-Si Foundry Alloys Containing Cu, Mg, and Fe

    Science.gov (United States)

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

    2015-07-01

    Post-eutectic reactions occurring in Al-Si hypoeutectic alloys containing different proportions of Cu, Mg, and Fe were thoroughly investigated in the current study. As-cast microstructures were initially studied by optical and electron microscopy to investigate the microconstituents of each alloy. Differential scanning calorimetry (DSC) was then used to examine the phase transformations occurring during the heating and cooling processes. Thermodynamic calculations were carried out to assess the phase formation under equilibrium and in nonequilibrium conditions. The Q-Al5Cu2Mg8Si6 phase was predicted to precipitate from the liquid phase, either at the same temperature or earlier than the θ-Al2Cu phase depending on the Cu content of the alloy. The AlCuFe-intermetallic, which was hardly observed in the as-cast microstructure, significantly increased after the solution heat treatment in the alloys containing high Cu and Fe contents following a solid-state transformation of the β-Al5FeSi phase. After the solution heat treatment, the AlCuFe-intermetallics were mostly identified with the stoichiometry of the Al7Cu2Fe phase. Thermodynamic calculations and microstructure analysis helped in determining the DSC peak corresponding to the melting temperature of the N-Al7Cu2Fe phase. The effect of Cu content on the formation temperature of π-Al8Mg3FeSi6 is also discussed.

  15. Effect of aging on mechanical properties of Al-8Si-8Fe-1.4V/SiCp composites

    Directory of Open Access Journals (Sweden)

    A. Essari

    2016-04-01

    Full Text Available In this study, Al-8Fe-8Si-1.4V/SiCp composites fabricated by squeeze casting process were age-hardened to study the influence of heat treatment on mechanical properties, such as hardness, bending strength and modulus of elasticity. The cast samples were solid sоluted at 540 °C for one hour, then quenched in water to room temperature, and finally aged at 190 °C for 2, 4, 6, 8 and 10 hours for hardness test and at 195 °C for 2, 6 and 10 hours for bending strength determination.

  16. Thermodynamics of Nitrogen in Fe-Mn-Al-Si-C Alloy Melts

    Science.gov (United States)

    Paek, Min-Kyu; Chatterjee, Saikat; Pak, Jong-Jin; Jung, In-Ho

    2016-04-01

    Thermodynamic behavior of nitrogen in the entire range of the Fe-Mn-Al-Si-C liquid solution was modeled based on the critical evaluation and optimization of all available experimental data. The Gibbs energy of liquid solution was described using the Modified Quasichemical Model (MQM) in the pair approximation, instead of classical Wagner Interaction Parameter Formalism, to consider the strong interactions between species in liquid state. In particular, the dissolution behavior of N and formation of AlN in the entire ternary and higher order liquids were accurately predicted from the MQM only with binary model parameters of N.

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

    Science.gov (United States)

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

    2013-11-01

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

  18. Thin films of the Heusler compounds Co2FeAl and Co2FeAl0.6Si0.4

    Energy Technology Data Exchange (ETDEWEB)

    Arbelo Jorge, Elena; Herbort, Christian; Jourdan, Martin [Institut of Physics, Johannes-Gutenberg University, Mainz (Germany)

    2009-07-01

    Heusler compounds are potential candidates for showing half metallic properties (100% spin polarization) with a large band gap at the Fermi energy and a high Curie temperature above room temperature. Epitaxial thin films of the Heusler compounds Co{sub 2}FeAl and Co{sub 2}FeAl{sub 0.6}Si{sub 0.4} were grown by rf sputtering. A study of their crystallographic structure, surface morphology and magnetization has been carried out. For Co{sub 2}FeAl a B2 structure is found after annealing at 550 C. For Co{sub 2}FeAl{sub 0.6}Si{sub 0.4} L21 order is found after annealing at the same temperature. The crystallographic order depending on different annealing temperatures is shown. In both compounds a small tetragonal distortion is observed. The surface morphology of each compound is also analysed and compared. Magnetization measurements made in a Quantum Design SQUID magnetometer show a magnetic moment of 4.86 {mu}B/f.u and 4.47 {mu}B/f.u for Co{sub 2}FeAl and Co{sub 2}FeAl{sub 0.6}Si{sub 0.4} annealed at 550 C respectively, which is 2.8% and 17,2% less than the value predicted theoretically from the Slater-Pauling rule for half metals, 5.0 {mu}B/f.u and 5.4 {mu}B/f.u, respectively. The magnetic moment depending on different annealing temperatures is presented. Finally, TMR results obtained up to now are shown.

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

    International Nuclear Information System (INIS)

    Highlights: → Fabricated a kind of high performance Al-Si alloy with low production costs. → Clarified two different morphologies of α-Fe and corresponding crystal structures. → Analyzed the crystallography of Cu-rich phases before and after T6 treatment. → Fracture mechanism of precipitates in experimental alloys during tensile process. -- Abstract: In this paper, we report a novel kind of eutectic Al-Si-Cu-Fe-Mn alloy with ultimate tensile strength up to 336 MPa and 144.3 MPa at room temperature and 300 oC, respectively. This kind of alloy was prepared by metal mold casting followed by T6 treatment. The microstructure is composed of eutectic and primary Si, α-Fe, Al2Cu and α-Al phases. Iron-rich phases, which were identified as BCC type of α-Fe (Al15(Fe,Mn)3Si2), exist in blocky and dendrite forms. Tiny blocky Al2Cu crystals disperse in α-Fe dendrites or at the grain boundaries of α-Al. During T6 treatment, Cu atoms aggregate from the super-saturation solid solution to form GP zones, θ'' or θ'. Further analysis found that the enhanced mechanical properties of the experimental alloy are mainly attributed to the formation of α-Fe and copper-rich phases.

  1. 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.

  2. Microstructural path of recrystallization in a commercial Al-Mn-Fe-Si (AA3003 alloy

    Directory of Open Access Journals (Sweden)

    Paulo Rangel Rios

    2003-12-01

    Full Text Available The phenomenological analysis of recrystallization data is described. The concept of microstructural path is briefly introduced as well as some of its relevant equations. The correct equation for the impingement compensated chord length is introduced and used here for the first time. The theory is then applied to data from the recrystallization of a commercial Al-Mn-Fe-Si (AA3003 alloy. It is concluded that nucleation is site saturated and that the grain boundary velocity decreases with time. The analysis also shows that the shape of the recrystallized regions significantly deviates from spherical as the reaction progresses, probably because of the boundary/precipitates interaction.

  3. Evaluation of Cast Al-Si-Fe alloy/Coconut Shell Ash Particulate Composites

    OpenAIRE

    S.Y. Aku; D.S. Yawas; ADOKMA, Apasi

    2013-01-01

    Al-7wt%Si-2wt%Fe alloy/Coconut shell ash(CSAp) composites having 3-15wt%coconut shell ash were fabricated by double stir-casting method.  The microstructure, hardness values and density of the composites were evaluated. The density of the composites decreased as the percentage of coconut shell ash increases in the aluminum alloy. This means that composites of lower weight component can be produced by adding CSAp.  Microstructural analysis showed fairy distribution of coconut shell a...

  4. Spectrographic semi-quantitative determination of Al, Ca, Fe, Na y Si in minerals and rocks

    International Nuclear Information System (INIS)

    Here is described a method for to determine semi quantitatively Al, Ca, Fe, Na and Si in rocks and minerals. It is used the total combustion technique which uses in jointly germanium oxide (GeO2) and lithium tetraborate (Li2B4O7). The first one acts as regulator and internal standard and the second one acts as regulator and fusing. The excitation is carry out in a emission spectrograph of three meters of focal length. For certificating the obtained results, it was made a comparative study with the atomic absorption spectroscopy technique. (Author)

  5. First principles study of structural, electronic and magnetic properties of ZrFeTiAl, ZrFeTiSi, ZrFeTiGe and ZrNiTiAl

    Energy Technology Data Exchange (ETDEWEB)

    Berri, Saadi, E-mail: berrisaadi12@yahoo.fr [Laboratory for Developing New Materials and their Characterizations, University of Setif (Algeria); Ibrir, Miloud [Department of Physics, Faculty of sciences, University of Msila (Algeria); Maouche, Djamel [Laboratory for Developing New Materials and their Characterizations, University of Setif (Algeria); Attallah, Mourad [Department of Physics, Faculty of sciences, University of Msila (Algeria)

    2014-12-15

    The electronic and magnetic properties of the ZrFeTiAl, ZrFeTiSi, ZrFeTiGe and ZrNiTiAl quaternary Heusler compounds have been investigated using first-principles calculations. Our calculations predict that ZrFeTiAl, ZrFeTiSi, ZrFeTiGe and ZrNiTiAl are half-metallic ferromagnets (HMFs) with a magnetic moment of 1, 2, 2, 3 µ{sub B}/fu and HM flip gaps of 0.56, 0.92, 0.86 and 0.65 eV, respectively. Our calculations show that these compounds are candidate materials for future spintronic applications. - Highlights: • First-principles investigate the electronic and magnetic properties of Zr(Fe,Ni)Ti(Al, Si, Ge). • Zr(Fe,Ni)Ti(Al, Si, Ge) quaternary Heusler compounds are a half-metallic ferromagnetic. • Exchange splitting of TMs-t{sub 2g} electrons are responsible for ground state ferromagnetism.

  6. 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.

  7. 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

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

    OpenAIRE

    A. Dulęba; M. Cholewa

    2012-01-01

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

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

    International Nuclear Information System (INIS)

    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, Tp, and Curie temperature, TC, 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

  10. Crystal structure and microwave permeability of very thin Fe-Si-Al flakes produced by microforging

    International Nuclear Information System (INIS)

    Fine flakes of Fe-Si-Al produced by long-duration microforging exhibit a peculiar dual-peak dispersion in their frequency characteristics of the imaginary part of the permeability. This dual dispersion has a high potential to be a electromagnetic noise suppressor, works effectively in the microwave band. In a previous report we clarified that one of the dispersions (D II), which appears in the lower frequency range, is correlated to a shape anisotropy of the flakes. In this article, the origin of another dispersion (D III) is studied by analyses of crystalline structure changes during forging (100-180 h) and annealing processes. X-ray diffraction and Moessbauer spectra strongly suggest that the annealed flakes have a composition gradient structure consisting of an Fe-rich mother phase and a Si/Al-rich surface layer. The fact that dispersion D III is enhanced with development of this phase separation leads to the conclusion that dispersion D III is caused by a magnetoelastic anisotropy near the flake surface

  11. Comparative investigation of microarea quasilattice parameters of Al-Si-Mn and Al-Cu-Fe icosahedral phases using HOLZ line patterns

    International Nuclear Information System (INIS)

    Some differences between the higher-order Laue zone (HOLZ) line patterns of Al76Si4Mn20 and Al65Cu20Fe15 icosahedral phases (I phases) have been observed. These differences originate from the fact that Al76Si4Mn20 belongs to a simple icosahedral quasilattice whereas Al65Cu20Fe15 belongs to an ordered face-centred icosahedral quasilattice, and from the minor difference in their quasilattice parameters. By computer simulation of these HOLZ line patterns using a 'standard' quasilattice parameter of 0.460 nm for the I phase of Al76Si4Mn20, the quasilattice parameter of the I phase of Al65Cu20Fe15 has been determined to be 0.8966 nm. (orig.)

  12. GREAT MAGNETIC ENTROPY CHANGE IN La(Fe, M)13 (M=Si, Al) WITH Co DOPING

    Institute of Scientific and Technical Information of China (English)

    Hu Feng-xia; Shen Bao-gen; Sun Ji-rong; Zhang Xi-xiang

    2000-01-01

    Very large magnetic entropy change SM, which originates from a fully reversible second-order transition at Curie temperature TC, has been discovered in compounds La(Fe, Si)13, La(Fe, Al)13 and those with Co doping. The maximum change S M19 J-1-1, achieved in LaFe11.4Si1.6 at 209K upon a 5T magnetic field change, exceeds that of Gd by more than a factor of 2. The TC of the Co-doped compounds shifts to higher temperatures. SM still has a considerable large magnitude near room temperature. The phenomena of very large SM, convenience of adjustmentof TC, and also thesuperiority of low cost, strongly suggest that the compoundsLa(Fe, M)13 (M=Si, Al) with Co doping are suitable candidatesfor magnetic refrigerants at high temperatures.

  13. 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.

  14. Epitaxially grown L10-FePt/(C, SiO2, and Al2O3) granular films

    International Nuclear Information System (INIS)

    Additive effects of C, SiO2, and Al2O3 on L10-FePt epitaxial thin film were studied. Samples were fabricated by co-sputtering of FePt and (C, SiO2, and Al2O3) on MgO (1 0 0) substrate at 973 K. These additives effectively reduce the particle size of FePt. C additive deteriorates the crystal orientation, while Al2O3 additive gradually degrades the L10 ordering. On the other hand, SiO2 additive can reduce the particle size while keeping the high c-axis orientation and higher degree of L10 ordering

  15. RF and microwave noise suppression in a transmission line using Fe-Si-Al/Ni-Zn magnetic composite films

    International Nuclear Information System (INIS)

    Radio-frequency (RF) and microwave noise suppression by using magnetic composite films on a microstrip line (MSL) was studied in the frequency range from 50 MHz to 13.5 GHz. The MSL was composed of a Cu transmission line, dielectric materials, and a Cu substrate. The Fe-Si-Al/Ni-Zn magnetic composite films were placed on the MSL, and the reflection and the transmission characteristics were investigated. We observed that RF and microwave noise suppression caused by the Fe-Si-Al/Ni-Zn magnetic composite films varied with the concentration ratio of the sendust (Fe-Si-Al) and the Ni-Zn ferrite. The frequency dependence of the power loss due to the composite films on the MSL was measured and the power loss increased at higher frequencies with increasing concentration of the sendust in the composites. The electromagnetic interference shielding efficiencies of the magnetic composite films in the far-field region are also discussed.

  16. Microstructural characterization of in situ TiC/Al and TiC/Al-20Si-5Fe-3Cu-1Mg composites prepared by spray deposition

    International Nuclear Information System (INIS)

    An innovative spray-deposition technique has been applied to produce in situ TiC/Al and TiC/Al-20Si-5Fe-3Cu-1Mg composites. This technique provides a new route to solve the problems of losses and agglomeration of the reinforcement particles when they are injected into the spray cone of molten droplets during spray forming process. Experimental results have shown that the presence of needle-like Al3Ti and Al-Si-Fe compounds, which are detrimental not only to the fracture toughness, but also to the stability of the microstructure, can be eliminated completely from the final product by using a proper Ti:C molar ratio of 1:1.3 in the Ti-C-Al preforms and adding 5 wt% TiC particles to Al-20Si-5Fe-3Cu-1Mg alloy. Moreover, another major problem of coarsening of silicon particles usually encountered in the hypereutectic Al-Si alloys has also been solved by the technique. The silicon particles in the spray-deposited 5 wt% TiC/Al-20Si-5Fe-3Cu-1Mg composite were much refined (∼2 μm) compared to those (∼5 μm) obtained in the matrix alloy without TiC addition. The formation and elimination mechanisms of Al3Ti phase in TiC/Al composites can be explained based on thermodynamic theory. The modification of the microstructures in the spray-deposited Al-20Si-5Fe-3Cu-1Mg alloy can be interpreted in the light of the knowledge of atomic diffusion. The experimental results also showed that the ultimate tensile strength of the TiC/Al composites was improved over that of the unreinforced Al matrix

  17. Thermodynamic analysis of oxygen solutions in Fe-Ni-Cr melt doped with Mn, V, Si, Ti, Al

    International Nuclear Information System (INIS)

    Alloys Fe-10%Ni-20%Cr and Fe-40%Ni-15%Cr are taken as examples to investigate the influence of deoxidising elements (Mn, V, Si, Ti, Al) on oxygen concentration in the melt. It is stated that at low reducer contents the oxygen concentration in the melt is determined by a chromium content. At high contents of deoxidising elements the oxygen concentration in the melt is mainly dependent on the reducer itself. The amounts of deoxidising elements promoting the change of reducing mechanism are determined. The thermodynamic analysis shows that only Si, Ti and Al should be used for deoxidising of the alloys studied

  18. Influence of annealing treatment on the structure and magnetic properties of Fe-Al-Cu-Nb-Si-B alloys

    International Nuclear Information System (INIS)

    In this paper we present experimental results on influence of Al content on the structure and saturation magnetostriction of Fe-Al-Cu-Nb-Si-B alloys after heat treatment. Transmission electron microscopy observations confirmed the existence of nanocrystalline structure after annealing at 490 oC and 550 oC for all samples. The crystallization temperature of FeSi phase and the temperature at which the polycrystalline transformation starts were determined from temperature dependence of electrical resistivity. Aluminium slightly decreases the first crystallization temperature and considerably decreases the saturation magnetostriction in as-quenched state. (author)

  19. 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.

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

    Science.gov (United States)

    Mohanta, Ojaswini; Basumallick, A.; Mitra, A.; Panda, A. K.

    2010-01-01

    The effect of substituting Al for Si in Co 36Fe 36Si 4-xAl xB 20Nb 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 ' Tg'. 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.

  1. Galvanomagnetic properties of Fe2YZ (Y = Ti, V, Cr, Mn, Fe, Ni; Z = Al, Si) heusler alloys

    Science.gov (United States)

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

    2015-11-01

    The Hall effect and the magnetoresistance of Fe2YZ Heusler alloys, where Y = Ti, V, Cr, Mn, Fe, and Ni, are the 3 d 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 0) and anomalous ( R 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 s in the ferromagnetic alloys is positive, proportional to the residual resistivity ratio ( R s ∝ ρ 0 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.

  2. Icosahedral Phase Formation In Al-Cu-Fe-Tm (Tm=Si, Mg, B) Alloys

    International Nuclear Information System (INIS)

    Discovery of quasicrystals is considered to be one of the most significant discoveries in material science in last over fifteen years. To date, both stable and metastable quasicrystalline phases investigated in a great number of binary, ternary and multicomponent metallic systems. In the present investigation, the effect of forth element (TM=Si, Mg, B) on the formation of quasicrystal structure in mechanically alloyed Al65Cu20Fe10TM5 alloys was investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). It was found that icosahedral quasicrystalline phase (i-phase) was formed directly by mechanical alloying of crystalline elemental powders. The present investigation showed that the i-phase was unstable with long time milling and transformed into crystalline β-Al(Cu,Fe) solid solution phase (β-phase). DTA traces obtained from the powders during heating, up to 1200 degree, showed an exothermic peak around 840 degree and an endothermic peak around 1000 degree. The exothermic peak corresponded to the formation of i-phase and the endothermic effect corresponded to melting of the alloys. The results of the present investigation are discussed in light of the current understanding of the phase stability in complex systems.

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

    Science.gov (United States)

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

    2016-05-01

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

  4. Corrosion resistance of the NdFeB coated with AlN/SiC bilayer thin films by magnetron sputtering under different environments

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Lei [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Shen, Jiong [Earth-Panda Advance Magnetic Material Co., Ltd., Anhui Lujiang 231500 (China); Qiao, Kai; Wang, Wei; Zhou, Chu [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Anhui Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Anhui Hefei 230009 (China)

    2015-02-01

    The AlN/SiC bilayer and SiC monolayer thin films were deposited on sintered NdFeB by RF magnetron sputtering to improve the corrosion resistance. Their structures and morphologies were studied by XRD and AFM and SEM. The corrosion behaviors of AlN/SiC and SiC-coated NdFeB in 3.5 wt% NaCl, 20 wt% NaOH and 0.1 mol/L H{sub 2}SO{sub 4} solutions were characterized with potentiodynamic polarization curves. The results show that AlN/SiC and SiC thin films can evidently improve the corrosion resistance of NdFeB, and the AlN/SiC films have the better resistance than the SiC film. - Highlights: • SiC monolayer and AlN/SiC bilayer thin films have been prepared on NdFeB at room temperature by RF magnetron sputtering. • NdFeB coated with AlN/SiC bilayer films has more corrosion resistance than that coated with SiC monolayer film under different environments. • The grains of the AlN/SiC bilayer films are finer and the surface roughness is lower than that of SiC monolayer film.

  5. Effect of Heat Treatment on Morphology of Fe-Rich Intermetallics in Hypereutectic Al-Si-Cu-Ni Alloy with 1.26 pct Fe

    Science.gov (United States)

    Sha, Meng; Wu, Shusen; Wan, Li; Lü, Shulin

    2013-12-01

    Cobalt is generally considered as the element that can neutralize the negative effects of iron in Al alloys, such as inducing fracture and failure for stress concentration. Nevertheless, Fe-rich intermetallics would be inclined to form coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles when the content of Fe was high, which could also cause inferior mechanical properties. The dissolution and transformation of δ-Al4(Fe, Co, Ni)Si2 phase in solution heat-treated samples of Al-20Si-1.85Cu-1.05Ni-1.26Fe-1.35Co alloy were studied using optical microscopy, image analysis, and scanning electron microscopy. The effects of solution heat treatment time ranging from 0 to 9 hours at 783.15 K (510 °C) on mechanical properties were also investigated. The coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles varied slowly through concurrent dissolution along widths and at the plate tips as solution treatment time increased, which could be explained from diffusion-induced grain boundary migration. Solution heat treatment also has an important influence on mechanical properties. The maximum ultimate tensile strength and yield strength after T6 treatment were 258 and 132 MPa, respectively, while the maximum hardness was 131 HB. Compared with those of the samples in the as-cast state, they increased by 53, 42, and 28 pct, respectively. Moreover, δ-Al4(Fe, Co, Ni)Si2 phase, which appears as a coarse plate-like particle in two dimensions, is actually a cuboid in three dimensions. The length of this cuboid is close to the width, while the height is much smaller.

  6. A novel Al-10Si-2Fe master alloy and its effect on inoculation of eutectic cells in Sr-modified A356 alloy

    OpenAIRE

    Zhang Yong; Zheng Hongliang; Liu Yue

    2014-01-01

    To investigate the possibility of inoculating eutectic cells, a novel Al-10Si-2Fe master alloy was synthesized and tested in Sr-modified A356 alloy. The new master alloy that consists of メ-Al, Si and モ-Al5FeSi phases was prepared by a casting process, and the silicon phase was found to grow epitaxially from the モ-Al5FeSi particles. The inoculation efficiency of the new master alloy on Sr-modified A356 alloy has been investigated by quenching experiment and thermal analysis. With the addition ...

  7. Magnetic and structural properties of Co2FeAl thin films grown on Si substrate

    Science.gov (United States)

    Belmeguenai, Mohamed; Tuzcuoglu, Hanife; Gabor, Mihai; Petrisor, Traian; Tiusan, Coriolan; Berling, Dominique; Zighem, Fatih; Mourad Chérif, Salim

    2015-01-01

    The correlation between magnetic and structural properties of Co2FeAl (CFA) thin films of different thicknesses (10 nmSi/SiO2 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/cm2.

  8. 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.

  9. Corrosion behaviour of Fe-Mn-Si-Al austenitic steel in chloride solution

    Directory of Open Access Journals (Sweden)

    W. Krukiewicz

    2009-04-01

    Full Text Available Purpose: The aim of the paper is to investigate the corrosion behaviour of the new-developed high-manganese austenitic steel in 0.5n NaCl solution.Design/methodology/approach: The steel used for the investigation was thermomechanically rolled and solution heat-treated from a temperature of 850°C. Corrosion resistance of investigated steel was examined using weight and potentiodynamic methods. In the weight method, the specimens were immersed in the prepared solution for 24h. In the potentiodynamic method, anodic polarization curves with a rate of potential changes of 1 mV/s in the anodic direction were registered. After the current density being equal 1 mA/cm2 was achieved, the direction of polarization has been changed. Basing on the registered curves, the pitting potential, repassivation potential, polarization resistance and corrosion current were determined.Findings: It was found that the steel is characterized by a partially recrystallized austenitic microstructure with numerous annealing twins and slip bands. According to the results of potentiodynamic analyses it was found that the samples of examined steel show poor corrosion resistance in the NaCl solution. The observed corrosion pits are related to the chemical composition. It is connected with the high dissolution rate of Mn and Fe atoms in NaCl solution. Fractographic analyses of samples revealed corrosion products on their surface in a form of pits with diversified size.Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese steel, the investigations should include steels with a wider Al concentration.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of a modern group of high-manganese austenitic steels.Originality/value: The corrosion behaviour in chloride solution of a new-developed Fe-Mn-Si-Al steel was investigated.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Vaporization behavior of lead from the FeO-CaO-SiO2-Al2O3 slag system

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Vaporization behavior (1163-1463 K) of lead in the slag system of FeO-CaO-SiO2-Al2O3 with CaCl2 was examined.A thermodynamic estimation with the principle of Gibbs free energy minimization showed that the major vapor species from the sample of the FeO-CaO-SiO2-AI203 system+PbO+CaCl2 were metallic Pb,PbC1,PbCl2,and FeC12,at the experimental temperature range.The experimental results show that the mole ratio of vaporized CI in lead chlorides to vaporized Pb,simply expressed as CI/Pb,decreases with increasing temperature.The larger CUPb means a larger ratio of gaseous PbCl2,since metallic Pb and PbCI vapors are formed in a similar reduction atmosphere.The evaporation is initially rapid and becomes steady after holding for 10 rain.Gaseous PbCI2 is mainly formed during the heating period,and at the holding stage,it reacts with FeO to produce gaseous FeCI2.With regard to slag composition,FeO content and basicity significantly affect the evaporation of lead.High FeO content and high basicity promotes the formation of metallic Pb and PbCI,whereas,it prohibits PbCl2 evaporation.

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

    OpenAIRE

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

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

    OpenAIRE

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

    2005-01-01

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

  17. 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.

  18. 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

  19. 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.

  20. Heat capacity and phase equilibria of almandine, Fe3Al2Si3O12

    Science.gov (United States)

    Anovitz, Lawrence M.; Essene, E.J.; Metz, G.W.; Bohlen, S.R.; Westrum, E.F., Jr.; Hemingway, B.S.

    1993-01-01

    The heat capacity of a synthetic almandine, Fe3Al2Si3O12, was measured from 6 to 350 K using equilibrium, intermittent-heating quasi-adiabatic calorimetry and from 420 to 1000 K using differential scanning calorimetry. These measurements yield Cp298 = 342.80 ?? 1.4 J/mol ?? K and S298o = 342.60 J/mol ?? K. Mo??ssbauer characterizations show the almandine to contain less than 2 ?? 1% of the total iron as Fe3+. X-ray diffraction studies of this synthetic almandine yield a = 11.521 ?? 0.001 A?? and V298o = 115.11 +- 0.01 cm3/mol, somewhat smaller than previously reported. The low-temperature Cp data indicate a lambda transition at 8.7 K related to an antiferromagnetic-paramagnetic transition with TN = 7.5 K. Modeling of the lattice contribution to the total entropy suggests the presence of entropy in excess of that attributable to the effects of lattice vibrations and the magnetic transition. This probably arises from a low-temperature electronic transition (Schottky contribution). Combination of the Cp data with existing thermodynamic and phase equilibrium data on almandine yields ??Gf,298o = -4938.3 kJ/mol and ??Hf,298o= -5261.3 kJ/mol for almandine when calculated from the elements. The equilibrium almandine = hercynite + fayalite + quartz limits the upper T P for almandine and is metastably located at ca. 570??C at P = 1 bar, with a dP dT of +17 bars/??C. This agrees well with reversed experiments on almandine stability when they are corrected for magnetite and hercynite solid-solutions. In {norm of matrix}O2-T space, almandine oxidizes near QFM by the reactions almandine + O2 = magnetite + sillimanite + quartz and almandine + 02 = hercynite + magnetite + quartz. With suitable correction for reduced activities of solid phases, these equilibria provide useful oxygen barometers for medium- to high-grade metamorphic rocks. ?? 1993.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2009-04-01

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

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

    Directory of Open Access Journals (Sweden)

    Jozef Petrík

    2009-09-01

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

  4. Partitioning behavior of Al in a nanocrystalline Fe71.5Si13.5B9Nb3Cu1Al2 alloy

    International Nuclear Information System (INIS)

    The nanocrystalline Fe-Si-B-Nb-Cu alloy, known as FINEMET, is now a well established commercial soft magnetic material exhibiting excellent permeability while maintaining a high saturation magnetization. It is produced by melt-spinning to form a ribbon with an amorphous structure. The purpose of this investigation was to use 3-dimensional atom probe microanalysis to experimentally quantify the local phase chemistries of this nanocomposite microstructure, with particular reference to the partitioning behavior of the Al

  5. Thermodynamic modelling of phase equilibria in melts of Fe-Ca-Al-Si-Mn-V-Nb-Ni-Mo-P-C-O system

    International Nuclear Information System (INIS)

    A thermodynamic analysis of the phase equilibria in the Fe-Ca-Al-Si-Mn-V-Nb-Ni-Mo-P-C-O system at fixed concentrations of silicon, manganese, vanadium, niobium, nickel, molybdenum, phosphorus and carbon was performed. The formation of nonmetallic phases at 1873 K in liquid metal solutions of various compositions was studied. It has been established that, depending on the concentrations of calcium and aluminum, the metal melt can be in equilibrium with (FeO, CaO, Al2O3, SiO2, MnO) liquid solutions, |FeO, CaO, MnO| and |Al2O3, V2O3| solid solutions, individual compounds 3Al2O3·SiO2, CaO·2Al2O3, CaO·6Al2O3 and {Ca} gas

  6. Microstructure and Microhardness Evolutions of High Fe Containing Near-Eutectic Al-Si Rapidly Solidified Alloy

    Directory of Open Access Journals (Sweden)

    Emad M. Ahmed

    2014-01-01

    Full Text Available Al-11 wt.% Si-11 wt.% Fe (11.29 at.% Si-5.6 at.% Fe melt was rapidly solidified into ribbons and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDS, and microhardness technique. The Rietveld X-ray diffraction analysis was applied successfully to analyze microstructure and phase precipitations. On the basis of the aluminum peak shifts measured in the XRD scans, a solid solubility extension value of 1 at.% Si in α-Al was determined. SEM investigations confirmed presence of a spherical shape α-phase particles in addition to needle and spherical shape β-phase particles with contents of 1.1 wt.% and 10.1 wt.% as deduced by XRD analysis. During prolonged annealing process at 350°C/25 h, α-phase disappeared, β-phase content increased to 30 wt.%, and Si presence becomes more evident as deduced by XRD analysis. EDS analysis confirmed that these β particles observed in the as-melt spun alloy are of lower Fe content comparing to those usually observed in the as-cast counter-part alloy. Besides, the length distribution of needle shape β-particles has been shortened to be diverse from 1 to 5 μm. The as-melt spun ribbons exhibited enhancement of hardness to 277 HV and further increased during heat treatment (150°C/12 h to 450 HV. This improvement of microstructure and hardness are the influence of microstructural refinement and modification obtained during the rapid solidification process.

  7. Extrusion, Properties, and Failure of Spray-Formed Hypereutectic Al-Si Alloys Based on the Optimization of Fe-Bearing Phase

    Science.gov (United States)

    Hou, L. G.; Yu, H.; Cui, H.; Cai, Y. H.; Zhuang, L. Z.; Zhang, J. S.

    2013-04-01

    Based on the densification of the spray-formed hypereutectic Al-Si (hyper-AS) alloys, the microstructural evolution, mechanical properties, as well as the failure are studied in this investigation. The appropriate process and parameters for the densification of the deposits are gained from the thermomechanical simulation. Besides of the spray-formed Al-25Si-5Fe-3Cu (3C) alloy, the microstructures of other spray-formed alloys with Mn/Cr addition are stable without coarsening of the refined α-Al(Fe,TM)Si (TM = Mn/Cr/(Mn+Cr)) particles, which can improve the heat resistance. Especially, a great number of the submicrosized α-Al(Fe,TM)Si phases are observed in the hot-extruded TM-containing alloys. The critical ranges of the major parameter TM/Fe mass ratios that can affect the formation of the α-Al(Fe,TM)Si phases in the cast or spray-formed hyper-AS alloys are severally determined. The structure and lattice constant of the refined α-Al(Fe,TM)Si phases also are characterized. The mechanical properties of the current extruded hyper-AS alloys at room or elevated temperatures are close to or higher than some commercial alloys or other published results. Therefore, the hyper-AS alloys can be proposed as new lightweight, heat-resistant, and high-strength alloys, which can be used in the complex working conditions, such as advanced engine systems. The main reason for the enhanced properties would be the formation of a large quantity of microsized/submicrosized α-Al(Fe,TM)Si phases and abundant dislocations, which can greatly reinforce the matrix and transform the brittle fracture of the needle-like Fe-bearing phases into ductile fracture.

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

    Directory of Open Access Journals (Sweden)

    A. Dulęba

    2012-05-01

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

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

    OpenAIRE

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

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    V. A. Andreyachshenko

    2016-07-01

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

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

    OpenAIRE

    Jacek Antonkiewicz

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

  13. Microstructure of hot rolled and cast Fe-Al-Si-C alloy

    Czech Academy of Sciences Publication Activity Database

    Kopeček, Jaromír; Jarošová, Markéta; Jurek, Karel; Šíma, V.; Schindler, I.

    Madrid : Facultad de Químicas. Universidad Complutense de Madrid, 2011 - (Trujillo, F.; Morris, D.), s. 167-170 ISBN N. [Discussion Meeting on the Development of Innovative Iron Aluminium Alloys FeAl 2011. Lanzarote (ES), 05.10.2011-07.10.2011] R&D Projects: GA ČR(CZ) GAP107/10/0438 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : iron aluminides * EBSD method * scanning electron microscopy * recrystallization Subject RIV: BM - Solid Matter Physics ; Magnetism

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

    Science.gov (United States)

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

    2015-05-01

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

  15. Interfacial exchange coupling in cubic Heusler Co2FeZ (Z = Al and Si)/tetragonal Mn3Ga bilayers

    Science.gov (United States)

    Ranjbar, R.; Suzuki, K.; Sugihara, A.; Ma, Q. L.; Zhang, X. M.; Miyazaki, T.; Ando, Y.; Mizukami, S.

    2015-05-01

    We have fabricated bilayer films of tetragonal Heusler-like D022 Mn3Ga and cubic Heusler Co2FeZ (Z = Si and Al) on (100) single-crystalline MgO substrates and investigated their structural and interfacial exchange coupling. The coupling in the Mn3Ga/Co2FeAl bilayer was either ferromagnetic or antiferromagnetic, depending on annealing temperature, whereas only antiferromagnetic exchange coupling was observed in the Mn3Ga/Co2FeSi bilayers. The effects of annealing on the structure and coupling strength in the bilayers are discussed.

  16. Moessbauer study of the phase distribution of Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} powder

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, D.R. de E-mail: denis@macbeth.if.usp.br; Partiti, C.S.M

    2001-05-01

    In this work, by using X-ray diffraction, magnetization and Moessbauer measurements, magnetic and structural properties of Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} (x=10, 20, 30) have been studied. These three sets of specimens in nominal composition Fe{sub 78-x}Al{sub x}Si{sub 9}B{sub 13} were produced by mechanically processing blended Fe, Al, B and Si powders, using different times in the range from 2 up to 300 h. Moessbauer spectra show a strong line broadening and were fitted by considering Gaussian distributions of hyperfine fields. The crystalline phase present in the spectra was identified as {alpha}-Fe. Magnetic hyperfine data are discussed in conjunction with X-ray diffraction and magnetic measurements.

  17. 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.

  18. Effect of Cr and Mn on the microstructure of spray-formed Al-25Si-5Fe-3Cu alloy

    International Nuclear Information System (INIS)

    Research highlights: → Cr is more effective than Mn in changing rod-like β phase to particulate α-phase → The modification effect of Mn plus Cr on β phase is superior to that of Mn or Cr. → Mn or Cr can greatly change the onset temperatures of Si, δ/β phase and α phase. - Abstract: The hypereutectic Al-Si-Fe alloys with different Mn and Cr addition were synthesized by spray forming technique, and the microstructural evolutions induced by Mn and Cr have been investigated using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the modification effect of co-addition of Mn and Cr is more effective than the individual Mn or Cr addition in transforming harmful rod-like Fe-bearing β phase to particulate α-phase. Meanwhile, the modification effect of Cr is superior to that induced by Mn. The Mn/Cr ratio plays an important role in the combined addition. The addition of 2 wt% Mn + 1 wt% Cr to spray formed alloy has induced an ideal microstructure with entirely fine granular intermetallic compounds dispersed in Al matrix. DSC analyses indicate that both Mn and Cr can greatly influence the onset temperatures and the region widths of primary Si, δ phase and α phase, but bring little changes on multi-phase reaction, which would contribute to the modification effects of Mn, Cr and Mn + Cr.

  19. Effect of Cr and Mn on the microstructure of spray-formed Al-25Si-5Fe-3Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Cai Yuanhua, E-mail: yhcaiustb@163.com [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Liang Ruiguang [Agricultural Machine Management Office of Rencheng District, Jining City 272000 (China); Hou Longgang; Zhang Jishan [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2011-05-15

    Research highlights: {yields} Cr is more effective than Mn in changing rod-like {beta} phase to particulate {alpha}-phase {yields} The modification effect of Mn plus Cr on {beta} phase is superior to that of Mn or Cr. {yields} Mn or Cr can greatly change the onset temperatures of Si, {delta}/{beta} phase and {alpha} phase. - Abstract: The hypereutectic Al-Si-Fe alloys with different Mn and Cr addition were synthesized by spray forming technique, and the microstructural evolutions induced by Mn and Cr have been investigated using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the modification effect of co-addition of Mn and Cr is more effective than the individual Mn or Cr addition in transforming harmful rod-like Fe-bearing {beta} phase to particulate {alpha}-phase. Meanwhile, the modification effect of Cr is superior to that induced by Mn. The Mn/Cr ratio plays an important role in the combined addition. The addition of 2 wt% Mn + 1 wt% Cr to spray formed alloy has induced an ideal microstructure with entirely fine granular intermetallic compounds dispersed in Al matrix. DSC analyses indicate that both Mn and Cr can greatly influence the onset temperatures and the region widths of primary Si, {delta} phase and {alpha} phase, but bring little changes on multi-phase reaction, which would contribute to the modification effects of Mn, Cr and Mn + Cr.

  20. 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)

    International Nuclear Information System (INIS)

    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

  1. Effects of manganese on corrosion behaviour of welded Al-Fe-Si alloy in NaCl medium

    Directory of Open Access Journals (Sweden)

    Isiaka Oluwole OLADELE

    2014-11-01

    Full Text Available The effects of manganese on the corrosion behaviour of welded and un-weld as–cast Al-Fe-Si alloy has been studied. Alloys of varying percentage of manganese from 0.019-0.24 (0.019, 0.15, 0.16, 0.17, 0.24 wt. % were sand cast into rectangular test sheets of dimension 300´20´5 mm. Each of the alloys were cut into two equal parts and welded together. The corrosion characteristics of the five categories of alloys (welded and un-weld in 0.5M NaCl at room temperature over a period of 1464 hours were investigated by weight loss method. The results obtained showed that Al-Fe-Si samples (un-weld and welded in 0.5 M NaCl medium displayed a very good resistant to corrosion according to the percentage of manganese added. It was observed that sample A1 and A2 with manganese percentage of 0.17Mn in NaCl medium displayed a very good resistance to corrosion while sample D1 and D2 with manganese percentage of 0.24Mn in the same medium has the lowest corrosion resistance. The result actually confirmed that the addition of manganese aided corrosion resistance but to a certain level, since the addition of 0.150-0.170Mn leads to progressive inhibiting but after this range the corrosion rate increases.

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

    Science.gov (United States)

    Panda, A. K.; Mohanta, Ojaswini; Basumallick, A.; Mitra, A.

    2010-12-01

    The investigation addresses low temperature magnetization behavior in Co 36Fe 36Si 3Al 1Nb 4B 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 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/ TC 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.

  3. 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.

  4. Effect of on-site Coulomb interaction (U) on the electronic and magnetic properties of Fe2MnSi, Fe2MnAl and Co2MnGe

    Science.gov (United States)

    Sharma, Sonu; Pandey, Sudhir K.

    2016-04-01

    The electronic band structures, density of states' plots and magnetic moments of Fe2MnSi, Fe2MnAl, and Co2MnGe are studied by using the first principles calculation. The FM solutions using LSDA without U show the presence of half-metallic ferromagnetic (HFM) ground state in Fe2MnSi, whereas the ground state of Fe2MnAl is found to be metallic. In both compounds the maximum contribution to the total magnetic moment is from the Mn atom, while the Fe atom contributes very less. The electronic structures and magnetic moments of Fe-based compounds are affected significantly by U under around-the-mean-field (AMF) double counting scheme, whereas its effect is very less on Co2MnGe. The magnetic moment of Fe atom in Fe2MnSi (Fe2MnAl) increased by ∼70% (∼75%) and in Mn atom it decreases by ∼50% (∼70%) when the value of U is increased from 1 to 5 eV. Hund's like exchange interactions are increasing in Fe atom while decreasing in Mn atom with increase in U. The Fe and Mn moments are ferromagnetically coupled in Fe2MnSi for all values of U, whereas in Fe2MnAl they are coupled antiferromagnetically below U=2 eV and ferromagnetically above it. Above U=2 eV the metallic ground state of Fe2MnAl changes to semiconducting ground state and the ferromagnetic coupling between Fe and Mn atoms appears to be responsible for this. This shows that the validity of AFM double counting scheme is not robust for the entire range of U in the Fe2MnAl compound.

  5. Nuclear magnetic resonance study of thin Co2FeAl0.5Si0.5 Heusler films with varying thickness

    Science.gov (United States)

    Alfonsov, A.; Peters, B.; Yang, F. Y.; Büchner, B.; Wurmehl, S.

    2015-02-01

    Type, degree, and evolution of structural order are important aspects for understanding and controlling the properties of highly spin-polarized Heusler compounds, in particular, with respect to the optimal film growth procedure. In this work, we compare the structural order and the local magnetic properties revealed by nuclear magnetic resonance (NMR) spectroscopy with the macroscopic properties of thin Co2FeAl 0.5Si 0.5 Heusler films with varying thickness. A detailed analysis of the measured NMR spectra presented in this paper enables us to find a very high degree of L 21 -type ordering up to 81% concomitantly with excess Fe of 8%-13% at the expense of Al and Si. We show that the formation of certain types of order depends not only on the thermodynamic phase diagrams as in bulk samples, but also that the kinetic control may contribute to the phase formation in thin films. It is an exciting finding that Co2FeAl 0.5Si 0.5 can form an almost ideal L 21 structure in films, though with a considerable amount of Fe-Al/Si off stoichiometry. Moreover, the very good quality of the films as demonstrated by our NMR study suggests that the technique of off-axis sputtering used to grow the films sets the stage for the optimized performance of Co2FeAl 0.5Si 0.5 in spintronic devices.

  6. 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)

  7. Nanostructure and phases formation under mechanical alloying of binary powder mixtures of Fe and sp-elements (M); M=C, B, Mg, Al, Si, Ge, Sn

    International Nuclear Information System (INIS)

    Full text: Common and distinctive features of mechanical alloying (MA) of Fe with sp-element have been established using a complex of experimental methods including Moessbauer spectroscopy. The common regularities are the following: the formation of a nano-structural state in α-Fe particles, sp-atoms penetration along the α-Fe grain boundaries, their segregation and the first Fe-M phase formation in the interfaces (boundary and close-to-boundary distorted zones) at the initial stage of MA. In MA α-Fe with Al (Si, Ge, Sn) having approximately equal (Al, Si, Ge) or substantially larger (Sn) atomic size intermetallic compounds are formed in interfaces at the first stage. At the final stage supersaturated solid solutions (SSS) are formed in the grain bulk if sp-element concentration in the initial mixture xM≤32 at.% Si (Ge, Sn) and ≤50 at.% Al. In the Fe-Al (Si, Ge) systems the sp-element concentration in SSS becomes maximum simultaneously with the SSS formation, while in the Fe-Sn the SSS is saturated with Sn gradually. In MA α-Fe with C and B having a small radius an amorphous like phase (Am(Fe-M)) is formed in interfaces at the initial stage. The Am(Fe-B) formation is characterized by a substantially slower kinetics in comparison with that of the Am(Fe-C) one. If xM>15 at.% C(B) the second stage - the carbide and boride formation - takes place after amorphization. In the case of immiscible in equilibrium elements (Fe and Mg) mechanical alloying is a one-stage process of the SSS formation with the Mg concentration of not higher than 7 at.%

  8. 59Co nuclear magnetic resonance study of the local distribution of atoms in the Heusler compound Co2FeAl0.5Si0.5

    Science.gov (United States)

    Wurmehl, Sabine; Kohlhepp, Jürgen T.; Swagten, Henk J. M.; Koopmans, Bert

    2012-02-01

    In this work, the spin-echo nuclear magnetic resonance (NMR) technique is used to probe the local structure of Co2FeAl0.5Si0.5 bulk samples. The 59Co NMR spectrum of the Heusler compound Co2FeAl0.5Si0.5 consists of four main resonance lines with an underlying sub-structure. The splitting into the main resonance lines is explained by contributions of the B2 type structure. The sub-lines are attributed to a random distribution of Al and Si. By comparing the experimental results with an appropriate multinomial distribution, the fraction of the Al/Si intermixing and the ratio between the contributing structure types is assigned. The main structural contribution of as-cast bulk samples is of B2 type with 38% of L21 contributions. The L21 contribution can be enhanced to 59% by an appropriate annealing process. However, B2 contributions are still present after annealing. Additional foreign phases such as fcc-Co and Co-Al, with relative contributions of less than one percent, are also found in both as-cast and annealed samples. Resonance lines related to slight amounts of the ternary, parental Heusler compounds Co2FeAl and Co2FeSi are also observed.

  9. Magnetocrystalline anisotropy constants, rotational hysteresis energy and magnetic domain structure in UFe6Al6, UFe9AlSi2 and ScFe10Si2 intermetallic compounds

    International Nuclear Information System (INIS)

    The magnetic torque, T, was applied to determine the anisotropy constants K1 and K2 of the UFe6Al6, UFe9AlSi2 and ScFe10Si2 compounds. The mechanism of magnetization reversal processes in these compounds was investigated on the basis of the analysis of the rotational hysteresis energy, Wr and rotational hysteresis integral, R, calculated from the magnetic torque curves. Applying the powder pattern method, magnetic domain structures were observed. Moreover, the fundamental parameters of the domain structure were determined. (orig.)

  10. 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.

  11. 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 ...

  12. Composition of sediments, Al-Si gelatine and precipitates related to the occurrence of elemental Al, Si, Fe from monitoring borewells by wellfield Podluží

    Czech Academy of Sciences Publication Activity Database

    Ďurďová, Libuše

    Vol. Part 2. Ostrava : VŠB-TU Ostrava, 2005, s. 235-241. ISBN 80-248-0787-4. [Conference on environment and mineral processing /9./. Ostrava (CZ), 23.06.2005-25.06.2005] R&D Projects: GA AV ČR IAA3060102; GA AV ČR KSK3046108 Institutional research plan: CEZ:AV0Z2060917 Keywords : high sulphate concentration * Al and Si gelatines * sediment Subject RIV: DA - Hydrology ; Limnology

  13. Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    Science.gov (United States)

    Belmeguenai, M.; Tuzcuoglu, H.; Gabor, M. S.; Petrisor, T.; Tiusan, C.; Zighem, F.; Chérif, S. M.; Moch, P.

    2014-01-01

    10 nm and 50 nm Co2FeAl (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 (Ta), 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 Ta, while the uniaxial anisotropy field is nearly unaffected by Ta 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 Ta. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10-3 and 1.3×10-3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively).

  14. Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    International Nuclear Information System (INIS)

    10 nm and 50 nm Co2FeAl (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 (Ta), 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 Ta, while the uniaxial anisotropy field is nearly unaffected by Ta 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 Ta. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10−3 and 1.3×10−3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

  15. X-Ray Diffraction Studies of Structures of Be, Al, LiF, Fe+3%Si, Si, SiO2, KCl under Dynamic Pressures from 2 Gpa to 20 Gpa

    OpenAIRE

    Egorov, L.; Barenboim, A.; Mokhova, V.; Dorohin, V.; Samoilov, A.

    1997-01-01

    Currently, the only direct method to study behaviour of solid crystal substance structures under dynamic compression is method to record X-rays diffraction pictures of crystal structures under shock compression. The paper presents results of X-rays diffraction measurements conceming structural parameters of shock compressed substances at pressures higher than Hugoniot elastic limit (Be. Al, LiF, Fe+3%Si), lower than Hugoniot elastic limit (Si, SiO2, LiF) and in the area of pressures of phase ...

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

    Directory of Open Access Journals (Sweden)

    A. Dulęba

    2011-07-01

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

  17. Electrical memory features of ferromagnetic CoFeAlSi nano-particles embedded in metal-oxide-semiconductor matrix

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ja Bin [Novel Functional Materials and Devices Laboratory, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Ki Woong [Semiconductor R and D Center, Samsung Electronics Co. Ltd, Gyeonggi-Do 445-701 (Korea, Republic of); Lee, Jun Seok; An, Gwang Guk [Novel Functional Materials and Devices Laboratory, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, Jin Pyo, E-mail: jphong@hanyang.ac.kr [Novel Functional Materials and Devices Laboratory, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2011-07-01

    Half-metallic Heusler material Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} (CFAS) nano-particles (NPs) embedded in metal-oxide-semiconductor (MOS) structures with thin HfO{sub 2} tunneling and MgO control oxides were investigated. The CFAS NPs were prepared by rapid thermal annealing. The formation of well-controlled CFAS NPs on thin HfO{sub 2} tunneling oxide was confirmed by atomic force microscopy (AFM). Memory characteristics of CFAS NPs in MOS devices exhibited a large memory window of 4.65 V, as well as good retention and endurance times of 10{sup 5} cycles and 10{sup 9} s, respectively, demonstrating the potential of CFAS NPs as promising candidates for use in charge storage.

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

    Science.gov (United States)

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

    2015-04-01

    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 stronger concurrent precipitation and retards recrystallization, which finally leads to a coarse grain structure, accompanied by strong P {011} and/or M {113} texture components and a ND- rotated cube {001} component. A refined grain structure with Cube {001} and/or a weak P component as the main texture components were obtained when the pre-existing dispersoids are coarser and fewer, and concurrent precipitation is limited. The different recrystallization textures are discussed with respect to the effect of second-phase particles using two different heating rates.

  19. 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.

  20. 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.

  1. 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.

  2. Constituent phase diagrams of the Al-Cu-Fe-Mg-Ni-Si system and their application to the analysis of aluminium piston alloys

    Energy Technology Data Exchange (ETDEWEB)

    Belov, N.A. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Eskin, D.G. [Netherlands Institute for Metals Research, Rotterdamseweg 137, 2628AL Delft (Netherlands)]. E-mail: deskin@nimr.nl; Avxentieva, N.N. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation)

    2005-10-15

    The evaluation of phase equilibria in quinary systems that constitute the commercially important Al-Cu-Fe-Mg-Ni-Si alloying system is performed in the compositional range of casting alloys by means of metallography, electron probe microanalysis, X-ray diffractometry, differential scanning calorimetry, and by the analysis of phase equilibria in the constituent systems of lesser dimensionality. Suggested phase equilibria are illustrated by bi-, mono- and invariant solidification reactions, polythermal diagrams of solidification, distributions of phase fields in the solid state, and isothermal and polythermal sections. Phase composition of as-cast alloys is analyzed in terms of non-equilibrium solidification. It is shown that the increase in copper concentration in piston Al-Si alloys results in the decrease in the equilibrium solidus from 540 to 505 deg C. Under non-equilibrium solidification conditions, piston alloys finish solidification at {approx}505 deg C. Iron is bound in the quaternary Al{sub 8}FeMg{sub 3}Si{sub 6} phase in low-iron alloys and in the ternary Al{sub 9}FeNi and Al{sub 5}FeSi phases in high-iron alloys.

  3. Constituent phase diagrams of the Al-Cu-Fe-Mg-Ni-Si system and their application to the analysis of aluminium piston alloys

    International Nuclear Information System (INIS)

    The evaluation of phase equilibria in quinary systems that constitute the commercially important Al-Cu-Fe-Mg-Ni-Si alloying system is performed in the compositional range of casting alloys by means of metallography, electron probe microanalysis, X-ray diffractometry, differential scanning calorimetry, and by the analysis of phase equilibria in the constituent systems of lesser dimensionality. Suggested phase equilibria are illustrated by bi-, mono- and invariant solidification reactions, polythermal diagrams of solidification, distributions of phase fields in the solid state, and isothermal and polythermal sections. Phase composition of as-cast alloys is analyzed in terms of non-equilibrium solidification. It is shown that the increase in copper concentration in piston Al-Si alloys results in the decrease in the equilibrium solidus from 540 to 505 deg C. Under non-equilibrium solidification conditions, piston alloys finish solidification at ∼505 deg C. Iron is bound in the quaternary Al8FeMg3Si6 phase in low-iron alloys and in the ternary Al9FeNi and Al5FeSi phases in high-iron alloys

  4. Substituting the main group element in cobalt - iron based Heusler alloys: Co$_2$FeAl$_{1-x}$Si$_x$

    OpenAIRE

    Fecher, G. H.; Felser, C.

    2006-01-01

    This work reports about electronic structure calculations for the Heusler compound Co$_2$FeAl$_{1-x}$Si$_x$. Particular emphasis was put on the role of the main group element in this compound. The substitution of Al by Si leads to an increase of the number of valence electrons with increasing Si content and may be seen as electron-doping. Self-consistent electronic structure calculations were performed to investigate the consequences of the electron doping for the magnetic properties. The ser...

  5. 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

    2016-06-01

    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 (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.

  6. 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.

  7. Chemical mixing at "Al on Fe" and "Fe on Al" interfaces

    Science.gov (United States)

    Süle, P.; Kaptás, D.; Bujdosó, L.; Horváth, Z. E.; Nakanishi, A.; Balogh, J.

    2015-10-01

    The chemical mixing at the "Al on Fe" and "Fe on Al" interfaces was studied by molecular dynamics simulations of the layer growth and by 57Fe Mössbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp "Al on Fe" interfaces were found when Al grows over (001) and (110) oriented Fe layers. The Al/Fe(111) interface is also narrow as compared to the intermixing found at the "Fe on Al" interfaces for any orientation. Conversion electron Mössbauer measurements of trilayers—Al/57Fe/Al and Al/57Fe/Ag grown simultaneously over Si(111) substrate by vacuum evaporation—support the results of the molecular dynamics calculations.

  8. Structure and magnetic properties of FeSiAl-based soft magnetic composite with AlN and Al2O3 insulating layer prepared by selective nitridation and oxidation

    International Nuclear Information System (INIS)

    FeSiAl is widely used in switching power supply, filter inductors and pulse transformers. But when used under higher frequencies in some particular condition, it is required to reduce its high-frequency loss. Preparing a homogeneous insulating coating with good heat resistance and high resistivity, such as AlN and Al2O3, is supposed to be an effective way to reduce eddy current loss, which is less focused on. In this project, mixed AlN and Al2O3 insulating layers were prepared on the surface of FeSiAl powders after 30 min exposure at 1100 °C in high purity nitrogen atmosphere, by means of surface nitridation and oxidation. The results revealed that the insulating layers increase the electrical resistivity, and hence decrease the loss factor, improve the frequency stability and increase the quality factor, especially in the high-frequency range. The morphologies, microstructure and compositions of the oxidized and nitrided products on the surface were characterized by Scanning Electron Microscopy/Energy Disperse Spectroscopy, X-Ray Diffraction, Transmission Electron Microscopy, Selected Area Electron Diffraction and X-ray Photoelectron Spectroscopy. - Highlights: ► AlN and Al2O3 layers were produced on the surface of FeSiAl powder. ► Thermodynamics involved in nitridation and oxidation process was studied. ► Morphologies of the nitrided and oxidized products were characterized. ► Insulating layers decrease the loss factor and increase the quality factor. ► Insulating layers improve the frequency stability in the high-frequency range.

  9. Effective magnetic anisotropy of amorphous and nanocrystalline Fe71.5Al2Cu1Nb3Si13.5B9 alloy ribbon

    International Nuclear Information System (INIS)

    The effective magnetic anisotropy of the Fe71.5Al2Cu1Nb3Si13.5B9 alloy with different nanostructures has been investigated. The nanostructured phase was produced by means of thermal treatment (520 - 600 degreeC during 1 h) to develop the devitrification of the precursor amorphous material. The effective magnetic anisotropy was evaluated from the measurement of the bias field dependence of the transverse susceptibility. Values of the effective anisotropy field, Hk, from 20 Oe (as-quenched sample) down to 7 Oe (optimum nanocrystalline state) were obtained. Such values of Hk are close to those obtained in the classical nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloy (8 - 10 Oe) alloy. The Al could enhance the intergranular coupling, leading to the ultrasoft magnetic character of this nanocrystalline Al-containing alloy. [copyright] 2001 American Institute of Physics

  10. Heat capacity measurements for cryolite (Na3AlF6) and reactions in the system NaFeAlSiOF

    Science.gov (United States)

    Anovitz, Lawrence M.; Hemingway, B.S.; Westrum, E.F., Jr.; Metz, G.W.; Essene, E.J.

    1987-01-01

    The heat capacity of cryolite (Na3AlF6) has been measured from 7 to 1000 K by low-temperature adiabatic and high-temperature differential scanning calorimetry. Low-temperature data were obtained on material from the same hand specimen in the calorimetric laboratories of the University of Michigan and U.S. Geological Survey. The results obtained are in good agreement, and yield average values for the entropy of cryolite of: S0298 = 238.5 J/mol KS0T-S0298 = 145.114 ln T+ 193.009*10-3T- 10.366* 105 T2- 872.89 J/mol K (273-836.5 K)??STrans = 9.9J/mol KS0T-S0298 =198.414 ln T+73.203* 10-3T-63.814* 105 T2-1113.11 J/mol K (836.5-1153 K) with the transition temperature between ??- and ??-cryolite taken at 836.5 K. These data have been combined with data in the literature to calculate phase equilibria for the system NaFeAlSiOF. The resultant phase diagrams allow constraints to be placed on the fO2, fF2, aSiO2 and T conditions of formation for assemblages in alkalic rocks. A sample application suggests that log fO2 is approximately -19.2, log fF2 is -31.9 to -33.2, and aSiO2 is -1.06 at assumed P T conditions of 1000 K, 1 bar for the villiaumite-bearing Ilimaussaq intrusion in southwestern Greenland. ?? 1987.

  11. Electronic and Magneto-Transport Across the Heusler Alloy (Co2FeAl)/ p-Si Interfacial Structure

    Science.gov (United States)

    Kumar, Arvind; Srivastava, P. C.

    2014-02-01

    Electronic and magneto-transport across the Heusler alloy Co2FeAl (CFA)/ p-Si structure have been studied. The morphology of the Heusler alloy film surface has also been characterized by atomic force microscopy and magnetic force microscopy (MFM). X-ray diffraction data revealed formation of the CFA alloy phase with the L21 structure. MFM results revealed formation of a fine domain structure of average size ˜10 nm and magnetic signal strength 0.23°. The I- V characteristics are strongly temperature-dependent between ˜80 K and 300 K for forward bias, compared with weak temperature dependence on reversing the polarity. At low temperature the I- V characteristics have the features of a backward diode. The observed strong temperature dependence is because of thermionic emission of carriers across the interface. The weak temperature dependence is because of dominant field-emission tunnelling of carriers across the interface. Large magnetic field sensitivity of the reverse current has also been observed. The observed magnetic field sensitivity for the reverse current shows the involvement of electronic spin in transport across the interface, from the Heusler alloy to the silicon. An MR of ˜35% in the presence of a magnetic field was estimated from the I- V data. The study has shown that spin-dependent tunnel transport from the CFA alloy to silicon across the interface results in the observed value of MR, which seems to be because of spin scattering.

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

    Science.gov (United States)

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

    2013-01-01

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

  13. X-ray diffraction analysis of aluminium containing Al8Fe2Si processed by equal channel angular pressing

    International Nuclear Information System (INIS)

    A 99.1% aluminium with initial grain size of ∼85 μm was deformed by equal channel angular (ECA) pressing. The sample undergoes an effective strain of 1.07 N by N passes through the die. The material contains a low volume fraction of Al8Fe2Si precipitates located essentially at the grain boundaries. The analysis of the X-ray diffraction peaks showed a significant broadening, which was related to grain refinement and lattice distortions. The crystallite size, calculated using the Halder-Wagner method, reached 225 nm after two passes and did not subsequently change. A decrease of the lattice parameter was also observed after ECA pressing. This is due to a partial dissolution of the precipitates. The microstructure was stable up an annealing of 200 deg. C due to the precipitates which delay the diffusion process. The annealing of the ECA pressed samples up to 400 deg. C leads to a decrease in the X-ray diffraction peaks broadening and an increase of the lattice parameter. This is due to grain growth

  14. 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

  15. A structure energy model for C2/c pyroxenes in the system Na-Mg-Ca-Mn-Fe-Al-Cr-Ti-Si-O

    International Nuclear Information System (INIS)

    The structure of C2/c pyroxenes in the Na-Mg-Ca-Fe-Al-Cr-Ti-Si-O system can be accurately simulated by the calculation of all interionic distances in the asymmetric unit, followed by a DLS treatment that optimizes cell parameters and atomic fractional coordinates. The precise structural simulation allows an accurate treatment of the static bulk lattice energy of the phase through two-body interaction potential calculations extended to all atoms within the asymmetric unit. The parametrization of the repulsive energy is achieved with the Huggins Mayer formulation that assumes the hardness factor of substances to be constant for all salts in the family and the repulsive factors of components to be variable from salt to salt. The linear relationship observed between repulsive factors of components and ionic radii of substituting ions on sites allows a rough estimate of lattice energy (hence of enthalpy, through the Born-Haber treatment) of unknown components. The structure-energy model developed for C2/c pyroxenes in the quadrilateral can be extended to the Na-Mg-Ca-Mn-Fe-Al-Cr-Ti-Si-O system when the molar abundances of minor components CaAl2SiO6, NaAlSi2O6, NaCrSi2O6, CaMnSi2O6, CaTiAl2O6 are limited to X ≤ 0.1 and the molar abundance of CaTiAl2O6 is restricted to X ≤ 0.05. The precision of the results rests on the precision of the enthalpy values selected at Tr, Pr reference conditions, as the uncertainty involved in the static lattice energy calculations is virtually negligible. Once new experimental data are available for the end-member components of interest, the model can be easily recast to obey the new limiting conditions

  16. New Scandium Platinum Silicides: ScPt2Si with `Inverse? MgCuAl2 Structure, and Sc5Pt9Si7, a Variant of the Zr2Fe12P7-Type

    OpenAIRE

    Jung, Walter

    2009-01-01

    Abstract Two new scandium platinum silicides, ScPt2Si (orthorhombic, Cmcm, a = 3.6653(6) ?, b = 9.831(1) ?, c = 6.967(1) ?, Z = 4) and Sc5Pt9Si7 (hexagonal, P?6, a = 9.9418(5) ?, c = 3.8832(2) ?, Z = 1) were prepared by reaction of the elements in an electric arc furnace and subsequent annealing. The crystal structures were solved and refined from single crystal diffraction data. ScPt2Si crystallizes with an `inverse? MgCuAl2 structure while Sc5Pt9Si7 forms a variant of the Zr2Fe...

  17. Development and characterization of high strength impact resistant Fe-Mn-(Al-, Si) TRIP/TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Bruex, U.; Frommeyer, G. [Dept. of Materials Technology, Max-Planck-Inst. fuer Eisenforschung, Duesseldorf (Germany); Graessel, O. [Pierburg AG, Neuss (Germany); Meyer, L.W.; Weise, A. [Lehrstuhl Werkstoffe des Maschinenbaus, TU Chemnitz, Chemnitz (Germany)

    2002-07-01

    Iron manganese steels with Mn mass contents of 15 to 30% exhibit microstructural related superior ductility and extraordinary strengthening behaviour during plastic deformation, which strongly depends on the Mn content. This influences the austenite stability and stacking fault energy {gamma}{sub fcc} and shows a great impact on the microstructure to be developed under certain stress state or during severe plastic deformation. At medium Mn mass contents (15 to 20%) the martensitic {gamma}-{epsilon}-{alpha}' phase transformation plays an important role in the deformation mechanisms of the TRIP effect in addition to dislocation glide. With increasing Mn mass content large elongation is favoured by intensive twinning formation. The mechanical properties of plain iron manganese alloys are strongly influenced by the alloying elements, Al and Si. Alloying with Al increases the stacking fault energy and therefore strongly suppresses the martensitic {gamma}-{epsilon} transformation, while Si sustains the {gamma}-{epsilon} transformation by decreasing the stacking fault energy {gamma}{sub fcc}. The {gamma}-{epsilon} phase transformation takes place in Fe-Mn-X alloys with {gamma}{sub fcc} {<=} 20 mJm{sup -2}. The developed light weight high manganese TRIP and TWIP (twinning induced plasticity) steels exhibit high ultimate tensile strength (600 to 1100 MPa) and extremely large elongation of 60 to 95% even at high strain rates of {epsilon}= 10{sup 3} s{sup -1}. Particularly due to the advanced specific energy absorption of TRIP and TWIP steels compared to conventional deep drawing steels high dynamic tensile and compression tests were carried out in order to investigate the change in the microstructure under near crash conditions. Tensile and compression tests of iron manganese alloys with varying Mn content were performed at different temperatures and strain rates. The resulting formation of {gamma} twins, {alpha}'- and {epsilon} martensite by plastic deformation

  18. The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

    International Nuclear Information System (INIS)

    The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

  19. Preheated shock experiments in the molten CaAl_2Si_2O_8-CaFeSi_2O_6-CaMgSi_2O_6 ternary: A test for linear mixing of liquid volumes at high pressure and temperature

    OpenAIRE

    Thomas, Claire W.; Asimow, Paul D.

    2013-01-01

    We performed 17 new shock wave experiments on preheated (1673 K) hedenbergite liquid (CaFeSi_2O_6) and two model basalt liquids (an equimolar binary mix of CaAl_2Si_2O_8 + CaFeSi_2O_6 and an equimolar ternary mix of CaAl_2Si_2O_8 + CaFeSi_2O_6 +CaMgSi_2O_6) in order to determine their equations of state (EOS). Ambient pressure density measurements on these and other Fe-bearing silicate liquids indicate that FeO has a partial molar volume that is highly dependent on composition, which leads to...

  20. Improved tunnel magnetoresistance of magnetic tunnel junctions with Heusler Co2FeAl0.5Si0.5 electrodes fabricated by molecular beam epitaxy

    International Nuclear Information System (INIS)

    The authors have developed a magnetic tunnel junction of Co2FeAl0.5Si0.5 electrodes and a MgO barrier fabricated by molecular beam epitaxy and observed that this device had a tunnel magnetoresistance ratio of 386% at approximately 300 K and 832% at 9 K. The lower Co2FeAl0.5Si0.5 electrode was annealed during and after deposition resulting in a highly ordered structure with small roughness. This highly ordered structure could be obtained by annealing treatment even at low temperatures. Furthermore, a weak temperature dependence of the tunnel magnetoresistance ratio was observed for the developed magnetic tunnel junction.

  1. Characterization of Fe/C catalysts supported on Al2O3, SiO2 and TiO2

    International Nuclear Information System (INIS)

    Structural and magnetic properties of Fe/C catalysts synthesized by ball milling and deposited onto Al2O3, SiO2 and TiO2 supports are reported. Ball milling α-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 FexC 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 TiO2 supported catalyst.

  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. Structure and magnetic properties of amorphous and nanocrystalline Fe40Co40Cu0.5Zr9Al2Si4B4.5 alloys

    International Nuclear Information System (INIS)

    Crystallisation behaviour and magnetic properties of as-spun and annealed Fe40Co40Cu0.5Zr9Al2Si4B4.5 alloy have been studied. The annealing was performed at 873 K for 15 min. XRD and TEM studies shows the formation of nanocrystalline α-(Fe,Co)(SiAl) particles with 7.5±2 nm in diameter dispersed in an amorphous matrix. The Curie temperature of the as-spun amorphous ribbon is 736 K. Saturation magnetisation of the annealed sample decreases at a rate of 0.5 emu/g/K in the measured temperature range of 300-1000 K. Excellent room temperature AC magnetic properties are achieved for the nanocrystalline sample. The low value of the imaginary part of the permeability and the high cut-off frequency (20 kHz) suggest that the eddy current contribution in the annealed materials is low. The coercivity of the annealed sample remains almost constant at 95 A/m up to the frequency of 20 kHz. High saturation magnetisation, high Curie temperature and excellent soft magnetic properties in the nanocrystalline state suggests that Fe40Co40Cu0.5Zr9Al2Si4B4.5 alloy is a strong candidate for high temperature magnetic application

  4. Effect of oxide films, inclusions and Fe on reproducibility of tensile properties in cast Al-Si-Mg alloys: Statistical and image analysis

    Energy Technology Data Exchange (ETDEWEB)

    Eisaabadi B, G., E-mail: G_eisaabadi@mehr.sharif.ir [Department of materials science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Foundry Technology Center, Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Davami, P. [Department of materials science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Kim, S.K. [Foundry Technology Center, Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Varahram, N. [Department of materials science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Yoon, Y.O.; Yeom, G.Y. [Foundry Technology Center, Korea Institute of Industrial Technology, Incheon (Korea, Republic of)

    2012-12-15

    Double oxide films (hereafter: oxides), inclusions and Fe-rich phases are known to be the most detrimental defects in cast Al-Si-Mg alloys. The effects of these defects on reproducibility of tensile properties in Al-7Si-0.35Mg alloy have been investigated in this study. Four different casting conditions (low oxide-low Fe, high oxide-low Fe, low oxide-high Fe and high oxide-high Fe) were studied. In each case, 30 tensile test samples were prepared by casting in a metallic mold and machining (total of 120 tensile test samples). Results of tensile test were analyzed by Weibull three-parameter and mixture analyses. The microstructure and fracture surface of samples were studied by optical and scanning electron microscopes. Total of 800 metallography images (200 images for each experiment) were taken and analyzed by image analysis software. Finally, the relationship between tensile properties and defects characteristics was discussed. According to the results, Fe (Fe-related phases) had larger negative impact on tensile properties of the alloy compared to oxides. On the other hand, Weibull analysis revealed that the scattering of tensile properties was mainly due to the presence of oxides in microstructure. Results of image analysis showed that the shape factor and number of pores were mainly controlled by oxides and Fe, respectively. Also, there was a clear relationship between Weibull modules of UTS and El% and shape factor of pores. Furthermore, tensile properties of the examined alloy showed strong dependence to the number of pores.

  5. Magnetism, superconductivity and their interplay. A study of three novel intermetallic compounds: La(Fe,Al)13, UNiSn, URu2Si2

    International Nuclear Information System (INIS)

    In this thesis the magnetic and superconducting properties are discussed for three novel types of intermetallic compounds. These compounds are studied with methods probing the magnetism, electrical transport and superconductivity. First, the LaFe13-type compounds were studied. The author establishes the magnetic phase diagram of La(Fe,Al)13, consisting of a mictomagnetic, ferromagnetic and antiferromagnetic regime. Second, uranium-based compounds were studied. In several equiatomic ternary (1-1-1) compounds (UNiSn, URu2Si2) they observed a broad variety of magnetic properties, ranging from local-moment magnetism to Kondo-lattice behaviour. Finally, the magnetic and superconducting properties are described for several RT2Si2 compounds, with T a transition metal. For R=Y, La and Lu type-I superconductivity was observed, which is explained with BCS-theory. (Auth.)

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

    Science.gov (United States)

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

    2010-03-01

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

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

    International Nuclear Information System (INIS)

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

  8. Ferroindialite (Fe2+,Mg)2Al4Si5O18, a new beryl-group mineral from the Eifel volcanic region, Germany

    Science.gov (United States)

    Chukanov, N. V.; Aksenov, S. M.; Pekov, I. V.; Ternes, B.; Schüller, W.; Belakovskiy, D. I.; Van, K. V.; Blass, G.

    2014-12-01

    A new mineral, ferroindialite, a Fe2+-dominant analog of indialite, has been found in a pyrometamorphosed xenolith of pelitic rock hosted in alkaline basalts. Associated minerals are phlogopite, sanidine, sillimanite, pyroxenes of the enstatite-ferrosilite series, wagnerite, fluorapatite, tridymite, zircon and almandine. Ferroindialite forms brown-purple to gray with a violet-blue tint short prismatic or thick tabular hexagonal crystals up to 1.5 mm in size. The new mineral is brittle, with a Mohs' hardness of 7. Cleavage is not observed. D meas = 2.66(1), D calc = 2.667 g/cm3. IR spectrum shows neither H2O nor OH groups. Ferroindialite is anomalously biaxial (-), α = 1.539(2), β = 1.552(2), γ = 1.554(2), 2 V meas = 30(10)°. The mineral is weakly pleochroic, ranging from colorless on X to pale violet on Z. Dispersion is weak, r < v. The chemical composition (electron microprobe, mean of five point analyses, wt %) is as follows: 0.14 Na2O, 0.46 K2O, 4.95 MgO, 1.13 MnO, 12.66 FeO, 2.64 Fe2O3, 30.45 Al2O3, 47.22 SiO2, total is 99.65. The distribution of total iron content between Fe2+ and Fe3+ was carried out according to structural data. The empirical formula of ferroindialite is: (K0.06Na0.03)(Fe{1.12/2+}Mg0.78Mn0.10)Σ2.00(Al3.79Fe{0.21/3+})Σ4.00Si4.98O18. The simplified formula is: (Fe2+,Mg)2Al4Si5O18. The crystal structure has been refined on a single crystal, R = 0.049. Ferroindialite is hexagonal, space group P6/ mcc; a = 9.8759(3), c = 9.3102(3) Å, V = 786.40(3) Å3, Z = 2. The strongest lines in the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are: 8.59 (100) (100), 4.094 (27) (102), 3.390 (35) (112), 3.147 (19) (202), 3.055 (31) (211), 2.657 (12) (212), 1.695 (9) (224). The type specimen of ferroindialite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4400/1.

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

    International Nuclear Information System (INIS)

    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 (1 Oe = 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 °C. 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. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Generation and evolution of nanoscale AlP and Al13Fe4 particles in Al-Fe-P system

    International Nuclear Information System (INIS)

    Highlights: • Diffusion and gradual solid reactions between Al and FexP 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 FexP 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 Al13Fe4 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 Al13Fe4 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

  11. Constraints on silicates formation in the Si-Al-Fe system: Application to hard deposits in steam generators of PWR nuclear reactors

    Science.gov (United States)

    Berger, Gilles; Million-Picallion, Lisa; Lefevre, Grégory; Delaunay, Sophie

    2015-04-01

    Introduction: The hydrothermal crystallization of silicates phases in the Si-Al-Fe system may lead to industrial constraints that can be encountered in the nuclear industry in at least two contexts: the geological repository for nuclear wastes and the formation of hard sludges in the steam generator of the PWR nuclear plants. In the first situation, the chemical reactions between the Fe-canister and the surrounding clays have been extensively studied in laboratory [1-7] and pilot experiments [8]. These studies demonstrated that the high reactivity of metallic iron leads to the formation of Fe-silicates, berthierine like, in a wide range of temperature. By contrast, the formation of deposits in the steam generators of PWR plants, called hard sludges, is a newer and less studied issue which can affect the reactor performance. Experiments: We present here a preliminary set of experiments reproducing the formation of hard sludges under conditions representative of the steam generator of PWR power plant: 275°C, diluted solutions maintained at low potential by hydrazine addition and at alkaline pH by low concentrations of amines and ammoniac. Magnetite, a corrosion by-product of the secondary circuit, is the source of iron while aqueous Si and Al, the major impurities in this system, are supplied either as trace elements in the circulating solution or by addition of amorphous silica and alumina when considering confined zones. The fluid chemistry is monitored by sampling aliquots of the solution. Eh and pH are continuously measured by hydrothermal Cormet© electrodes implanted in a titanium hydrothermal reactor. The transformation, or not, of the solid fraction was examined post-mortem. These experiments evidenced the role of Al colloids as precursor of cements composed of kaolinite and boehmite, and the passivation of amorphous silica (becoming unreactive) likely by sorption of aqueous iron. But no Fe-bearing was formed by contrast to many published studies on the Fe

  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. Assessment of Si and Al diffusion for the production of high Si and high Si-Al electrical steel

    International Nuclear Information System (INIS)

    A trend in the production of electrical steel is to increase the concentration of Si and Al (over 3 wt%) in order to reduce magnetic losses through increased electrical resistivity. This can hardly be done in early stages of the production process due to the appearance of brittle phases; however, a concentration increase of (Si, Al) can be reached by surface deposition of Si and/or Al, followed by diffusion into the bulk. Diffusion of Si and/or Al modifies substantially the mechanical and magnetic properties of the substrate and a study of the diffusion process leading to Fe-Si-Al alloys with homogeneous or inhomogeneous distribution of (Si, Al) is needed. The industrial production of these alloys requires models predicting the concentration profile of (Si, Al) resulting from the diffusion process and the changes of the mechanical and magnetic properties associated with the resulting concentration profiles of (Si, Al). This paper assesses the diffusion process using commercial software for the modelling of diffusion-controlled transformations. Experimental validation was made on some base alloys and results for the 3 wt% Si material are reported. Substrates were coated by dipping in a molten Al-25 wt% Si alloy, followed by annealing at different temperatures and times. The results show that Si concentration profiles can be accurately predicted. However, when considering both Si and Al diffusion their interaction causes important disagreements between experimental results and model calculations

  14. Phase Equilibria Study of the ZnO-"FeO"-SiO2-Al2O3 System at Po2 10-8 atm

    Science.gov (United States)

    Liu, Hongquan; Cui, Zhixiang; Chen, Mao; Zhao, Baojun

    2016-04-01

    Phase equilibria studies on ZnO-"FeO"-SiO2-Al2O3 system have been carried out in the temperature range between 1523 K and 1573 K (1250 °C and 1300 °C) at Po2 10-8 atm. Experimental techniques applied in the present study include high temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA). The compositions of the phases present in the quenched samples were measured by EPMA and used to construct phase diagrams of the pseudo-ternary sections at fixed Al2O3 content. The experimental results show that, spinel, SiO2, and willemite are the major primary phase fields in the composition range investigated. With 2 wt pct Al2O3 content in the liquid phase, the liquidus temperature can be increased by 35 K in the spinel primary phase in comparison with Al2O3-free system. The partitioning of ZnO and Al2O3 between the spinel and liquid phases is also discussed in the paper.

  15. Effect of Heat Treatments on the Microstructure, Hardness and Corrosion Behavior of Nondendritic AlSi9Cu3(Fe Cast Alloy

    Directory of Open Access Journals (Sweden)

    Nacer ZAZI

    2013-09-01

    Full Text Available In this paper we studied the influence of heat treatments on properties of AlSi9Cu3(Fe nondendritic cast alloy. Solution heat treatment, six hours at 520 °C, while making the grains more spherical modifies corrosion morphology into intergranular corrosion and corrosion surrounding spherical particles in 3 % NaCl solution. Past solution treatment, quenching at 520 °C after one hour with two weeks of natural aging transform the shape of grains into equiaxes form. Two weeks of natural aging and 30 minutes of aging at 150, 200, 250 °C after solution treatment and quenching give birth to the "Chinese script" form of the Al15(MnFe3Si intermetallic particles. The prolongation of the duration period of aging to one hour at 200 °C is sufficient to transform the morphology of corrosion into located corrosion by pitting, and a longer aging cancels the "Chinese script" form. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1397

  16. 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.

  17. 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.

  18. 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.

  19. 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

    Science.gov (United States)

    Bertol, Ana Paula Lamberti; Hinrichs, Ruth; Vasconcellos, Marcos A. Z.

    2015-12-01

    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.

  20. Spin state of iron and elastic properties of (MgFe)(SiAl)O3 under conditions of the lower mantle

    Science.gov (United States)

    Glazyrin, K.; Boffa Ballaran, T.; Frost, D. J.; McCammon, C. A.; Kantor, A.; Merlini, M.; Hanfland, M.; Dubrovinsky, L. S.

    2012-12-01

    Iron is incorporated into crystal structures of the dominant lower mantle phases, namely, magnesium silicate perovskite (Pv) and ferropericlase (Fp). There is no doubt that iron is the most abundant transition element of the lower mantle. Depending on conditions imposed by the latter, charge distribution between different electronic orbitals of iron may change, giving rise to spin state transitions (SST) which, in turn, may modify bulk elastic and transport properties of the material. Critical conditions promoting SST vary depending on iron cation charge and crystallographic environment. In the case of Pv, it was shown that Fe2+ will occupy exclusively the distorted dodecahedral (A) site, while Fe3+ can substitute in both the A and the B (octahedral) sites. However, the problem becomes more complicated if we consider Fe/Al coupled substitution in Pv and realistic compositions of the lower mantle. Although SST in Pv is a current and highly debated topic, there is clearly a lack of experimental data, and the literature shows strong controversies between theoretical calculations and experiment. The problem of iron SST in Pv is one of the most challenging and important for our understanding of mantle processes and dynamics. We conducted a single crystal diffraction experiment on Mg0.6Fe0.4Si0.63Al0.37O3 Pv at the ID09 beamline, ESRF, Grenoble. Comprehensive characterization of this sample synthesized in a multianvil apparatus revealed that almost all iron in this material is ferric and occupies exclusively the A site (Fe3+A). We studied the combined effect of compression and temperature on the crystal structure and elastic properties of the material, and we observed that (a) below 77 GPa, 1800K there is no SST for Fe3+A and (b) high pressure-high temperature treatment has no effect on Fe/Al cation distribution between different crystallographic sites. These observations are in good agreement with recent theoretical work. Based on a thermal equation of state derived

  1. 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

  2. Fabrication and characterization of spin injector using a high-quality B2-ordered-Co2FeSi0.5Al0.5/MgO/Si(100) tunnel contact

    Science.gov (United States)

    Kawame, Yu; Akushichi, Taiju; Takamura, Yota; Shuto, Yusuke; Sugahara, Satoshi

    2015-05-01

    We successfully fabricate a (100)-orientated B2-type-Co2FeSi0.5Al0.5 (CFSA)/MgO/Si(100) tunnel contact that is promising for an efficient spin injector for Si channels. The MgO barrier is formed by radical oxidation of an Mg thin film deposited on a Si(100) surface at room temperature and successive radical oxygen annealing at 400 °C. The CFSA electrode is grown on the MgO barrier at 400 °C by ultrahigh-vacuum molecular beam deposition, and it exhibits a (100)-orientated columnar polycrystalline structure with a high degree (63%) of B2-order. The MgO barrier near the interface of the CFSA/MgO junction is crystallized with the (100) orientation, i.e., the spin filter effect due to the MgO barrier could be expected for this junction. A three-terminal Si-channel spin-accumulation device with a CFSA/MgO/Si(100) spin injector is fabricated, and the Hanle effect of accumulated spin polarized electrons injected from this contact to the Si channel is observed.

  3. Fabrication and characterization of spin injector using a high-quality B2-ordered-Co{sub 2}FeSi{sub 0.5}Al{sub 0.5}/MgO/Si(100) tunnel contact

    Energy Technology Data Exchange (ETDEWEB)

    Kawame, Yu, E-mail: kawame-y@isl.titech.ac.jp; Akushichi, Taiju; Shuto, Yusuke; Sugahara, Satoshi, E-mail: sugahara@isl.titech.ac.jp [Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa (Japan); Takamura, Yota [Department of Physical Electronics, Tokyo Institute of Technology, Tokyo (Japan)

    2015-05-07

    We successfully fabricate a (100)-orientated B2-type-Co{sub 2}FeSi{sub 0.5}Al{sub 0.5} (CFSA)/MgO/Si(100) tunnel contact that is promising for an efficient spin injector for Si channels. The MgO barrier is formed by radical oxidation of an Mg thin film deposited on a Si(100) surface at room temperature and successive radical oxygen annealing at 400 °C. The CFSA electrode is grown on the MgO barrier at 400 °C by ultrahigh-vacuum molecular beam deposition, and it exhibits a (100)-orientated columnar polycrystalline structure with a high degree (63%) of B2-order. The MgO barrier near the interface of the CFSA/MgO junction is crystallized with the (100) orientation, i.e., the spin filter effect due to the MgO barrier could be expected for this junction. A three-terminal Si-channel spin-accumulation device with a CFSA/MgO/Si(100) spin injector is fabricated, and the Hanle effect of accumulated spin polarized electrons injected from this contact to the Si channel is observed.

  4. Fabrication and characterization of spin injector using a high-quality B2-ordered-Co2FeSi0.5Al0.5/MgO/Si(100) tunnel contact

    International Nuclear Information System (INIS)

    We successfully fabricate a (100)-orientated B2-type-Co2FeSi0.5Al0.5 (CFSA)/MgO/Si(100) tunnel contact that is promising for an efficient spin injector for Si channels. The MgO barrier is formed by radical oxidation of an Mg thin film deposited on a Si(100) surface at room temperature and successive radical oxygen annealing at 400 °C. The CFSA electrode is grown on the MgO barrier at 400 °C by ultrahigh-vacuum molecular beam deposition, and it exhibits a (100)-orientated columnar polycrystalline structure with a high degree (63%) of B2-order. The MgO barrier near the interface of the CFSA/MgO junction is crystallized with the (100) orientation, i.e., the spin filter effect due to the MgO barrier could be expected for this junction. A three-terminal Si-channel spin-accumulation device with a CFSA/MgO/Si(100) spin injector is fabricated, and the Hanle effect of accumulated spin polarized electrons injected from this contact to the Si channel is observed

  5. On the Production of He, Ne, and AR Isotopes from Mg, Al, Si, Ca, Fe, and NI in an Artificially Irradiated Meteoroid

    Science.gov (United States)

    Wieler, R.; Signet, P.; Rosel, R.; Herpers, U.; Lupke, M.; Lange, H.-J.; Michel, R.

    1992-07-01

    The production of He, Ne, and Ar isotopes from their main target elements was investigated in an experiment (1) by irradiating a 50-cm-diameter gabbro sphere isotropically with 1.6 GeV protons. The model meteoroid contained, among a large number of other targets, pure element foils of Mg, Al, Si, Fe, and Ni at 10 different depths and wollastonite targets at 3 different depths in central bores. After the irradiation, radionuclide production in these targets was measured by gamma spectrometry. Stable He, Ne, and Ar isotopes were measured in statically operated mass spectrometers. Here, we report the results for stable He, Ne, and Ar isotopes and for ^22Na. The production depth profiles vary widely, ranging from profiles with near-surface production 15% higher than in the center (^22Na from Fe) to such profiles with production in the center 45% higher than near the surface (^20Ne from Mg). The isotope ratios ^3He/^4He and ^3He/^21Ne in Mg, Al, Si and ^22Ne/^21Ne in Mg all decrease significantly with increasing shielding. The production rates of He, Ne, and ^22Na from Mg, Al, and Si in the 1600-MeV simulation experiment are 1.5 to 3 times higher than in the model meteoroid of similar size but irradiated earlier with 600 MeV protons (2). This increase is attributed to the increase of the production of secondary neutrons with primary energies rising from 600 to 1600 MeV. This effect also causes the depth dependences of isotope ratios observed in the 1600-MeV simulation that was not seen in the 600-MeV experiment. Model calculations of the production of He, Ne, and Ar isotopes and of ^22Na were performed for the artificial meteorites of the 600- and 1600 MeV-exposures as well as for real meteoroids. Production rates were calculated from depth-dependent p- and n- spectra, which were derived by Monte Carlo techniques using the HERMES code system (3), and from cross sections for the relevant nuclear reactions as described earlier (4). The cross section database for p

  6. 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. 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.

  8. Geochemical dispersion of Si, Al, Fe, Mn, Na, K, Cu and Zn elements in soils and their use for characterization areas geochemically homogeneous

    International Nuclear Information System (INIS)

    Variations in the chemical composition of soils are used to characterize sub-areas geochemically - homogenous. The application of this methodology in a tropical humid region of accentuated topography constitute the principal objective of the present research. Samples of red latosols (Horizon B) developed over granite, sandstone and basalt occurring in the Central Granite Region of the Serra dos Carajas, Para State, Brazil were analized for the elements Si, Al, Fe, Mn, Na, K, Cu e Zn, by atomic absorption spectrophotometry. Based on the criterion of similarity in the chemical composition (Cluster Analysis, Factor Analysis) the soils were separeted in to different groups. The geographical distribution of the different groups permit the establishment of a close relationship between the different parent lithologies and their corresponding soils. (author)

  9. Anomalous decrease in X-ray diffraction intensities of Cu-Ni-Al-Co-Cr-Fe-Si alloy systems with multi-principal elements

    International Nuclear Information System (INIS)

    With an aim to understand the great reduction in the X-ray diffraction (XRD) intensities of high-entropy alloys, a series of Cu-Ni-Al-Co-Cr-Fe-Si alloys with systematic addition of principal elements from pure element to seven elements was investigated for quantitative analysis of XRD intensities. The variation of XRD peak intensities of the alloy system is similar to that caused by thermal effect, but the intensities further drop beyond the thermal effect with increasing number of incorporated principal elements. An intrinsic lattice distortion effect caused by the addition of multi-principal elements with different atomic sizes is expected for the anomalous decrease in XRD intensities. The mathematical factor of this distortion effect for the modification of XRD structure factor is formulated analogue to that of thermal effect

  10. Structure of the quasicrystal-approximant phase Al61.3Cu7.4Fe11.1Cr17.2Si3

    International Nuclear Information System (INIS)

    The crystal structure of the compound Al61.3Cu7.4-Fe11.1Cr17.2Si3 has been determined. The structure is first described by a structure-simulation method and then identified by experimental single-crystal X-ray diffraction. It is a 'one-dimensional approximant' phase. The crystal is orthorhombic (space group Pnma) with parameters: a = 14.582 (1), b = 12.321 (1), c = 12.363 (1) A, V = 2221 A3, Z = 1, Dx = 4.25 g cm-3. Measurements were performed with Mo Kα radiation, μ = 98 cm-1, F(000) = 2732, T = 300 K, to give R = 0.038 (wR = 0.049) for 1837 reflections. (orig.)

  11. The influence of the disorder on the electronic states of the Heusler compound Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} studied by ARUPS and tunnelling spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Arbelo Jorge, Elena; Herbort, Christian; Hahn, Michaela; Scoenhense, Gerd; Jourdan, Martin [Institute of Physics, Johannes-Gutenberg University, Staudinger Weg 7, 55099 Mainz (Germany)

    2011-07-01

    Heusler compounds have attracted much interest based on their half metallic properties predicted by band structure calculations. However, a direct comparison of the theoretical predictions with experiments remains difficult, even if the spin degree of freedom is averaged. Additionally, the influence of atomic disorder on the band structure is of major interest and is in general expected to result in a broadening of the electronic states. We present in-situ spin averaged angular resolved UV-photoemission spectroscopy (ARUPS) of rf-sputtered Heusler thin films. Additionally, tunnelling spectroscopy on planar junctions of Heusler thin films with AlO{sub x} barrier is performed. Samples of the compound Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} with different degrees of disorder (B2 and L2{sub 1}) are studied. The ARUPS results at energies close to the Fermi edge are compared to measurements of the bias voltage dependent tunnelling conductivity of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7}/AlO{sub x}/Ag and Co{sub 2}FeAl{sub 0.3}Si{sub 0.7}/AlO{sub x}/CoFe junctions. Whereas the ARUPS shows clear correlations with the degree of disorder of the Heusler compound, the interpretation of the tunnelling spectroscopy results in terms of the density of states is challenging.

  12. 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.

  13. Kinetic Analysis of Recovery, Recrystallization, and Phase Precipitation in an Al-Fe-Si Alloy Using JMAEK and Sesták-Berggren Models

    Science.gov (United States)

    Luiggi Agreda, Ney José

    2015-02-01

    When studying the phase changes process in a rolled AA8011 alloy using DSC, we find that the peaks associated with phase precipitation under this microstructural condition are different from those obtained in homogenized microstructures. The differences observed are attributable, first, to the recovery process occurring at temperatures below 423 K (150 °C), which interacts with the precipitation of Si-rich precipitates or with Guinier-Preston zones both coexistent in that temperature range; and second, to the recrystallization above 473 K (200 °C), which coexists with precipitation of the α-AlFeSi phase. In this work, the precipitation and recovery-recrystallization kinetics are experimentally obtained and deconvoluted in peaks characteristic for each of the mechanisms involved; i.e., precipitation of GP zones, recovery, precipitation of α phase, and recrystallization. The deconvolution is achieved using functions of Gauss, Weibull, and Fraser-Suzuki; and the characterization of each reaction deconvoluted is realized through both Jhonson-Melh-Avrami-Erofeev-Kolmorokov kinetic models and Sesták-Berggren combined kinetic model. The kinetic study evinces that in addition to the expected reactions, other reactions, necessary for good experimental adjustment, appear. An isoconversional study is undertaken to numerically evaluate the kinetic triplet of every process.

  14. 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.

  15. Sound Velocities of Fe-C and Fe-Si alloying liquids at high pressures

    Science.gov (United States)

    Jing, Z.; Han, J.; Yu, T.; Wang, Y.

    2014-12-01

    Geophysical and geochemical observations suggest light elements such as S, Si, C, O, H, etc., are likely present in the Earth's outer core and the molten cores of other terrestrial planets and moons including Mercury, Mars, Earth's Moon, and Ganymede. In order to constrain the abundances of light elements in planetary cores, it is crucial to determine the density and sound velocity of Fe-light element alloying liquids under core conditions. In this study, sound velocities of Fe-rich liquids were determined by combining the ultrasonic measurements with synchrotron X-ray radiography and diffraction techniques under high-pressure and temperature conditions from 1 to 6 GPa and 1573 to 1973 K. An Fe-C composition (Fe-5wt%C) and four Fe-Si compositions (Fe-10wt%Si, Fe-17wt%Si, Fe-25wt%Si, and FeSi) were studied. Compared to our previous results on the velocity of Fe and Fe-S liquids at high pressures (Jing et al., 2014, Earth Planet. Sci. Lett. 396, 78-87), the presence of both C and Si increases the velocity of liquid Fe, in contrast to the effect of S. The measured velocities of Fe-C and Fe-Si liquids increase with compression and decrease slightly with increasing temperature. Combined with 1-atm density data in the literature, the high-pressure velocity data provide tight constraints on the equations of state and thermodynamic properties such as the adiabatic temperature gradient for Fe-C and Fe-Si liquids. We will discuss these results with implications to planetary cores.

  16. The Effect of SiO2-TiO2-Al2O3 Mixture Addition on the CuFe2O4 Ceramic for Negative Temperature Coefficient Thermistor

    International Nuclear Information System (INIS)

    The effect of SiO2-TiO2-Al2O3 mixture addition on the characteristics of CuFe2O4 ceramics for Negative Temperature Coefficient (NTC) thermistors has been studied. The ceramics were produced by pressing a homogenous mixture of composition 1: CuO, Fe3O4 and SiO2-TiO2-Al2O3 (0,5; 0,5 dan 0,5 w/o), composition 2: CuO, Fe3O4 dan SiO2-TiO2-Al2O3 (0,5; 0,5 and 1,0 w/o) and composition 3 : CuO, Fe3O4 and SiO2-TiO2-Al2O3 (0,5; 0,5 and 2,0 w/o) in appropriate proportions to produce CuFe2O4 based ceramics. The pressed powders were then sintered at 1100 oC for 2 hours in air. Electrical characterization was done by measuring electrical resistivity of the ceramics at various temperatures (25 oC - I00 oC). Microstructure and structure analysis were also carried out by using optical microscope and x-ray diffractometer (XRD), respectively. The XRD analyses showed that the CuFe2O4 and SiO2-TiO2-Al2O3 mixture added - CuFe2O4 ceramics have crystal structure of tetragonal spinel and the presence of second phase could not be identified. According to the electrical data, it was known that addition of the SiO2-TiO2-Al2O3 mixture changed the thermistor constant (B) and the temperature electrical resistivity (ρRT). The value of B of 2807-3293 oK and (ρRT) of 3,4-5,3 κΩcm of the produced CuFe2O4 based ceramics fitted market requirement. (author)

  17. 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.

  18. Tunnel Magnetoresistance and Spin-Transfer-Torque Switching in Polycrystalline Co2FeAl Full-Heusler-Alloy Magnetic Tunnel Junctions on Amorphous Si /SiO2 Substrates

    Science.gov (United States)

    Wen, Zhenchao; Sukegawa, Hiroaki; Kasai, Shinya; Inomata, Koichiro; Mitani, Seiji

    2014-08-01

    We study polycrystalline B2-type Co2FeAl (CFA) full-Heusler-alloy-based magnetic tunnel junctions (MTJs) fabricated on a Si /SiO2 amorphous substrate. Polycrystalline CFA films with a (001) orientation, a high B2 ordering, and a flat surface are achieved by using a MgO buffer layer. A tunnel magnetoresistance ratio up to 175% is obtained for a MTJ with a CFA /MgO/CoFe structure on a 7.5-nm-thick MgO buffer. Spin-transfer-torque-induced magnetization switching is achieved in the MTJs with a 2-nm-thick polycrystalline CFA film as a switching layer. By using a thermal activation model, the intrinsic critical current density (Jc0) is determined to be 8.2×106 A /cm2, which is lower than 2.9×107 A /cm2, the value for epitaxial CFA MTJs [Appl. Phys. Lett. 100, 182403 (2012), 10.1063/1.4710521]. We find that the Gilbert damping constant (α) evaluated by using ferromagnetic resonance measurements for the polycrystalline CFA film is approximately 0.015 and is almost independent of the CFA thickness (2-18 nm). The low Jc0 for the polycrystalline MTJ is mainly attributed to the low α of the CFA layer compared with the value in the epitaxial one (approximately 0.04).

  19. 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.

  20. SiCp/Al-Fe-V-Si的板材成形过程中显微组织和力学性能的演变%Microstructure and mechanical property evolution of SiCp/Al-Fe-V-Si composite during sheet forming process

    Institute of Scientific and Technical Information of China (English)

    贺毅强; 陈振华

    2012-01-01

    SiCp/Al-Fe-V-Si composite prepared by multi-layer spray deposition was densified by rolling process after extruding and rolling after pressing. The microstructure, phases and mechanical properties of the composite under different conditions were analyzed. And the density and hardness evolution of the composite during rolling process were investigated. The results show that the composite deposits can be densified and strengthened efficiently by rolling processes after extruding and pressing separately. More homogeneous, finer microstructure and more excellent mechanical properties of the composite are obtained by rolling process after pressing than by rolling process after extruding. The tensile strength and elongation of the composite as-rolled after extruding are 535 MPa and 4.0%, both of hardness and density of the composite as-extruded decrease firstly when reduction is below 25% and then raise during rolling process, which agrees with density evolution. The tensile strength and elongation of the composite as-rolled after pressing are 580 MPa and 6.3%. And those of the as-pressed composite firstly when reduction is below 10%, then decrease until the reduction reaches 40%, and finally rise during rolling process. The hardness varies as density does with reduction increases during rolling process for both of the composites.%采用多层喷射沉积工艺制备SiCp/Al-Fe-V-Si复合材料,并分别通过挤压后轧制和热压后轧制工艺制备了板材,分析了复合材料不同状态下的显微组织、物相和力学性能,并研究在轧制过程中复合材料密度和硬度的变化规律.结果表明:挤压后轧制和热压后轧制均能有效致密沉积坯.与挤压后再轧制相比,热压后再轧制材料组织更均匀细小,力学性能更优秀.挤压后再轧制板材抗拉强度为535MPa,伸长率为4.0%,压下25%前,挤压坯的密度和硬度随之降低;当压下25%时,密度和硬度升高.热压后轧制板材抗拉强度达580

  1. Precipitated phases and thermodynamic analysis during solidification of Al-Fe-X system at slow cooling rate

    Institute of Scientific and Technical Information of China (English)

    谭敦强; 黎文献; 肖于德; 王冲

    2003-01-01

    The solidification curves of Al-8.5Fe, Al-8.5Fe-1.7Fe, Al-8.5Fe-1.7Si-1.3V alloys were examined by DTA under the condition of slow cooling rate, the phase constitutes were examined by OM and XRD. The results show that, under slow cooling rate, the phases in Al-8.5Fe alloy are mainly α(Al) and Al13Fe4, the phases in Al-8.5Fe-1.7Si alloy are mostly α(Al), Al13Fe4, α-AlFeSi, β-AlFeSi, and comparing to Al-8.5Fe-1.7Si alloy, no other phases form in the Al-8.5Fe-1.3V-1.7Si alloy, but the chemical compositions of the phases are changed and the thermal stability of α-AlFeSi phase and β-AlFeSi phase is improved, due to the partial substitution of V for Fe atoms. The phase formation was calculated by Thermo-calc software at equilibrium condition, the calculated results were agreement with the experimental results.

  2. Discovery of Ahrensite γ-Fe2SiO4 and Tissintite (Ca,Na,[])AlSi2O6, Two New Shock-induced Minerals from the Tissint Martian Meteorite: a Nanomineralogy Investigation

    Science.gov (United States)

    Ma, C.; Tschauner, O. D.; Liu, Y.; Sinogeikin, S. V.; Zhuravlev, K. K.; Prakapenka, V.; Dera, P. K.; Taylor, L. A.

    2013-12-01

    The recent Martian meteorite fall, Tissint, is a fresh olivine-phyric shergottite, with strong shock features. During our nano-mineralogy investigation of the Tissint meteorite with a combined analytical scanning electron microscope and synchrotron diffraction approach, two new shock-induced minerals have been discovered; these provide new insights into understanding shock conditions and impact processes on Mars. Ahrensite (IMA 2013-028), the Fe-analogue (γ-Fe2SiO4) of ringwoodite, is a new high-pressure mineral identified in Tissint. Both ahrensite and ringwoodite occur in Tissint as fine-grained polycrystalline aggregates in the rims of olivines around some shock-melt pockets. The morphology and texture of these silicate-spinels suggest formation by a solid-state transformation from Fe-rich olivine. Associated with the ahrensite and ringwoodite, inside melt pockets, often resides a thin layer of vitrified silicate-perovskite and magnesio-wüstite or wüstite. Such transitions represent a unique pressure and temperature gradient. Tissintite (IMA 2013-027), (Ca,Na,[])AlSi2O6 with the C2/c clinopyroxene structure, is a new jadeite-like mineral in Tissint. It appears as fine-grained aggregates within plagioclase glass, inside many shock-melt pockets. Both ahrensite and tissintite are high-pressure minerals formed by shock during the impact event(s) on Mars that excavated and ejected the rock off Mars. We will discuss the path of structure analysis for both new-mineral cases. Such novel methodology be utilized for many cases of mineralogical phase identification or structure analysis; this demonstrates how nano-mineralogy can be addressed and how it may play a unique role in meteorite and Mars rock research, in general.

  3. Process optimization of atomized melt deposition for the production of dispersion strengthened Al-8.5%Fe-1.2%V-1.7%Si alloys

    International Nuclear Information System (INIS)

    Atomized melt deposition is a low cost manufacturing process with the microstructural control achieved through rapid solidification. In this process the liquid metal is disintegrated into fine droplets by gas atomization and the droplets are deposited on a substrate producing near net shape products. In the present investigation Al-8.5%Fe-1.2%V-1.7%Si alloy was produced using atomized melt deposition process to study the evolution of microstructure and assess the cooling rates and the undercooling achieved during the process. The size, morphology and the composition of second phase particles in the alloy are strong functions of the cooling rate and the undercooling and hence microstructural changes with the variation in process parameters were quantified. To define optimum conditions for the atomized melt deposition process, a mathematical model was developed. The model determines the temperature distribution of the liquid droplets during gas atomization and during the deposition stages. The model predicts the velocity distribution, cooling rates and the fraction solid, during the flight for different droplet sizes. The solidification heat transfer phenomena taking place during the atomized melt deposition process was analyzed using a finite difference method based on the enthalpy formulation

  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. Magnetic properties of amorphous Fe73.5Cu1Mo3Si12.5Al1B9 alloy

    International Nuclear Information System (INIS)

    The FINEMET type Fe73.5Cu1Mo3Si12.5Al1B9 (numbers indicate at.%) alloy has been synthesized using single wheel melt spinning technique. The samples have been thermally annealed at about 40 K less than the crystallization temperature for various durations. The samples show increase in Curie temperature of the amorphous phase with annealing. To get a better insight into their magnetic behaviour we have done spin wave analysis on the as-spun and thermally annealed samples and extracted the spin wave stiffness constant and mean square range of exchange interaction. Low temperature thermomagnetic measurements from 10 to 300 K were performed with an applied field of 0.5 T. The data were fitted using the Bloch equation. The value of the C/B ratio and the mean square range of exchange interaction were found to be characteristic of amorphous ferromagnets. The variation of spin wave stiffness constant is correlated to the changes in Curie temperature and the nature of the exchange interaction existing in this alloy is determined

  7. Effect of annealing on the microstructure and mechanical properties of cold rolled Fe-24Mn-3Al-2Si-1Ni-0.06C TWIP steel

    International Nuclear Information System (INIS)

    Research highlights: → Recrystallisation is nearly complete after 300 s isochronal annealing at 850 deg. C. → Four work hardening regions evolve upon tensile testing after partial recrystallisation. → A modified empirical Hollomon-Ludwigson scheme is suggested to fit the flow curve. - Abstract: Fe-24Mn-3Al-2Si-1Ni-0.06C TWinning Induced Plasticity (TWIP) steel was 42% cold-rolled and isochronally annealed at temperatures between 600 and 850 deg. C. Optical, secondary and transmission electron microscopy found that a majority of as cold-rolled grains contain a large fraction of primary twin densities and a smaller fraction of secondary twins. Partially recrystallised microstructures comprise a mix of recrystallised grains and annealing twins as well as remanent deformed grains with heavy dislocation substructures and deformation twins. Both deformation and annealing twins follow the {1 1 1} relationship. All partially recrystallised samples exhibited four work hardening regions and a decreasing twinning onset stress with greater percentage softening. A modification to the Hollomon-Ludwigson scheme is suggested to empirically account for the effect of strain on microstructural refinement.

  8. Efeito dos teores de Mn e de Fe na evolução microestrutural de duas ligas do sistema Al-Fe-Mn-Si obtidas por fundição contínua de chapas (Twin Roll Caster Effect of Mn and Fe contents on the microstructural evolution of two twin roll caster Al-Fe-Mn-Si alloys

    Directory of Open Access Journals (Sweden)

    Ricardo do Carmo Fernandes

    2008-06-01

    Full Text Available Com o crescimento constante da utilização do processo twin roll caster para a obtenção de chapas de alumínio, torna-se cada vez mais necessário um melhor conhecimento das características das chapas obtidas por este processo. Foram estudadas, nesse trabalho, duas ligas não tratáveis termicamente, 3003 (1,2%Mn; 0,6%Fe e 8106 (0,4%Mn; 1,5%Fe. As amostras foram retiradas de chapas com 7 mm de espessura a partir de bobinas brutas de fundição e após tratamento térmico de homogeneização de 500°C por 12 horas. As técnicas utilizadas para a caracterização das amostras foram: microscopia óptica com auxílio de luz polarizada, ensaio de microdureza, além dos ensaios de condutividade elétrica.The continuous growth in the usage of the twin roll caster process for aluminum plate production demands a better understanding of the plate's final characteristics. In this work two non-heat treatable largely-used aluminum alloys, namely 3003 (1.2%Mn; 0.6%Fe and 8106 (0.4%Mn; 1.5% Fe, have been studied. Samples were obtained from 7mm thick plates stemming from rolls in the as-cast condition and after 500°C/12h homogenizing heat treatment. The techniques employed in the sample characterization included: polarized light optical microscopy, microhardness and electrical conductivity tests.

  9. Effect of Al content on the order of phase transition and magnetic entropy change in LaFe11Co0.8(Si1−xAlx)1.2 alloys

    International Nuclear Information System (INIS)

    The comparative studies of the effect of partial substitution of Al by Si on the structure and magnetic entropy change in LaFe11Co0.8(Si1−xAlx)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)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 LaFe11.0Co0.8(Si1−xAlx)1.2 where x=0;0.6. • Negative change of lattice parameter near Curie temperature in LaFe11.0Co0.8Si1.2. • Landau theory of phase transitions

  10. Microstructure And Texture Evolution During Cold-Rolling In The Fe-23Mn-3Si-3Al Alloy

    Directory of Open Access Journals (Sweden)

    Kowalska J.

    2015-09-01

    Full Text Available Fe–23wt.%Mn–3wt.%Si–3wt.%Al alloy was cast, homogenized at 1150ºC, hot-rolled at temperatures between 1200ºC and 900ºC and next cold-rolled from 5% up to 40% reductions in thickness. Microstructure and texture of this alloy, which has a low stacking fault energy, were defined after cold-rolling. Investigation of transmission electron microscopy and X-ray diffraction showed that mechanical twinning and martensitic transformations (γfcc→εhcp and γfcc→εhcp→α′bcc took place during cold-rolling. The crystallographic Shoji-Nishiyama (S-N {00.2}ε║{111}γ, ε ║ γ and Kurdjumov-Sachs (K-S {111}γ║{101}α’, γ║α’ relations between martensite (ε, α’ and austenite (γ, were found in the coldrolled material.

  11. Texture evolution of cold rolled and annealed Fe-24Mn-3Al-2Si-1Ni-0.06C TWIP steel

    International Nuclear Information System (INIS)

    Highlights: → Slip and micro-shear banding contribute to the development of Brass orientation. → Annealing twins evolve since the early nucleation stage. → F orientation forms upon recrystallisation due to relatively random nucleation. → Second order twinning and favoured growth relation lead to Rotated Copper component. → The modified Hall-Petch equation adequately predicts the 0.2% proof stress. - Abstract: The microstructure and texture evolution of 42% cold-rolled Fe-24Mn-3Al-2Si-1Ni-0.06C TWinning Induced Plasticity (TWIP) steel is investigated during isochronal annealing at temperatures between 600 and 850 deg. C. In the cold rolled condition, bulk texture returned the distinctive α-fibre for low stacking fault energy materials, with higher intensities for Goss ({1 1 2}) compared to Brass ({1 1 1}). A comparison between bulk and micro-textures, showed a significant slip contribution to the development of the Brass orientation, along with a possible role for micro-shear banding. Annealing twins contribute to recrystallisation from the early stages of nucleation and participate in generating new orientations thereafter. Unlike texture studies on other austenitic steels, the F ({1 1 1}) and Rotated Copper ({1 1 2}) orientations were detected in this work. The former is due to a more homogeneous distribution of nucleation sites, while the latter can be ascribed to second order twinning and the preferred-growth 30o relation with the Brass rolling component. Based on the microstructural parameters from Electron Back-Scattering Diffraction (EBSD), the modified Hall-Petch (H-P) relation was successfully applied to the 0.2% proof stress.

  12. Stress-impedance effects in layered FeSiB/Cu/FeSiB films with a meander line structure

    International Nuclear Information System (INIS)

    Stress-impedance (SI) effects were realized in layered FeSiB/Cu/FeSiB films with a meander line structure by magnetron sputtering on thin glass substrate. The SI effects were studied in the frequency range of 1-40MHz for the layered FeSiB/Cu/FeSiB films with different film thickness of FeSiB film and Cu layer. Experimental results show that the values of SI ratio increase nearly linear with the deflection of the layered FeSiB/Cu/FeSiB films at high frequencies, and a large negative SI ratio of -18.3% at a frequency of 25MHz with the deflection of 1000μm is obtained in the layered FeSiB/Cu/FeSiB films with a thicker FeSiB film, which is very attractive for the applications of stress sensors

  13. Thermoelasticity of Fe3+- and Al-bearing bridgmanite: Effects of iron spin crossover

    Science.gov (United States)

    Shukla, Gaurav; Cococcioni, Matteo; Wentzcovitch, Renata M.

    2016-06-01

    We report ab initio (LDA + Usc) calculations of thermoelastic properties of ferric iron (Fe3+)- and aluminum (Al)-bearing bridgmanite (MgSiO3 perovskite), the main Earth forming phase, at relevant pressure and temperature conditions and compositions. Three coupled substitutions, namely, [Al]Mg-[Al]Si, [Fe3+]Mg-[Fe3+]Si, and [Fe3+]Mg-[Al]Si have been investigated. Aggregate elastic moduli and sound velocities are successfully compared with limited experimental data available. In the case of [Fe3+]Mg-[Fe3+]Si substitution, the high-spin (S = 5/2) to low-spin (S = 1/2) crossover in [Fe3+]Si induces a volume collapse and elastic anomalies across the transition region. However, the associated anomalies should disappear in the presence of aluminum in the most favorable substitution, i.e., [Fe3+]Mg-[Al]Si. Calculated elastic properties along a lower mantle model geotherm suggest that the elastic behavior of bridgmanite with simultaneous substitution of Fe2O3 and Al2O3 in equal proportions or with Al2O3 in excess should be similar to that of (Mg,Fe2+)SiO3 bridgmanite. However, excess of Fe2O3 should produce elastic anomalies in the crossover pressure region.

  14. Penentuan Kualitas Aluminium Ingot Dengan Pengukuran Kadar Fe, Si Dan Cu, Menggunakan Optical Emission Spectrometer

    OpenAIRE

    Putra, Andika

    2012-01-01

    Based on the research results were found: for the first aluminum has a purity of Al =99,81% (Fe 0,1445%, Si 0,0473% and Cu 0,0003%), the second almunium has purity of Al = 99.92%, (Fe 0,0521%, Si 0,0335% and Cu 0,0002%),the third aluminum has purity of Al = 99.81%,(Fe 0,1475%, Si 0,0442% and Cu 0,0002%), the fourth alumunium has purity of Al = 99.91% , (Fe 0,0463%, Si 0,0373% and Cu = 0,0001%), the fifth aluminum has purity of Al = 99.82%, (Fe 0,1406%, Si 0,0421% and Cu 0,0003%), t...

  15. The microstructure evolution of an Al-Mg-Si-Mn-Cu-Ce alloy during homogenization

    International Nuclear Information System (INIS)

    The microstructure evolution in an Al-Mg-Si-Mn-Cu-Ce alloy during homogenization was investigated by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy techniques in this paper. The purpose is to study the transformation of coarse intermetallic phases and the precipitation process of dispersoids. The results show that the phase constituents in the as-cast microstructure are Al(MnFe)3Si2, AlCuMgSi, AlCuSiCe, and ternary eutectic α-Al + AlCuMgSi +Si. After homogenization (3 h at 470 deg. C), the low melting point phase (AlCuMgSi) and ternary eutectic phase (α-Al + AlCuMgSi + Si) were almost completely dissolved. The obvious dissolution of the Al(MnFe)3Si2 phase started at 570 deg. C. Long-time heat treatment impels Mn to substitute for Fe in this phase. Because of the low solid solubility of Ce in Al-matrix, enrichment of the Ce was observed in the resulting AlCuSiCe particles after homogenization. Otherwise many dispersoid particles containing Mn precipitated during homogenization. The uniformity of dispersoid distribution is mostly dependent on the diffusion rate of Si through Al-matrix. A lot of Q phases were also discovered in this alloy after furnace cooling due to the effect of Cu on the precipitation process.

  16. 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.

  17. Effects of CaO, MgO, Al2O3 and SiO2 on the carbothermic reduction of synthetic FeCr2O4

    Directory of Open Access Journals (Sweden)

    Wang Y.

    2015-01-01

    Full Text Available In order to optimize the current reduction process of chromite, a good knowledge of reduction mechanism involved is required. The basic component in chromite ore is FeCr2O4 with gangue component like MgO and Al2O3. In lack of clear and consistent explanation about the effect of addition on the reduction of FeCr2O4, investigation of synthetic FeCr2O4 with different kind and amount of additions was carried out at 1673K under isothermal mode. Kinetic mechanism was also studied by linear fitting of different kinetic equations. Combined with rate-controlling step, it could be concluded as follows. CaO could enhance the reduction because Ca2+ would replace Fe2+, thus facilitated the ion diffusion in solid phase. Al2O3 had a positive influence as well, since Al3+ could form a solid solution phase with Cr3+ and made Cr3+ reduced more easily. MgO would hinder the reduction due to formation of a more stable phase MgCr2O4. SiO2 would also hamper the Cr metallization because there was a liquid phase formed when Cr3+ was reduced to divalent, which would impede the nucleation of reduction product.

  18. 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).

  19. Enhanced hardness and fracture toughness of the laser-solidified FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy by martensite strengthening

    International Nuclear Information System (INIS)

    A FeCoNiCrCuTiMoAlSiB0.5 high-entropy alloy (HEA) comprised of a lath-like martensite phase was fabricated by laser cladding. The alloy combines attractive properties including hardness (11.6 GPa), elastic constant (187.1 GPa), fracture toughness (50.9 MPa m0.5) and softening resistance (up to 900 °C). The nucleation of the martensite phase is co-triggered by laser rapid solidification and interstitial boron solute, owing to the improved lattice strain energy. The designed strengthening by martensite and interstitial solutes may enhance both hardness and toughness in other rapidly solidified HEAs

  20. 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

    2016-04-01

    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.

  1. 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.

  2. 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.

  3. Orientation relationship of eutectoid FeAl and FeAl2

    Science.gov (United States)

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  4. Deuterium thermal desorption from FeAl thin films

    International Nuclear Information System (INIS)

    Deuterium thermal desorption experiments were performed on B2 FeAl thin films deposited by electron-beam evaporation on Si substrates, annealed at temperatures ranging from 673 to 773 K and implanted with 20 keV D2 ions at fluences of 3x1016 D2+ cm-2. D2 desorption spectra, recorded in isochronal heating conditions (0.5 K s-1 temperature ramp), show two well resolved desorption peaks at ∼500 and 820 K. The first peak is attributed to the desorption of deuterium contained in FeAl weakly bonding sites of the FeAl lattice, probably point defects (vacancies) produced by the ion implantation process. The second peak is attributed to deuterium release from trapping sites in the FeAl lattice that could be the defect complexes formed by the association of a vacancy in the Fe sublattice and a substitutional Fe atom in the Al sublattice (VFe-FeAl). The desorption kinetics can be reproduced by assuming that: (a) deuterium desorption at ∼500 K is controlled by the D2 surface recombination process with Edes=1.57±0.02 eV as activation energy; (b) deuterium desorption at ∼820 K is controlled by the release of D atoms from the trap sites, a process which occurs in connection with defect relaxation. The energy of interaction of deuterium with this trapping site can be estimated to be ∼2 eV. (author)

  5. Improvement of magnetic and structural stabilities in high-quality Co2FeSi1-xAlx/Si heterointerfaces

    Science.gov (United States)

    Yamada, S.; Tanikawa, K.; Oki, S.; Kawano, M.; Miyao, M.; Hamaya, K.

    2014-08-01

    We study high-quality Co2FeSi1-xAlx Heusler compound/Si (0 ≤ x ≤ 1) heterointerfaces for silicon (Si)-based spintronic applications. In thermal treatment conditions, the magnetic and structural stabilities of the Co2FeSi1-xAlx/Si heterointerfaces are improved with increasing x in Co2FeSi1-xAlx. Compared with L21-ordered Co2FeSi/Si, B2-ordered Co2FeAl/Si can suppress the diffusion of Si atoms into the Heusler-compound structure. This experimental study will provide an important knowledge for applications in Si-based spin transistors with metallic source/drain contacts.

  6. Microstructural characteristics and paint-bake response of Al-Mg-Si-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    JI Yan-li; GUO Fu-an; PAN Yan-feng

    2008-01-01

    The microstructural characteristics and paint-bake response of 6022 alloy with 0.3% Cu (mass fraction) were studied using optical microscope, scanning electron microscope(SEM), transmission electron microscope(TEM) and tensile tester. The results indicate that the phase constituents in the as-cast microstructure are Mg2Si, Si, Al5Cu2Mg8Si6, Al5FeSi, α-Al(MnCrFe)Si and CuAl2. During the following homogenization, CuAl2, Al5Cu2Mg8Si6 and Mg2Si phases are almost completely dissolved, and Al5FeSi transforms to α-Al(MnCrFe)Si particles. After rolling, the phase constituents in the alloy change less except the precipitation of Mg2Si particles, and the precipitation behavior of Mg2Si strongly depends on the thermomechanical conditions. Cu addition significantly increases the paint-bake response of 6022 alloy by facilitating the formation of β" phase. Therefore, the tensile strength of 6022 alloy with 0.3% Cu is higher than that of 6022 alloy without Cu after paint-bake cycle.

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Half-metallic band gap is obtained for Fe2Mn1−xTixSi0.5Al0.5 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

  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

    OpenAIRE

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  11. 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.

  12. Atomically controlled hetero-epitaxy of Fe3Si/SiGe for spintronics application

    International Nuclear Information System (INIS)

    Molecular beam epitaxy of the ferromagnetic silicide Fe3Si on Ge and Si substrates was investigated in a wide temperature range (60-400 deg. C). Epitaxial growth of Fe3Si layers was achieved on Ge (110), Ge (111), and Si (111) substrates. Especially, very low value (2.2%) of the minimum scattering yield in RBS measurements was obtained from Fe3Si layers, which were grown on Ge (111) at low temperature (60-130 deg. C) under the stoichiometric condition (Fe:Si = 3:1). Transmission electron microscopy measurements confirmed the formation of DO3-type Fe3Si and atomically flat interface between Fe3Si and Ge (111). In addition, thermal stability of Fe3Si was guaranteed up to 300 deg. C. Such high quality Fe3Si on Ge (111) substrates can be employed to realize Ge channel spin transistors, which can be integrated with Si large-scale integrated circuits

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

    International Nuclear Information System (INIS)

    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

  14. 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.

  15. Al/Fe isomorphic substitution versus Fe2O3 clusters formation in Fe-doped aluminosilicate nanotubes (imogolite)

    International Nuclear Information System (INIS)

    Textural, magnetic and spectroscopic properties are reported of Fe-doped aluminosilicate nanotubes (NTs) of the imogolite type, IMO, with nominal composition (OH)3Al2−xFexO3SiOH (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 N2 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. Fe3+/Al3+ 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 Fe3+ sites. Higher loadings give rise, besides IS, to the formation of Fe2O3 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 Al3+ ions in pre-formed IMO NTs, a much simpler procedure compared with direct synthesis

  16. Analysis of optical and magnetooptical spectra of Fe5Si3 and Fe3Si magnetic silicides using spectral magnetoellipsometry

    International Nuclear Information System (INIS)

    The optical, magnetooptical, and magnetic properties of polycrystalline (Fe5Si3/SiO2/Si(100)) and epitaxial Fe3Si/Si(111) films are investigated by spectral magnetoellipsometry. The dispersion of the complex refractive index of Fe5Si3 is measured using multiangle spectral ellipsometry in the range of 250–1000 nm. The dispersion of complex Voigt magnetooptical parameters Q is determined for Fe5Si3 and Fe3Si in the range of 1.6–4.9 eV. The spectral dependence of magnetic circular dichroism for both silicides has revealed a series of resonance peaks. The energies of the detected peaks correspond to interband electron transitions for spin-polarized densities of electron states (DOS) calculated from first principles for bulk Fe5Si3 and Fe3Si crystals

  17. 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.

  18. A model of Fe3+-Kaolinite, Al3+-Goethite, Al3+-Hematite equilibria in laterites

    OpenAIRE

    Trolard, F.; Tardy, Yves

    1989-01-01

    Cet article propose un modèle thermodynamique, basé sur un équilibre idéal solide-solution, pour le système Fe2O3-Al2O3-SiO2-H2O prenant en compte les activités de l'eau et de la silice. Le modèle permet de calculer la quantité des phases présentes, les pourcentages de substitution en Al et Fe pour la geothite, l'hématite, la Kaolinite ainsi que la stabilité des phases sous différentes conditions.

  19. Design and manufacture of X-ray analyser of CaO, Fe2O3, SiO2 and Al2O3, investment opportunity of Vietnam cement factories

    International Nuclear Information System (INIS)

    Cement is produced by heating naturally occurring raw materials containing the required oxides in kiln, which results in a product called clinker. To obtain the finished cement, the clinker is then ground together with gypsum, which controls setting properties, to a fine powder. Portland cement is a mixture of compounds formed from the oxides of Ca(CaO), Si(SiO2), Al(Al2O3), and Fe(Fe2O3). In addition to these four main constituents it also contains smaller amounts of MgO, K2O, SO3, etc. Effective process control of cement is important to ensure high quality of the product. Traditionally wavelength dispersive x-ray fluorescence (WDXRF) spectrometers are used for cement quality control at the modern cement factories. The XRF-NCS02 is a compact energy dispersive X-ray fluorescence (EDXRF) analyzer. These spectrometers also are used for cement quality control at the small size cement plant. Product description: The XRF-NCS02 , table-top cement analyzer is a computer-based EDXRF spectrometer. The high efficiency and high resolution Si PIN detector is coupled to a 4096 channel MCA for data collection. The special low-power x-ray tube of the system requires no cooling and obligates the need for radioisotopes, as commonly found on such instruments. Computer: Compatible notebook or desktop PC, Pentium processor with CD-ROM. Software: XRF - NCS02 software for quantitative analysis; Interactive, operation under Windows XP. Installation: dimensions 500x380x300 mm (W x D x H); weight: 10 kg. (author)

  20. Fatigue of an Al-Si gravity die casting alloy

    Energy Technology Data Exchange (ETDEWEB)

    Styles, C.M. [Defence Evaluation and Res. Agency, Farnborough (United Kingdom). MSS; Reed, P.A.S.

    2000-07-01

    Fatigue crack initiation, short crack and long crack growth studies were performed on a high performance cast piston type alloy (Al-Si-Cu-Ni-Mg). Crack initiation was mainly associated with large blocky Si particles although a few cracks were initiated at clusters of FeNiAl{sub 9} intermetallics. Classical short crack growth was shown with crack arrest for up to 15000 fatigue cycles at second phase particles. Long crack growth showed no evidence of stage I like facets near threshold or ductile striations in the mid {delta}K region. A large number of fractured Si particles were, however, observed on the fracture surfaces and crack profiles the incidence of which increased with {delta}K. The findings of this study suggest this alloy is brittle in nature with the Si particle content generally controlling fatigue crack initiation and growth. (orig.)

  1. 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.

  2. Magnetism in bcc Fe-Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M.E. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.; Yousif, A.A. [Sultan Qaboos Univ., Al-Khod (Oman). Dept. of Phys.

    1994-11-01

    The magnetic moment {mu}, hyperfine field B{sub hf} and isomer shift IS at the Fe site in bcc Fe-Al alloys were calculated from first principle. Contrary to the belief that Al atoms reside in the iron lattice as magnetic holes, it was found that the local magnetic moment of Fe is decreased when Al is at a nearest neighbour site (NN), while it increases if Al is at a next-nearest neighbour site (NNN). Consequently, the average {mu} per Fe atom was found to be, initially, independent of Al content. Assuming a linear dependence of {mu}{sub Fe} on the number of Al atoms at NN and NNN sites, we calculated the average {mu}, which was found to agree with experimental results of cold worked alloys for disordered Fe-Al alloy. On the other hand, antiferromagnetic coupling appears in the CsCl ordered structures. The average B{sub hf} was also calculated and compared to experimental data and the trends in the IS are considered. (orig.)

  3. Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

    International Nuclear Information System (INIS)

    The chemical mixing at the “Al on Fe” and “Fe on Al” interfaces was studied by molecular dynamics simulations of the layer growth and by 57Fe Mössbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp “Al on Fe” interfaces were found when Al grows over (001) and (110) oriented Fe layers. The Al/Fe(111) interface is also narrow as compared to the intermixing found at the “Fe on Al” interfaces for any orientation. Conversion electron Mössbauer measurements of trilayers—Al/57Fe/Al and Al/57Fe/Ag grown simultaneously over Si(111) substrate by vacuum evaporation—support the results of the molecular dynamics calculations

  4. Deuterium thermal desorption from FeAl thin films

    Energy Technology Data Exchange (ETDEWEB)

    Checchetto, R. [Istituto Nazionale per la Fisica della Materia (INFM), Dipartimento di Fisica dell' Universita di Trento, Povo (Italy)]. E-mail: checchet@science.unitn.it; Miotello, A.; Tosello, C. [Istituto Nazionale per la Fisica della Materia (INFM), Dipartimento di Fisica dell' Universita di Trento, Povo (Italy); Principi, G. [Istituto Nazionale per la Fisica della Materia (INFM), Dipartimento di Ingegneria Meccanica e Strutturale dell' Universita di Padova, Padova (Italy); Mengucci, P. [Istituto Nazionale per la Fisica della Materia (INFM), Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio dell' Universita di Ancona, Ancona (Italy)

    2002-07-01

    Deuterium thermal desorption experiments were performed on B2 FeAl thin films deposited by electron-beam evaporation on Si substrates, annealed at temperatures ranging from 673 to 773 K and implanted with 20 keV D{sub 2} ions at fluences of 3x10{sup 16} D{sub 2}{sup +} cm{sup -2}. D{sub 2} desorption spectra, recorded in isochronal heating conditions (0.5 K s{sup -1} temperature ramp), show two well resolved desorption peaks at {approx}500 and 820 K. The first peak is attributed to the desorption of deuterium contained in FeAl weakly bonding sites of the FeAl lattice, probably point defects (vacancies) produced by the ion implantation process. The second peak is attributed to deuterium release from trapping sites in the FeAl lattice that could be the defect complexes formed by the association of a vacancy in the Fe sublattice and a substitutional Fe atom in the Al sublattice (V{sub Fe}-Fe{sub Al}). The desorption kinetics can be reproduced by assuming that: (a) deuterium desorption at {approx}500 K is controlled by the D{sub 2} surface recombination process with E{sub des}=1.57{+-}0.02 eV as activation energy; (b) deuterium desorption at {approx}820 K is controlled by the release of D atoms from the trap sites, a process which occurs in connection with defect relaxation. The energy of interaction of deuterium with this trapping site can be estimated to be {approx}2 eV. (author)

  5. 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.

  6. Magnetic phase transitions in Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6}, La{sub 1−x}Sm{sub x}Mn{sub 2}Si{sub 2}, Lu{sub 2}(Fe{sub 1−x}Mn{sub x}){sub 17}, and La(Fe{sub 0.88}Si{sub x}Al{sub 0.12−x}){sub 13} intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Mushnikov, N.V., E-mail: mushnikov@imp.uran.ru; Kuchin, A.G.; Gerasimov, E.G.; Terentev, P.B.; Gaviko, V.S.; Serikov, V.V.; Kleinerman, N.M.; Vershinin, A.V.

    2015-06-01

    Magnetic properties have been measured for the Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6}, La{sub 1−x}Sm{sub x}Mn{sub 2}Si{sub 2}, Lu{sub 2}(Fe{sub 1−x}Mn{sub x}){sub 17}, and La(Fe{sub 0.88}Si{sub x}Al{sub 0.12–x}){sub 13} systems which show up transitions from antiferromagnetic to ferromagnetic state upon changing concentration of the constituents or application of magnetic field. We determined the concentrations and temperatures of the magnetic phase transitions and plotted magnetic phase diagrams. Near a critical concentration, the AF–F transition can be realized in low magnetic fields, which makes these compounds attractive for magnetothermal applications. Using the data of the magnetization measurement, we determined the isothermal magnetic entropy change in a wide temperature range. All the studied systems have a layered magnetic structure with the positive intralayer exchange interaction and the interlayer exchange integrals of different signs depending on the composition and temperature. For the compounds La(Fe{sub 0.88}Si{sub x}Al{sub 0.12−x}){sub 13} with the cubic crystal structure, the origin of formation of a layered magnetic structure is discussed based on the data of Mössbauer studies which revealed a difference in the local surrounding of resonant atoms in the compounds with different magnetic orders. - Highlights: • We determine magnetic phase diagrams of four 4f–3d intermetallic systems. • Isothermal magnetic entropy change of different sign is observed in compounds with magnetic phase transitions. • For La(Fe,Al,Si){sub 13}, hyperfine parameters depend on the type of magnetic order.

  7. Magneto-optical characterization of single crystalline Co2FeAl0.4Si0.6 thin films on MgO(1 0 0) substrates with Cr and MgO seed layers

    International Nuclear Information System (INIS)

    We report on the experimental investigation of the influence of a seed layer on the magnetic properties of the full-Heusler alloy Co2FeAl0.4Si0.6 (CFAS). The studied magnetic films are grown epitaxially on MgO (1 0 0) substrates with Cr and/or MgO seed layers. By employing magneto-optical Kerr effect magnetometry we show that magnetic anisotropy can be tuned by choosing the proper seed layer. The results on CFAS show an overall uniaxial anisotropy plus a biaxial contribution which depends on the seed layer. In addition, if grown on MgO, a sharp increase in the coercive field HC at a series of angles symmetric with respect to the easy axis is present. Scanning Kerr-microscope imaging is performed during the magnetization reversal process in order to reveal the type of magnetic domain formation taking place at these angles. (paper)

  8. Polythermal cutting of Al-Si-YAl2 system

    International Nuclear Information System (INIS)

    Given the out come of the research of the Al-Si-YAl2 system with studies of polythermal cutting. It was found out that the most cutting of Al-YSi2Al2, Al-YSiAl2, Al-Y5SiAl14, YSiAl2-YSi2Al2, Y5SiAl14-YSiAl2 and Y5SiAl14-YAl2, Si-YSiAl2 has the nature of quasibinary eutectics

  9. Bonding in MgSi and AlMgSi Compounds Relevant to AlMgSi Alloys

    OpenAIRE

    Froseth, A. G.; Derlet, P. M.; Andersen, S.J.; Marioara, C. D.; Holmestad, R.

    2003-01-01

    The bonding and stability of MgSi and AlMgSi compounds relevant to AlMgSi alloys is investigated with the use of (L)APW+(lo) DFT calculations. We show that the $\\beta$ and $\\beta''$ phases found in the precipitation sequence are characterised by the presence of covalent bonds between Si-Si nearest neighbour pairs and covalent/ionic bonds between Mg-Si nearest neighbour pairs. We then investigate the stability of two recently discovered precipitate phases, U1 and U2, both containing Al in addi...

  10. Moessbauer-spectroscopic study of structure and magnetism of the exchange-coupled layer systems Fe/FeSn2, and Fe/FeSi/Si and the ion-implanted diluted magnetic semiconductor SiC(Fe)

    International Nuclear Information System (INIS)

    In line with this work the strucural and magnetic properties of the exchange coupled layered systems Fe/FeSn2 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 57Fe conversion electron Moessbauer spectroscopy (CEMS), mostly in connection with the 57Fe 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 FeSn2(001) films and of the exchange-bias system Fe/FeSn2(001) on InSb(001) were investigated. With the application of 57Fe-tracer layers and CEMS both the Fe-spin structure and the temperature dependence of the magnetic hyperfine field (Bhf) of FeSn2 could be examined. The evaporation of Fe films on the FeSn2 films produced in the latter ones a high perpendicular spin component at the Fe/FeSn2 interface. In some distance from the interface the Fe spins rotate back into the sample plane. Furthermore 57Fe-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 FeSn2. Temperature dependent CEMS-measurements yielded informations about the spin dynamics within the AF. The transition temperatures TB*, which were interpreted as superparamagnetic blocking temperatures, obtain higher values compared to the temperatures TB 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 tFeSi=10-12 A of the ''lower'' FeSi layers the interdiffusion of Fe is inhibited. For thicker FeSi layers (tFeSi ∼ 20 A

  11. SANS study of nanocrystalline Fe3Si particles in amorphous FeSiBCuNb matrix

    International Nuclear Information System (INIS)

    Complete text of publication follows. The amorphous FeSiBCuNb alloy is the precursor material for the well-known nanocrystalline soft-magnetic finemets. In previous analyses the fully crystallised state with up to 70 vol% nanocrystals has been studied. There, the maximum appearing in the small-angle neutron scattering (SANS) curves was interpreted as a consequence of interparticle interferences. In the present study partially crystallised samples with 2 to 30 vol% of Fe3Si particles are analyzed. The results show that the maximum of the SANS curves must be considered as an intrinsic property of the isolated nanocrystalline precipitates. Our analysis of both the magnetic and the nuclear scattering contributions show that the Fe3Si particles are surrounded by a diffusion zone giving rise to interferences of this zone with the core of the particles. At high volume fractions of nanocrystals, additional interparticle interferences appear. (author)

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. High speed twin roll casting of Al-3Si-0.6Mg strip

    Directory of Open Access Journals (Sweden)

    T. Haga

    2006-04-01

    Full Text Available Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast Al-3%Si-0.6%Mg strip was purpose, too.Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed.Findings: Findings are that Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 mm-thick. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not occurred at the outer surface.Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production.Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminum alloy will becomes easy. The content of Fe in the recycled aluminum alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle.Originality/value: The result means the roll cast Al-3%Si-0.6%Mg has ability to be used as the body sheet of the auto mobile.

  17. Magnetic phase transitions in Y1−xTbxMn6Sn6, La1−xSmxMn2Si2, Lu2(Fe1−xMnx)17, and La(Fe0.88SixAl0.12−x)13 intermetallic compounds

    International Nuclear Information System (INIS)

    Magnetic properties have been measured for the Y1−xTbxMn6Sn6, La1−xSmxMn2Si2, Lu2(Fe1−xMnx)17, and La(Fe0.88SixAl0.12–x)13 systems which show up transitions from antiferromagnetic to ferromagnetic state upon changing concentration of the constituents or application of magnetic field. We determined the concentrations and temperatures of the magnetic phase transitions and plotted magnetic phase diagrams. Near a critical concentration, the AF–F transition can be realized in low magnetic fields, which makes these compounds attractive for magnetothermal applications. Using the data of the magnetization measurement, we determined the isothermal magnetic entropy change in a wide temperature range. All the studied systems have a layered magnetic structure with the positive intralayer exchange interaction and the interlayer exchange integrals of different signs depending on the composition and temperature. For the compounds La(Fe0.88SixAl0.12−x)13 with the cubic crystal structure, the origin of formation of a layered magnetic structure is discussed based on the data of Mössbauer studies which revealed a difference in the local surrounding of resonant atoms in the compounds with different magnetic orders. - Highlights: • We determine magnetic phase diagrams of four 4f–3d intermetallic systems. • Isothermal magnetic entropy change of different sign is observed in compounds with magnetic phase transitions. • For La(Fe,Al,Si)13, hyperfine parameters depend on the type of magnetic order

  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. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    Science.gov (United States)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  20. Effect of traveling magnetic field on separation and purification of Si from Al-Si melt during solidification

    Science.gov (United States)

    Zou, Q. C.; Jie, J. C.; Liu, S. C.; Wang, T. M.; Yin, G. M.; Li, T. J.

    2015-11-01

    Separation and purification of the Si crystal during solidification process of hypereutectic Al-30Si melt under traveling magnetic field (TMF) were investigated in the present study. The results showed that under a proper condition the Si-rich layer can be formed in the periphery of the ingot while the inner microstructure is mainly the Al-Si eutectic structure. The intense melt flow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is first precipitated close to the inner wall of the crucible with a relatively lower temperature, which resulting in the remarkable segregation of the primary Si phase. The impurity contents of the refined Si can be reduced to a very low level. The typical metallic impurities have removal fraction higher than 99.5%. In addition, there is a significant difference in the P contents between the primary and eutectic Si phases, which might be ascribed to the formation of AlP phase that acts as the heterogeneous nucleation sites. Furthermore, a considerable amount of Fe-containing particles with a size about 100-300 nm is found inside the eutectic Si phase, indicating an unintended entrapment of Fe in Si.

  1. 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.

  2. Reaction behaviour of Ux Siy- and U6 Fe-Al dispersions

    International Nuclear Information System (INIS)

    The paper describes the experiments carried out using differential thermal analysis (DTA) to investigate he reactions in fuel plates with U3Si, U3Si2 and U6Fe-Al dispersions up to and beyond clad melting. In all cases, exothermic reactions are observed at about 630 deg. C. In the case of the silicides UAl3 with silicon in solution is the main reaction product; in the case of U6Fe, UAl4 i the main reaction product. The enthalpies of reaction were determined after calibration with suitable standards. The values obtained reveal the largest energy release in the case of the U6Fe-Al dispersions. Reactions in the U3Si2-Al system are less exothermic than in the U3Si-Al system. (author)

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

    International Nuclear Information System (INIS)

    The objective of this work was to determine whether Al rich Al-Si-Ge and 2000 type Al-Cu-Si-Ge alloys have sufficient hardness to be useful for structural applications. It is shown that in Al-Si-Ge it is not possible to achieve satisfactory hardness through a conventional heat treatment. This result is explained in terms of sluggish precipitation of the diamond-cubic Si-Ge phase coupled with particle coarsening. However, Al-Cu-Si-Ge displayed a uniquely fast aging response, a high peak hardness and a good stability during prolonged aging. The high hardness of the Cu containing alloy is due to the dense and uniform distribution of fine θ' precipitates (metastable Al2Cu) which are heterogeneously nucleated on the Si-Ge particles. High resolution TEM demonstrated that in both alloys all the Si-Ge precipitates start out, and remain multiply twinned throughout the aging treatment. Since the twinned section of the precipitate does not maintain a low index interface with the matrix, the Si-Ge precipitates are equiaxed in morphology. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  4. Al/Au/n-Si/Al surface barrier detector

    International Nuclear Information System (INIS)

    Charged-particle detectors are required to be operated sometimes in ambient light for applications like alpha counting and range finding. Detectors like Al/p-Si surface barrier with aluminium on the front side are found quite suitable. Gold/n-Si surface barrier detectors are not usable because of their excessive background photo current. These detectors, we fabricate for use in nuclear experiments, were given an aluminium coating on their gold side for use in room light. The Au/n-Si/Al surface barrier diodes were characterized for their electrical properties and performance as alpha detectors. Detectors showing good energy resolution (∼ 50 KeV) were selected and provided with another thin reflecting coat of aluminium on their front sides

  5. 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

  6. 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)

  7. Formation of intermetallic phases on 55 wt.%Al-Zn-Si hot dip strip

    International Nuclear Information System (INIS)

    A study has been conducted to probe the formation of intermetallic phases on steel substrates immersed in 55 wt.%Al-Zn-Si hot dip baths as a function of dipping time and bath silicon content. Two bath compositions containing 1.3 and 1.5 wt.% Si, respectively, combined with two immersion times of 3 and 9 s were studied. It was found that the reaction rate and intermetallic phase formation varied in response to silicon content. Optical microscopy revealed a quantifiable difference in the development of the reaction layer between the two bath compositions. SEM-EDS revealed that the reaction layer that evolved on samples dipped in the 1.5 wt.% silicon bath were comprised of two intermetallic species, α-AlFeSi/Fe2Al5, whilst in the 1.3 wt.% bath there were three clearly identifiable intermetallic species α-AlFeSi/FeAl3/Fe2Al5. A fourth phase appeared to be present in samples immersed in the 1.3 wt.% Si bath that, due to its fine structure, could not be conclusively identified. Experimental results from the literature and from this study have been assessed with reference to the phase stability predicted by MTDATA, a thermodynamic modelling package

  8. 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.

  9. X-Ray Videomicroscopy Studies of Eutectic Al-Si Solidification in Al-Si-Cu

    Science.gov (United States)

    Mathiesen, R. H.; Arnberg, L.; Li, Y.; Meier, V.; Schaffer, P. L.; Snigireva, I.; Snigirev, A.; Dahle, A. K.

    2011-01-01

    Al-Si eutectic growth has been studied in-situ for the first time using X-ray video microscopy during directional solidification (DS) in unmodified and Sr-modified Al-Si-Cu alloys. In the unmodified alloys, Si is found to grow predominantly with needle-like tip morphologies, leading a highly irregular progressing eutectic interface with subsequent nucleation and growth of Al from the Si surfaces. In the Sr-modified alloys, the eutectic reaction is strongly suppressed, occurring with low nucleation frequency at undercoolings in the range 10 K to 18 K. In order to transport Cu rejected at the eutectic front back into the melt, the modified eutectic colonies attain meso-scale interface perturbations that eventually evolve into equiaxed composite-structure cells. The eutectic front also attains short-range microscale interface perturbations consistent with the characteristics of a fibrous Si growth. Evidence was found in support of Si nucleation occurring on potent particles suspended in the melt. Yet, both with Sr-modified and unmodified alloys, Si precipitation alone was not sufficient to facilitate the eutectic reaction, which apparently required additional undercooling for Al to form at the Si-particle interfaces.

  10. Micromagnetic simulation of critical current density of spin transfer torque switching in a full-Heusler Co2FeAl0.5Si0.5 alloy spin valve nanopillar

    International Nuclear Information System (INIS)

    We investigated the critical current density of spin transfer torque switching in a full-Heusler Co2FeAl0.5Si0.5 alloy spin-valve nanopillar through micromagnetic simulations. The simulations explain the experimental results on the resistance versus external magnetic field and yield good agreement with the measured switching behavior. It is shown that different magnitudes of current densities and directions of external magnetic fields give rise to a shift of resistance hysteretic loop and a variable range of switching. We demonstrated that three critical current densities have different slopes with Gilbert damping constant α and spin polarization constant η, indicating that α and η have different contributions to the critical current densities. Furthermore, we found that the area of resistance–current hysteretic loop decreases as the nanopillar size decreases. The domain structures indicated that the magnetization reversals have different switching processes between small and large sizes of pillars. - Highlights: ► We investigate critical current density of switching through micromagnetic simulation. ► Different currents and fields give rise to a shift of hysteretic loop. ► Three critical current densities have different slopes with α and η. ► The area of resistance–current hysteretic loop decreases as the size decreases. ► Magnetization reversals have different switching processes between different sizes.

  11. 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.

  12. ACTIVITY AND PRESSURE OF MAGNESIUM STEAM IN ALLOYS Ni-Mg-Si-Fe and Cu-Mg-Si-Fe

    Directory of Open Access Journals (Sweden)

    V. N. Vlasov

    2016-02-01

    Full Text Available The calculation of activity and pressure of magnesium vapour in melts Ni-Si-Mg-Fe and Cu-Si-Mg-Fe in metal systems at constant magnesium contents 6, 10, 14 и 18 mas.% and temperatures 1350 and 1450 °С is carried out in this work.

  13. Mechanical alloying of Fe-Si and milling of α- and β-FeSi2 bulk phases

    International Nuclear Information System (INIS)

    Research highlights: Mechanical alloying of Fe-Si and milling of α- and β-FeSi2 bulk phases deals with the formation of various Fe-Si phases applying milling technique. Systematic studies were performed on the relative intensities on the different structures depending on the milling periods. - Abstract: Iron disilicide synthesis by mechanical alloying was performed. ε-FeSi, α-Fe1-xSi2, amorphous FeSi2 were formed with relative intensities depending on the milling period. β-FeSi2 phase was formed after annealing the gridded powder at the temperature where this phase is stable. Moessbauer spectroscopy and X-ray diffraction methods were applied to determine the different phases formed. The morphology of the resulting particles was observed by high resolution scanning electron microscopy. The effect of the milling on bulk iron-silicide samples was and studied chemical effects of the ball milling on Fe-Si2 systems have been studied.

  14. Mechanical alloying of Fe-Si and milling of {alpha}- and {beta}-FeSi{sub 2} bulk phases

    Energy Technology Data Exchange (ETDEWEB)

    Dezsi, I., E-mail: dezsi@kfki.rmki.h [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, 114 P.O. Box 49 (Hungary); Fetzer, Cs. [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, 114 P.O. Box 49 (Hungary); Bujdoso, L. [MTA Research Institute for Solid State Physics and Optics, H-1525 Budapest, 114 P.O. Box 49 (Hungary); Broetz, J.; Balogh, A.G. [Institute of Materials Science, Technische Universitaet Darmstadt, 64287 Darmstadt (Germany)

    2010-10-15

    Research highlights: Mechanical alloying of Fe-Si and milling of {alpha}- and {beta}-FeSi{sub 2} bulk phases deals with the formation of various Fe-Si phases applying milling technique. Systematic studies were performed on the relative intensities on the different structures depending on the milling periods. - Abstract: Iron disilicide synthesis by mechanical alloying was performed. {epsilon}-FeSi, {alpha}-Fe{sub 1-x}Si{sub 2}, amorphous FeSi{sub 2} were formed with relative intensities depending on the milling period. {beta}-FeSi{sub 2} phase was formed after annealing the gridded powder at the temperature where this phase is stable. Moessbauer spectroscopy and X-ray diffraction methods were applied to determine the different phases formed. The morphology of the resulting particles was observed by high resolution scanning electron microscopy. The effect of the milling on bulk iron-silicide samples was and studied chemical effects of the ball milling on Fe-Si{sub 2} systems have been studied.

  15. Structure and properties of nitrided binary Fe-Al, Fe-V, Fe-Ti alloys

    International Nuclear Information System (INIS)

    The structure of binary alloys Fe-Al (up to 6.85% Al), Fe-V (up to 1.86% V), and Fe-Ti (up to 1.26% Ti) nitrated for 1 hr at 500 deg C has been investigated. The forming of the nitrous phases in the diffusion layers corresponds to the Fe-N diagram. The surface layer consists of epsilon -/nitride of Fe3N, then follows the γ'-phase, and further a wide region of a nitrous α-solid solution. Separate crystals of Al2O3 have been found on the surface of nitrated Fe-Al alloys. The ferrite hardness is increased most efficiently by titanium, less noticeably by vanadium, and only slightly by aluminium. It has been established that the diffusion sublayer of the Fe-Ti and Fe-V alloys contains, in addition to the segregations of the excess γ'-phase, another nitride phase Fe16N2, which is isomorphous with the matrix. The matrix reflexes indicate the effect of diffusion scattering in the form of rods, which points to the formation of clusters or Guinier-Preston zones coherent or partly coherent with the matrix

  16. 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

  17. Model of Cu-Al-Fe-Ni Bronze Crystallization

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek

    2013-07-01

    Full Text Available According to the analysis of the current state of the knowledge shows that there is little information on the process of phase transformations that occur during the cooling Cu-Al-Fe-Ni hypo-eutectoid bronzes with additions of Cr, Mo and/or W, made additions individually or together, for the determination of: the type of crystallizing phases, crystallizing phases, order and place of their nucleation. On the basis of recorded using thermal and derivative analysis of thermal effects phases crystallization or their systems, analysis of the microstructure formed during crystallization - observed on the metallographic specimen casting ATD10-PŁ probe, analysis of the existing phase equilibrium diagrams forming elements tested Cu-Al-Fe-Ni bronze, with additions of Cr, Mo, W and/or Si developed an original model of crystallization and phase transformation in the solid state, the casting of high quality Cu-Al-Fe-Ni bronze comprising: crystallizing type phase, crystallizing phase sequence, place of nucleation.

  18. The effect of Si in Al-alloy on electromigration performance in Al filled vias

    Science.gov (United States)

    Kageyama, Makiko; Hashimoto, Keiichi; Onoda, Hiroshi

    1998-01-01

    Electromigration performance of vias filled with Al-Si-Cu alloys on Ti glue layers was investigated in comparison with W-stud vias. In Al-Si-Cu filled vias, voids were formed at only a few locations in the test structure, while voids were formed at every via in W-stud via chains. It is supposed that Al moves through the Al-Si-Cu via during electromigration in spite of the existence of a glue layer at the via bottom. This phenomenon was observed only in the vias filled with Al-Si-Cu alloy. Al movement was prohibited in Al-Cu filled vias. In Al-Si-Cu filled vias, an Al-Ti-Si alloy was formed at the via bottom while Al3Ti was formed at Al-Cu filled vias. Al is speculated to move through this Al-Ti-Si alloy during electromigration.

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

    Science.gov (United States)

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

    2014-08-01

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

  20. First principles investigation of Fe and Al bearing phase H

    Science.gov (United States)

    Tsuchiya, J.; Tsuchiya, T.

    2015-12-01

    The global circulation of water in the earth is important to investigate the evolution history and dynamics of the earth, since the physical properties (e.g. atomic diffusivity, melting temperature, electrical conductivity and seismic velocities) of the constituent minerals are considerably changed by the presence of water. It has been believed that water is carried into the deep Earth's interior by hydrous minerals such as the dense hydrous magnesium silicates (DHMSs) which are also known as alphabet phases (phase A, superhydrous phase B, and phase D etc.) in the descending cold plate. It has been thought that the relay of these hydrous phases was terminated at ~1200 km depth by the dehydration of phase D which was the highest pressure phase of DHMSs. Recently, we have theoretically predicted the high pressure phase of phase D and experimentally confirmed the existence of this new DHMS in lower mantle pressure conditions above ~45 GPa. This phase has MgSiO4H2chemical composition and named as phase H. At the lower mantle pressure conditions, Al and H-bearing SiO2, δ-AlOOH, ɛ-FeOOH and phase H may be the relevant hydrous phases in the subducting slabs. Interestingly, the crystal structure of these hydrous phases are almost same and have CaCl2type structure. This suggests that these hydrous phases may potentially be able to make the wide range of solid solution. Some experimental studies already reported that Al preferentially partitioned into phase H and the stability of phase H drastically increased by incorporation of Al (Nishi et al. 2014, Ohira et al. 2014). The density of subducted MORB is reported to be denser than that of pyrolite in the lower mantle (e.g. Kawai et al. 2009). Therefore, there is a possibility that phase H containing Al and Fe in subducted MORB survive down to the bottom of lower mantle and the melting of phase H at the core mantle boundary may contribute to the cause of ultra-low velocity zones. In this study, we further extends our

  1. Structure and magnetic properties of amorphous and nanocrystalline Fe{sub 40}Co{sub 40}Cu{sub 0.5}Zr{sub 9}Al{sub 2}Si{sub 4}B{sub 4.5} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, A. E-mail: amitra9@yahoo.com; Kim, H.-Y.; Louzguine, D.V.; Nishiyama, N.; Shen, B.; Inoue, A

    2004-07-01

    Crystallisation behaviour and magnetic properties of as-spun and annealed Fe{sub 40}Co{sub 40}Cu{sub 0.5}Zr{sub 9}Al{sub 2}Si{sub 4}B{sub 4.5} alloy have been studied. The annealing was performed at 873 K for 15 min. XRD and TEM studies shows the formation of nanocrystalline {alpha}-(Fe,Co)(SiAl) particles with 7.5{+-}2 nm in diameter dispersed in an amorphous matrix. The Curie temperature of the as-spun amorphous ribbon is 736 K. Saturation magnetisation of the annealed sample decreases at a rate of 0.5 emu/g/K in the measured temperature range of 300-1000 K. Excellent room temperature AC magnetic properties are achieved for the nanocrystalline sample. The low value of the imaginary part of the permeability and the high cut-off frequency (20 kHz) suggest that the eddy current contribution in the annealed materials is low. The coercivity of the annealed sample remains almost constant at 95 A/m up to the frequency of 20 kHz. High saturation magnetisation, high Curie temperature and excellent soft magnetic properties in the nanocrystalline state suggests that Fe{sub 40}Co{sub 40}Cu{sub 0.5}Zr{sub 9}Al{sub 2}Si{sub 4}B{sub 4.5} alloy is a strong candidate for high temperature magnetic application.

  2. 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.

  3. Paravinogradovite, (Na,□)2 [(Ti4+, Fe3+)4 {Si2 O6}2 {Si3 Al O10} (OH)4] H2O, a new mineral species for the Khibina alkaline massif, Kola Peninsula, Russia: description and crystal structure

    International Nuclear Information System (INIS)

    resulting empirical formula on the basis of 26 anions (including OH = 4 apfu and excluding H2O) is (Na2. 293K0.169) (Ti4+3.386Fe3+0.471 Mg0.029 Nb0.034) (Si6.626 Al1.098 Be0.276) O22 (OH)4 (H2O)1.16. There are prominent endothermic effects at 280 and 460oC; the principal losses in weight are within the temperature ranges 150-400 (3.8%) and 400-600oC (2.8%), and the total loss in weight at 980oC is 7.1%. The principal absorptions in the infrared are as follows: 3520, 3330, 3240, 1633, 1105, 989, 940, 725, 691, 638, 599, 568, 523, 459 and 418 cm-1, indicative of both OH and H2O in the structure. The name recognizes the close structural and chemical relations between paravinogradovite and vinogradovite, ideally Na5 Ti4+4 (Si7Al) O26 (H2O)3. The crystal structure of paravinogradovite was solved by direct methods and refined to an R1 index of 4.5% based on 4373 observed [F0> 4σF] unique reflections measured with MoKα X-radiation and a Bruker P4 diffractometer with a CCD detector. Four (SiO4) tetrahedra form pyroxene-like [Si2O6] chains, and three (SiO4) tetrahedra and one (AlO4) tetrahedron form vinogradovite-like [Si3AlO10] chains parallel to [100]. (MO6) octahedra (M ∼ Ti4+) share common edges to form two distinct zig-zag brookite-like chains along [100]. One chain is decorated by (XO6) octahedra (X ∼ Na) and linked into a sheet parallel to (100) by [Si3AlO10] chains. The other distinct brookite-like chain is not decorated by (XO6) octahedra, but is linked into a sheet parallel (100) by [Si3AlO10] chains. Chains of tetrahedra and chains of octahedra link to form a framework with channels along [100]. These channels contain disordered (H2O) groups, the A(5) site partly occupied (14%) by K, and the A(1)-A(4) sites partly occupied (15-19%) by Na, giving a channel content of [Na0.72K0.14 (H2O)1.16]. The triclinic cell of paravinogradovite is related to the C-centered monoclinic cell of vinogradovite, ideally Na5 Ti4+4 (Si7Al) O26 (H20)3 [monoclinic, a 24.490(10), b 8

  4. 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.

  5. High speed twin roll casting of recycled Al-3Si-0.6Mg strip

    Directory of Open Access Journals (Sweden)

    S. Kumai

    2007-03-01

    Full Text Available Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of recycled Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast recycled Al-3%Si-0.6%Mg strip was purpose, too.Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed.Findings: Findings are that recycled Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 mm-thick. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not occurred at the outer surface. This result means the roll cast recycled Al-3%Si-0.6%Mg can be used as the body of the auto mobile.Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production.Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminum alloy will becomes easy. The content of Fe in the recycled aluminum alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle.Originality/value: The economy sheet of Al-3%Si-0.6%Mg can be made by the high productivity of the HSTRC. The result of this report contributes to make the economy aluminum alloy sheet for the automobile.

  6. Morphology and distribution of Al3Fe phase in hypereutectic Al-Fe alloy solidified under magnetic field

    OpenAIRE

    Ban Chunyan; Zhang Jianfeng; Qian Peng

    2011-01-01

    In this study, the (low) DC and AC magnetic fields and the high magnetic field were applied separately during the solidification process of Al-2.89%Fe alloy. The influences of these magnetic fields on the morphology and distribution of Al3Fe phase in Al-2.89%Fe alloy were investigated. The microstructure and macrostructure of the samples were observed using an optical microscope. The results show that the majority of the primary Al3Fe phase particles in the hypereutectic Al-2.89%Fe alloy is g...

  7. The post-spinel transition in Fe3O4-Fe2SiO4 and Fe3O4- FeCr2O4 solid solutions

    Science.gov (United States)

    Woodland, Alan; Schollenbruch, Klaus; Frost, Daniel; Langenhorst, Falko

    2010-05-01

    Minerals with spinel structure are important phases in the Earth's mantle. Both magnetite (mt, Fe3O4) and chromite (chr, FeCr2O4) are known to transform to denser orthorhombic post-spinel phases at pressures≥10 GPa and ≥12.5 GPa, respectively (Schollenbruch et al. 2009a; Chen et al. 2003). On the other hand, Fe2SiO4 decomposes to its constituent oxides, FeO and SiO2 at high P and no post-spinel polymorph appears to be stable (e.g. Ito & Takahashi 1989). An important question is how spinel solid solutions behave at high pressures and temperatures since such compositions are arguably more petrologically relevant. In addition, since h-Fe3O4 is apparently not quenchable, it is difficult to investigate its structure. In contrast, two high-P polymorphs of FeCr2O4-rich compositions have been found in a meteorite (Chen et al. 2003), suggesting that the addition of Cr might allow us to recover the post-spinel phase of Fe3O4-bearing compositions from experiments. Building on recent results for the Fe3O4 end member (Schollenbruch et al. 2009a, 2009b), we have begun a study of the high-pressure behaviour of solid solutions along the Fe3O4 -Fe2SiO4 and Fe3O4- FeCr2O4 joins. Multianvil experiments were performed at 10 and 13 GPa and 1200-1300°C on pre-synthesised spinels with compositions 85mt-15 Fe2SiO4, 50mt-50chr and 80mt-20chr. For the Si-bearing experiments, stishovite was present in the run products. This occurrence, along with observed twinning in the Fe-oxide phase (Schollenbruch et al. 2009a) allows us to conclude that the original spinel had transformed to a high-P polymorph at a pressure and that Si is essentially excluded from this new structure. However, the powder XRD data from the run products could not be indexed either to magnetite (spinel structure) or to any other expected phase, including the known post-spinel structures. Interestingly, these are the same reflections reported by Koch et al. (2004) for an unidentified phase in their high-P (> 9 GPa

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

    Institute of Scientific and Technical Information of China (English)

    冯俊

    2002-01-01

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

  9. Structure of molten Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dahlborg, U. [CNRS, Ecole des Mines, Nancy, France; Besser, M. [Ames Laboratory; Calvo-Dahlborg, M. [CNRS, Ecole des Mines, Nancy, France; Cuello, G. [Institut Laue-Langevin (ILL); Dewhurst, C. D. [Institut Laue-Langevin (ILL); Kramer, Matthew J. [Ames Laboratory; Morris, James R [ORNL; Sordelet, Daniel [Ames Laboratory

    2007-01-01

    The temperature variation of the structure and microstructure of molten eutectic Al{sub 1-x}Si{sub x} alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q).

  10. Isothermal section of the Er-Fe-Al ternary system at 800 oC

    International Nuclear Information System (INIS)

    Physico-chemical analysis techniques, including X-ray diffraction and Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy, were employed to construct the isothermal section of the Er-Fe-Al system at 800 oC. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe12-xAlx with 5 ≤ x ≤ 8 (ThMn12-type), ErFe1+xAl1-x with -0.2 ≤ x ≤ 0.75 (MgZn2-type), ErFe3-xAlx with 0.5 2Al-type), Er2Fe17-xAlx with 4.74 ≤ x ≤ 5.7 (TbCu7-type) and Er2Fe17-xAlx with 5.7 2Zn17-type), seven extensions of binaries into the ternary system; ErFexAl3-x with x 3Cu-type), ErFexAl2-x with x ≤ 0.68 (MgCu2-type), Er2FexAl1-x with x ≤ 0.25 (Co2Si-type), ErFe2-xAlx with x ≤ 0.5 (MgCu2-type), ErFe3-xAlx with x ≤ 0.5 (Be3Nb-type), Er6Fe23-xAlx with x ≤ 8 (Th6Mn23-type), and Er2Fe17-xAlx with x ≤ 4.75 (Th2Ni17-type) and one intermetallic compound; the ErFe2Al10 (YbFe2Al10-type).

  11. Incorporation of Fe into NiSi[subscript 2] precipitates

    OpenAIRE

    Langkau, S.; Wagner, G.; Bertoni, Mariana I.; Kloess, G.; Buonassisi, Tonio

    2011-01-01

    The present paper provides evidence that Fe can be incorporated into NiSi[subscript 2] precipitates by solid-state diffusion. Furthermore, analysis of Si crystals contaminated with Ni and Fe at 1100°C and post annealed at 600°C and 800°C for 20–240 min revealed a strong indication that this incorporation is limited by bulk diffusion rather than incorporation kinetics.

  12. 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.

  13. Overview of the development of FeAl intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.; Liu, C.T.; Goodwin, G.M.

    1995-09-01

    B2-phase FeAl ordered intermetallic alloys based on an Fe-36 at.% Al composition are being developed to optimize a combination of properties that includes high-temperature strength, room-temperature ductility, and weldability. Microalloying with boron and proper processing are very important for FeAl properties optimization. These alloys also have the good to outstanding resistance to oxidation, sulfidation, and corrosion in molten salts or chlorides at elevated temperatures, characteristic of FeAl with 30--40 at.% Al. Ingot- and powder-metallurgy (IM and PM, respectively) processing both produce good properties, including strength above 400 MPa up to about 750 C. Technology development to produce FeAl components for industry testing is in progress. In parallel, weld-overlay cladding and powder coating technologies are also being developed to take immediate advantage of the high-temperature corrosion/oxidation and erosion/wear resistance of FeAl.

  14. 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.

  15. Magnetic ordering in Ho2Fe2Si2C

    International Nuclear Information System (INIS)

    We have used neutron diffraction and 57Fe Mössbauer spectroscopy, complemented by magnetisation and specific heat measurements, to examine the magnetic ordering of Ho2Fe2Si2C. We have established that Ho2Fe2Si2C orders antiferromagnetically below TN = 16(1) K with a magnetic structure involving ordering of the Ho sublattice along the b-axis with a propagation vector k=[0 0 1/2 ]. 57Fe Mössbauer spectra collected below TN show no evidence of a magnetic splitting, demonstrating the absence of long range magnetic ordering of the Fe sublattice. A small line broadening is observed in the 57Fe spectra below TN, which is due to a transferred hyperfine field—estimated to be around 0.3 T at 10 K—from the Ho sublattice

  16. Ion implantation and diffusion of Al in a SiO{sub 2}/Si system

    Energy Technology Data Exchange (ETDEWEB)

    La Ferla, A. [Catania Univ. (Italy). Ist. di Fisica; Galvagno, G. [Catania Univ. (Italy). Ist. di Fisica; Rinaudo, S. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Raineri, V. [CNR-IMETEM, Stradale Primosole 50, 95100 Catania (Italy); Franco, G. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Camalleri, M. [CORIMME, Stradale Primosole 50, 95100 Catania (Italy); Gasparotto, A. [Dipartimento di Fisica, via Marzolo 8, 35131 Padova (Italy); Carnera, A. [Dipartimento di Fisica, via Marzolo 8, 35131 Padova (Italy); Rimini, E. [Catania Univ. (Italy). Ist. di Fisica

    1996-08-01

    The diffusion and segregation of ion implanted Al in SiO{sub 2} and Si layers were studied for several experimental conditions. Al ions were implanted into SiO{sub 2}, Si and through a SiO{sub 2} layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4.10{sup 14}-1.10{sup 15} cm{sup -2}). The Al diffusion coefficient in SiO{sub 2} was measured at 1200 C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO{sub 2} capping layer, but segregate at the SiO{sub 2}/Si interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the SiO{sub 2}/Si system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data. (orig.).

  17. Ion implantation and diffusion of Al in a {SiO 2}/{Si} system

    Science.gov (United States)

    La Ferla, A.; Galvagno, G.; Rinaudo, S.; Raineri, V.; Franco, G.; Camalleri, M.; Gasparotto, A.; Carnera, A.; Rimini, E.

    1996-08-01

    The diffusion and segregation of ion implanted Al in SiO 2 and Si layers were studied for several experimental conditions. Al ions were implanted into SiO 2, Si and through a SiO 2 layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4 × 10 14-1 × 10 15 cm -2). The Al diffusion coefficient in SiO 2 was measured at 1200°C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO 2 capping layer, but segregate at the {SiO 2}/{Si} interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the {SiO 2}/{Si} system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data.

  18. Ion implantation and diffusion of Al in a SiO2/Si system

    International Nuclear Information System (INIS)

    The diffusion and segregation of ion implanted Al in SiO2 and Si layers were studied for several experimental conditions. Al ions were implanted into SiO2, Si and through a SiO2 layer into Si substrates at several energies (80, 300, 650 and 6000 keV) and doses (3.4.1014-1.1015 cm-2). The Al diffusion coefficient in SiO2 was measured at 1200 C for times up to 5 days, and it results five orders of magnitude lower than in Si. The experiments show that the Al atoms implanted into Si do not out-diffuse during thermal treatments from the SiO2 capping layer, but segregate at the SiO2/Si interface. The high segregation coefficient gives rise to a trapping of Al into the oxide layer comparable to the out-diffusion of Al from uncapped Si substrates. The determined parameters for Al diffusion and segregation in the SiO2/Si system were introduced in a simulation code to calculate the Al diffusion profiles which result in agreement with the experimental data. (orig.)

  19. 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

    2010-07-01

    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. PMID:20614981

  20. The Calculation of Fe-Al-O Interaction Coefficient

    International Nuclear Information System (INIS)

    Aluminum is a very common deoxidizer in steel-making processes. The solubility of oxygen in molten iron decreases with increasing aluminum content. For the deoxidation process, the solubility of oxygen in Fe-Al melts decreases with increasing aluminum content. When %Al is increased to 0.34 wt.%, %O decreases to 6.4 ppm, which is the lowest point of the FeAl2O4 curve. Then the Al2O3 curve appears and replaces the FeAl2O4 curve, where the interconnection point of the two curves is the coexistence point of FeAl2O4 and Al2O3 phases. When %Al is increased to 0.4%, the %O decreases to 6.35 ppm, which is the lowest point of the Al2O3 curve. The solubility of oxygen in Fe-Al alloys is about 6.35 ppm with 0.4 wt.% aluminum at 1873 K. Liquid FeO-Al2O3, hercynite (FeAl2O4), and alumina (Al2O3) are three possible products during the deoxidation process. Based on thermodynamic calculation, the value of the interaction coefficient of eoAl was determined as -0.75 at 1873 K. This value is in good agreement with experimental curves in the literature.

  1. 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.

  2. Electron channelling enhanced microanalysis on Ni-Al-Mn and Al-Mn-Si

    International Nuclear Information System (INIS)

    Atom location by channelling enhanced microanalysis (ALCHEMI) was performed for Ni-Al-Mn compounds and Al-Mn-Si quasicrystals. For Ni75Al25-xMnx (x=5,9) with the L12-type structure, an occupation fraction of Mn atoms at the Ni site was quantitatively determined using planar channelling conditions. The occupation fraction increases with the Mn concentration or by quenching the compound from high temperature. In quasicrystals of Al74Mn20Si6 and Al68Mn20Ru8Si4, axial channelling conditions were used to locate Si and Ru, respectively. It was shown that Si atoms occupy the Al site in Al74Mn20Si6 whereas Ru atoms occupy the site different from that of Al in Al68Mn20Ru8Si4. (author)

  3. 99Ru and 57Fe Moessbauer spectroscopy of a ruthenium alloy, RuFe2Si

    International Nuclear Information System (INIS)

    99Ru and 57Fe-Moessbauer spectroscopic and magnetization measurements were made in order to clarify the magnetic properties of a Huesler alloy, RuFe2Si. The result obtained from 99Ru-Moessbauer spectrum leads to the conclusion that Ru atoms were substituted by both Fe[A,C] and Fe[B], but the latter preferentially. (author) 6 refs.; 5 figs

  4. Thermodynamic prediction of thixoformability in alloys based on the Al-Si-Cu and Al-Si-Cu-Mg systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, D. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Atkinson, H.V. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Jones, H. [Department of Engineering Materials, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2005-08-15

    Most commercial semi-solid processing (of which thixoforming is one type) utilises the conventional casting alloys A356 and A357. There is, however, a demand to widen the range of alloys, including those with higher performance which tend to show poor characteristics for thixoforming. Thermodynamic calculation packages, such as MTDATA, provide a tool for predicting thixoformability. Here, the effects of compositional variations, in particular the effect of added copper on the thixoformability of alloy A356 and the effect of added silicon on the thixoformability of alloy 2014, have been investigated using MTDATA thermodynamic and phase equilibrium software combined with the MTAL database. Criteria for thixoformability are identified and a range of alloy compositions based on Al-Si-Cu and Al-Si-Cu-Mg evaluated in relation to these criteria. Compositions which satisfy these criteria include: 308 (Al-5.5Si-4.5Cu); 319 (Al-6Si-3.5Cu); 238 (Al-10Cu-4Si-0.3Mg); 355 (Al-5Si-1.3Cu-0.5Mg); 2014 based alloys Al-4.4Cu-0.5Mg-(4-6)Si; and a range of alloys (7.5 Si + Cu 9 and 1.5 Si/Cu 2.33) and alloys (9 < Si + Cu 10 and Si/Cu = 1.5) based on the Al-Si-Cu-Mg system.

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

    Science.gov (United States)

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

    2013-07-01

    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.

  6. 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.

  7. AlON-SiAlON复合材料的制备及特性%Preparation and properties of AlON-SiAlON composites

    Institute of Scientific and Technical Information of China (English)

    山下敬; 山口明良

    2003-01-01

    为提高AlON陶瓷材料的抗氧化性能,制备了AlON-SiAl7O2N7复相材料.在1750℃、0.5 MPa的N2气氛中,保温2 h烧成不同Al2O3/AlN/Si3N4配比的原料得到不同AlON/SiAl7O2N7比的复相材料.因为在烧结SiAl7O2N7的过程中,蒸发-凝聚的同时伴随着SiO气体的挥发,因此很难得到致密的AlON-SiAl7O2N7复相材料.研究了AlON-SiAl7O2N7复相材料在1300℃、空气中的抗氧化性能,同时作为比较,研究了相同条件下单相的AlON材料的抗氧化性能.结果表明,AlON-SiAl7O2N7复相材料显示了较之单相的AlON陶瓷材料更好的抗氧化性能,这是因为氧化过程中所形成的含玻璃相的表面氧化层抑制了氧的向内扩散所致.

  8. Mechanism of Corrosion in Al-Si-Cu

    Science.gov (United States)

    Hayasaka, Nobuo; Koga, Yuri; Shimomura, Koji; Yoshida, Yukimasa; Okano, Haruo

    1991-07-01

    An Al-Cu local cell was formed between the Cu precipitation and adjacent Al in an Al-Si-Cu alloy when Cu was added in excess to the alloy. Once an Al-Cu local cell was formed, corrosion took place simply by dipping the alloy in deionized water without any contamination. Furthermore, it was found that corrosion was enhanced at the Al-Si-Cu lines in contact with the p+-n junction of Si. The reason for this is that holes are injected into Al-Si-Cu from p+-Si due to electromotive force produced by light irradiation and an external circuit connecting the alloy and n-Si formed by the adsorption of moisture on the surface. Furthermore, it was found that the irradiation of light with a wavelength between 320 to 380 nm was most effective in enhancing the corrosion reaction.

  9. Effect of Sr on forming properties of Al-Mg-Si based alloy sheets

    Institute of Scientific and Technical Information of China (English)

    LU Guang-xi; CHEN Hai-jun; GUAN Shao-kang

    2006-01-01

    The effects of Sr element on the forming properties of the Al-Mg-Si based alloy sheets were studied by tensile test,metallograph, DSC, XRD, SEM and TEM. The results show that the tensile strength of aluminum alloy sheet added 0.033%(mass fraction)Sr increases comparing with that of free Sr. Simultaneously, the forming properties of sheets evidently increase, the elongation hardenability (n) and plastic strain ratio (r) and Erichsen number increase 27.8%, 11.1%, 10.8% and 12%, respectively,and the forming limit diagram increases evidently, too. The analysis shows that Sr is surface active element, which can refine grains of alloys, promote precipitation, reduce activation energy ofβ" phase, and lead the formation of α-(Al8Fe2Si) phase instead of β-(Al5FeSi) phase. As a result, the forming properties of the alloy sheet increase.

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

    OpenAIRE

    Courbiere, M.; Mocellin, A.

    1993-01-01

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

  11. Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

    Directory of Open Access Journals (Sweden)

    Teddy M. Keller

    2010-02-01

    Full Text Available The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, a-FeSi2 and b-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR. The silicon-rich b-FeSi2 is a direct band gap material usable in light emitting diode (LED applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.

  12. Epitaxial growth of Fe3Si/CaF2/Fe3Si magnetic tunnel junction structures on CaF2/Si(111) by molecular beam epitaxy

    International Nuclear Information System (INIS)

    The Fe3Si(24 nm)/CaF2(2 nm)/Fe3Si(12 nm) magnetic tunnel junction (MTJ) structures were grown epitaxially on CaF2/Si(111) by molecular beam epitaxy (MBE). The 12-nm-thick Fe3Si underlayer was grown epitaxially on CaF2/Si(111) at approximately 400 deg. C; however, the surface of the Fe3Si film was very rough, and thus a lot of pinholes are considered to exist in the 2-nm-thick CaF2 barrier layer. The average roughness (Ra) of the CaF2 barrier layer was 7.8 nm. This problem was overcome by low-temperature deposition of Fe and Si at 80 deg. C on CaF2/Si(111), followed by annealing at 250 deg. C for 30 min to form the Fe3Si layer. The Ra roughness was significantly reduced down to approximately 0.26 nm. A hysteresis loop with coercive field Hc of approximately 25 Oe was obtained in the magnetic field dependence of Kerr rotation at room temperature (RT)

  13. Analysis of depth redistribution of implanted Fe near SiO{sub 2}/Si interface

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Y., E-mail: yhoshino@kanagawa-u.ac.jp; Yokoyama, A.; Yachida, G.; Nakata, J.

    2013-11-01

    We have studied diffusion and clustering processes of room-temperature (RT)-implanted Fe ions in a SiO{sub 2}/Si structure during annealing at 600 and 800 °C temperatures. The depth profile of implanted Fe was analyzed by Rutherford backscattering spectroscopy (RBS). In the previous study, we found that the hot-implanted Fe ions near the SiO{sub 2}/Si interface at high substrate temperatures of 600 and 800 °C were distributed significantly different from the result predicted in the TRIM simulation. We think that the diffusion phenomena during the ion implantation at such elevated temperatures are recognized to be strongly enhanced by ion-beam-irradiation effect. In this study, to simplify the diffusion phenomenon, we particularly treat thermal diffusion process of RT-Fe implantation around the SiO{sub 2}/Si interface in the post annealing at high temperatures. It is clearly seen that Fe atoms post-annealed at 800 °C are preferably gathered at a definitive depth in the SiO{sub 2} layer around 15 nm distances from the interface. We finally compare the Fe depth distribution for hot-implanted samples to that for the post-annealed ones by RBS analysis quantitatively.

  14. 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.

  15. Magnetic transition induced by mechanical deformation in Fe60Al40−xSix ternary alloys

    International Nuclear Information System (INIS)

    Highlights: • Fe60Al40−xSix 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 Fe60Al40−xSix alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe60Al40 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

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  17. Formation of phases with the structure of Ca3Ga2Ge4O14 in the AO-BO2-M2O3-SiO2 systems (A = Ca, Sr, Ba; B = Ge, Ti, Sn, Zr; M = Ga, Fe, Al)

    International Nuclear Information System (INIS)

    A search was arranged for phases of the structure Ca3Ga2Ge4O14 (I), featuring promising piezoelectric properties, in the systems AO-BO2-M2O3-SiO2 (A = Ca, Sr, Ba; B = Ge, Ti, Sn, Zr; M = Ga, Fe, Al), using the method of X-ray phase analysis. In 17 systems studied phases of variable composition A3BxM2Si4-xO14 with disordered structure of I have been detected. In joins A3M2B4O14 - A3M2Si4O14 homogeneity regions have been defined, which are localized inside tetrahedron of the compositions in 14 systems with B = Ti, Sn, Zr and emerging on one of the tetrahedron faces in three Ge-systems. Thermal stability is studied and cations distribution over synthesized phases is discussed

  18. Solidification and Microstructural Evolution of Hypereutectic Al-15Si-4Cu-Mg Alloys with High Magnesium Contents

    Science.gov (United States)

    Tebib, M.; Ajersch, F.; Samuel, A. M.; Chen, X.-G.

    2013-09-01

    The low coefficient of thermal expansion and good wear resistance of hypereutectic Al-Si-Mg alloys with high Mg contents, together with the increasing demand for lightweight materials in engine applications have generated an increasing interest in these materials in the automotive industry. In the interests of pursuing the development of new wear-resistant alloys, the current study was undertaken to investigate the effects of Mg additions ranging from 6 to 15 pct on the solidification behavior of hypereutectic Al-15Si-4Cu-Mg alloy using thermodynamic calculations, thermal analysis, and extensive microstructural examination. The Mg level strongly influenced the microstructural evolution of the primary Mg2Si phase as well as the solidification behavior. Thermodynamic predictions using ThermoCalc software reported the occurrence of six reactions, comprising the formation of primary Mg2Si; two pre-eutectic binary reactions, forming either Mg2Si + Si or Mg2Si + α-Al phases; the main ternary eutectic reaction forming Mg2Si + Si + α-Al; and two post-eutectic reactions resulting in the precipitation of the Q-Al5Mg8Cu2Si6 and θ-Al2Cu phases, respectively. Microstructures of the four alloys studied confirmed the presence of these phases, in addition to that of the π-Al8Mg3FeSi6 (π-Fe) phase. The presence of the π-Fe phase was also confirmed by thermal analysis. The morphology of the primary Mg2Si phase changed from an octahedral to a dendrite form at 12.52 pct Mg. Any further Mg addition only coarsened the dendrites. Image analysis measurements revealed a close correlation between the measured and calculated phase fractions of the primary Mg2Si and Si phases. ThermoCalc and Scheil calculations show good agreement with the experimental results obtained from microstructural and thermal analyses.

  19. 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.

  20. Thermal annealing and magnetic anisotropy of NiFe thin films on n+-Si for spintronic device applications

    International Nuclear Information System (INIS)

    To ensure that the magnetic metal electrodes can meet the requirements of the spin injection, NiFe films prepared both on HfO2 dielectric layer and n+-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 HfO2 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/HfO2/Si sample by thermal annealing. Those results suggest that Al/NiFe/HfO2/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 HfO2 dielectric layer between NiFe and Si partially suppressed the diffusion of Ni into Si

  1. The role of iron in the formation of porosity in Al-Si-Cu-based casting alloys. Part 2: A phase-diagram approach

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J.A.; Schaffer, G.B.; StJohn, D.H. [Univ. of Queensland, Brisbane (Australia)

    1999-06-01

    The mechanism by which iron causes casting defects in the AA309 (Al-5 pct Si-1.2 pct Cu-0.5 pct Mg) may be related to the solidification sequence of the alloy. Superimposing calculated segregation lines on the liquidus projection of the ternary Al-Si-Fe phase diagram suggests that porosity is minimized at a critical iron content when solidification proceeds directly from the primary field to the ternary Al-Si-{beta}Al{sub 5}FeSi eutectic point. Solidification via the binary Al-{beta}Al{sub 5}FeSi eutectic is detrimental to casting integrity. This hypothesis was tested by comparing the critical iron content observed in the standard AA309 alloy to that of a high-silicon (10 pct Si) variant of this alloy.

  2. Morphology and distribution of Al3Fe phase in hypereutectic Al-Fe alloy solidified under magnetic field

    Directory of Open Access Journals (Sweden)

    Ban Chunyan

    2011-11-01

    Full Text Available In this study, the (low DC and AC magnetic fields and the high magnetic field were applied separately during the solidification process of Al-2.89%Fe alloy. The influences of these magnetic fields on the morphology and distribution of Al3Fe phase in Al-2.89%Fe alloy were investigated. The microstructure and macrostructure of the samples were observed using an optical microscope. The results show that the majority of the primary Al3Fe phase particles in the hypereutectic Al-2.89%Fe alloy is gathered at the bottom of the sample under DC and AC magnetic fields or without magnetic field. The primary Al3Fe phase becomes coarse when the alloy solidifies under DC magnetic field, while it are refined and accumulated towards the center of the sample under the AC magnetic field. When the high magnetic field of 12 T is applied, the primary Al3Fe phase distributes throughout the sample homogeneously because the magnetic force acting on the primary Al3Fe phase balances with the gravity force; and the long axis of the Al3Fe phase aligns perpendicularly to the magnetic field direction. Also, the mechanism of the effect of magnetic fields is discussed.

  3. 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

  4. 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

  5. Pyrosmalite-(Fe), Fe8Si6O15(OH,Cl)10

    OpenAIRE

    Hexiong Yang; Robert T. Downs; Yang, Yongbo W.; Warren H. Allen

    2011-01-01

    Pyrosmalite-(Fe), ideally FeII8Si6O15(OH,Cl)10 [refined composition in this study: Fe8Si6O15(OH0.814Cl0.186)10·0.45H2O, octairon(II) hexasilicate deca(chloride/hydroxide) 0.45-hydrate], is a phyllosilicate mineral and a member of the pyrosmalite series (Fe,Mn)8Si6O15(OH,Cl)10, which includes pyrosmalite-(Mn), as well as friedelite and mcgillite, two polytypes of pyrosmalite-(Mn). This study presents the first structure determination of pyrosmalite-(Fe) based on single-crystal X-ray d...

  6. Pengaruh Kadar Besi (Fe) Dan Silikon (Si) Di Dalam Pot Reduksi Terhadap Mutu Produk Akhir Yang Dihasilkan Di Pt Inalum

    OpenAIRE

    Kaban, Muhammad Agus Salim

    2010-01-01

    Aluminum is one element in nature that is very much usefulness to humans. Aluminum bar (ingot) aluminum molding is obtained from liquid (molten). Raw materials used include alumina (Al2O3), anode, cathode, kliorit (Na3AlF6), soda ash (Na2CO3) and aluminum fluoride (AlF3). Generated a lot of aluminum bars contain impurities, such as Fe and Si. Because of iron (Fe) can cause corrosion (rusting), while the element silicon (Si) causes the aluminum color to yellow. When levels of ...

  7. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

  9. 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.

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

    OpenAIRE

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

    2011-01-01

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

  11. Phase diagram of the Nb-Al-Si ternary system

    International Nuclear Information System (INIS)

    A high-efficiency diffusion-multiple approach was employed to map the phase diagram of the Nb-Al-Si ternary system which is very valuable for the design of niobium silicide-based composites. These composites have high potential as a replacement for Ni-base superalloys for jet engine applications. Aluminum is an alloying element for these composites, thus the Nb-Al-Si phase diagram, especially solubility of Al in Nb5Si3, is important information for the composite design. An isothermal section at 1000 deg. C was constructed from the results obtained from a diffusion multiple using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). A ternary phase Nb3Si5Al2 was observed. The solubility data of Al in αNb5Si3 and NbSi2 as well as Si solubility in Nb3Al, Nb2Al and NbAl3 were obtained. The new isothermal section helps to judge the reliability of the existing literature results and to add new data to the Nb-Al-Si phase equilibria

  12. Electronic and magnetic properties of Si substituted Fe3Ge

    International Nuclear Information System (INIS)

    Using first principles calculations, we studied the effect of Si substitution in the hexagonal Fe3Ge. We find the low temperature magnetic anisotropy in this system to be planar and originating mostly from the spin-orbit coupling in Fe-d states. Reduction of the unitcell volume reduces the magnitude of in-plane magnetic anisotropy, eventually turning it positive which reorients the magnetic moments to the axial direction. Substituting Ge with the smaller Si ions also increases the anisotropy, potentially enhancing the region of stability of the axial magnetization, which is beneficial for magnetic applications such as permanent magnets. Our experimental measurements on samples of Fe3Ge1−xSix confirm these predictions and show that substitution of about 6% of the Ge with Si increases by approximately 35 K the temperature range over which anisotropy is uniaxial

  13. Electronic structures of nanocrystalline Fe90-xCuxSi10-yBy soft magnets

    Science.gov (United States)

    Park, Jihoon; Hong, Yang-Ki; Lee, Woncheol; Bae, Seok; Kim, Seong-Gon; Choi, Chul-Jin

    2016-05-01

    We have calculated electronic structures of nanocrystalline Fe90-xCuxSi10-yBy using first principles calculations based on density functional theory (DFT) to obtain saturation magnetic flux density (Bs). The Bs of crystalline (Fe3Si) and amorphous (Fe-B) phases in Fe90-xCuxSi10-yBy were separately calculated, and the total Bs of Fe90-xCuxSi10-yBy was derived by the summation of the Bs for the Fe3Si and Fe-B phases. The calculated Bs of Fe3Si is 1.35 T, and that of Fe-B varies from 2.08 to 2.22 T based on Fe to B ratios. Therefore, a total Bs higher than 1.80 T can be obtained with y ≥ 4 for both x = 1 and 2 in Fe90-xCuxSi10-yBy.

  14. Diffusion mobilities in the fcc{sub A}1 Cu-Si, Al-Si and Al-Cu-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Dachun [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan Province 411105 (China); Liu, Ya [School of Materials Science and Engineering, Changzhou University, 1 Gehu Road, Changzhou, Jiangsu Province 213164 (China); Su, Xuping, E-mail: sxping@cczu.edu.cn [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan Province 411105 (China); School of Materials Science and Engineering, Changzhou University, 1 Gehu Road, Changzhou, Jiangsu Province 213164 (China); Wang, Jianhua; Tu, Hao [School of Materials Science and Engineering, Changzhou University, 1 Gehu Road, Changzhou, Jiangsu Province 213164 (China); Huang, Jianfeng [School of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan Province 411105 (China)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer The atomic mobilities of fcc Cu-Si, Al-Si and Al-Cu-Si alloys have been assessed. Black-Right-Pointing-Pointer The calculated results agree well with various experimental diffusivities. Black-Right-Pointing-Pointer The temperature and concentration dependence are taken into consideration. Black-Right-Pointing-Pointer The mobility parameters obtained can be used to predict many diffusion phenomena. - Abstract: Based on the available thermodynamic parameters and experimental data of self-diffusivity, impurity diffusivity, intrinsic diffusivity, tracer diffusivity and interdiffusivity in the Cu-Si, Al-Si and Al-Cu-Si alloys, the atomic mobilities of Cu, Al and Si in face-centered cubic (fcc{sub A}1) Cu-Si, Al-Si and Al-Cu-Si alloys have been critically assessed as a function of temperature and composition using the CALPHAD-type and DICTRA software package. Comparisons between the calculated and measured coefficients reveal that most of the diffusivities can be reproduced satisfactorily. The obtained mobility parameters can be used to study diffusion-related characteristics for fcc{sub A}1 Cu-Si, Al-Si and Al-Cu-Si alloys.

  15. 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.

  16. Microstructure of the Al-La-Ni-Fe system

    Energy Technology Data Exchange (ETDEWEB)

    Vasil’ev, A. L., E-mail: a.vasiliev56@gmail.com [National Research Centre “Kurchatov Institute” (Russian Federation); Ivanova, A. G. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Bakhteeva, N. D. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation); Kolobylina, N. N. [National Research Centre “Kurchatov Institute” (Russian Federation); Orekhov, A. S. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Presnyakov, M. Yu. [National Research Centre “Kurchatov Institute” (Russian Federation); Todorova, E. V. [Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation)

    2015-01-15

    The microstructure of alloys based on the Al-La-Ni-Fe system, which are characterized by a unique ability to form metal glasses and nanoscale composites in a wide range of compositions, has been investigated. Al{sub 85}Ni{sub 7}Fe{sub 4}La{sub 4} and Al{sub 85}Ni{sub 9}Fe{sub 2}La{sub 4} alloys have been analyzed by electron microscopy (including high-resolution scanning transmission electron microscopy), energy-dispersive X-ray microanalysis, electron diffraction (ED), and X-ray diffraction (XRD). It is found that, along with fcc Al and Al{sub 4}La (Al{sub 11}La{sub 3}) particles, these alloys contain a ternary phase Al{sub 3}Ni{sub 1−x}Fe{sub x} (sp. gr. Pnma) isostructural to the Al{sub 3}Ni phase and a quaternary phase Al{sub 8}Fe{sub 2−x}Ni{sub x}La isostructural to the Al{sub 8}Fe{sub 2}Eu phase (sp. gr. Pbam). The unit-cell parameters of the Al{sub 3}Ni{sub 1−x}Fe{sub x} and Al{sub 8}Fe{sub 2−x}Ni{sub x}La compounds, determined by ED and refined by XRD, are a = 0.664(1) nm, b = 0.734(1) nm, and c = 0.490(1) nm for Al{sub 3}Ni{sub 1−x}Fe{sub x} and a = 1.258(3) nm, b = 1.448(3) nm, and c = 0.405(8) nm for Al{sub 8}Fe{sub 2−x}Ni{sub x}La. In both cases Ni and Fe atoms are statistically arranged, and no ordering is found. Al{sub 8}Fe{sub 2−x}Ni{sub x}La particles contain inclusions in the form of Al{sub 3}Fe δ layers.

  17. 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.

  18. Oxidative dehydrogenation of propane with N2O over Fe-ZSM-5 and Fe-SiO2: Influence of the iron species and acid sites

    OpenAIRE

    Ates, Ayten; Hardacre, Christopher; Goguet, Alexandre

    2012-01-01

    A series of iron containing zeolites with varying Si/Al ratios (11.5-140) and low iron content (similar to 0.9 wt.% Fe) have been synthesised by solid-state ion exchange with commercially available zeolites and tested, for the first time, in the oxidative dehydrogenation of propane (ODHP) with N2O. The samples were characterised by XRD, N-2-Adsorption, NH3-TPD and DR-UV-vis spectroscopy. The acidity of the Fe-ZSM-5 can be controlled by high temperature and steam treatments and Si/Al ratio. Th...

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

    Science.gov (United States)

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

    2016-03-01

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

  20. 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.

  1. Magnetic properties of Fe doped SiC crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kuryliszyn-Kudelska, I.; Dobrowolski, W. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw (Poland); Diduszko, R.; Tymicki, E. [Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland); Grasza, K. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warsaw (Poland); Institute of Electronic Materials Technology, ul. Wolczynska 133, 01-919 Warsaw (Poland)

    2007-05-15

    In this paper we report on the crystal growth and magnetic as well as structural studies of SiC:Fe. SiC crystals were grown by Physical Vapor Transport method. We used Fe enriched source material to dope crystals. The magnetic properties were examined by AC/DC magnetometry. AC magnetic susceptibility as well as DC magnetization measurements revealed ferromagnetic type of magnetic ordering. The structural measurements using powder X-ray diffraction were performed. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Chemical ordering and large tunnel magnetoresistance in Co2FeAl/MgAl2O4/Co2FeAl(001) junctions

    Science.gov (United States)

    Scheike, Thomas; Sukegawa, Hiroaki; Inomata, Koichiro; Ohkubo, Tadakatsu; Hono, Kazuhiro; Mitani, Seiji

    2016-05-01

    Epitaxial magnetic tunnel junctions (MTJs) with a Co2FeAl/CoFe (0.5 nm)/MgAl2O4/Co2FeAl(001) structure were fabricated by magnetron sputtering. High-temperature in situ annealing led to a high degree of B2-order in the Co2FeAl layers and cation order of the MgAl2O4 barrier. Large tunnel magnetoresistance (TMR) of up to 342% was obtained at room temperature (616% at 4 K), in contrast to the TMR ratio ( ≲ 160%) suppressed by the band-folding effect in Fe/cation-ordered MgAl2O4/Fe MTJs. The present study reveals that the high degree of B2-order and the resulting high spin polarization in the Co2FeAl electrodes enable us to bypass the band-folding problem in spinel barriers.

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

    International Nuclear Information System (INIS)

    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, Ti0.50Al0.50N, Ti0.90Si0.10N, CrN, and Cr0.90Si0.10N. 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 Ti0.50Al0.50N, Ti0.90Si0.10N, and Cr0.90Si0.10N 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

  4. 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‰ (2

  5. Si adatoms as catalyst for the growth of monolayer Al film on Si(111)

    Science.gov (United States)

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

    2010-03-01

    Recently, we reported the growth of atomically smooth Al(111) films on Si(111) with continuously controllable thickness down to the extreme level of 1 ML. Here, we study the underlying unexpected Si adatom-mediated clustering-melting mechanism by scanning tunneling microscopy and by the first-principles calculations. The Si adatoms in the initial Si(111)3x3-Al surface act as seeds to form SiAl2 clusters. The clusters are then transformed into Al(111)1x1 by incorporating further incoming Al atoms and spontaneously releasing the Si atoms, which then participate in the next cycle of the process. As a result, a two-dimensional growth of monolayer Al(111) is achieved.

  6. Al-Si/B4C composite coatings on Al-Si substrate by plasma spray technique

    International Nuclear Information System (INIS)

    Plasma-sprayed coatings of Al-Si/B4C have been prepared on Al-Si piston alloys for diesel engine motors. The Al-Si/B4C composite powders including 5-25 wt% B4C were prepared by mixing and ball-milling processes. These powders were deposited on Al-Si substrate using an atmospheric plasma spray technique. The coatings have been characterised with respect to phase composition, microstructure, microhardness, bond strength and thermal expansion. It was found that Al, Si, B4C and Al2O3 phases were determined in the coatings with approximately 600 μm thick by using X-ray diffraction analysis. Scanning electron microscope observation revealed that boron carbide particles were uniformly distributed in composite coatings and B4C particles were fully wetted by Al-Si alloy. Also, no reaction products were observed in Al-Si/B4C composite coatings. It was found that surface roughness, porosity, bond strength and thermal expansion coefficient of composite coatings decreased with increasing fraction of the boron carbide particle. It was demonstrated that the higher the B4C content, the higher the hardness of coatings because the hardness of B4C is higher than that of Al-Si

  7. Interface Stability of the SiC Particles/Fe Matrix Composite System

    Institute of Scientific and Technical Information of China (English)

    TANG Wenming; ZHENG Zhixiang; WU Yucheng; JIN Zhihao

    2006-01-01

    The interface reaction between the SiC particles (SiCp) and Fe was studied during sintering the SiCp reinforced Fe matrix composites at 1423 K for 1 h. In the composite having 3wt% (weight ratio) SiCp (the 3SiCp/Fe composite), the interface reaction products of Fe3Si, the carbon precipitates, and Fe3C or pearlite were generated. Fe3Si constructs the bright matrix of the reaction zone in the original situation of the SiCp. The carbon precipitates are randomly embedded in the reaction zone. Fe3C or pearlite exists at the grain boundaries of the Fe matrix. As increasing the SiCp concentration in the SiCp/Fe composite, the intensity of the interface reaction between SiCp and Fe increases. After the 10SiCp/Fe composite (having 10wt.% SiCp) sintered at 1423 K for 1 h, all of SiCp are decomposed, and replaced by the reaction zone composed of Fe3Si and the carbon precipitates. No Fe3C or pearlite was generated during the reaction. The effects of the techniques of oxidizing of SiCp, coating SiCp by interaction with the Cr powder, and alloying the Fe matrix by adding the Cr element on the interface stability of the SiCp/Fe composite system were also investigated, respectively. The oxide membrane and the coating layer on SiCp can inhibit the interface reaction between SiCp and Fe by isolating SiCp from the Fe matrix during sintering. The interface reaction does not occur in the 3SiCp/Fe-10Cr composite but in the 3SiCp/Fe-5Cr composite. In the SiCp/Fe-Cr alloy composites, the interface reaction between SiCp and the Fe-Cr alloys is weaker than that between SiCp and Fe. The Cr element behaves as a diluent, it causes a reduction in the interface reaction, which is proportional to the amount of the element added.

  8. High Aluminous Orthopyroxene in the Join (Mg_<0.754>Fe_<0.246>)SiO_3-Al_2O_3 at 10 and 15 kbar : Implications for the Stability of Orthopyroxene-spinel-quartz in the Granulite Facies Metamorphic Rocks

    OpenAIRE

    Arima, Makoto

    1987-01-01

    The solubility of alumina in orthopyroxene in a part of the join (Mg_Fe_)SiO_3-Al_2O_3 has been determined experimentally in a temperature range of 950-1200℃ at 10 and 15 kbar. The join studied consists of a single phase field of orthopyroxene solid solution (ss) and an assemblage of orthopyroxene (ss)+spinel (ss)+quartz. The alumina content of orthopyroxene coexisting with spinel and quartz increases with increasing temperature and pressure. The present results suggest, combined with previou...

  9. Selective dissolution in AlFeNb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Drensler, Stefanie; Mardare, Cezarina Cela; Hassel, Achim Walter [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Linz (Austria); Milenkovic, Srdjan [IMDEA Materials, Parque Cientifico de la Universidad Carlos III de Madrid, Avda. del mar Mediterraneo 22, 28918 Leganes (Spain)

    2012-05-15

    Three different AlFeNb alloys of various compositions were prepared by arc melting. X-ray diffraction (XRD) investigation of the melted samples proved the presence of two phases identified as a bcc {alpha}(Fe,Al) solid solution and a hexagonal C14 (Fe,Al){sub 2}Nb Laves phase. Subsequent electrochemical treatment allowed for a selective dealloying of the {alpha}(Fe,Al) or respective FeAl phase and resulted in releasing differently microstructured surfaces. These structures ranged from regular lamellar structures towards branched, fibrous structures. Scanning electron microscope (SEM) characterisation along with a local energy dispersive X-ray spectroscopic (EDX) analysis of the samples and atomic absorption spectrometry (AAS) analysis of the electrolyte revealed a preferential Fe dissolution and the passive nature of the Nb. The results demonstrate that the phases present in the alloys strongly depend on the production and heat treatment history of the sample. SEM micrograph of (A) Fe-15Al-10Nb and (B) Fe-26Al-4Nb after anodisation in 0.4 M borate buffer. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. 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.

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

    OpenAIRE

    Oshikiri, Jouji; Umezawa, Osamu; Nakamura, Norio

    2011-01-01

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

  12. Single Crystal Fe Nanowire Arrays Encapsulated by SiO2 Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Qing LIN; Lianzeng YAO; Guowei JIANG; Chuangui JIN; Weifeng LIU; Weili CAI; Zhen YAO

    2004-01-01

    Aligned silicon dioxide nanotubes with diameter of 60~70 nm were synthesized inside the nanoholes of an anodic Al membrane (AAM) template by pressure impregnating the AAM pores with the SiO2 sol. The SiO2 nanotubes with different wall thickness were produced by repeating the process. Using the second-order template of porous AAM with silicon dioxide nanotubes, it was fabricated the nanostructure of Fe nanowires encapsulated by SiO2 nanotubes by electrochemical deposition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the nanotubes and nanocables are compact, continuous and uniform. Selected area electron diffraction (SAED) pattern shows the Fe nanowire is a single crystal. The magnetic properties of these samples were checked by a vibrating sample magnetometer (VSM). The coercivities of the samples are greatly improved compared to the corresponding bulk materials.

  13. The annealing behaviour of hydrogen implanted into Al metal and Al-Si alloy

    International Nuclear Information System (INIS)

    In the present experiment, we have investigated how defects and elements as additive play a role as trap site by observing the annealing behaviour of hydrogen implanted into Al and Al-Si alloy. It was found that hydrogen is trapped as molecules in grain boundaries of Si in Al. (author)

  14. Microstructures and Properties of FeAl-Fe3AlC0.5 Composites Prepared by SHS Casting

    Institute of Scientific and Technical Information of China (English)

    Jun DINC; Jun YANG; Qinling BI; Jiqiang MA; Weimin LIU; Qunji XUE

    2008-01-01

    FeAl composites with 21, 37 and 50 wt pct Fe3AIC0.5 were fabricated by a self-propagating high temperature synthesis (SHS) casting. Phases and microstructures were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness and bending strength of the composites were measured. The composites with 21 and 50 wt pct Fe3AlCo.5 mainly consisted of FeAI and Fe3AlC0.5 phases, whereas the composite with 37 wt pct Fe3AIC0.5 was composed of FeAl, Fe3AlC0.5 and graphite phases. The bonding of the reinforcement and the matrix was good. Hardness and bending strength of the composite with 37 wt pct Fe3AlC0.5 was lower than those of the 21 and 50 wt pct composites owing to the presence of the soft graphite phase.

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

    International Nuclear Information System (INIS)

    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. (paper)

  16. Induced anisotropy in nanocrystalline FeCuNbSiB

    International Nuclear Information System (INIS)

    The kinetics of induced anisotropy Kind was studied in nanocrystalline Fe73.5Cu1Nb3Si13.5B9, as well as in the amorphous precursor and in amorphous Fe78B13Si9. The nanocrystalline alloy was produced from the precursor by annealing at 813 K for 1 h and possessed an average FeSi grain size of 13 nm, as determined from x-ray diffraction. Annealing in a 0.2 T field at 723--773 K, above Tc of the amorphous phase, resulted in low values of Kind. The data were compared to the micromagnetic theory of Kronmueller to determine activation energy spectra. Kind for the nanocrystalline alloy is well described by this theory, however, with an activation energy spectrum that is much narrower than for the amorphous alloys. The limiting value of the anisotropy is K∞ ∼ 13 J/m3 consistent with that expected for the anisotropy in Fe-20at%.Si with the DO3 structure

  17. 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.

  18. Structural properties of amorphous and nanocrystallized Fe-Cu-Nb-Si-B and Fe-Gd-Cu-Nb-Si-B ribbons

    International Nuclear Information System (INIS)

    The influence of Gd addition on the structural properties of Fe-Cu-Nb-Si-B nanocrystallized and amorphous alloys is studied. The crystallization temperature increases and the microstructure of the annealed samples changes. Gd addition induces the formation of Gd-Fe-B phases. In fully crystallized Fe-Gd-Cu-Nb-Si-B alloys the α-Fe(Si), Fe-Nb-B, Gd3Fe62B14 and Gd1.1Fe4B4 phases are observed. The evolution of the microstructure is followed as a function of the cumulative effects of annealing time and temperature. The results suggest the transformation of the metastable Gd3Fe62B14 phase into Gd1.1Fe4B4 and α-Fe. The hyperfine parameters of the Gd3Fe62B14 Moessbauer contribution are reported. (orig.)

  19. Elastic anisotropy of FeSiO3 end-members of the perovskite and post-perovskite phases

    OpenAIRE

    Stackhouse, S.; Brodholt, J. P.; Price, G. D.

    2006-01-01

    The athermal elastic constants of the perovskite and post-perovskite polymorphs of pure end-member FeSiO3 were calculated from ab initio calculations. We predict that incorporating ten mole percent FeSiO3 together with four mole percent Al2O3 into MgSiO3 reduces the perovskite to post-perovskite phase transition pressure by 5 GPa. Small changes in the seismic properties of the post-perovskite phase due to the incorporation of iron and alumina are compatible with observations for the lower man...

  20. 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...

  1. Synthesis and performance of Ca-α/β-SiAlON composites from tailings

    Science.gov (United States)

    Hao, Hong-shun; Yang, Yang; Lian, Fang; Gao, Wen-yuan; Liu, Gui-shan; Hu, Zhi-qiang

    2014-05-01

    Ca-α/β-SiAlON composites were prepared using Ca-α/β-SiAlON powder synthesized from gold ore tailings, which contained abundant Si and Al elements as the major raw materials together with minor additives, through a pressure-less sintering method. The influences of sintering temperature on the phase composition and microstructure of the composites were analyzed. The scanning electron microscopy images of the composites show the interlacing of grains with elongated columnar, short columnar and plate-like morphologies. The composites sintered at 1520°C for 6 h have a flexural strength of 352 MPa, Vickers hardness of 11.2 GPa, and fracture toughness of 4.8 MPa·m1/2. The relative content of each phase in the products is I(Ca-α-SiAlON): I(β-SiAlON): I(Fe3Si) = 23:74:3, where I i stands for the diffraction peak intensity of phase i.

  2. Magnetic properties, morphology and interfaces of (Fe/Si)n nanostructures

    Science.gov (United States)

    Bartolomé, J.; Badía-Romano, L.; Rubín, J.; Bartolomé, F.; Varnakov, S. N.; Ovchinnikov, S. G.; Bürgler, D. E.

    2016-02-01

    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-Fe1-xSi 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.

  3. 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.

  4. Water vapor effect on high-temperature oxidation behavior of Fe3Al intermetallics

    Directory of Open Access Journals (Sweden)

    Sebastian Chevalier, Pitor Juzon, Kazimierz Przybylski and Jean-Pierre Larpin

    2009-01-01

    Full Text Available Fe3Al intermetallics (Fe3Al, Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb were oxidized at 950 °C in dry and humid (11 vol% water synthetic air. Thermogravimetric measurements showed that the oxidation rates of the tested intermetallics were lower in humid air than in dry air (especially for Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb. The addition of small amounts of Zr, Mo or Nb improved the kinetics compared with that of the undoped Fe3Al. Fe3Al showed massive spallation, whereas Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb produced a flat, adherent oxide layer. The rapid transformation of transient alumina into alpha alumina may explain the decrease in the oxidation rate in humid air.

  5. 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.

  6. 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.

  7. Impact of firing on surface passivation of p-Si by SiO2/Al and SiO2/SiNx/Al stacks

    Science.gov (United States)

    Chen, J.; Cornagliotti, E.; Loozen, X.; Simoen, E.; Vanhellemont, J.; Lauwaert, J.; Vrielinck, H.; Poortmans, J.

    2011-12-01

    Firing impacts on surface passivation provided by a SiO2 and SiO2/SiNx stack with evaporated Al films are studied by capacitance-based techniques on MIS capacitors. For devices with insulator layers consisting solely of as-deposited SiO2, the densities of either interface states (Dit) or fixed charges (Qfc) are hardly influenced by firing. Capping the SiO2 layer with a SiNx layer results in a shift of the peak activation energy of Dit toward the valence band (Ev) of Si. Firing this SiO2/SiNx stack leads to an increase of Qfc, a reduction of Dit, and a moderate shift of peak activation energy of Dit toward Ev. Co-firing with the Al film on top significantly reduces the Qfc, Dit, and Dit peak activation energy, which is resulting from the atomic hydrogen passivation. These results are of particular interest for the development of solar cells with rear surface passivation and local contacts.

  8. Half-metallic {Co2MnSi/Co2FeSi} multilayered Heusler electrodes in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    It is demonstrated that the atomic ordering of Co2FeSi can significantly be improved in terms of magnetization and tunnel magnetoresistance using multilayered {Co2MnSi5nm/Co2FeSi5nm}10 full-Heusler magnetic electrodes in magnetic tunnel junctions

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

    OpenAIRE

    K. Labisz

    2013-01-01

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

  10. Wetting in Al composites reinforced with SiC particles

    OpenAIRE

    A.C. Vieira; Rocha, L A; Gomes, J. R.

    2006-01-01

    Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al matrix, coating of the SiC particles and to promote a passive oxidation of SiC pa...

  11. Pyrosmalite-(Fe, Fe8Si6O15(OH,Cl10

    Directory of Open Access Journals (Sweden)

    Hexiong Yang

    2012-01-01

    Full Text Available Pyrosmalite-(Fe, ideally FeII8Si6O15(OH,Cl10 [refined composition in this study: Fe8Si6O15(OH0.814Cl0.18610·0.45H2O, octairon(II hexasilicate deca(chloride/hydroxide 0.45-hydrate], is a phyllosilicate mineral and a member of the pyrosmalite series (Fe,Mn8Si6O15(OH,Cl10, which includes pyrosmalite-(Mn, as well as friedelite and mcgillite, two polytypes of pyrosmalite-(Mn. This study presents the first structure determination of pyrosmalite-(Fe based on single-crystal X-ray diffraction data from a natural sample from Burguillos del Cerro, Badajos, Spain. Pyrosmalite-(Fe is isotypic with pyrosmalite-(Mn and its structure is characterized by a stacking of brucite-type layers of FeO6-octahedra alternating with sheets of SiO4 tetrahedra along [001]. These sheets consist of 12-, six- and four-membered rings of tetrahedra in a 1:2:3 ratio. In contrast to previous studies on pyrosmalite-(Mn, which all assumed that Cl and one of the four OH-groups occupy the same site, our data on pyrosmalite-(Fe revealed a split-site structure model with Cl and OH occupying distinct sites. Furthermore, our study appears to suggest the presence of disordered structural water in pyrosmalite-(Fe, consistent with infrared spectroscopic data measured from the same sample. Weak hydrogen bonding between the ordered OH-groups that are part of the brucite-type layers and the terminal silicate O atoms is present.

  12. Spark plasma sintering of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy

    Science.gov (United States)

    Zúñiga, Alejandro; Ajdelsztajn, Leonardo; Lavernia, Enrique J.

    2006-04-01

    The microstructure and aging behavior of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was studied. The nanocrystalline powders were produced by milling at liquid nitrogen temperature and then consolidated using spark plasma sintering (SPS). The microstructure after SPS consisted of a bimodal aluminum grain structure (coarse-grained and fine-grained regions), along with Al9FeNi and Al2CuMg particles dispersed throughout. The microstructure observed in the as-consolidated sample is rationalized on the basis of high current densities that are generated during sintering. Solution treatment and aging of the SPS Al-Cu-Mg-Fe-Ni-Sc sample resulted in softening instead of hardening. This observation can be explained by the reduced amount of Cu, Mg, and Si in solid solution available to form S' Al2CuMg due to the precipitation of Al7FeCu2 and Si-rich particles, and by the fact that rodlike S' Al2CuMg particles could only precipitate out in the coarse-grained regions, greatly decreasing their influence on the hardness. This lack of precipitation in the fine-grained region is argued to represent a new physical observation and is rationalized on the basis of physical and thermodynamic effects. The nanocrystalline SPS Al-Cu-Mg-Fe-Ni-Sc sample was also extremely thermally stable, retaining a fine-grained structure even after solution treatment at 530°C for 5 h. The observed thermal stability is rationalized on the basis of solute drag and Zener pinning caused by the impurities introduced during the cryomilling process.

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    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 L21 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.

  16. Microstructure Evolution of Atomized Al-0.61 wt pct Fe and Al-1.90 wt pct Fe Alloys

    Science.gov (United States)

    Chen, Jian; Dahlborg, Ulf; Bao, Cui Min; Calvo-Dahlborg, Monique; Henein, Hani

    2011-06-01

    The microstructure evolution of impulse atomized powders of Al-0.61 wt pct and Al-1.90 wt pct Fe compositions have been investigated with a scanning electron microscope, transmission electron microscope, neutron diffraction, and backscattering electron diffraction (EBSD). Both hypoeutectic and hypereutectic compositions demonstrated similar macrostructure ( i.e., primary α-Al dendrites/cells with eutectic Al-Fe intermetallics decorated at the dendritic/cellular walls). Selected area electron diffraction (SAED) analysis and SAED pattern simulation identified the eutectic Al-Fe intermetallic as AlmFe ( m = 4.0-4.4). This is verified by neutron diffraction analysis. Cubic texture was observed by EBSD on the droplets with dendritic growth direction close to . The possible reasons are discussed.

  17. Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites

    International Nuclear Information System (INIS)

    An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle

  18. Fabrication of highly oriented D03-Fe3Si nanocrystals by solid-state dewetting of Si ultrathin layer

    International Nuclear Information System (INIS)

    In this paper, highly oriented nanocrystals of Fe3Si with a D03 structure are fabricated on SiO2 using ultrathin Si on insulator substrate. First, (001) oriented Si nanocrystals are formed on the SiO2 layer by solid state dewetting of the top Si layer. Then, Fe addition to the Si nanocrystals is performed by reactive deposition epitaxy and post-deposition annealing at 500 °C. The structures of the Fe–Si nanocrystals are analyzed by cross-sectional transmission electron microscopy and nanobeam electron diffraction. We observe that Fe3Si nanocrystals with D03, B2, and A2 structures coexist on the 1-h post-annealed samples. Prolonged annealing at 500 °C is effective in obtaining Fe3Si nanocrystals with a D03 single phase, thereby promoting structural ordering in the nanocrystals. We discuss the formation process of the highly oriented D03-Fe3Si nanocrystals on the basis of the atomistic structural information. - Highlights: • Highly oriented Fe–Si nanocrystals (NCs) are fabricated by reactive deposition. • Si NCs formed by solid state dewetting of Si thin layers are used as seed crystals. • The structures of Fe–Si NCs are analyzed by nanobeam electron diffraction. • Most of Fe–Si NCs possess the D03 structure after post-deposition annealing

  19. Surface acoustic wave devices on AlN/3C–SiC/Si multilayer structures

    International Nuclear Information System (INIS)

    Surface acoustic wave (SAW) propagation characteristics in a multilayer structure including a piezoelectric aluminum nitride (AlN) thin film and an epitaxial cubic silicon carbide (3C–SiC) layer on a silicon (Si) substrate are investigated by theoretical calculation in this work. Alternating current (ac) reactive magnetron sputtering was used to deposit highly c-axis-oriented AlN thin films, showing the full width at half maximum (FWHM) of the rocking curve of 1.36° on epitaxial 3C–SiC layers on Si substrates. In addition, conventional two-port SAW devices were fabricated on the AlN/3C–SiC/Si multilayer structure and SAW propagation properties in the multilayer structure were experimentally investigated. The surface wave in the AlN/3C–SiC/Si multilayer structure exhibits a phase velocity of 5528 m s−1 and an electromechanical coupling coefficient of 0.42%. The results demonstrate the potential of AlN thin films grown on epitaxial 3C–SiC layers to create layered SAW devices with higher phase velocities and larger electromechanical coupling coefficients than SAW devices on an AlN/Si multilayer structure. Moreover, the FWHM values of rocking curves of the AlN thin film and 3C–SiC layer remained constant after annealing for 500 h at 540 °C in air atmosphere. Accordingly, the layered SAW devices based on AlN thin films and 3C–SiC layers are applicable to timing and sensing applications in harsh environments. (paper)

  20. Untersuchungen auf dem Gebiet der Al-Mg-Si- und Al/Mg2Si-in-situ Legierungen

    OpenAIRE

    Uyma, Falko

    2009-01-01

    Das Ziel dieser Arbeit bestand in der Entwicklung eines Werkstoffes auf Basis der Legierung AlSi13,5Mg9,5 (=Al-15Mg2Si-8Si), die sich durch ein verbessertes Verschleißverhalten, geringere thermische Ausdehnung und geringere Dichtewerte auszeichnet. Eine wesentliche Aufgabe der Arbeit bestand in der Einstellung bester mechanischer Eigenschaften durch die Feinung der Primär-Phase (Mg2Si) sowie durch Mikrolegieren. Ausbleibende Resultate begründeten die Wahl einer angepassten Legierungszusammens...

  1. 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.

  2. 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.

  3. Work of Adhesion in Al/SiC Composites with Alloying Element Addition

    Science.gov (United States)

    Fang, Xin; Fan, Tongxiang; Zhang, Di

    2013-11-01

    In the current work, a general methodology was proposed to demonstrate how to calculate the work of adhesion in a reactive multicomponent alloy/ceramic system. Applying this methodology, the work of adhesion of Al alloy/SiC systems and the influence of different alloying elements were predicted. Based on the thermodynamics of interfacial reaction and calculation models for component activities, the equilibrium compositions of the melts in Al alloy/SiC systems were calculated. Combining the work of adhesion models for reactive metal/ceramic systems, the work of adhesion in Al alloy/SiC systems both before and after the reaction was calculated. The results showed that the addition of most alloying elements, such as Mg, Si, and Mn, could increase the initial work of adhesion, while Fe had a slightly decreasing effect. As for the equilibrium state, the additions of Cu, Fe, Mn, Ni, Ti, and La could increase the equilibrium work of adhesion, but the additions of Mg and Zn had an opposite effect. Si was emphasized due to its suppressing effect on the interfacial reaction.

  4. 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.

  5. Intermetallic phase particles in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys

    Directory of Open Access Journals (Sweden)

    G. Mrówka-Nowotnik

    2009-08-01

    Full Text Available Purpose: In the technical Al alloys even small quantity of impurities - Fe and Mn - causes the formation of new phase components. Intermetallic particles form either on solidification or whilst the alloy is at a relatively high temperature in the solid state, e.g. during homogenization, solution treatment or recrystallization. The exact composition of the alloy and casting condition will directly influence the selection and volume fraction of intermetallic phases. The main objective of this study was to analyze the morphology and composition of complex microstructure of intermetallic phases in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminium alloys.Design/methodology/approach: In this study, several methods were used such as: optical light microscopy (LM, scanning (SEM electron microscopy in combination with X-ray analysis (EDS using polished sample, and X-ray diffraction (XRD to identify intermetallics in cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys.Findings: The results show that the microstructure of cast AlSi5Cu1Mg and AlCu4Ni2Mg2 aluminum alloys in T6 condition consisted a wide range of intermetallic phases. By using various instruments (LM, SEM, XRD and techniques (imagine, EDS following intermetallic phases were identified: β-Al5FeSi, α-Al15(FeMn3Si - in AlSi5Cu1Mg alloy and Al7Cu4Ni, Al12Cu23Ni, Al2CuMg, AlCuFeNi - in AlCu4Ni2Mg2 alloy.Research limitations/implications: In order to complete and confirm obtained results it is recommended to perform further analysis of the investigated aluminium alloys. Therefore it is planned to include in a next studies, microstructure analysis of the alloys by using transmission electron microscopy technique (TEM.Practical implications: Since the morphology, crystallography and chemical composition affect the intermetallic properties, what involves changes of alloy properties, from a practical point of view it is important to understand their formation conditions in order to control final constituents of

  6. Role of silicon in solidification microstructure in hot-dipped 55 wt% Al-Zn-Si coatings

    International Nuclear Information System (INIS)

    An experimental study has been carried out into the effect of silicon content on 55 wt% Al-Zn-Si metallic coating solidification. Immersion experiments were conducted on a metal coating simulator, and the resulting solidification structure was characterised in terms of spangle size and secondary dendrite arm spacing (SDAS). It was found that at bath temperatures of 600 deg. C as silicon content was increased from 1.05 to 1.5 wt% there were an increase in spangle size without any change in SDAS. Thermodynamic modelling was utilised to probe the phase stability of intermetallic species in the baths. Two competing intermetallic phases, α-AlFeSi and Fe3Al, are stabilised dependant upon bath silicon content and temperature. Literature data for the lattice mismatch between α-Al, the primary solidification phase in this study, with these two intermetallic phases indicates that FeAl3 has much better crystallographic fit than does α-AlFeSi. This supports the proposal that FeAl3 has a higher nucleation site density for solidification, which results in a reduced spangle size. The thermodynamic modelling has been used to provide compositional and temperature ranges for spangle size control

  7. Magnetization Processes of Fe–(Si,Al)—Steels With Homogeneous and Inhomogeneous Distributions of (Si,Al)

    OpenAIRE

    Verstraete, Jurgen; Verbeken, K.; Schneider, J.; Houbaert, Y.

    2008-01-01

    Recently, there has been a lot of activity trying to produce steel with an increased concentration, i.e., over 3 wt.%, of Si and/or Al. Materials with homogeneous as well as inhomogeneous spatial distributions of (Si,Al) have been obtained. We will discuss in this paper aspects of the magnetization processes in these new types of materials. We will compare the resulting structure properties and magnetization behavior for samples with a large gradient of the (Si,Al) content and a more smooth d...

  8. 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.

  9. 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+.

  10. Alloy development and processing of FeAl: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.; Goodwin, G.M.; Alexander, D.J.; Viswanathan, S.

    1997-03-01

    In the last few years, considerable progress has been made in developing B2-phase FeAl alloys with improved weldability, room-temperature ductility, and high-temperature strength. Controlling the processing-induced microstructure is also important, particularly for minimizing trade-offs in various properties. FeAl alloys have outstanding resistance to high-temperature oxidation, sulfidation, and corrosion in various kinds of molten salts due to formation of protective Al{sub 2}O{sub 3} scales. Recent work shows that FeAl alloys are carburization-resistant as well. Alloys with 36 to 40 at. % Al have the best combination of corrosion resistance and mechanical properties. Minor alloying additions of Mo, Zr, and C, together with microalloying additions of B, produce the best combination of weldability and mechanical behavior. Cast FeAl alloys, with 200 to 400 {mu}m grain size and finely dispersed ZrC, have 2 to 5% tensile ductility in air at room-temperature, and a yield strength > 400 MPa up to about 700 to 750{degrees}C. Extruded ingot metallurgy (I/M) and powder metallurgy (P/M) materials with refined grain sizes ranging from 2 to 50 {mu}m, can have 10 to 15% ductility in air and be much stronger, and can even be quite tough, with Charpy impact energies ranging from 25 to 105 J at room-temperature. This paper highlights progress made in refining the alloy composition and exploring processing effects on FeAl for monolithic applications. It also includes recent progress on developing FeAl weld-overlay technology, and new results on welding of FeAl alloys. It summarizes some of the current industrial testing and interest for applications.

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

    Institute of Scientific and Technical Information of China (English)

    Yuna Wu; Hengcheng Liao

    2013-01-01

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

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

    Science.gov (United States)

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

    2013-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-12-15

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

  15. Important research targets to be explored for β-FeSi2 device making

    International Nuclear Information System (INIS)

    To place β-FeSi2 as a 3rd generation Kankyo (Environmentally Friendly) Semiconductor after GaAs, one should demonstrate its superior features by fabricating practical devices. One has to prepare high-quality β-FeSi2 films with (1) precisely controlled Fe/Si ratio (1:2), (2) flat and cracks-free surface, (3) pinhole-free surface and interfaces, (4) flat interfaces, (5) well-controlled electron or hole concentration with residual carrier concentration as low as ∼10 16 cm-3. One should accordingly explore novel thin film manufacturing technologies by considering specific properties of constituent Fe and Si atoms. Conventional growth methods used for III-V and II-VI compound semiconductor films are not suited for β-FeSi2. Here we summarize the current status of film preparation technologies and describe their advantages and drawbacks. To explore the possibility of β-FeSi2 for low cost and high conversion efficiency solar cells, high quality β-FeSi2 films have been formed on Si substrates by molecular beam epitaxy (MBE) and sputtering methods. The critical feature about the device structure is an optimized thin β-FeSi2 template buffer layer on Si(111) substrate. The template served as a substrate for epitaxial growth of single crystal β-FeSi2 film and restrains the Fe diffusion into Si at β-FeSi2/Si interface. For n-β-FeSi2/p-Si structure under air mass 1.5, an energy conversion efficiency of 3.7% was obtained, showing that β-FeSi2 is practically a promising semiconductor for making solar cells

  16. Preparation of Al-Cr-Si oxide tritium permeation barrier by double glow plasma technology

    International Nuclear Information System (INIS)

    Al-Cr-Si oxide coatings were prepared on 316L stainless steel by double glow plasma surface alloying technique in order to promote the capability against tritium permeation. Microstructures and compositions of the coatings were studied by scanning electron microscope, transmission electron microscope and X-ray diffraction. Adhesion strength of the oxide coatings was tested by scratch adhesion test and thermal shock test. The results showed that dense and continuous Al2O3 films were formed on the substrate owing to the addition of elements Cr and Si. Besides, the spinel-type composite metal oxide Fe(AlCr)2O4 was formed of Al2O3 and iron/chromic oxide in the outer layer. The coatings prepared at oxygen flow rate of 10 standard cubic centimeter per minute exhibited the best microstructure and mechanical properties with a bonding force of 68 N. No cracks were found in the coatings after thermal shock testing. (authors)

  17. Tetragonal phase in Al-rich region of U-Fe-Al system

    Energy Technology Data Exchange (ETDEWEB)

    Meshi, L. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Zenou, V. [Nuclear Research Center-Negev, P.O. Box 9001, Beer-Sheva (Israel); Ezersky, V. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Munitz, A. [Nuclear Research Center-Negev, P.O. Box 9001, Beer-Sheva (Israel); Talianker, M. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)]. E-mail: mital@bgumail.bgu.ac.il

    2005-10-27

    A new ternary aluminide U{sub 2}FeAl{sub 20} with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m.

  18. Tetragonal phase in Al-rich region of U-Fe-Al system

    International Nuclear Information System (INIS)

    A new ternary aluminide U2FeAl20 with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m

  19. Water vapor effect on high-temperature oxidation behavior of Fe3Al intermetallics

    OpenAIRE

    Sebastian Chevalier, Pitor Juzon, Kazimierz Przybylski and Jean-Pierre Larpin

    2009-01-01

    Fe3Al intermetallics (Fe3Al, Fe3Al-Zr, Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb) were oxidized at 950 °C in dry and humid (11 vol% water) synthetic air. Thermogravimetric measurements showed that the oxidation rates of the tested intermetallics were lower in humid air than in dry air (especially for Fe3Al-Zr,Mo and Fe3Al-Zr,Mo,Nb). The addition of small amounts of Zr, Mo or Nb improved the kinetics compared with that of the undoped Fe3Al. Fe3Al showed massive spallation, whereas Fe3Al-Zr, Fe3Al-Zr,Mo a...

  20. Oxidation Resistant Ti-Al-Fe Diffusion Barrier for FeCrAlY Coatings on Titanium Aluminides

    Science.gov (United States)

    Brady, Michael P. (Inventor); Smialke, James L. (Inventor); Brindley, William J. (Inventor)

    1996-01-01

    A diffusion barrier to help protect titanium aluminide alloys, including the coated alloys of the TiAl gamma + Ti3Al (alpha2) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C is disclosed. The coating may comprise FeCrAlX alloys. The diffusion barrier comprises titanium, aluminum, and iron in the following approximate atomic percent: Ti-(50-55)Al-(9-20)Fe. This alloy is also suitable as an oxidative or structural coating for such substrates.

  1. 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.

  2. Refinement of primary Si grains in Al-20%Si alloy slurry through serpentine channel pouring process

    Science.gov (United States)

    Zheng, Zhi-kai; Mao, Wei-min; Liu, Zhi-yong; Wang, Dong; Yue, Rui

    2016-05-01

    In this study, a serpentine channel pouring process was used to prepare the semi-solid Al-20%Si alloy slurry and refine primary Si grains in the alloy. The effects of the pouring temperature, number of curves in the serpentine channel, and material of the serpentine channel on the size of primary Si grains in the semi-solid Al-20%Si alloy slurry were investigated. The results showed that the pouring temperature, number of the curves, and material of the channel strongly affected the size and distribution of the primary Si grains. The pouring temperature exerted the strongest effect, followed by the number of the curves and then the material of the channel. Under experimental conditions of a four-curve copper channel and a pouring temperature of 701°C, primary Si grains in the semi-solid Al-20%Si alloy slurry were refined to the greatest extent, and the lath-like grains were changed into granular grains. Moreover, the equivalent grain diameter and the average shape coefficient of primary Si grains in the satisfactory semi-solid Al-20%Si alloy slurry were 24.4 μm and 0.89, respectively. Finally, the refinement mechanism and distribution rule of primary Si grains in the slurry prepared through the serpentine channel pouring process were analyzed and discussed.

  3. 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.

  4. Dispersion of ultrafine SiC particles in molten Al- 12Si alloy

    Institute of Scientific and Technical Information of China (English)

    Jin-Ju PARK; Sang-Hoon LEE; Min-Ku LEE; Chang-Kyu RHEE

    2011-01-01

    The bulk Al-12 Si eutectic composites were fabricated through a conventional liquid metal casting route, especially with the help of ultrafine ceramic powders made by self-propagating high-temperature synthesis (SHS) process. The SHS powders were fabricated by the chemical reaction between micro-sized SiC and Al particles at very high combustion temperatures, producing the coarse Al particles (several tens of microns) containing ultrafine SiC ceramic particles. Microstmctural observation revealed that the addition of ultrafine SiC particles has a crumbling tendency of Si eutectic phase. It is suggested that the casting method combined with SHS process is promising for fabricating the Al-based MMC with ultrafine ceramic particles.

  5. A magnetic tunnel junction with an L21-ordered Co2FeSi electrode formed by all room-temperature fabrication processes

    International Nuclear Information System (INIS)

    We explore magnetic tunnel junctions consisting of Co60Fe40/AlOx/Co2FeSi trilayers on Si(111) by room-temperature molecular beam epitaxy. Even for the all room-temperature fabrication processes, the Co2FeSi layer includes L21-ordered structures. We demonstrate reproducible tunneling magnetoresistance ratios of ∼ 44% and ∼ 28% at 30 K and 300 K, respectively. Assuming the same room-temperature spin polarization (P) of CoFe alloys, P for Co2FeSi grown at room temperature is larger than that for D03-Fe3Si grown at 130 °C. - Highlights: • Room-temperature fabrication processes of magnetic tunnel junctions were developed. • Room-temperature grown Co2FeSi film formed an L21-ordered structure. • Spin polarization for the L21-Co2FeSi was higher than 130 °C-grown D03-Fe3Si

  6. A magnetic tunnel junction with an L2{sub 1}-ordered Co{sub 2}FeSi electrode formed by all room-temperature fabrication processes

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Yuichi; Yamada, Shinya; Maeda, Yuya [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Miyao, Masanobu [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); CREST, Japan Science and Technology Agency, Chiyoda, Tokyo 102-0076 (Japan); Hamaya, Kohei, E-mail: hamaya@ed.kyushu-u.ac.jp [Department of Electronics, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2014-04-30

    We explore magnetic tunnel junctions consisting of Co{sub 60}Fe{sub 40}/AlO{sub x}/Co{sub 2}FeSi trilayers on Si(111) by room-temperature molecular beam epitaxy. Even for the all room-temperature fabrication processes, the Co{sub 2}FeSi layer includes L2{sub 1}-ordered structures. We demonstrate reproducible tunneling magnetoresistance ratios of ∼ 44% and ∼ 28% at 30 K and 300 K, respectively. Assuming the same room-temperature spin polarization (P) of CoFe alloys, P for Co{sub 2}FeSi grown at room temperature is larger than that for D0{sub 3}-Fe{sub 3}Si grown at 130 °C. - Highlights: • Room-temperature fabrication processes of magnetic tunnel junctions were developed. • Room-temperature grown Co{sub 2}FeSi film formed an L2{sub 1}-ordered structure. • Spin polarization for the L2{sub 1}-Co{sub 2}FeSi was higher than 130 °C-grown D0{sub 3}-Fe{sub 3}Si.

  7. Modification of Surface Roughness and Area of FeCrAl Substrate for Catalytic Converter using Ultrasonic Treatment

    Directory of Open Access Journals (Sweden)

    Yanuandri Putrasari

    2012-03-01

    Full Text Available Surface roughness and area play important role especially in deposition and reaction of the catalyst in the catalytic converter substrate. The aim of this paper is to show the modification of surface roughness and area of FeCrAl substrate for catalytic converter using ultrasonic method. The method was conducted by agitating the FeCrAl in 10 minutes 35 kHz ultrasonic cleaning bath. The  surface roughness, morphology, and chemical components of FeCrAl catalytic converter substrate after ultrasonic treatment were analyzed using atomic force microscope (AFM and examined with scanning electron microscope (SEM in combination with energy dispersive X-ray spectroscopy (EDS. The ultrasonic treatment assisted with Al2O3 powders successfully increased the roughness and surface area of FeCrAl better than SiC powders. 

  8. Fe--Sialon复合材料中 Fe3 Si 合成热力学分析及实验验证%Thermodynamic analysis and experimental confirmation of Fe3 Si synthesis in Fe--Sialon composites

    Institute of Scientific and Technical Information of China (English)

    郝洪顺; 苏青; 连芳; 郭伟华; 靳闪闪; 刘贵山; 高文元

    2015-01-01

    A thermodynamic analysis was performed on possible reactions of Fe3 O4 in sediment material, intermediate product FeO, Fe, and other matters. In combination with the predominant area phase diagram of the Fe-Si system under different carbon mon-oxide partial pressures and excess carbon and silicon dioxide as well as the thermodynamic parameter state diagram of the Fe-O-N sys-tem, it is found that Fe finally exists in the form of Fe3 Si, which provides a thermodynamic theoretical basis for using sediment to syn-thesize O′-Sialon-SiC-Fe3 Si ( Fe-Sialon) composites. These Fe-Sialon matrix composites made from sediment were prepared by car-bothermal reduction-nitridation on the basis of thermodynamic analysis. X-ray diffraction and scanning electron microscopy results in-dicate that plentiful O′-Sialon phase and a small quantity of SiC and Fe3 Si phases appear in samples, and the crystalline grains are fi-ber-, cotton-, or short column-shaped, which is consistent with thermodynamic analysis results.%对淤泥沙原料中Fe3 O4及其中间产物FeO和Fe可能参与的反应进行了热力学分析。结合绘制的不同CO分压下Fe-Si体系在C和SiO2过量下的优势区相图及Fe-O-N体系热力学参数状态图,得出体系中Fe元素最终以Fe3 Si形式存在,为淤泥沙合成O′-Sialon-SiC-Fe3 Si (即Fe-Sialon)复合材料提供了热力学理论依据。在热力学分析的基础上,以淤泥沙为主要原料,采用碳热还原氮化法制备了Fe-Sialon复合材料,并借助X射线衍射仪和扫描电子显微镜对烧结体的物相和显微形貌进行了表征,得出产物的主晶相为O′-Sialon,还含有少量的SiC和Fe3 Si相,晶粒呈现为纤维状、絮状或短柱状,与热力学分析结果( Fe元素最终以Fe3 Si存在)吻合。

  9. Effect of Fe coating of nucleation sites on epitaxial growth of Fe oxide nanocrystals on Si substrates

    Science.gov (United States)

    Ishibe, Takafumi; Watanabe, Kentaro; Nakamura, Yoshiaki

    2016-08-01

    We studied the effect of Fe coating on the epitaxial growth of Fe3O4 nanocrystals (NCs) over Fe-coated Ge epitaxial nuclei on Si(111). To completely cover Ge nuclei with Fe, some amount of Fe (>8 monolayers) must be deposited. Such covering is a key to epitaxial growth because an Fe coating layer prevents the oxidation of Ge surfaces during Fe3O4 formation, resulting in the epitaxial growth of Fe3O4 on them. This study demonstrates that an appropriate Fe coating of nucleation sites leads to the epitaxial growth of Fe3O4 NCs on Si substrates, indicating the realization of environmentally friendly and low-cost Fe3O4 NCs as the resistance random access memory material.

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

    OpenAIRE

    F.L. Alcântara; Barbosa, R; Cunha, M.A.

    2013-01-01

    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 grow...

  11. 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.

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  13. Dependence of BiFeO3 thickness on exchange bias in BiFeO3/ Co2FeAl multiferroic structures

    Science.gov (United States)

    Zhang, X.; Zhang, D. L.; Wang, Y. H.; Miao, J.; Xu, X. G.; Jiang, Y.

    2011-01-01

    We have grown BiFeO3 (BFO) thin films with different thickness on Si/SiO2/Ti/Pt(111) substrates by pulsed laser deposition. Half-metallic Co2FeAl (CFA) films with a thickness of 5 nm were then grown on the BFO films by magnetron sputtering. Through the magnetic hysteresis loops of the BFO/CFA heterostructure, we observe a direct correlation between the thickness of the BFO film and exchange bias (EB) field. The EB field exhibits fluctuation behavior with a cyclical BFO thickness of 60 nm, which is close to the spiral modulation wavelength (62 nm) of BFO. It indicates the influence of spiral modulation on the EB in the BFO/CFA multiferroic structure.

  14. A polarized neutron study of the magnetization distribution in Co2FeSi

    International Nuclear Information System (INIS)

    The magnetization distribution in Co2FeSi which has the largest moment per formula unit ∼6 μB of all Heusler alloys, has been determined using polarized neutron diffraction. The experimentally determined magnetization has been integrated over spheres centred on the three sites of the L12 structure giving μ Fe = 3.10(3) μB and μ Co = 1.43(2) μB, results which are slightly lower than the moments in atomic spheres of similar radii obtained in recent LDA + U band structure calculations (Li et al 2010 Chin. Phys. B 19 097102). Approximately 50% of the magnetic carriers at the Fe sites were found to be in orbitals with eg symmetry. This was higher, ≃65%, at the Co sites. Both Fe and Co were found to have orbital moments that are larger than those predicted. Comparison with similar results obtained for related alloys suggests that there must be a finite density of states in both spin bands at the Fermi energy indicating that Co2FeSi is not a perfect half-metallic ferromagnet. (paper)

  15. Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

    Science.gov (United States)

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

    2016-05-01

    Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

  16. 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.

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

    OpenAIRE

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

    2016-01-01

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

  18. Room-temperature magnetocurrent in antiferromagnetically coupled Fe/Si/Fe

    Science.gov (United States)

    Gareev, Rashid; Schmid, Maximilian; Vancea, Johann; Back, Christian; Schreiber, Reinert; Buergler, Daniel; Schneider, Claus; Stromberg, Frank; Wende, Heiko

    2011-03-01

    Epitaxial Si-based ferromagnet/semiconductor structures demonstrate strong antiferromagnetic coupling (AFC) as well as resonant-type tunneling magnetoresistance, which vanishes at temperatures above T ~ 50 K. Magnetoresistance effects in Fe/Si/Fe close to room temperature (RT) were not established yet. By using the ballistic electron magnetomicroscopy (BEMM) techniques, with its nanometer-scaled locality we observed for the first time a spin-dependent ballistic magnetotransport in AFC structures. We found that the hot-electron collector current with energies above the Fe/GaAsP Schottky barrier reflects magnetization alignment and changes from IcAP ~ 50 fA for antiparallel alignment to IcP ~ 150 fA for the parallel one. Thus, the magnetocurrent [(IcP -IcAP) / IcAP ]*100% is near 200 % at RT. The measured BEMM hysteresis loops match nicely with the magnetic MOKE data. This work is supported by the project DFG 9209379.

  19. Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

    Science.gov (United States)

    Lei, Hong; Gu, Qian; Chen, Ruling; Wang, Zhanyong

    2015-08-20

    Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR. PMID:26368752

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Li Runxia

    2011-02-01

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

  2. 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.

  3. The influence of Al content on the Zener relaxation of Fe-Al alloys

    International Nuclear Information System (INIS)

    The effect of Al content on the Zener relaxation peak of annealed Fe-Al alloys has been investigated using a computer-controlled automatic inverted torsion pendulum through the method of free decay and forced vibration. It has been shown that alloys with medium Al contents show strong relaxation while lower or higher Al contents lead to relatively weak Zener relaxation peaks. The Zener relaxation in Fe-Al alloys originates from the next-nearest-neighbour atom pairs and their interaction rather than the nearest-neighbour atom pairs. The latter may not produce Zener relaxation because of the ordered structure, which suppresses Zener relaxation

  4. Fe-Co-Al-O soft magnetic films for main pole of CF-SPT head and underlayer of perpendicular double-layered media

    International Nuclear Information System (INIS)

    A cusp-field single-pole (CF-SPT) head and perpendicular double-layered media were examined by using sputtered Fe-Co-Al-O/Ni-Fe films with excellent soft magnetic properties in a wide range of film thicknesses. The CF-SPT head with a high Bs Fe-Co-Al-O main pole of 2.4 T shows a better overwrite property than that with a lower Bs Fe-Si-N main pole of 1.9 T. The medium with a high Bs Fe-Co-Al-O soft magnetic underlayer (SUL) had a lower transition noise, and consequently a higher SNR than that with a lower Bs Fe-Si and Ni-Fe-Nb SUL. Furthermore, it also shows good write sensitivity and overwrite property

  5. Enhancement of the Si p-n diode NIR photoresponse by embedding β-FeSi2 nanocrystallites

    OpenAIRE

    A. V. Shevlyagin; Goroshko, D. L.; Chusovitin, E. A.; Galkin, K.N.; Galkin, N. G.; A. K. Gutakovskii

    2015-01-01

    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 efficie...

  6. Ab initio studies of Co2FeAl1-xSix Heusler alloys

    Science.gov (United States)

    Szwacki, N. Gonzalez; Majewski, Jacek A.

    2016-07-01

    We present results of extensive theoretical studies of Co2FeAl1-xSix Heusler alloys, which have been performed in the framework of density functional theory employing the all-electron full-potential linearized augmented plane-wave scheme. It is shown that the Si-rich alloys are more resistive to structural disorder and as a consequence Si stabilizes the L21 structure. Si alloying changes position of the Fermi level, pushing it into the gap of the minority spin-band. It is also shown that the hyperfine field on Co nuclei increases with the Si concentration, and this increase originates mostly from the changes in the electronic density of the valence electrons.

  7. STUDY ON INTERNAL FRICTION OF Al-Mg-Si AND Al-Mg-Si-0.6% Cu ALLOYS%Al-Mg-Si合金和Al-Mg-Si-0.6%Cu合金的内耗研究

    Institute of Scientific and Technical Information of China (English)

    金曼; 杨丽丽; 夏朝峰

    2011-01-01

    采用低频力学谱仪对Al-Mg-Si合金和Al-Mg-Si-0.6% Cu合金的内耗进行了研究.结果表明:两种合金的内耗在加热过程先升高后降低.利用TEM对AI-Mg-Si合金和Al-Mg-Si-0.6%Cu合金的微观结构进行观察,显示合金内耗的变化是合金中的析出相和位错相互作用的结果.%The internal friction of Al-Mg-Si and Al-Mg-Si-0.6% Cu Alloys was studied by low frequency mechanical spectrum apparatus.The result showed that there was an internal friction peak in the internal friction spectrum of Al-Mg-Si Alloy and Al-Mg-Si-0.6% Cu Alloy.The microstructure of Al-Mg-Si and Al-Mg-Si-0.6% Cu Alloys were observed by TEM.The result showed that the interaction between the precipitates and dislocations led to the change of internal friction.

  8. 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.

  9. Effects of the ratio of Fe to Co over Fe-Co/SiO2 bimetallic catalysts on their catalytic performance for Fischer-Tropsch synthesis

    Institute of Scientific and Technical Information of China (English)

    Xiangdong Ma; Qiwen Sun; Weiyong Ying; Dingye Fang

    2009-01-01

    The Fe-Co/SiO2 bimetallic catalysts with different ratios of Fe to Co were prepared by aqueous incipient wetness impregnation. The catalysts of 10%Fe:0%Co/SiO2, 10%Fe:6%Co/SiO2, 10%Fe:2%Co/SiO2, 10%Fe: 10%Co/SiO2, 6%Fe: 10%Co/SiO2, 2%Fe: 10%Co/SiO2 and 0%Fe: 10%Co/SiO2 by mass were tested in a fixed reactor by the Fischer-Tropsch synthesis. Activity and hydrocarbon distribution were found to be determined by the ratio of iron to cobalt of the catalysts. Higher iron content inhibited the activity, whereas higher cobalt content enhanced the activity of the Fe-Co/SiO2 catalysts. On the other hand, for the catalysts of 10%Fe:6%Co/SiO2, 10%Fe: 10%Co/SiO2, 6%Fe: 10%Co/SiO2, and 2%Fe: 10%Co/SiO2, the total C2-C4 fraction increased (from 10.65% to 26.78%) and C5+ fraction decreased (from 75.75% to 57.63%) at 523 K. Temperature programmed reduction revealed that the addition of cobalt enhanced the reducibility of the Fe-Co/SiO2 catalyst. Metal oxides were present in those catalysts as shown by XRD. The Fe-Co alloy phase was found in the 2%Fe: 10%Co/SiO2, 6%Fe: 10%Co/SiO2, 10%Fe:10%Co/SiO2, 10%Fe:6%Co/SiO2 catalysts and their crystals were perfect.

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

    International Nuclear Information System (INIS)

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

  11. 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.

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

    OpenAIRE

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

    2011-01-01

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

  13. 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

    International Nuclear Information System (INIS)

    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. - Highlights: • The SrFe12O19 film deposited on different Si(100), Si(100)/Pt(111) and Al2O3(0001) substrates by PLD. • The SrM/Pt(111) and SrM/Al2O3(0001) films showed the c-axis perpendicular orientation. • The SrM/Al2O3(0001) films exhibited more perpendicular magnetic anisotropy than SrM/Pt(111) films. • The Al2O3(0001) substrate can be replaced by the Si(100)/Pt(111) substrate

  14. 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.

  15. Crystallization behavior of Fe78Si13B9 metallic glass under high magnetic field

    Institute of Scientific and Technical Information of China (English)

    Yuanfei Yu; Baozhu Liu; Min Qi

    2008-01-01

    The effects of high magnetic field on the crystallization behavior of the Fe78Si13B9 metallic glass ribbon were studied. The samples were isothermal annealed for 30 min under high magnetic field and no field, respectively. Mierostructure transformation during crystallization was identified by X-ray diffraction and transmission electron microscopy. It was found that the crystallizations of Fe78Si13B9 metallic glass processed under different conditions were that the precipitation of dendrite α-Fe(Si) and spherulite (Fe,Si)3B phases forms amorphous matrix and then the metastable (Fe, Si)3B phase transforms into the stable Fe2B phase. The grain size of the crystals is smaller and more homogeneous for the isothermal annealed samples under high magnetic field in comparison with that under no field indicating that the crystallization behavior of Fe78Si13B9 metallic glass is suppressed by high magnetic field.

  16. Effect of Si content on the dry sliding wear properties of spray-deposited Al-Si alloy

    International Nuclear Information System (INIS)

    In the present investigation, Al-12Si, Al-20Si and Al-25Si (wt%) alloys were synthesized by spray atomization and deposition technique. The wear resistance of the alloys was studied using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. The microstructures, worn surfaces and the debris were analyzed in a scanning electron microscope. It has been found that the effect of Si content on dry sliding wear of spray-deposited Al-Si alloy was associated with applied loads. At lower load (8.9 N), with increasing Si content, the wear rate of the alloy was decreased. At higher load (35.6 N), spray-deposited Al-20Si alloy exhibited superior wear resistance to the Al-12Si and Al-25Si alloys

  17. 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.

  18. (Si)5-2y(AlP)y alloys assembled on Si(100) from Al-P-Si3 building units

    International Nuclear Information System (INIS)

    An original class of IV/III-V hybrid (Si)5-2y(AlP)y/Si(100) semiconductors have been produced via tailored interactions of molecular P(SiH3)3 and atomic Al yielding tetrahedral ''Al-P-Si3'' building blocks. Extensive structural, optical, and vibrational characterization corroborates that these units condense to assemble single-phase, monocrystalline alloys containing 60%-90% Si (y = 0.3-1.0) as nearly defect-free layers lattice-matched to Si. Spectroscopic ellipsometry and density functional theory band structure calculations indicate mild compositional bowing of the band gaps, suggesting that the tuning needed for optoelectronic applications should be feasible.

  19. Assessment of Mn-Fe-Si-C Melt in Unified Interaction Parameter Formalism

    Science.gov (United States)

    Shin, Jung Pil; Lee, Young E.

    2016-02-01

    The solubility of C in Mn-Fe-Si-C melt decreases with increasing Si content, and its decrease becomes greater when the phase in equilibrium with Mn-Fe-Si-C melt changes from carbon to SiC. Such behavior has an industrial implication for low carbon products and processes of steels and Mn alloys. Li and Morris assessed the solution properties of Mn-Fe-Si-C system in the UIP formalism, but the effectiveness of their assessment was limited in applicable ranges of composition to Mn-rich solution and of temperature to around 1673 K (1400 °C). This study develops the information of activity coefficients of C and Si of Mn-Fe-Si-C system from the consistent experimental solubility of C and assesses them in the UIP formalism. This assessment of Mn-Fe-Si-C system describes confidently the behavior of solution properties in a wide range of composition and temperature.

  20. Oxidation Behavior of FeCrAl -coated Zirconium Cladding prepared by Laser Coating

    International Nuclear Information System (INIS)

    From the recent research trends, the ATF cladding concepts for enhanced accident tolerance are divided as follows: Mo-Zr cladding to increase the high temperature strength, cladding coating to increase the high temperature oxidation resistance, FeCrAl alloy and SiC/SiCf material to increase the oxidation resistance and strength at high temperature. To commercialize the ATF cladding concepts, various factors are considered, such as safety under normal and accident conditions, economy for the fuel cycle, and developing development challenges, and schedule. From the proposed concepts, it is known that the cladding coating, FeCrAl alloy, and Zr-Mo claddings are considered as a near/mid-term application, whereas the SiC material is considered as a long-term application. Among them, the benefit of cladding coating on Zr-based alloys is the fuel cycle economy regarding the manufacturing, neutron cross section, and high tritium permeation characteristics. However, the challenge of cladding coating on Zr-based alloys is the lower oxidation resistance and mechanical strength at high-temperature than other concepts. Another important point is the adhesion property between the Zr-based alloy and coating materials. A laser coating method supplied with FeCrAl powders was developed to decrease the high-temperature oxidation rate in a steam environment through a systematic study for various coating parameters, and a FeCrAl-coated Zircaloy-4 cladding tube of 100 mm in length to the axial direction can be successfully manufactured

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-08-01

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

  3. 57Fe Mössbauer spectroscopy and magnetic study of Al13Fe4

    International Nuclear Information System (INIS)

    Highlights: • We show that Mössbauer spectra of Al13Fe4 can be fitted well with three quadrupole doublets. • The shape of the in-field Mössbauer spectrum is well accounted for with five component subspectra. • The electronic density of states has a pseudogap around the Fermi energy. • We find that the Debye temperature of the compound studied is 383(3) K. - Abstract: The results of ab initio electronic structure and electric field gradient (EFG) calculations, and of X-ray diffraction, 57Fe Mössbauer spectroscopy, and magnetic studies of Al13Fe4 are reported. It is shown that Al13Fe4 crystallizes in the monoclinic space group C2/m, in which Fe atoms are located at five inequivalent crystallographic sites, with the lattice parameters a=15.503(2) Å, b=8.063(2) Å, c=12.464(2) Å, and β=107.71(2)°. We demonstrate that zero-field Mössbauer spectra can be decomposed into three quadrupole doublets. With the aid of the calculated EFG parameters we show that the first doublet results from one Fe site, the second doublet is due to two other Fe sites, and the third doublet originates from the last two Fe sites. We find that the shape of the Mössbauer spectrum of Al13Fe4 measured in an external magnetic field of 90 kOe can be accounted for with five component subspectra generated using the calculated EFG parameters at five inequivalent Fe sites. The quadrupole splittings corresponding to three component doublets are shown to increase with decreasing temperature and are well described by a T3/2 power-law relation. The Debye temperature of Al13Fe4 is found to be 383(3) K. We find a pseudogap in the density of states (DOS), with a width of ∼0.2 eV, that is centered 0.1 eV above the Fermi energy. The finite DOS at the Fermi energy confirms good metallicity of Al13Fe4. The 1/T-like dependence of the magnetic susceptibility shows that Al13Fe4 is a paramagnet

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

    Science.gov (United States)

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

    2015-09-01

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

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

    OpenAIRE

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

    2008-01-01

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

  6. Structure of molten Al-Si alloys

    International Nuclear Information System (INIS)

    The temperature variation of the structure and microstructure of molten eutectic Al1-xSix alloys (x = 0.122 and 0.20) have been studied by neutron diffraction and small-angle neutron scattering (SANS), as well as measurements performed on pure liquid Al. All measurements have been performed at five temperatures in a heating-cooling loop. The SANS results unambiguously show that for the eutectic alloy (x = 0.122) the microstructure changes with increasing temperature in a partly reversible way while for the hypereutectic (x = 0.20) alloy the change is almost completely irreversible. This change in microstructure also manifests itself in the shape of the static structure factor S(Q)

  7. Irradiation mixing of Al into U3Si

    International Nuclear Information System (INIS)

    Thermal and irradiation induced intermixing of uranium silicide reactor fuels with the aluminum cladding is an important consideration in understanding their fission gas and fuel swelling behavior. The authors have used Rutherford backscattering to follow the behavior of an Al thin film on U3Si and U3Si2 during 1.5 MeV Kr ion irradiation at temperatures of 30 and 350 C. After an initial dose during which no intermixing occurs, the Al mixes quickly into U3Si. The threshold dose is believed to be associated with an oxide layer between the Al and the uranium silicide. At 300 C and doses greater than threshold, rates of mixing and aluminide phase growth are extracted

  8. 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.

  9. Photoelectric phenomena in ZnO(ITO)/α-Si:H(n)/c-Si(p)/Al solar cells

    International Nuclear Information System (INIS)

    Solar cells (Sc) AlZnO/α-Si:H(n)/c-Si(p)/Al and Al/ITO/α-Si:H(n)/c-Si(p)/Al on silicon substrate have been obtained. Photoelectrical properties of SC under natural and linearly polarized light (LPL) at 300 K were investigated. The polarized photosensitivity of SC arising under inclined linearly polarized irradiation was detected. The nature of induced photopleochroism of SC with ZnO and ITO coatings was established

  10. Synthesis, characterization and electrochemical performance of Li2FeSiO4/C cathode materials doped by vanadium at Fe/Si sites for lithium ion batteries

    Science.gov (United States)

    Hao, Hao; Wang, Junbo; Liu, Jiali; Huang, Tao; Yu, Aishui

    2012-07-01

    Li2FeSiO4/C composites doped by vanadium at Fe/Si sites have been investigated as cathode materials for lithium ion batteries. Effects of vanadium substitution at different sites on the structure of Li2FeSiO4/C are examined by X-ray diffraction, X-photoelectron spectroscopy and scanning electron microscopy. XPS results show that the oxidation state of vanadium doped at Fe sites is +3, whereas is +5 when doped at Si sites. Electrochemical measurements show that the Li2FeSi0.9V0.1O4/C sample exhibits the best electrochemical performance with initial discharge capacity of 159 mAh g-1 and excellent cyclability with capacity of 145 mAh g-1 at 30th cycle, which can be ascribed to larger cell volume and higher lithium ion diffusion coefficient, however, the initial discharge of the Li2Fe0.9V0.1SiO4/C sample is only 90% of the undoped Li2FeSiO4, which can be attributed to the loss of Fe content.

  11. Anisotropy of spin polarization and spin accumulation in Si/Al2O3/ferromagnet tunnel devices

    OpenAIRE

    Sharma, S; Dash, S. P.; Saito, H; Yuasa, S.; van Wees, B. J.; Jansen, R.

    2012-01-01

    The contribution of the spin accumulation to tunneling anisotropy in Si/Al2O3/ferromagnet devices was investigated. Rotation of the magnetization of the ferromagnet from in-plane to perpendicular to the tunnel interface reveals a tunneling anisotropy that depends on the type of the ferromagnet (Fe or Ni) and on the doping of the Si (n or p type). Analysis shows that different contributions to the anisotropy coexist. Besides the regular tunneling anisotropic magnetoresistance, we identify a co...

  12. Development and cytotoxicity evaluation of SiAlONs ceramics

    International Nuclear Information System (INIS)

    SiAlONs are ceramics with high potential as biomaterials due to their chemical stability, associated with suitable mechanical properties, such as high fracture toughness and fracture resistance. The objective of this work was to investigate the mechanical properties and the cytotoxicity of these ceramic materials. Three different compositions were prepared, using silicon nitride, aluminum nitride and a rare earth oxide mixture as starting powders, yielding Si3N4-SiAlON composites or pure SiAlON ceramics, after hot-pressing at 1750 deg. C, for 30 min. The sintered samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Furthermore, hardness and fracture toughness were determined using the Vicker's indentation method. The biological compatibility was evaluated by in vitro cytotoxicity tests. Ceramic with elevated hardness, ranging between 17 and 21 GPa, and high fracture toughness of 5 to 6 MPa m1/2 were obtained. Since a nontoxic behavior was observed in the cytotoxicity tests, it may be assumed that SiAlON-based ceramics are viable materials for clinical applications

  13. Structural Investigation of Fe-Ni-S and Fe-Ni-Si Melts by High-temperature Fluorescence XAFS Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Manghnani, M.; Hong, X.; Newville, M.; Balogh, J. (Hawaii); (UC)

    2007-03-01

    Iron-nickel (Fe-Ni) alloy is regarded as the most abundant constituent of Earth's core, with an amount of 5.5 wt% Ni in the core based on geochemical and cosmochemical models. The structural role of nickel in liquid Fe-Ni alloys with light elements such as S or Si is poorly understood, largely because of the experimental difficulties of high-temperature melts. Recently, we have succeeded in acquiring Ni K-edge fluorescence x-ray absorption fine structure (XAFS) spectra of Fe-Ni-S and Fe-Ni-Si melts and alloys. Different structural environment of Ni atoms in Fe-Ni-S and Fe-Ni-Si melts is observed, supporting the effect of light elements in Fe-Ni melts.

  14. Production of AlN-Si-Al Ceramic-Metal Composites via Pressurless Infiltration Method

    OpenAIRE

    KALEMTAŞ, Ayşe; ARSLAN, Gürsoy; KARA, Ferhat

    2014-01-01

    In this work, the production of light (∼2,9 g/cm3) and dense (> 99 %) AlN based ceramic metal composites was conducted by the pressureless melt infiltration method. These composites contain a high ceramic volume fraction (> 50 vol %) which is the result of the reaction between Si3N4 and Al in the Si3N4-Al system. The production of the ceramic-metal composites was achieved via infiltrating 2024 Al alloys at different temperatures and holding times into the porous pellets which were prepared us...

  15. Comparison of Fe-AlPILC and Fe-ZSM-5 catalysts used for degradation of methomyl

    Science.gov (United States)

    Lázár, Károly; Tomašević, Andjelka; Bošković, Goran; Kiss, Ernő

    2009-07-01

    Catalytic performances of Fe-AlPILC (14 wt.% Fe) and Fe-ZSM-5 (5 wt.% Fe) catalysts are compared in the wet oxidative degradation of methomyl. Fe-ZSM-5 exhibits outstanding whereas Fe-AlPILC shows only mediocre activity. Positions of iron are analysed in the two catalysts by Mössbauer spectroscopy. Iron is in highly dispersed state in Fe-AlPILC whereas in the other case a hematite/ZSM-5 composite is formed. The catalytic activity is attributed to iron located and stabilized in ionic dispersion.

  16. Comparison of Fe-AlPILC and Fe-ZSM-5 catalysts used for degradation of methomyl

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, Karoly [Institute of Isotopes (Hungary); Tomasevic, Andjelka [Pesticide and Environment Research Institute (Serbia); Boskovic, Goran; Kiss, Erno, E-mail: ekiss@tehnol.ns.ac.yu [University of Novi Sad, Faculty of Technology (Serbia)

    2009-07-15

    Catalytic performances of Fe-AlPILC (14 wt.% Fe) and Fe-ZSM-5 (5 wt.% Fe) catalysts are compared in the wet oxidative degradation of methomyl. Fe-ZSM-5 exhibits outstanding whereas Fe-AlPILC shows only mediocre activity. Positions of iron are analysed in the two catalysts by Moessbauer spectroscopy. Iron is in highly dispersed state in Fe-AlPILC whereas in the other case a hematite/ZSM-5 composite is formed. The catalytic activity is attributed to iron located and stabilized in ionic dispersion.

  17. The effect of Fe-coverage on the structure, morphology and magnetic properties of α-FeSi2 nanoislands

    Science.gov (United States)

    Tripathi, J. K.; Garbrecht, M.; Kaplan, W. D.; Markovich, G.; Goldfarb, I.

    2012-12-01

    Self-assembled α-FeSi2 nanoislands were formed using solid-phase epitaxy of low (˜1.2 ML) and high (˜21 ML) Fe coverages onto vicinal Si(111) surfaces followed by thermal annealing. At a resulting low Fe-covered Si(111) surface, we observed in situ, by real-time scanning tunneling microscopy and surface electron diffraction, the entire sequence of Fe-silicide formation and transformation from the initially two-dimensional (2 × 2)-reconstructed layer at 300 °C into (2 × 2)-reconstructed nanoislands decorating the vicinal step-bunch edges in a self-ordered fashion at higher temperatures. In contrast, the silicide nanoislands at a high Fe-covered surface were noticeably larger, more three-dimensional, and randomly distributed all over the surface. Ex situ x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy indicated the formation of an α-FeSi2 island phase, in an α-FeSi2{112} ∥ Si{111} orientation. Superconducting quantum interference device magnetometry showed considerable superparamagnetism, with ˜1.9 μB/Fe atom at 4 K for the low Fe-coverage, indicating stronger ferromagnetic coupling of individual magnetic moments, as compared to high Fe-coverage, where the calculated moments were only ˜0.8 μB/Fe atom. Such anomalous magnetic behavior, particularly for the low Fe-coverage case, is radically different from the non-magnetic bulk α-FeSi2 phase, and may open new pathways to high-density magnetic memory storage devices.

  18. A study of the thermal desorption of deuterium from Fe-Al multilayers

    International Nuclear Information System (INIS)

    Multilayer samples have been obtained by evaporating 15 couples of 10 nm Fe and 14 nm Al layers on (100)-oriented Si wafers in an UHV chamber. After deposition the samples have been heat treated at temperatures ranging from 673 to 773 K. Some samples were also annealed in air to promote the formation of a surface oxide layer. After deposition and heat treatments the samples have been studied by Thermal Desorption Spectroscopy (TDS), Conversion Electron Moessbauer Spectroscopy (CEMS), Rutherford Backscattering Spectroscopy (RBS), Glancing Angle X-Rays Diffraction (GAXRD) and X-Ray Reflectometry (XRR) in order to achieve a complete characterisation of the deposited layers. Results can be summarised as follows: the samples are formed of the stoichiometric FeAl compound, the D2 effusion spectra showed a first peak attributed to the effusion of deuterium contained in the point defects (vacancies) produced by the ion implantation process and a second peak attributed to deuterium release from trapping sites in the FeAl lattice that could be the defect complex formed by the association of a vacancy in the Fe sublattice and a substitutional Fe atom in the Al sublattice (VFe-FeAl). The effusion kinetics can be reproduced by assuming that: (a) deuterium effusion at ∼500 K is controlled by the D2 surface recombination process with Edes = 1.57 ± 0.02 eV as activation energy; (b) deuterium effusion at ∼820 K is controlled by the release of D atoms from the trap sites, a process which occurs in connection with defects relaxation. The role of the lattice defects and the microstructure of the samples in the effusion process has been also investigated. (Authors)

  19. 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.

  20. Thermoelectric properties of Al doped Mg2Si material

    International Nuclear Information System (INIS)

    In the present paper we have calculated thermoelectric properties of Al doped Mg2Si material (Mg2−xAlxSi, x=0.06) using Pseudo potential plane wave method based on DFT and Semi classical Boltzmann theory. The calculations showed n-type conduction, indicating that the electrical conduction are due to electron. The electrical conductivity increasing with increasing temperature and the negative value of Seebeck Coefficient also show that the conduction is due to electron. The thermal conductivity was increased slightly by Al doping with increasing temperature due to the much larger contribution of lattice thermal conductivity over electronic thermal conductivity

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

    International Nuclear Information System (INIS)

    Highlights: • Electrical resistivity and hardness show an evolution at TC 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−1 K−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

  2. Effect of Different Production Methods on the Mechanical and Microstructural Properties of Hypereutectic Al-Si Alloys

    Science.gov (United States)

    Fatih Kilicaslan, M.; Uzun, Orhan; Yilmaz, Fikret; Çağlar, Seyit

    2014-10-01

    In this study, the effects of different production methods like melt spinning, high-energy ball milling, and combined melt spinning and high-energy ball milling on the mechanical and microstructural properties of hypereutectic Al-20Si-5Fe alloys were investigated. While microstructural and spectroscopic analyses were performed using scanning electron microscopy and X-ray diffractometry, mechanical properties were measured using a depth-sensing indentation instrument with a Berkovich tip. Microstructural and spectroscopic analyses demonstrate that high-energy ball milling process applied on the melt-spun Al-20-Si-5Fe alloy for 10 minutes brings about a reduction in the size of silicon particles and intermetallic compounds. However, further increase in milling time does not yield any significant reduction in size. High-energy ball milling for 10 minutes on the starting powders is not enough to form any intermetallic phase. According to the depth-sensing indentation experiments, high-energy milling of melt-spun Al-20Si-5Fe alloys shows an incremental behavior in terms of hardness values. For the Al-20Si-5Fe alloys investigated in this study, the production technique remarkably influences their elastic-plastic response to the indentation process in terms of both magnitude and shape of P- h curves.

  3. 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. PMID:26706526

  4. Laser-induced time-resolved luminescence of natural sillimanite Al2SiO5 and synthetic Al2SiO5 activated by chromium

    International Nuclear Information System (INIS)

    Luminescence of natural sillimanite Al2SiO5 was studied by a laser-induced time-resolved technique combined with absorption spectroscopy. It was found that two red broad emission bands are connected to Fe3+ and Cr3+ luminescence centers. Chromium participation in luminescence was proved by the study of synthetic sillimanite activated by Cr. Several narrow emission lines have been found which were preliminary ascribed to Mn4+ and V2+ luminescence centers. - Highlights: ► We studied luminescence centers in natural sillimanite by time-resolved technique ► We proved Cr3+ emission by the study of artificial sillimanite activated by Cr ► We proved that broad red emission band with long decay is connected to Fe3+ ► We substantiate that narrow emission lines are connected to Mn4+ and V2+.

  5. 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.

  6. Parameters controlling the microstructure of Al-11Si-2.5Cu-Mg alloys

    International Nuclear Information System (INIS)

    This study investigated the effects of cooling rate during solidification, heat treatment, and the addition of Mn and Sr on the formation of intermetallic phases in Al-11Si-2.5Cu-Mg alloys. Microstructures were monitored using optical microscopy and EPMA techniques. The results reveal that the volume fractions of intermetallic phases are generally much lower in the furnace-cooled samples than in the air-cooled ones due to the dissolution of the β-AlFeSi and Al2Cu phases during slow cooling at critical dissolution temperatures. Strontium additions increased the volume fraction of the Al2Cu phase in the as-cast conditions at low and high cooling rates, as well as at varying ranges of Mn levels. Platelets of the β-AlFeSi phase were to be observed in the microstructure of the as-cast air-cooled samples with a DAS of 40 μm at both Mn levels, while none of these particles were to be found in the furnace-cooled samples with a DAS of 120 μm. Sludge particles were observed in almost all of the air-cooled alloys with sludge factors of between 1.4 and 1.9. These particles, however, were not observed in the furnace-cooled alloys with similar sludge factors. Solution heat treatment coarsens the Si particles in the non-modified alloys under both sets of cooling conditions studied. In the Sr-modified alloys, solution treatment has varied effects depending on the cooling rate and the level of Mn present.

  7. FeAl-TiC and FeAl-WC composites - melt infiltration processing, microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

    TiC-based and WC-based cermets were processed with iron aluminide, an intermetallic, as a binder by pressureless melt infiltration to near full density (> 97 % theoretical density). Phase equilibria calculations in the quaternary Fe-Al-Ti-C and Fe-Al-W-C systems at 145{degrees}C were performed to determine the solubility of the carbide phases in liquid iron aluminide. This was done by using Thermocalc{trademark} and the results show that molten Fe-40 at.% Al in equilibrium with Ti{sub 0.512}C{sub 0.488} and graphite, dissolves 4.9 at% carbon and 64 atomic ppm titanium. In the Fe-Al-W-C system, liquid Fe-40 at.% Al in equilibrium with graphite dissolves about 5 at.% carbon and 1 at.% tungsten. Due to the low values for the solubility of the carbide phases in liquid iron aluminide, liquid phase sintering of mixed powders does not yield a dense, homogeneous microstructure for carbide volume fractions greater than 0.70. Melt infiltration of molten FeAl into TiC and WC preforms serves as a successful approach to process cermets with carbide contents ranging from 70 to 90 vol. %, to greater than 97% of theoretical density. Also, the microstructures of cermets prepared by melt infiltration were very homogeneous. Typical properties such as hardness, bend strength and fracture toughness are reported. SEM observations of fracture surfaces suggest the improved fracture toughness to result from the ductility of the intermetallic phase. Preliminary experiments for the evaluation of the oxidation resistance of iron aluminide bonded cermets indicate that they are more resistant than WC-Co cermets.

  8. Quantification of precipitate fraction in Al-Si-Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. [Sente Software Ltd., Surrey Technology Centre, Guildford GU2 7YG (United Kingdom); Sha, W. [Metals Research Group, School of Civil Engineering, Queen' s University of Belfast (United Kingdom)]. E-mail: w.sha@qub.ac.uk

    2005-02-15

    Quantification of precipitate fraction is difficult when the precipitates formed are of low volume fraction. A simple method is proposed in the present work to estimate the precipitate fraction of Al{sub 2}Cu phase in Al-Si-Cu alloys based on X-ray diffraction analysis. The change in the lattice parameter of the matrix due to ageing, measured from X-ray diffraction profiles, is correlated to the fraction of Al{sub 2}Cu phase formed during ageing. JMatPro, a software package for calculating the properties of metallic systems, is used to calculate the phase constitution and composition in the Al-Si-Cu alloys studied after different heat treatments. Factors that affect the lattice parameter of the matrix have been discussed and considered in the calculations.

  9. Structural, magnetic, and transport properties of Co$_2$FeSi Heusler films

    OpenAIRE

    Schneider, H.; Herbort, Ch.; Jakob, G.; Adrian, H.; Wurmehl, S.; Felser, C.

    2006-01-01

    We report the deposition of thin Co$_2$FeSi films by RF magnetron sputtering. Epitaxial (100)-oriented and L2$_1$ ordered growth is observed for films grown on MgO(100) substrates. (110)-oriented films on Al$_2$O$_3$(110) show several epitaxial domains in the film plane. Investigation of the magnetic properties reveals a saturation magnetization of 5.0 $mu_B/f.u.$ at low temperatures. The temperature dependence of the resistivity $rho_{xx}(T)$ exhibits a crossover from a T^3.5 law at T

  10. Hydrothermal synthesis of nanocrystalline H[Fe, Al]ZSM-5 zeolites for conversion of methanol to gasoline

    International Nuclear Information System (INIS)

    Graphical abstract: Nanocrystalline H[Fe, Al]ZSM-5 zeolites with different Fe content were synthesized by hydrothermal method. Methanol to gasoline (MTG) reaction was chosen to test the catalytic performance of as-prepared nanocrystalline H[Fe, Al]ZSM-5 zeolites, indicating that the nanocrystalline H[Fe, Al]ZSM-5 catalysts exhibited the outstanding catalytic performance in MTG process. - Highlights: • Nanocrystalline H[Fe, Al]ZSM-5 zeolites were synthesized by in situ hydrothermal method. • Fe species could be introduced into ZSM-5 framework and new active sites are created. • The H[Fe, Al]ZSM-5 catalysts exhibit improved catalytic performance in MTG process. - Abstract: Nanocrystalline H[Fe, Al]ZSM-5 zeolites with different Fe content were synthesized by hydrothermal method with tetrapropylammonium hydroxide (TPAOH) as structure-directing agent (SDA), in which tetraethyl orthosilicate (TEOS) and sodium aluminate (NaAlO2) were used as Si and Al sources, respectively. The prepared samples were characterized by means of techniques such as XRD, SEM, N2 adsorption–desorption, ICP-AES, UV–Vis, NH3-TPD, pyridine-FTIR and FT-IR. The results indicated that Fe species could be incorporated into ZSM-5 zeolite framework in the forms of isolated Fe3+ and small oligomeric FexOy clusters, resulting in the formation of some new active sites and the lower Brønsted acid sites content. The catalytic performances of prepared nanocrystalline H[Fe, Al]ZSM-5 zeolites were evaluated by methanol to gasoline (MTG) reaction in a fixed bed stainless-steel reactor. The catalytic results illustrated that the incorporation of Fe enhanced the activity and stability of nanocrystalline H[Fe, Al]ZSM-5 catalysts in MTG reaction and reduced the yield of aromatics in gasoline. The methanol conversion was higher than 99% for about 110 h by optimizing the Fe content, meanwhile, the gasoline yield reached up to 32.7%, the aromatics and durene selectivity were controlled to a low level of 38

  11. Formation of amorphous Fe 50Si 50 alloy by diffusion reaction

    Science.gov (United States)

    Yan, Zhihua; Wang, Wenkui; Li, Jingfeng; Wang, Yuming

    1989-02-01

    The solid state reaction in the multilayer film with alternative polycrystalline Fe and amorphous Si layers has been studied with X-ray diffraction. Amorphous Fe 50Si 50 phase was formed after annealing isothermally at 300°C, which is explained in view of the consideration that an amorphous phase can be more favorable to form than a supersaturated solution in thermodynamics as well as than an equilibrium compound FeSi in kenetics.

  12. Fe-bearing MgSiO3 perovskite up to the Earth's lower mantle conditions

    International Nuclear Information System (INIS)

    We investigated structural and electronic behaviors of Fe-MgSiO3 under pressure up to that in the Earth's lower mantle using the first-principles theory. The Fe- MgSiO3 crystals have phase transform from the orthorhombic perovskite (OPv) structure into the orthorhombic post-perovskite (OPPv) phase and the transition pressure decreasing with increasing Fe concentration. Electronic transitions occur in the pressure range of about 70 to 90 GPa for an (Mg,Fe)(Si,Fe)O3 OPv crystal, in which the moment of the Fe4+ ion decreases gradually to zero at which the magnetic moment of the Fe2+ ion becomes zero. That electronic transition provides the possible mechanism to understand experiments. Keywords: Fe-MgSiO3, pressure, Earth's lower mantle, first-principles theory. (Author) 10 refs.

  13. Identification of phase composition of AlSi5Cu2Mg aluminium alloy in T6 condition

    Directory of Open Access Journals (Sweden)

    M. Wierzbińska

    2008-04-01

    Full Text Available Purpose: The purpose of this paper is to present the results of studies of AlSi5Cu2Mg cast alloy in T6 condition at an angle of intermetallic phases composition. It was found that the investigated alloy microstructure consists of three different, as regards shape intermatallic phases.Design/methodology/approach: In this study, several methods were used, such as: optical light microscopy (LM scanning electron microscopy (SEM in combination with X-ray analysis (EDS using polished samples, and calorimetric analysis (DSC, to identify of phase composition in AlSi5Cu2Mg alloy.Findings: The results show that three intermetallic phases in AlSi5Cu2Mg alloy microstructure presented only one type of the phase, the α–AlFeMnSi phase. The chemical composition, morphology, shape (needle or “Chinese script” and distribution of α – AlFeMnSi phase depend on the parameters of the crystallization process. Netherless, it is possible to change this parameters during heat treatment process.Research limitations/implications: Although the morphology and α – AlFeMnSi phase particles distribution have a significant impact on the mechanical properties (especially on the crack resistance of the AlSi5Cu2Mg alloy, the main strengthening factor is the existence of the dispersion phase which was not subjected to examination in the research presented in this paper. Therefore, in order to complete and confirm obtained results it is recommended to perform further analysis of the alloy by using transmission electron microscopy technique (TEM.Practical implications: From a practical point of view it is important, that there is a possibility to influence morphology, shape and distribution of intermetallic α – AlFeMnSi phase by heat treatment parameters, to obtain optimal mechanical properties of AlSi5Cu1Mg alloy according to application.Originality/value: This paper proposes the best experimental techniques for analysis of the intermetallic phases occurrnig in the 4

  14. 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.

  15. Correlation induced paramagnetic ground state in FeAl

    Czech Academy of Sciences Publication Activity Database

    Mohn, P.; Persson, C.; Blaha, P.; Schwarz, K.; Novák, Pavel; Eschrig, H.

    2001-01-01

    Roč. 87, č. 19 (2001), s. 196401-1-196401-4. ISSN 0031-9007 Institutional research plan: CEZ:AV0Z1010914 Keywords : FeAl * paramagnetic ground state Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.668, year: 2001

  16. 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.

  17. Učinak postupka topline obrade na morfologiju intermetalne faze ljevačke legure AlSi9Cu3

    OpenAIRE

    E. Tillová; M. Panušková

    2008-01-01

    Učinak postupka topline obrade na morfologiju intermetalne faze ljevačke legure AlSi9Cu3. U članku je dano istraživanje utjecaja toplinskog otapanja na 505°C, 515°C i 525°C ± 2°C sa različitim vremenima držanja 2, 4, 8, 16 i 32 sata na mikrostrukturu komercijalne ljevačke legure AlSi9Cu3. Tijekom toplinske odredbe došlo je do sferoidizacije eutektičkog Si, postepenog raspada željeznih intermetalnih faza sa osnovom Al(FeMnMg)Si, skraćivanje i stanjivanje iglica faze Al5FeSi i otapanje intermet...

  18. Spin transport and accumulation in n+-Si using Heusler compound Co2FeSi/MgO tunnel contacts

    International Nuclear Information System (INIS)

    We investigate spin transport and accumulation in n+-Si using Heusler compound Co2FeSi/MgO/Si on insulator (SOI) devices. The magnitudes of the non-local four- and three-terminal Hanle effect signals when using Heusler compound Co2FeSi/MgO/SOI devices are larger than when using CoFe/MgO/SOI devices, whereas the preparation methods of MgO layers on SOI are exactly same in both devices. Different bias voltage dependencies on the magnitude of spin accumulation signals are also observed between these devices. Especially, Co2FeSi/MgO/SOI devices show large spin accumulation signals compared with CoFe/MgO/SOI devices in the low bias voltage region less than ∼1000 mV in which the increase of the spin polarization is expected from the estimation of the density of states in Heusler compound Co2FeSi and CoFe under spin extraction conditions. These results indicate that the species of ferromagnetic material definitely affects the magnitude and behavior of the spin signals. The use of highly polarized ferromagnets such as Heusler compounds would be important for improving the spin polarization and the magnitude of spin signals through Si channels

  19. Thermoelectric Properties of n-Type Si0,8Ge0,2-FeSi2 Multiphase Nanostructures

    Science.gov (United States)

    Usenko, Andrey; Moskovskikh, Dmitry; Korotitskiy, Andrey; Gorshenkov, Mikhail; Voronin, Andrey; Arkhipov, Dmitry; Lyange, Maria; Isachenko, Grigory; Khovaylo, Vladimir

    2016-04-01

    We report on thermoelectric properties of n-type nanostructured bulk Si0.8Ge0.2 with the addition of FeSi2 prepared via two sintering routes: the conventional spark plasma sintering method and a direct current pressing technique. The thermal conductivity, the electrical conductivity, and the Seebeck coefficient have been determined over the temperature range from 25°C to 900°C in a helium atmosphere. The highest ZT value for the multiphase nanostructured composite was reached at ˜0.6 at 900°C. Embedding of 10 at.% FeSi2 phase had a positive impact on thermal properties but dramatically affected the power factor, which eventually resulted in a drop of the thermoelectric efficiency. It was also shown that the orthorhombic β-FeSi2 phase transforms to a tetragonal α-FeSi2 phase during high temperature sintering.

  20. 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

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

    Science.gov (United States)

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

    2012-01-01

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

  2. Magnetostriction of the polycrystalline Fe80Al20 alloy doped with boron

    International Nuclear Information System (INIS)

    Highlights: ► Fe80Al20 polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. ► B stabilizes α-FeAl phase and a coexistence of α-FeAl + Fe3Al improves magnetostriction. ► Presence of Fe2B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe80Al20 polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic α-FeAl and/or Fe3Al and Fe2B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of α-FeAl and a correspondent decrease of the Fe3Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe2B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe80Al20 alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the α-FeAl and Fe3Al phases could be reached.

  3. Validation of Predicted Precipitate Compositions in Al-Si-Ge

    Energy Technology Data Exchange (ETDEWEB)

    Dracup, B; Turchi, P A; Radmilovic, V; Dahmen, U; Morris, Jr., J W

    2004-04-21

    Aged alloys of Al-0.5Si-0.5Ge (at.%) contain diamond cubic (A4) precipitates in a dispersion that is much finer than is found in alloys with Si or Ge alone. To help understand this aging behavior, the present work was undertaken to determine alloy composition as a function of aging temperature. The composition was estimated theoretically using a CALPHAD approach, and measured experimentally with energy dispersive spectroscopy (EDS) in a high-resolution electron microscope. Theory and experiment are in reasonable agreement. As the aging temperature rises, the precipitates become enriched in Si, changing from 50 at. % in the low-temperature limit to about 80 at.% Si as temperature approaches 433 C, the high-temperature limit of the precipitate field.

  4. Structural and magnetic characterization of Fe-Al2 O3 composites

    International Nuclear Information System (INIS)

    Full text. We report on the structural nd magnetic characterization f co-evaporated Fe 60%-(Al2 O3) 40% on Si (111) substrates. Co-evaporation was performed in a vacuum of 10 -7 mbar at room temperature using a dual e-beam system. The sample's composition was measured by Rutherford backscattering spectroscopy (RBS). Granular alloys near percolation limit, 60% of iron were obtained. The I-V curves show a non-ohmic behaviour for low values of V, indicating a tunnel conductivity between the Fe grains. This tunnel conductivity is responsible for the negative magneto resistance appearing in this samples. Hysteresis curves obtained using an Alternate Gradient magnetometer (AGM) show a superparamagnetic behavior. We believe that very small Fe grains are homogeneously dispersed through the Al2 O3 matrix. No evidence of Fe crystalline grains was observed by X-ray diffraction. To test the local order in the Fe grains, X-ray Absorption spectroscopy will be future at Brazilian National Synchrotron Light Laboratory (LNLS). (author)

  5. 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

  6. Precipitation hardening in ternary alloys of the Al-Sc-Cu and Al-Sc-Si systems

    International Nuclear Information System (INIS)

    The processes of precipitation hardening in cast ternary alloys of the Al-Sc-Cu and Al-Sc-Si systems were studied in the temperature range of aging from 100 to 450 C and at exposures to 200 h. It was shown that the CuAl2 and ScAl3 phases were involved in the process of aging in ternary Al-Sc-Cu alloys, and the Si and V (AlSiSc) phases, in ternary Al-Sc-Si alloys with excess silicon in a supersaturated solid solution. The V phase was for the first time revealed as the hardening phase in aluminum alloys

  7. 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.

  8. 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.

  9. 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.

  10. Influence of additives on the microstructure and tensile properties of near-eutectic Al-10.8%Si cast alloy

    International Nuclear Information System (INIS)

    The continuing quest for aluminum castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in aluminum-silicon alloys. In Al-Si alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and tensile properties of as-cast and heat-treated new experimental alloy belonging to cast Al-Si near-eutectic alloys have been investigated as a function of Fe, Mn, Cu, and Mg content. Microstructural examination was carried out using optical microscopy, image analysis, and electron probe microanalysis (EPMA), wavelength dispersive spectroscopic (WDS) analysis facilities. Tensile properties upon artificial aging in the temperature range of 155-240 oC for 5 h were also investigated. The results show that the volume fraction of Fe-intermetallics increases as the iron or manganese contents increase. Compact polygonal or star-like particles form when the sludge factor is greater than 2.1. The Al2Cu phase was observed to dissolve almost completely during solution heat treatment of all the alloys studied, especially those containing high levels of Mg and Fe, while Al5Cu2Mg8Si6, sludge, and α-Fe phases were found to persist after solution heat treatment. The β-Al5(Fe,Mn)Si phase dissolved partially in Sr-modified alloys, and its dissolution became more pronounced after solution heat treatment. At 0.5% Mn, the β-Fe phase forms when the Fe content is above 0.75%, causing the tensile properties to decrease drastically. The same results are obtained when the levels of both Fe and Mn are increased beyond 0.75%, because of sludge formation. On the other hand, the tensile properties of the Cu-containing alloys are affected slightly at high levels of Mg as a result of the formation of Al5Cu2Mg8Si6 which decreases the amount of free Mg available to form the Al2Cu

  11. Correlation of the structural properties of a Pt seed layer with the perpendicular magnetic anisotropy features of full Heusler-based Co2FeAl/MgO/Co2Fe6B2 junctions via a 12-inch scale Si wafer process

    Science.gov (United States)

    Chae, Kyo-Suk; Lee, Du-Yeong; Shim, Tae-Hun; Hong, Jin-Pyo; Park, Jea-Gun

    2013-10-01

    We elucidated the interfacial-perpendicular magnetic anisotropy (i-PMA) features of full Heusler-based Co2FeAl/MgO/Co2Fe6B2 magnetic-tunnel-junctions as functions of the structural properties of the Pt seed layer including its thickness and ex situ annealing temperature. All of the samples were prepared in a 12-inch silicon wafer process for real industry applications. The observations of the M-H loops emphasize that a thinner Pt seed layer and a high ex situ annealing temperature enhance the surface roughness of the seed layer, providing better i-PMA characteristics. HR-TEM images of the samples were evaluated to understand the structural effects of thin and thick Pt seed layers.

  12. High noise suppression using magnetically isotropic (CoFe-AlN)/(AlN) multilayer films

    Science.gov (United States)

    Kijima, Hanae; Ohnuma, Shigehiro; Masumoto, Hiroshi; Shimada, Yutaka; Endo, Yasushi; Yamaguchi, Masahiro

    2015-05-01

    Magnetically isotropic (CoFe-AlN)n/(AlN)n+1 multilayer films, in which the number of CoFe-AlN magnetic layers n ranged from 1 to 27, were prepared by radio frequency sputtering to achieve noise suppression at gigahertz frequencies. The soft CoFe-AlN magnetic layers consisted of nanometer-sized CoFe ferromagnetic grains embedded in an insulating AlN amorphous matrix, while the insulating AlN layers comprised AlN columnar crystals. All films showed a similar frequency dependence of permeability and ferromagnetic resonance of 1.7 GHz. Noise suppression was evaluated using a microstrip line as a noise source by determining the in-line conductive loss and the near-field intensity picked up by magnetic field detective probes. High noise suppression effects were observed in every direction in the film plane. Maximum noise suppression values amounted to 60% for the in-line conductive loss and -20 dB for the magnetic near-field intensity at around 1.7 GHz in the 27-layer film. These high-frequency noise suppression levels may be attributed to eddy current losses and ferromagnetic resonance.

  13. The effects of amorphous Al2O3 underlayer on the microstructure and magnetic properties of BaFe12O19 thin films

    International Nuclear Information System (INIS)

    Single phase nanostructured BaFe12O19 thin films have been deposited on Si(110) substrate and Si(110) substrate with amorphous Al2O3 underlayer by a sol–gel method. The effects of the amorphous Al2O3 underlayer on the composition, microstructure and magnetic properties were explored by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometery techniques. The results revealed that the amorphous Al2O3 underlayer promoted some perpendicular c-axis orientation with ΔHc=Hcperpendicular−Hc∥=300 Oe. - Highlights: • The BaFe12O19 film fabricated by the Pechini method, deposited on Si(110), Si(110)/Al2O3 substrates. • The Al2O3 underlayer induced some c-axis perpendicular orientation. • Out-of-plane magnetic properties of the film with underlayer are better than those of in-plane orientation

  14. 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

  15. Thermal expansion measurements on Fe substituted URu2Si2

    Science.gov (United States)

    Ran, Sheng; Wolowiec, Christian; Jeon, Inho; Pouse, Naveen; Kanchanavatee, Noravee; Huang, Kevin; Maple, M. Brian; Dapron, Tyler; Williamsen, Mark; Snow, David; Martien, Dinesh; Spagna, Stefano

    The search for the order parameter of the hidden order (HO) phase in URu2Si2 has attracted an enormous amount of attention for the past three decades. The small antiferromagnetic moment of only ~0.03 μB/U found in the HO phase is too small to account for the entropy of ~0.2Rln(2) derived from the second order mean field BCS-like specific heat anomaly associated with the HO transition that occurs below To = 17.5 K. A first order transition from the HO phase to a large moment antiferromagnetic (LMAFM) phase occurs under pressure. We have recently demonstrated that tuning URu2Si2B>by substitution of Fe for Ru reproduces the temperature vs applied pressure phase diagram.and offers an opportunity to study the HO and LMAFM phases at atmospheric pressure. Motivated by this observation, we performed thermal expansion measurements on URu2-xFexSi2 single crystals for various values of x in both the HO and LMAFM regions of the phase diagram. Interesting preliminary results have emerged from these studies that shed light on the LMAFM phase and its relationship with the elusive HO phase. Research in UCSD is supported by US DOE BES under Grant No. DE-FG02-04-ER46105 (materials synthesis and characterization) and US NSF under Grant No. DMR-1206553 (low temperature measurements).

  16. Anomalous Hall effect in the Co-based Heusler compounds Co2FeSi and Co2FeAI

    Science.gov (United States)

    Imort, I.-M.; Thomas, P.; Reiss, G.; Thomas, A.

    2012-04-01

    The anomalous Hall effect (AHE) in the Heusler compounds Co2FeSi and Co2FeAl is studied in dependence of the annealing temperature to achieve a general comprehension of its origin. We have demonstrated that the crystal quality affected by annealing processes is a significant control parameter to tune the electrical resistivity ρxx as well as the anomalous Hall resistivity ρahe. Analyzing the scaling behavior of ρahe in terms of ρxx points to a temperature-dependent skew scattering as the dominant mechanism in both Heusler compounds.

  17. Fabrication, phase transformation studies, and characterization of SiC-AlN-Al2OC ceramics

    International Nuclear Information System (INIS)

    Principal focus was on phase transformation, microstructure development, and elevated temperature creep, with some effort on room- temperature mechanical properties of selected materials. Fabrication was largely hot pressing, although many of the compositions can be densified by pressureless sintering; hot pressing was to ensure full attainment of density with fine microstructure. Most of the work was on SiC-AlN and AlN-Al2OC pseudobinaries

  18. 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.

  19. Ab initio study of 59Co NMR spectra in Co2FeAl1-xSix Heusler alloys

    Science.gov (United States)

    Nishihara, H.; Sato, K.; Akai, H.; Takiguchi, C.; Geshi, M.; Kanomata, T.; Sakon, T.; Wada, T.

    2015-05-01

    Ab initio electronic structure calculation of a series of Co2FeAl1-xSix Heusler alloys has been performed, using the Korringa-Kohn-Rostoker-coherent potential approximation method to explain experimental 59Co NMR spectra. Two prominent features are explained semi-quantitatively-a global shift of the 59Co resonance line due to alloying with Al and Si atoms in Co2FeAl1-xSix, and the effect of local disorder in creating distinct satellite lines of 59Co NMR in Co2FeAl. The importance is stressed of the positive contribution to the 59Co hyperfine field from valence electron polarization, which emerges from the half-metallic band structure inherent in Co-based Heusler alloys.

  20. Study of the U(Al,Si)3 vertex location in the 400°C isothermal section of the U-Al-Si phase diagram

    International Nuclear Information System (INIS)

    Ternary U-Al-Si system has been extensively investigated due to the high potential of Uranium alloyed with Silicon as low-enriched fuel. Another interest in the U-Al-Si ternary system originates from the use of Aluminum alloy, where Silicon is a major alloying element, as U-fuel cladding. Due to the high exploitation temperature, U-Al-Si interaction layer forms among the Uranium fuel and Al-Si-alloy cladding. Thus, investigation of the U-Al-Si system is of technological importance. In order to perform thermodynamic modeling (one of the options to study the ternary U-Al-SI phase diagram) the exact composition of invariant points and exact homogeneity ranges of intermetallides formed in this phase diagram have to be determined empirically. In the past, thermodynamic modeling of the U-Al-Si system was based on the isothermal section suggested by Dwight. In this work the U(Al,Si)3 ordered phase was not identified, whereas in a later research it was found to be stable in a wide range of compositions. This emphasizes the need to verify his results. U(Al,Si)3 vertex is one of the critical locations required for thermodynamic calculations . With an intention to either contradict or support previous results on the U(Al,Si)3 vertex location, two alloys with different compositions existing within the Al-Si-U(Al,Si)3 triangle were characterized. The alloys were heat treated in order to obtain equilibrium state. Phase characterization of the alloys was performed using scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Rietveld method was applied on XRD data for quantitative analysis. Experimental results imply that the location of the U(Al,Si)3 vertex should be at 25at.% U-13at.% Al- 62at.%Si. This result contradicts previous results reported in