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Sample records for al si fe

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

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

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

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  4. Effect of Strontium and Phosphorus on Eutectic Al-Si Nucleation and Formation of β-Al5FeSi in Hypoeutectic Al-Si Foundry Alloys

    Science.gov (United States)

    Cho, Y. H.; Lee, H.-C.; Oh, K. H.; Dahle, A. K.

    2008-10-01

    The present investigation was carried out on hypoeutectic Al-Si alloys containing two levels of Fe, 0.5 and 1.1 wt pct, and Sr in the range of 30 to 500 ppm. The addition of Sr in excess of 100 ppm significantly reduced the number of eutectic grains and also resulted in the formation of polygonal-shaped Al2Si2Sr intermetallics. Transmission electron microscopy studies revealed that the Al2Si2Sr phase surrounded the P-rich particles. This may suggest that the otherwise potent nuclei for the Al-Si eutectic, aluminum phosphide (AlP), become poisoned or deactivated by the formation of the Al2Si2Sr phase around the particles. At the high-Fe level (1.1 wt pct Fe), pre-eutectic formation of β-Al5FeSi platelets further reduced the number of eutectic Al-Si nucleation events. It is proposed that both eutectic silicon and β-Al5FeSi are preferentially nucleated on AlP particles. Nucleation of eutectic silicon, therefore, becomes more difficult when it is preceded by the formation of Al2Si2Sr or β-Al5FeSi, because fewer nuclei are available to nucleate silicon. Addition of up to 60 ppm P to the alloys increased the formation temperature of the β-Al5FeSi platelets but did not significantly alter the size, whereas the addition of Sr decreased the β-Al5FeSi nucleation temperature by reducing the potency of the AlP particles.

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

    OpenAIRE

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

    2016-01-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecip...

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

    Science.gov (United States)

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

    2016-04-20

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

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  8. 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)

    Belmares-Perales, S.; Zaldivar-Cadena, A.A.

    2010-01-01

    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-Calc 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 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.

  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. Synthesis, microstructure and magnetic properties of Fe3Si0.7Al0.3@SiO2 core-shell particles and Fe3Si/Al2O3 soft magnetic composite core

    Science.gov (United States)

    Wang, Jian; Fan, Xi'an; Wu, Zhaoyang; Li, Guangqiang

    2015-11-01

    Fe3Si0.7Al0.3@SiO2 core-shell particles and Fe3Si/Al2O3 soft magnetic composite core have been synthesized via a modified stöber method combined with following high temperature sintering process. Most of conductive Fe3Si0.7Al0.3 particles could be uniformly coated by insulating SiO2 using the modified stöber method. The Fe3Si0.7Al0.3@SiO2 core-shell particles exhibited good soft magnetic properties with low coercivity and high saturation magnetization. The reaction 4Al+3SiO2=2α-Al2O3+3Si took place during the sintering process. As a result the new Fe3Si/Al2O3 composite was formed. The Fe3Si/Al2O3 composite core displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher electrical resistivity and lower core loss than the pure Fe3Si0.7Al0.3 core. The method of introducing insulating layers surrounding magnetic particles provides a promising route to develop new and high compact soft magnetic materials with good magnetic and electric properties.

  11. Interdiffusion behavior of U3Si2 with FeCrAl via diffusion couple studies

    Science.gov (United States)

    Hoggan, Rita E.; He, Lingfeng; Harp, Jason M.

    2018-04-01

    Uranium silicide (U3Si2) is a candidate to replace uranium oxide (UO2) as light water reactor (LWR) fuel because of its higher thermal conductivity and higher fissile density relative to the current standard, UO2. A class of Fe, Cr, Al alloys collectively known as FeCrAl alloys that have superior mechanical and oxidation resistance are being considered as an alternative to the standard Zirconium based LWR cladding. The interdiffusion behavior between FeCrAl and U3Si2 is investigated in this study. Commercially available FeCrAl, along with U3Si2 pellets were placed in diffusion couples. Individual tests were ran at temperatures ranging from 500 °C to 1000 °C for 30 h and 100 h. The interdiffusion was analyzed with an optical microscope, scanning electron microscope, and transmission electron microscope. Uniform and planar interdiffusion layers along the material interface were illustrated with backscatter electron micrographs and energy-dispersive X-ray spectroscopy. Electron diffraction was used to validate phases present in the system, including distinct U2Fe3Si/UFe2 and UFeSi layers at the material interface. U and Fe diffused far into the FeCrAl and U3Si2 matrix, respectively, in the higher temperature tests. No interaction was observed at 500 °C for 30 h.

  12. Microstructure and corrosion resistance of Sm-containing Al-Mn-Si-Fe-Cu alloy

    Directory of Open Access Journals (Sweden)

    Han Yuyin

    2017-12-01

    Full Text Available Optimizing alloy composition is an effective way to improve physical and chemical properties of automobile heat exchanger materials.A Sm-containing Al-Mn-Si-Fe-Cu alloy was investigated through transmission electron microscopy,scanning electron microscopy,and electrochemical measurement.Experimental results indicated that main phases distributed in the alloy wereα-Al(Mn,FeSi,Al2Sm and Al10Cu7Sm2.Alloying with Sm element could refine the precipitated α-Al(Mn,FeSi phase.Polarization testing results indicated that the corrosion surfacewas mainly composed of pitting pits and corrosion products.Sea water acetic acid test(SWAAT showed that corrosion loss increased first and then slowed downwith increase of the corrosion time.

  13. Effect of Si and Zr on the Microstructure and Properties of Al-Fe-Si-Zr Alloys

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    Anna Morozova

    2017-11-01

    Full Text Available The effects of Si and Zr on the microstructure, microhardness and electrical conductivity of Al-Fe-Si-Zr alloys were studied. An increase in the Zr content over 0.3 wt. % leads to the formation of primary Al3Zr inclusions and also decreases mechanical properties. Therefore, the Zr content should not be more than 0.3 wt. %, although the smaller content is insufficient for the strengthening by the secondary Al3Zr precipitates. The present results indicate that high content of Si significantly affects the hardness and electrical conductivity of the investigated alloys. However, the absence of Si led to the formation of harmful needle-shaped Al3Fe particles in the microstructure of the investigated alloys after annealing. Therefore, the optimum amount of Si was 0.25–0.50 wt. % due to the formation of the Al8Fe2Si phase with the preferable platelet morphology. The maximum microhardness and strengthening effects in Al-1% Fe-0.25% Si-0.3% Zr were observed after annealing at 400–450 °C due to the formation of nanosized coherent Al3Zr (L12 dispersoids. The effect of the increasing of the electrical conductivity can be explained by the decomposition of the solid solution. Thus, Al-1% Fe-0.25% Si-0.3% Zr alloy annealed at 450 °C has been studied in detail as the most attractive with respect to the special focus on transmission line applications.

  14. Natural gels: crystal-chemistry of short range ordered components in Al, Fe, and Si systems

    Energy Technology Data Exchange (ETDEWEB)

    Ildefonse, Ph.; Calas, G. [Paris-6 et 7 Univ. and IPGP, Lab. de Mineralogie-Cristallographie, UA CNRS 09, 75 (France)

    1997-07-01

    In this review, the most important inorganic natural gels are presented: opal, aluminosilicate (allophanes) and hydrous iron oxides and silicates. It is demonstrated that natural gels are ordered at the atomic scale. In allophanes, Al is distributed between octahedral and tetrahedral sites. The amount of Al increases as Al/Si ratio decreases. Si-rich allophane have a local structure around Al and Si very different of that is known in kaolinite or halloysite. Transformation of Si-rich allophanes to crystallized minerals implies dissolution-recrystallization processes. On the contrary, in iron silicate with Fe/Si = 0.72, Si and Fe environments are close to those found in nontronite. The gel transformation to Fe-smectite may occur by long range ordering during ageing. In ferric silicate gels, the similarity of local structure around Fe in poorly ordered precursors and what is known in crystallized minerals suggests a solid transformation during ageing. This difference between iron and aluminium is mainly due to the ability of Al to enter both tetrahedral and octahedral sites, while the affinity of iron for octahedral sites is higher at low temperature.

  15. Natural gels: crystal-chemistry of short range ordered components in Al, Fe, and Si systems

    International Nuclear Information System (INIS)

    Ildefonse, Ph.; Calas, G.

    1997-01-01

    In this review, the most important inorganic natural gels are presented: opal, aluminosilicate (allophanes) and hydrous iron oxides and silicates. It is demonstrated that natural gels are ordered at the atomic scale. In allophanes, Al is distributed between octahedral and tetrahedral sites. The amount of Al increases as Al/Si ratio decreases. Si-rich allophane have a local structure around Al and Si very different of that is known in kaolinite or halloysite. Transformation of Si-rich allophanes to crystallized minerals implies dissolution-recrystallization processes. On the contrary, in iron silicate with Fe/Si = 0.72, Si and Fe environments are close to those found in nontronite. The gel transformation to Fe-smectite may occur by long range ordering during ageing. In ferric silicate gels, the similarity of local structure around Fe in poorly ordered precursors and what is known in crystallized minerals suggests a solid transformation during ageing. This difference between iron and aluminium is mainly due to the ability of Al to enter both tetrahedral and octahedral sites, while the affinity of iron for octahedral sites is higher at low temperature

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

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yiqin [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Min; Tao, Lei; Wang, Wei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Bai, Peiwen [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)

    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. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  18. 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

  19. Calculation of solidification microstructure maps for the system Al-Fe-Si

    International Nuclear Information System (INIS)

    Gilgien, P.

    1996-01-01

    Computer programs have been developed in order to calculate solidification microstructure maps for binary and ternary alloys. These programs are based on recent analytical models for the constrained growth of dendrites and eutectics. Due to the importance of phase diagrams data, programs for the calculation of growth kinetics are coupled with ThermoCalc, a commercial software for phase diagram calculations. These programs have been used to calculate a solidification microstructure map for the Al-Fe system from 0 to 4 at%Fe. Comparison of the calculated results with an experimental solidification microstructure map from the literature shows that all microstructure transitions were predicted. Nevertheless there remain significant discrepancies between some calculated and experimental transition velocities. The programs were also used to calculate solidification microstructure maps in the Al-rich corner of the Al-Fe-Si system (0 to 8 at% Fe and 0 to 8 at% Si). In this case also, calculated results were in satisfactory agreement with experimental solidification microstructure maps, although the comparison was only partial since experimental ternary microstructure maps are less complete than for the binary system, and because the available thermodynamic database does not, as yet, include metastable phases. Laser surface remelting experiments were carried out on an Al-4 at% Fe alloy in order to link results from the literature, obtained at high solidification rates by laser surface remelting and at low solidification rates by Bridman experiments. Finally, Bridman experiments were carried out with an Al-2.63 wt% Fe alloy in order to determine the critical velocity at which a planar Al-Al 13 Fe 4 eutectic front is destabilised in a cellular eutectic by a small amount of Si. The critical solidification velocity thus obtained was in agreement with a criterion of constitutional undercooling. (author) figs., tabs., refs

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-02-23

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

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

    Science.gov (United States)

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

    2018-03-01

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

  3. In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy

    International Nuclear Information System (INIS)

    Bjurenstedt, Anton; Casari, Daniele; Seifeddine, Salem; Mathiesen, Ragnvald H.; Dahle, Arne K.

    2017-01-01

    Morphology and growth of primary α-Al(FeMnCr)Si intermetallics have been studied in-situ during solidification of a commercial secondary aluminum alloy employing X-radiographic imaging combined with deep-etching. The α-Al(FeMnCr)Si intermetallics were found to nucleate primarily on surface oxides, and the continued growth yielded both rhombic dodecahedrons and elongated rod-like morphologies. Both morphologies were observed as hopper and massive types, where the hopper intermetallics had the higher growth rates. The growth rate, which determines the type, appears to be linked to nucleation frequency; higher nucleation frequency promoted massive types and lower nucleation frequency promoted hopper intermetallics.

  4. 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.

  5. Wear Behaviour of Al-Si-Fe Alloy/Coconut Shell Ash Particulate Composites

    Directory of Open Access Journals (Sweden)

    A. Apasi

    2012-03-01

    Full Text Available Wear behaviour of aluminium alloy (Al-Si-Fe reinforced with coconut shell ash particles (CSAp fabricated by stir casting process was investigated. The wear and frictional properties of the metal matrix composites was studied by performing dry sliding wear test using a pin-on-disc wear tester by varying the applied load from 10-50 N, speed 2.0 m/s and sliding distance 4000 m. The morphology of the worn out surface was determined by scanning electron microscope (SEM. The results show that the coefficient of friction increases with increasing load for the Al-Si-Fe alloy and the composites containing CSAp. It is observed that, as the applied load increases, the wear rate also increases but decreased with CSAp addition. This is because, whenever applied load increases, the friction at the contact surface of the material and rotating disc obviously increases. Hence, incorporation of the coconut shell particles in the Al-Si-Fe alloy matrix as reinforcement increases the wear resistance of the material

  6. Valence electron structure analysis of the cubic silicide intermetallics in rapidly solidified Al-Fe-V-Si alloy

    International Nuclear Information System (INIS)

    Wang, J.Q.; Qian, C.F.; Zhang, B.J.; Tseng, M.K.; Xiong, S.W.

    1996-01-01

    The application of rapid solidification for the development of elevated temperature aluminum alloys has resulted in the emergence of several alloys based on the Al-Fe alloy system. Of particular interest are Al-Fe-V-Si alloys which have excellent room temperature and high temperature mechanical properties. In a pioneering study, Skinner et al. showed the stabilization of the cubic phase in ternary Al-Fe-Si alloy by the addition of a quaternary element, vanadium. The evolution of the microstructure in these alloys both during rapid solidification and subsequent processing is of crucial importance. Kim has demonstrated that the composition of the silicide phase in rapidly solidified Al-Fe-V-Si alloy is very close to Al 12 (Fe,V) 3 Si with the body centered cubic (bcc) structure. The structure is closely related to that of quasicrystals.In view of the structural features and the relationship between the α 12 and α 13 phases, the researching emphasis should firstly be put on the α 12 phase. In this paper the authors analyzed the α -(AlFeSi)(α 12 -type) phase from the angle of atomic valence electron structure other than the traditional methods of obtaining the diffraction spots of the phase. Several pieces of information were obtained about the hybrid levels and bond natures of every kind of atom in the α -(AlFeSi) phase. Finally the authors explained the phenomenon which V atom can substitute for Fe atom in the α 12 phase and improve the thermal stability of the phase in Al-Fe-V-Si alloy

  7. 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.

  8. Dynamic magnetization of NiZn ferrite doped FeSiAl thin films fabricated by oblique sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Xiaoxi, E-mail: xiaoxi.zhong@gmail.com [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China); Phuoc, Nguyen N. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Soh, Wee Tee [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Ong, C.K. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Li, Lezhong [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China)

    2017-06-15

    Highlights: • We prepared NiZn ferrite doped FeSiAl-based thin films using oblique deposition technique. • The magnetic properties of FeSiAl-based thin films were systematically studied. • Two ferromagnetic resonance peaks were observed in the permeability spectra. • The thermal stability of microwave properties of FeSiAl-based films was studied. • The thermal stability of properties we studied was relatively good. - Abstract: In this study, we comprehensively investigate the dynamic magnetic properties of FeSiAl-NiZnFeO thin films prepared by the oblique deposition method via a shorted microstrip perturbation technique. For the films with higher oblique angle and NiZn ferrite doping amount, there are two ferromagnetic resonance peaks observed in the permeability spectra, and both of the two peaks originate from FeSiAl. Furthermore, the magnetic anisotropy field H{sub K} of the ferromagnetic resonance peak at higher frequency is enhanced with increasing doping amount, which is interpreted in terms of the contribution of reinforced stress-induced anisotropy and shape anisotropy brought about by doping elements and oblique sputtering method. In addition, the thermal stability of the ferromagnetic resonance frequency f{sub FMR} of FeSiAl-NiZnFeO films with oblique angles of 35° and 45° with respect to temperature ranging from 300 K to 420 K is deteriorated with increasing ferrite doping amount, which is mainly ascribed to the influence of pair-ordering anisotropy and/or the reduction of the FeSiAl grain size.

  9. Microstructural development in a rapidly solidified Al-Fe-V-Si alloy

    International Nuclear Information System (INIS)

    Park, W.J.; Baek, E.R.; Lee, Sunghak; Kim, N.J.

    1991-01-01

    TEM is used to investigate microstructural development in a rapidly solidified Al-Fe-V-Si alloy. The as-cast microstructure of a rapidly solidified Al-Fe-V-Si alloy was found to vary depending on casting conditions and also through the thickness of ribbon. For completely Zone A ribbon, intercellular phase consists of a microquasi-crystalline phase, while for the Zone A and Zone B mixed ribbon, it consists of a silicide phase. In either case, formation of globular particles of a cluster microquasi-crystalline phase is observed near the air side of the ribbon. Annealing study shows significant differences in the final microstructure depending on the initial status of the ribbon. Completely Zone A ribbon, whose microstructure is composed of a microquasi-crystalline phase, results in a very coarse microstructure after annealing as compared to the Zone A and Zone B mixed ribbon. This result has important implications for the development of high-performance elevated-temperature Al alloys. 12 refs

  10. 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.

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

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2010-04-01

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

  12. The Viscous Behavior of FeOt-Al2O3-SiO2 Copper Smelting Slags

    Science.gov (United States)

    Park, Hyun-Shik; Park, Su Sang; Sohn, Il

    2011-08-01

    Understanding the viscous behavior of copper smelting slags is essential in increasing the process efficiency and obtaining the discrete separation between the matte and the slag. The viscosity of the FeOt-SiO2-Al2O3 copper smelting slags was measured in the current study using the rotating spindle method. The viscosity at a fixed Al2O3 concentration decreased with increasing Fe/SiO2 ratio because of the depolymerization of the molten slag by the network-modifying free oxygen ions (O2-) supplied by FeO. The Fourier transform infrared (FTIR) analyses of the slag samples with increasing Fe/SiO2 ratio revealed that the amount of large silicate sheets decreased, whereas the amount of simpler silicate structures increased. Al2O3 additions to the ternary FeOt-SiO2-Al2O3 slag system at a fixed Fe/SiO2 ratio showed a characteristic V-shaped pattern, where initial additions decreased the viscosity, reached a minimum, and increased subsequently with higher Al2O3 content. The effect of Al2O3 was considered to be related to the amphoteric behavior of Al2O3, where Al2O3 initially behaves as a basic oxide and changes to an acidic oxide with variation in slag composition. Furthermore, Al2O3 additions also resulted in the high temperature phase change between fayalite/hercynite and the modification of the liquidus temperature with Al2O3 additions affecting the viscosity of the copper smelting slag.

  13. Properties of nanocrystalline Fe75Si15M10 (M-Cr and Al) powders prepared by mechanical alloying.

    Science.gov (United States)

    Kalita, M P C; Perumal, A; Srinivasan, A; Pandey, Brajesh; Verma, H C

    2008-08-01

    We report the structural and magnetic properties of the nanocrystalline Fe75Si15M10 (M-Al and Cr) powders prepared by mechanical alloying. The milling process produced a non-equilibrium solid solutions of bcc alpha-Fe(Si,Cr) and alpha-Fe(Si,Al). The average dislocation density increases and the average crystallite size decreases with increasing milling time. Magnetic property studies show that the coercivity of the sample increases and magnetization of the sample decreases with increasing milling time. The evolution of a non-equilibrium solid solution and the resulting magnetic properties of nanocrystalline powders are explained on the basis of Neel theory and modified random anisotropy model proposed by Shen et al.

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

    Directory of Open Access Journals (Sweden)

    Shengli Chen

    2017-01-01

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

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

    Science.gov (United States)

    Zuo, T. T.; Li, R. B.; Ren, X. J.; Zhang, Y.

    2014-12-01

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

  16. The effect of Mn and Al dopants on the β-FeSi2 stabilization by a two-step route: Mechanical alloying and annealing

    International Nuclear Information System (INIS)

    Desimoni, J.; Martinez, J.; Cotes, S.M.; Runco, J.; Taylor, M.A.

    2009-01-01

    Al and Mn dopant influence on β-FeSi 2 phase formation was studied using X-ray diffraction and Moessbauer spectroscopy. Samples of Fe 1-x R x Si 2 (R = Al, Mn with 0.00 ≤ x ≤ 0.12) were prepared by the simultaneous mill of pure Si, Fe and R, under Ar atmosphere followed by an annealing at 1123 K during 4 h at 1.33 x 10 -5 Pa. The results indicate that the addition of Al improved the stabilization of β-FeSi 2 phase, reducing the amount of ε-FeSi from 20% to 6%. Also a preferential substitution at the Fe- siteII by Mn atoms in β-FeSi 2 can be inferred from the present study. The sequence of phase formation is summarised by two reactions that account for the milling and the annealing effects.

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

    International Nuclear Information System (INIS)

    Tao, Lei; Li, Heqin; Shen, Jiong; Qiao, Kai; Wang, Wei; Zhou, Chu; Zhang, Jing; Tang, Qiong

    2015-01-01

    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 2 SO 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

  18. 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.

  19. Photoluminescence of the Mg2Al4Si5O18-Al2O3-MgAl2O4-SiO2 ceramic system containing Fe3+ and Cr3+ as impurity ions

    Science.gov (United States)

    Sosman, L. P.; López, A.; Pedro, S. S.; Papa, A. R. R.

    2018-02-01

    This work presents the results of photoluminescence, excitation and radiative decay time for a ceramic system containing Mg2Al4Si5O18-Al2O3-MgAl2O4-SiO2 with Fe3+ and Cr3+ as impurity ions. Emission data were obtained using several excitation wavelengths and the excitation data were acquired for the most intense emission bands. The optical results were analyzed according to the Tanabe-Sugano (TS) theory from which the crystalline field parameter Dq and Racah parameters B and C were obtained for the Fe3+ and Cr3+ sites. The results indicate that the Fe3+ and Cr3+ ions occupy tetrahedral and octahedral sites, respectively. The emission from Fe3+ and Cr3+ ions causes an intense and broad band ranging between 350 nm and 850 nm, showing that this material is a potential tunable radiation source at room temperature.

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

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2017-03-01

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

  1. Sensitivity analysis of FeCrAl cladding and U3Si2 fuel under accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-08-01

    The purpose of this milestone report is to highlight the results of sensitivity analyses performed on two accident tol- erant fuel concepts: U3Si2 fuel and FeCrAl cladding. The BISON fuel performance code under development at Idaho National Laboratory was coupled to Sandia National Laboratories’ DAKOTA software to perform the sensitivity analyses. Both Loss of Coolant (LOCA) and Station blackout (SBO) scenarios were analyzed using main effects studies. The results indicate that for FeCrAl cladding the input parameters with greatest influence on the output metrics of interest (fuel centerline temperature and cladding hoop strain) during the LOCA were the isotropic swelling and fuel enrichment. For U3Si2 the important inputs were found to be the intergranular diffusion coefficient, specific heat, and fuel thermal conductivity. For the SBO scenario, Young’s modulus was found to be influential in FeCrAl in addition to the isotropic swelling and fuel enrichment. Contrarily to the LOCA case, the specific heat of U3Si2 was found to have no effect during the SBO. The intergranular diffusion coefficient and fuel thermal conductivity were still found to be of importance. The results of the sensitivity analyses have identified areas where further research is required including fission gas behavior in U3Si2 and irradiation swelling in FeCrAl. Moreover, the results highlight the need to perform the sensitivity analyses on full length fuel rods for SBO scenarios.

  2. Two growth mechanisms in one-step fabrication of the oxide matrix for FeSiAl soft magnetic composites

    Science.gov (United States)

    Wu, Chen; Gao, Xinwei; Zhao, Guoliang; Jiang, Yinzhu; Yan, Mi

    2018-04-01

    Hydrolysis precipitation as a new method was used in the preparation of oxide insulation matrix for FeSiAl soft magnetic composites (SMCs). The growth and composition of the matrix can be tuned by the concentration of the Al(NO3)3 solution, reaction temperature and pH value during the hydrolysis. With optimized Al(NO3)3 concentration of 0.6 mol/L and hydrolysis temperature of 75 °C, two mechanisms have been revealed in the formation of the insulation coating depending on the pH of the Al(NO3)3 solution. When pH = 3, the coating layer contains a mixture of Al2O3 and Fe2O3, while Al2O3 and SiO2 form as the coating for pH = 8. Despite that the Al2O3 dominates for both conditions, it grows via different routes. The Al(OH)3 as the precursor forms through Al3+ hydrolysis and heterogeneous nucleation for pH = 3. With increased pH to 8, the Al3+ directly reacts with OH- to form Al(OH)3 colloidal particles which adsorb onto the surface of FeSiAl powders via electrostatic attraction. Both mechanisms give rise to satisfactory magnetic performance with high effective permeability (μe = 103.5 and 113.4) and low core loss (Pcv = 278.4 mW·cm-3 and 237.8 mW·cm-3) for pH = 3 and 8 measured at 100 mT, 50 kHz.

  3. Spin accumulation in Si channels using CoFe/MgO/Si and CoFe/AlOx/Si tunnel contacts with high quality tunnel barriers prepared by radical-oxygen annealing

    International Nuclear Information System (INIS)

    Akushichi, T.; Shuto, Y.; Sugahara, S.; Takamura, Y.

    2015-01-01

    We investigate spin injection into Si channels using three-terminal spin-accumulation (3T-SA) devices with high-quality CoFe/MgO/n-Si and CoFe/AlO x /n-Si tunnel spin-injectors whose tunnel barriers are formed by radical oxidation of Mg and Al thin films deposited on Si(100) substrates and successive annealing under radical-oxygen exposure. When the MgO and AlO x barriers are not treated by the radical-oxygen annealing, the Hanle-effect signals obtained from the 3T-SA devices are closely fitted by a single Lorentz function representing a signal due to trap spins. On the other hand, when the tunnel barriers are annealed under radical-oxygen exposure, the Hanle-effect signals can be accurately fitted by the superposition of a Lorentz function and a non-Lorentz function representing a signal due to accumulated spins in the Si channel. These results suggest that the quality improvement of tunnel barriers treated by radical-oxygen annealing is highly effective for spin-injection into Si channels

  4. Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites

    Directory of Open Access Journals (Sweden)

    Junfeng Xiang

    2018-02-01

    Full Text Available The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiCp/Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiCp/Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiCp/Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD and chemical vapor deposition (CVD diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiCp/Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting

  5. Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites.

    Science.gov (United States)

    Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

    2018-02-07

    The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiC p /Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiC p /Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiC p /Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiC p /Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different

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

    Directory of Open Access Journals (Sweden)

    Jacek Antonkiewicz

    2014-07-01

    Full Text Available Application of sewage sludge for environmental management of fly ashes landfill site affects chemical composition of plants. The aim of the present investigations was learning the effect of growing doses of municipal sewage sludge on the yield and uptake of Fe, Mn, Al, Si and Co by grass mixture used for environmental management of fly ashes landfill. The experimental design comprised of 5 objects differing by a dose of municipal sewage sludge supplied per 1 hectare: I. control, II. 25 t d.m., III. 50 t d.m., IV. 75 t d.m. and V. 100 t d.m. Application of sewage sludge resulted in the increase in yield. The content of analyzed elements in the grass mixture depended significantly on sewage sludge dose. Increasing doses of sewage sludge caused marked increase in Mn and Co contents, while they decreased Fe, Al and Si contents in the grass mixture. It was found that growing doses of sewage sludge caused an improvement of Fe to Mn ratio value in the grass mixture. Assessing the element content in the grass mixture in the view of forage value, it was found that Fe and Mn content did not meet the optimal value. Si content in plants was below the optimal value.

  7. High Temperature Creep of an Al-8,5Fe-1,3V-1,7Si Alloy

    Czech Academy of Sciences Publication Activity Database

    Kuchařová, Květa; Zhu, S. J.; Čadek, Josef

    2002-01-01

    Roč. 40, č. 2 (2002), s. 69-84 ISSN 0023-432X R&D Projects: GA AV ČR IBS2041001 Institutional research plan: CEZ:AV0Z2041904 Keywords : Al-8,5Fe 1,3V 1,7Si alloy * creep behavior , true threshold stress Subject RIV: JI - Composite Materials Impact factor: 0.493, year: 2002

  8. 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.

  9. (SiC/AlN)2 multilayer film as an effective protective coating for sintered NdFeB by magnetron sputtering

    Science.gov (United States)

    You, Yu; Li, Heqin; Huang, Yiqin; Tang, Qiong; Zhang, Jing; Xu, Jun

    2017-08-01

    SiC/AlN and (SiC/AlN)2 multilayer films with a well-arranged bilayer structure and a four-layer structure are prepared respectively on NdFeB substrates by a magnetron sputtering method. Crystal phase and microstructures of the SiC/AlN and (SiC/AlN)2 films are investigated using x-ray diffraction (XRD), field-emission scanning electron microscope (FESEM) and atomic force microscope (AFM). It is observed that the surface of the (SiC/AlN)2 four-layer film is much denser and smoother than that of the SiC/AlN bilayer film. Corrosion behaviors of the NdFeB substrates coated with SiC/AlN and (SiC/AlN)2 films as well as the bare NdFeB substrate are evaluated by potentiodynamic polarization curve tests. It is revealed that the lateral growth structures developed in interfaces are favorable for an enhanced corrosion resistance. Corrosion current densities of the (SiC/AlN)2 coated NdFeB measured in acid, alkali and salt solutions are 2.796  ×  10-9, 3.65  ×  10-6, and 2.912  ×  10-6 A cm-2, respectively, which are much lower than those of the bare NdFeB and the SiC/AlN coated NdFeB.

  10. Influence of Al grain structure on Fe bearing intermetallics during DC casting of an Al-Mg-Si alloy

    OpenAIRE

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

    2016-01-01

    207 mm diameter direct chill (DC) cast billets of 6063 aluminium-magnesium-silicon (Al-Mg-Si) alloy were produced with various different primary aluminium (α-Al) grain structures including feathery-dendrites, equiaxed-dendrites and equiaxed-globular morphologies. To control the α-Al grain structure (grain morphology and grain size) an intensive shearing melt conditioning technique and Al-5Ti-1B grain refiner were used. For the first time, due to the variety of controlled microstructures produ...

  11. 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.

  12. High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering.

    Science.gov (United States)

    Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

    2016-11-30

    In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al 15 (Fe,Cr)₃Si₂ or α-Al 15 (Fe,Mn)₃Si₂ phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5.

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

    International Nuclear Information System (INIS)

    Cam, N.F.; Yaprak, G.; Erduran, M.N.

    1999-01-01

    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)

  14. 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)

    Xiong, Lun; Yi, Lin; Gao, G.Y.

    2014-01-01

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

  15. PRELIMINARY EVALUATION OF FeCrAl CLADDING AND U-Si FUEL FOR ACCIDENT TOLERANT FUEL CONCEPTS

    Energy Technology Data Exchange (ETDEWEB)

    Hales, J. D.; Gamble, K. A.

    2015-09-01

    Since the accident at the Fukushima Daiichi Nuclear Power Station, enhancing the accident tolerance of light water reactors (LWRs) has become an important research topic. In particular, the community is actively developing enhanced fuels and cladding for LWRs to improve safety in the event of accidents in the reactor or spent fuel pools. Fuels with enhanced accident tolerance are those that, in comparison with the standard UO2-zirconium alloy system, can tolerate loss of active cooling in the reactor core for a considerably longer time period during design-basis and beyond design-basis events while maintaining or improving the fuel performance during normal operations and operational transients. This paper presents early work in developing thermal and mechanical models for two materials that may have promise: U-Si for fuel, and FeCrAl for cladding. These materials would not necessarily be used together in the same fuel system, but individually have promising characteristics. BISON, the finite element-based fuel performance code in development at Idaho National Laboratory, was used to compare results from normal operation conditions with Zr-4/UO2 behavior. In addition, sensitivity studies are presented for evaluating the relative importance of material parameters such as ductility and thermal conductivity in FeCrAl and U-Si in order to provide guidance on future experiments for these materials.

  16. Microstructural features and heat flow analysis of atomized and spray-formed Al-Fe-V-Si alloy

    International Nuclear Information System (INIS)

    Srivastava, A.K.; Ranganathan, S.; Ojha, S.N.

    1998-01-01

    Microstructural features of rapidly solidified powders and preforms of Al 80 Fe 10 V 4 Si 6 alloy produced by spray forming process have been studied. The atomization and spray deposition were carried out using a confined gas atomization process and the microstructural features were characterized using scanning electron microscopy and transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The microstructure of a wide size range of atomized powders invariably revealed cellular and dendritic morphology. The extent of dendritic region and the dendritic arm spacing were observed to increase with power particle size. The TEM investigations indicated the presence of ultrafine second-phase particles in the intercellular or interdendritic regions. In contrast, the spray deposits of the alloy showed considerable variation in microstructure and size and dispersion of the second-phase particles at specific distances from the deposit-substrate interface and the exterior regions of the deposit. Nevertheless, considerable homogeneity was observed in the microstructure toward the center of the spray deposit. The formation and distribution of a cubic phase α-Al(Fe, V)Si has been characterized in both atomized powders and spray deposits. A one-dimensional heat flow model has been used to analyze the evolution of microstructure during atomization and also during spray deposition processing of this alloy. The results indicate that thermal history of droplets in the spray on deposition surface and their solidification behavior considerably influence the microstructural features of the spray deposits

  17. 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)

  18. Petrografía y distribución de óxidos de Fe, Al y Si en fragipanes blancos de origen volcánico

    Directory of Open Access Journals (Sweden)

    Enrique Ortiz-Hernández

    2012-10-01

    Full Text Available El objetivo fue determinar la petrología y distribución de óxidos de Fe, Al y Si en tres perfiles de suelos de origen volcánico con horizontes endurecidos (fragipán, en la región noroeste del Estado de México. Se utilizaron técnicas químicas selectivas para extraer Fe, Al y Si. El fragipán blanco clasifica petrográficamente como toba dacítica poco soldada y alterada. Los perfiles muestran incipiente a moderado grado de alteración de minerales primarios que contienen Fe y Al dadas las condiciones climáticas de la región. Los contenidos de alofano, ferrihidrita, y óxidos de hierro cristalino se presentan en pocas cantidades, escasos contenidos de Ald y Si lábil en los perfiles indican presencia de aluminosilicatos cristalinos. Bajas relaciones de Alp/Alo y Fep/Feo evidencia que la mayor parte de Al y Fe están unidos a compuestos inorgánicos pobremente cristalinos. Relaciones bajas de Fep/Fed y Alp/Ald indican limitada asociación de Fe y Al con compuestos orgánicos. La relación arcilla/Fed revela emigración de arcilla y óxidos de Fe del horizonte superior al fragipán.  El Si, Al y Fe en el fragipán forman parte de la estructura de los silicatos y mínimo grado de cristalinidad de Fe y Al pedogenético. Valores mayores de relación Sid(Sid+Ald en el fragipán indican aumento en la dureza.

  19. The Effects of Fe-Particles on the Tensile Properties of Al-Si-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Anton Bjurenstedt

    2016-12-01

    Full Text Available The effect of Fe-rich particles has been a topic for discussion in the aluminum casting industry because of the negative impact they exert on the mechanical properties. However, there are still contradictions on the effects of various morphologies of Fe-particles. In this study, microstructural characterization of tensile tested samples has been performed to reveal how unmodified and modified Fe-rich particles impact on the tensile behavior. Analysis of additions of Fe modifiers such as Mn and Cr, showed higher amounts of primary Fe-rich particles (sludge with increased porosity and, as result, degraded tensile properties. From the fracture analysis of tensile tested hot isostatic pressed (HIPed samples it could be concluded that the mechanical properties were mainly governed by the Fe-rich particles, which were fracturing through cleavage, not by the porosity.

  20. 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.

  1. Influence of ECAP on Densification Behaviour in the PM Aluminium Al-Mg-Si-Cu-Fe Alloy

    Science.gov (United States)

    Bidulská, Jana; Kvačkaj, Tibor; Kočiško, Róbert; Bidulský, Róbert; Grande, Marco Actis

    2010-09-01

    The main aim of this paper is to show how ECAP influences the densification behaviour of PM aluminium alloys. An aluminium based powder (Al-Mg-Si-Cu-Fe) was used as material to be investigated. After applying different compacting pressures, specimens were dewaxed in a ventilated furnace at 400 °C for 60 min. Sintering was carried out in a vacuum furnace at 610 °C for 30 min. The specimens were ECAPed for 1 pass. Optical characterization was carried out on the minimum of 10 different image fields. The results were measured for each pore individually in order to describe the dimensional and morphological porosity characteristics. ECAP influences the porosity distribution in terms of the severe shear deformation involved.

  2. 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.

  3. 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.

  4. Tailoring of K0.8Al0.7Fe0.15Si2.25O6 Leucite Based Dental Ceramic Material

    Directory of Open Access Journals (Sweden)

    Aleksandar Kremenović

    2016-06-01

    Full Text Available Potassium based ceramic materials composed from leucite in which 5 % of Al is exchanged with Fe and 4 % of hematite was synthesized by mechanochemical homogenization and annealing of K2O-SiO2-Al2O3-Fe2O3 mixtures. Synthesized material was characterized by X-ray Powder Diffraction (XRPD and Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM/EDX. The two methods are in good agreement in regard to the specimen chemical composition suggesting that a leucite chemical formula is K0.8Al0.7Fe0.15Si2.25O6. Rietveld structure refinement results reveal that about 20 % of vacancies exist in the position of K atoms. This work is licensed under a Creative Commons Attribution 4.0 International License.

  5. Effect of on-site Coulomb interaction (U) on the electronic and magnetic properties of Fe{sub 2}MnSi, Fe{sub 2}MnAl and Co{sub 2}MnGe

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Sonu, E-mail: sonusharma@iitmandi.ac.in; Pandey, Sudhir K.

    2016-04-01

    The electronic band structures, density of states' plots and magnetic moments of Fe{sub 2}MnSi, Fe{sub 2}MnAl, and Co{sub 2}MnGe 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 Fe{sub 2}MnSi, whereas the ground state of Fe{sub 2}MnAl 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 Co{sub 2}MnGe. The magnetic moment of Fe atom in Fe{sub 2}MnSi (Fe{sub 2}MnAl) 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 Fe{sub 2}MnSi for all values of U, whereas in Fe{sub 2}MnAl they are coupled antiferromagnetically below U=2 eV and ferromagnetically above it. Above U=2 eV the metallic ground state of Fe{sub 2}MnAl 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 Fe{sub 2}MnAl compound. - Highlights: • The full-potential linearized augmented-plane wave methods have been employed. • On-site Coulomb interaction U under AMF double counting scheme has also considered. • The significant effect of U was observed on the properties of Fe{sub 2}-based compounds. • Very small effect of U under AMF scheme has been observed on Co{sub 2}MnGe. • The validity of the scheme is not robust for the entire range of U in Fe{sub 2}MnAl.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  7. High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water.

    Science.gov (United States)

    Wei, Yan; Yang, Ran; Zhang, Yong-Xing; Wang, Lun; Liu, Jin-Huai; Huang, Xing-Jiu

    2011-10-21

    γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.

  8. The Partial Molar Volume and Compressibility of the FeO Component in Model Basalts (Mixed CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6 Liquids) at 0 GPa: evidence of Fe2+ in 6-fold coordination

    Science.gov (United States)

    Guo, X.; Lange, R. A.; Ai, Y.

    2010-12-01

    FeO is an important component in magmatic liquids and yet its partial molar volume at one bar is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Moreover, there is growing evidence from spectroscopic studies that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and it is expected that the partial molar volume and compressibility of the FeO component will vary accordingly. We have conducted both density and relaxed sound speed measurements on four liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system: (1) Di-Hd (50:50), (2) An-Hd (50:50), (3) An-Di-Hd (33:33:33) and (4) Hd (100). Densities were measured between 1573 and 1838 K at one bar with the double-bob Archimedean method using molybdenum bobs and crucibles in a reducing gas (1%CO-99%Ar) environment. The sound speeds were measured under similar conditions with a frequency-sweep acoustic interferometer, and used to calculate isothermal compressibility. All the density data for the three multi-component (model basalt) liquids were combined with density data on SiO2-Al2O3-CaO-MgO-K2O-Na2O liquids (Lange, 1997) in a fit to a linear volume equation; the results lead to a partial molar volume (±1σ) for FeO =11.7 ± 0.3(±1σ) cm3/mol at 1723 K. This value is similar to that for crystalline FeO at 298 K (halite structure; 12.06 cm3/mol), which suggests an average Fe2+ coordination of ~6 in these model basalt compositions. In contrast, the fitted partial molar volume of FeO in pure hedenbergite liquid is 14.6 ± 0.3 at 1723 K, which is consistent with an average Fe2+ coordination of 4.3 derived from EXAFS spectroscopy (Rossano, 2000). Similarly, all the compressibility data for the three multi-component liquids were combined with compressibility data on SiO2-Al2O3-CaO-MgO liquids (Ai and Lange, 2008) in a fit to an ideal mixing model for melt compressibility; the results lead to a partial molar

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

    International Nuclear Information System (INIS)

    Korchef, Atef; Champion, Yannick; Njah, Nabil

    2007-01-01

    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 Al 8 Fe 2 Si 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

  10. Ladle and Continuous Casting Process Models for Reduction of SiO2 in SiO2-Al2O3-CaO Slags by Al in Fe-Al(-Si) Melts

    Science.gov (United States)

    Park, Jiwon; Sridhar, S.; Fruehan, Richard J.

    2015-02-01

    Based on a mixed control or two-phase mass transfer model considering mass transport in the metal and the slag phases, process models for ladle and continuous castor mold were developed to predict the changes in the metal and the slag chemistry and viscosity. In the ladle process model, the rate of reaction is primarily determined by stirring gas flow rate, which greatly alters the mass transports of the metal and the slag phases. In the continuous casting process model, the effects of the Al, Si, and SiO2 contents in the incoming flow of the fluid phases, casting speed, mold flux consumption rate, and depth of the liquid mold flux pool on the steady-state compositions of the metal and the mold flux were assessed.

  11. Anomalous Hall effect and current spin polarization in Co2Fe X Heusler compounds (X =Al , Ga , In , Si , Ge , and Sn ): A systematic ab initio study

    Science.gov (United States)

    Huang, Hung-Lung; Tung, Jen-Chuan; Guo, Guang-Yu

    2015-04-01

    Co-based Heusler compounds are ferromagnetic with a high Curie temperature and a large magnetization density, and thus are promising for spintronic applications. In this paper, we perform a systematic ab initio study of two principal spin-related phenomena, namely, anomalous Hall effect and current spin polarization, in Co2-based Heusler compounds Co2Fe X (X =Al , Ga , In , Si , Ge , Sn ) in the cubic L2 1 structure within the density functional theory with the generalized gradient approximation (GGA). The accurate all-electron full-potential linearized augmented plane-wave method is used. First, we find that the spin polarization of the longitudinal current (PL) in Co2Fe X (X =Al , Ga , In , Al0.5Si0.5 , and Sn ) is ˜100 % even though that of the electronic states at the Fermi level (PD) is not. Further, the other compounds also have a high current spin polarization with PL>85 %. This indicates that all the Co2Fe X compounds considered are promising for spin-transport devices. Interestingly, PD is negative in Co2Fe X (X =Si , Ge , and Sn ), differing in sign from the PL as well as that from the transport experiments. Second, the calculated anomalous Hall conductivities (AHCs) are moderate, being within 200 S/cm, and agree well with the available experiments on a highly L2 1 ordered Co2FeSi specimen although they differ significantly from the reported experiments on other compounds where the B2 antisite disorders were present. Surprisingly, the AHC in Co2FeSi decreases and then changes sign when Si is replaced by Ge and finally by Sn. Third, the calculated total magnetic moments agree well with the corresponding experimental ones in all the studied compounds except Co2FeSi where a difference of 0.3 μB/f .u . exists. We also perform the GGA plus on-site Coulomb interaction U calculations in the GGA + U scheme. We find that including the U affects the calculated total magnetic moment, spin polarization and AHC significantly, and in most cases, unfortunately

  12. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

  14. 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)

    Schuon, S.R.

    1982-01-01

    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

  15. 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.

  16. Dynamics of dissolved major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) elements along the lower Orinoco River

    OpenAIRE

    Mora, A.; Mahlknecht, J.; Baquero, J. C.; Laraque, Alain; Alfonso, J. A.; Pisapia, D.; Balza, L.

    2017-01-01

    This study addresses the changes in dissolved major and trace element concentrations along the Orinoco River, including the mixing zone between the Orinoco and Apure Rivers. Water samples from the Apure and Orinoco Rivers were collected monthly in four sectors over a period of 15months. Auxiliary parameters (pH, dissolved oxygen, conductivity, and temperature), total suspended sediments, dissolved organic carbon (DOC), and major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) e...

  17. Effect of T6 treatment on the coefficient of friction of Al25Mg2Si2Cu4Fe alloy

    Science.gov (United States)

    Sondur, D. G.; Mallapur, D. G.; Udupa, K. Rajendra

    2018-04-01

    Effect of T6 treatment on the coefficient of friction of Al25Mg2Si2Cu4Fe alloy was evaluated by conducting wear test on pin on disc wear testing machine. Wear test parameters such as the load and the speed were varied by keeping one constant and varying the other respectively. It was observed that the coefficient of friction is high for as cast condition due to the brittle microstructure. After T6 heat treatment the precipitates formed such as the Chinese scripts and the Mg2Si blocks got modified that lead to improvement in the hardness and the wear resistance. This reduces the coefficient of friction.

  18. Fe3Si surface coating on SiFe steel

    International Nuclear Information System (INIS)

    Schneeweiss, O.; Pizurova, N.; Jiraskova, Y.; Zak, T.; Cornut, B.

    2000-01-01

    Fe 3 Si layers were prepared using chemical vapor deposition of Si on the surface of Go steel and its subsequent heat treatment. The changes in the structure and phase composition after different heat treatment conditions have been analyzed. The coating is characterized by high hardness, good corrosion resistance, high electrical resistivity, and the spin texture which differs from the steel substrate

  19. DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

    OpenAIRE

    Sunardi, Sunardi; Muryono, Muryono

    2010-01-01

    Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec).  At this research condition of neutron generator was set at...

  20. Radioisotopic Study of Methanol Transformation over H- and Fe-Beta Zeolites; Influence of Si/Al Ratio on Distribution of Products

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Murzin, D.Yu.

    2006-01-01

    Complete text of publication follows. The acid-basic properties of Beta zeolite can be modified by dealumination and/or ionexchange. The wide-pore H-Beta zeolite has strong Bronsted acid sites and other chemical environment which govern adsorption and conversion of methanol to dimethyl ether and hydrocarbons during catalysis [1-2]. Partly Fe-ion-exchanged Beta i.e. Fe-H-Beta zeolite keeps this behavior to a certain extent; however, the presence of Fe ions can modify the reaction pathway. In the present work, the methanol conversion was studied over H- and Fe-Beta zeolites at two different Si/Al ratios. 11 C-methanol was used to follow-up adsorption as well as desorption of methanol and its derivates. Therefore, a radioactivity detector was integrated to the gas chromatograph for exact identification of the labelled methanol and its derivates. H-Beta and Fe-Beta zeolites were applied at two different Si/Al ratios i.e. H-Beta(25) and H-Beta(300) and Fe-H-Beta(25) and Fe- H-Beta (300), respectively. A glass tube fixed-bed reactor was used as a closed static reactor. The 11 C-radioisotope (T 1/2 =20.4 min) was produced in 11 C-labelled carbon dioxide form by cyclotron. The 11 C-methanol tracer was produced by radiochemical process [3]. The mixture of 11 C-methanol and non-radioactive methanol was then introduced into zeolite by He gas flow. The volatile products of catalytic conversion of 11 C-methanol were analyzed by radio-gas chromatography (gas chromatograph with flame ionization detector (FID) coupled on-line with a radioactivity detector). The methanol conversion rate and product selectivities to dimethyl ether, hydrocarbons (methane, C 2 -C 6 olefins and paraffins), formaldehyde and carbon-oxides were measured and calculated over H- and Fe-Beta zeolites at two different Si/Al ratios at 250 and 350 deg C. Over H-Beta(25) C 2 -C 6 hydrocarbons (mostly as alkanes) with high conversion rate and some dimethyl ether were detected due to presence of strong Bronsted

  1. Fabrication of highly spin-polarized Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} thin-films

    Energy Technology Data Exchange (ETDEWEB)

    Vahidi, M.; Zhang, S. K.; Yu, L.; Huang, M.; Newman, N., E-mail: Nathan.Newman@asu.edu [School of Materials, Arizona State University, Tempe, Arizona 85287-8706 (United States); Gifford, J. A.; Chen, T. Y. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Krishnamurthy, S.; Yu, Z. G. [SRI International, 301-64, Menlo Park, California 94025 (United States); Youngbull, C. [The Biodesign Institute, Arizona State University, Tempe, Arizona 85287 (United States)

    2014-04-01

    Ferromagnetic Heusler Co{sub 2}FeAl{sub 0.5}Si{sub 0.5} epitaxial thin-films have been fabricated in the L2{sub 1} structure with saturation magnetizations over 1200 emu/cm{sup 3}. 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.

  2. 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.

  3. 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

  4. DETERMINATION OF LIMIT DETECTION OF THE ELEMENTS N, P, K, Si, Al, Fe, Cu, Cd, WITH FAST NEUTRON ACTIVATION USING NEUTRON GENERATOR

    Directory of Open Access Journals (Sweden)

    Sunardi Sunardi

    2010-06-01

    Full Text Available Determination of limit detection of the elements N, P, K, Si, Al, Fe, Cu, Cd, with fast neutron activation using neutron generator has been done.  Samples prepared from SRM 2704, N, P, K elements from MERCK, Cu, Cd, Al from activation foil made in San Carlos, weighted and packed for certain weight then iradiated during 30 minutes with 14 MeV fast neutron using the neutron generator and then counted with gamma spectrometry (accuspec.  At this research condition of neutron generator was set at current 1 mA that produced neutron flux about 5,47.107 n/cm2.s and  experimental result shown that the limit detection for the elements N, P, K, Si, Al, Fe, Cu, Cd are  2,44 ppm, 1,88 ppm, 2,15 ppm, 1,44 ppm, 1,26 ppm, 1,35 ppm, 1,05 ppm, 2,99 ppm, respectively.  The data  indicate that the limit detection or sensitivity of appliance of neutron generator to analyze the element is very good, which is feasible to get accreditation AANC laboratory using neutron generator.   Keywords: limit detection, AANC, neutron generator

  5. Final thickness reduction and development of Goss texture in C- and Al-free Fe-3%Si-0.1%Mn-0.012%S electrical steel

    Science.gov (United States)

    Oh, Eun Jee; Heo, Nam Hoe; Koo, Yang Mo

    2017-11-01

    The correlation between final thickness reduction and development of Goss texture has been investigated in a C- and Al-free Fe-3%Si electrical steel. During final annealing, the annealing texture is transited from {110}⊥ND to {100}⊥ND texture with increasing final thickness reduction. This is due to the decrease in primary grain size after pre-annealing with increasing final thickness reduction which accelerates the selective growth rate of the {100} grains at the expense of the other {hkl} grains. At an optimal final thickness reduction of 75.8%, the high magnetic induction of 1.95 Tesla, which arises from the sharp {110} Goss texture and is comparable to that of conventional grain-oriented electrical steels, is obtained from the C- and Al-free Fe-3%Si-0.1%Mn electrical steel. Such a high magnetic property is produced through the surface-energy-induced selective grain growth of the Goss grains under the lower surface-segregated condition of sulfur which makes the surface energy of the {110} plane lowest among the {hkl} planes.

  6. 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

  7. Overview of lower length scale model development for accident tolerant fuels regarding U3Si2 fuel and FeCrAl cladding

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Laboratory

    2016-09-01

    U3Si2 and FeCrAl have been proposed as fuel and cladding concepts, respectively, for accident tolerance fuels with higher tolerance to accident scenarios compared to UO2. However, a lot of key physics and material properties regarding their in-pile performance are yet to be explored. To accelerate the understanding and reduce the cost of experimental studies, multiscale modeling and simulation are used to develop physics-based materials models to assist engineering scale fuel performance modeling. In this report, the lower-length-scale efforts in method and material model development supported by the Accident Tolerance Fuel (ATF) high-impact-problem (HIP) under the NEAMS program are summarized. Significant progresses have been made regarding interatomic potential, phase field models for phase decomposition and gas bubble formation, and thermal conductivity for U3Si2 fuel, and precipitation in FeCrAl cladding. The accomplishments are very useful by providing atomistic and mesoscale tools, improving the current understanding, and delivering engineering scale models for these two ATF concepts.

  8. 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.

  9. Microstructural Evolution of AlCoCrFeNiSi High-Entropy Alloy Powder during Mechanical Alloying and Its Coating Performance.

    Science.gov (United States)

    Tian, Lihui; Fu, Ming; Xiong, Wei

    2018-02-23

    High-entropy alloys (HEAs) are promising structural materials due to their excellent comprehensive performances. The use of mechanically alloyed powders to deposit HEA coatings through atmospheric plasma spraying (APS) is an effective approach that can broaden the application areas of the HEAs. In this paper, a ductility-brittleness AlCoCrFeNiSi system was chosen as an object of study, and the detailed evolution of the surface morphology, particle size distribution, and microstructure of the powder during mechanical alloying was investigated. An AlCoCrFeNiSi HEA coating was deposited using powder milled for 10 h, which can be used as an ideal feedstock for APS. The surface morphology, microstructure, microhardness, and wear behavior of the coating at room temperature were investigated. The results showed that as the milling time increased, the particle size first increased, and then decreased. At the milling time of 10 h, simple body-centered cubic (BCC) and face-centered cubic (FCC) solid solution phases were formed. After spraying, the lamellar structure inside a single particle disappeared. An ordered BCC phase was detected, and the diffraction peaks of the Si element also disappeared, which indicates that phase transformation occurred during plasma spraying. A transmission electron microscopy analysis showed that nanometer crystalline grains with a grain size of about 30 nm existed in the APS coating. For the coating, an average microhardness of 612 ± 41 HV was obtained. Adhesive wear, tribo-oxidation wear, and slight abrasion wear took place during the wear test. The coating showed good wear resistance, with a volume wear rate of 0.38 ± 0.08 × 10 -4 mm³·N -1 ·m -1 , which makes it a promising coating for use in abrasive environments.

  10. Microstructural Evolution of AlCoCrFeNiSi High-Entropy Alloy Powder during Mechanical Alloying and Its Coating Performance

    Directory of Open Access Journals (Sweden)

    Lihui Tian

    2018-02-01

    Full Text Available High-entropy alloys (HEAs are promising structural materials due to their excellent comprehensive performances. The use of mechanically alloyed powders to deposit HEA coatings through atmospheric plasma spraying (APS is an effective approach that can broaden the application areas of the HEAs. In this paper, a ductility–brittleness AlCoCrFeNiSi system was chosen as an object of study, and the detailed evolution of the surface morphology, particle size distribution, and microstructure of the powder during mechanical alloying was investigated. An AlCoCrFeNiSi HEA coating was deposited using powder milled for 10 h, which can be used as an ideal feedstock for APS. The surface morphology, microstructure, microhardness, and wear behavior of the coating at room temperature were investigated. The results showed that as the milling time increased, the particle size first increased, and then decreased. At the milling time of 10 h, simple body-centered cubic (BCC and face-centered cubic (FCC solid solution phases were formed. After spraying, the lamellar structure inside a single particle disappeared. An ordered BCC phase was detected, and the diffraction peaks of the Si element also disappeared, which indicates that phase transformation occurred during plasma spraying. A transmission electron microscopy analysis showed that nanometer crystalline grains with a grain size of about 30 nm existed in the APS coating. For the coating, an average microhardness of 612 ± 41 HV was obtained. Adhesive wear, tribo-oxidation wear, and slight abrasion wear took place during the wear test. The coating showed good wear resistance, with a volume wear rate of 0.38 ± 0.08 × 10−4 mm3·N−1·m−1, which makes it a promising coating for use in abrasive environments.

  11. Behavior of U3Si2 Fuel and FeCrAl Cladding under Normal Operating and Accident Reactor Conditions

    International Nuclear Information System (INIS)

    Gamble, Kyle Allan Lawrence; Hales, Jason Dean; Barani, Tommaso; Pizzocri, Davide; Pastore, Giovanni

    2016-01-01

    As part of the Department of Energy's Nuclear Energy Advanced Modeling and Simulation program, an Accident Tolerant Fuel High Impact Problem was initiated at the beginning of fiscal year 2015 to investigate the behavior of \\usi~fuel and iron-chromium-aluminum (FeCrAl) claddings under normal operating and accident reactor conditions. The High Impact Problem was created in response to the United States Department of Energy's renewed interest in accident tolerant materials after the events that occurred at the Fukushima Daiichi Nuclear Power Plant in 2011. The High Impact Problem is a multinational laboratory and university collaborative research effort between Idaho National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory, and the University of Tennessee, Knoxville. This report primarily focuses on the engineering scale research in fiscal year 2016 with brief summaries of the lower length scale developments in the areas of density functional theory, cluster dynamics, rate theory, and phase field being presented.

  12. 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.

  13. 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)

    Silva, W.R.L. da.

    1982-01-01

    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)

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

    Science.gov (United States)

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

    2017-05-01

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

  15. 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.

  16. 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.

  17. A Structural Study on the Foaming Behavior of CaO-SiO2-MO (MO = MgO, FeO, or Al2O3) Ternary Slag System

    Science.gov (United States)

    Park, Youngjoo; Min, Dong Joon

    2017-12-01

    The foaming index of the CaO-SiO2-MO (MO = MgO, FeO, or Al2O3) ternary slag system with a fixed CaO/SiO2 ratio is measured to understand the effect of the ionic structure. At 1773 K (1500 °C), the foaming index of the slag increases with Al2O3 addition and decreases with MgO or FeO addition at a fixed CaO/SiO2 ratio. It is verified that the previous correlation between the foaming index and the physical properties could also be valid for the CaO-SiO2-(MgO or Al2O3) system. Raman spectroscopy for the CaO/SiO2 = 1.0 slag is applied to explain the foaming behavior from an ionic structural perspective. From the ionic structural viewpoint, the fractional change in each silicate anion unit is identified by de-convoluted Raman spectra. The Raman spectra indicate that the silicate network structure is polymerized with Al2O3 as an aluminosilicate structure; in contrast, de-polymerization occurs by MgO or FeO addition. Furthermore, the relationship between the silicate structure and the thermodynamic stability function is discussed. Since the ionic structure of the molten slag affects various physical/thermodynamic properties, the foaming behavior could be successfully interpreted from the ionic structural viewpoint.

  18. Primary Crystals of AlfeMnSi Intermetallics in the Cast AlSi Alloys

    Directory of Open Access Journals (Sweden)

    Warmuzek M.

    2017-09-01

    Full Text Available In this paper the results of the microscopic observations of the intermetallic AlFeMnSi phases crystals formed in the liquid hypo- and eutectic AlSi alloys containing transition metals 3.0 wt.% Fe and 0.1, 0.5 and 2.0 wt.% Mn were presented. The crystals morphology has been revealed on both polished and deep etched microsections. The different stages of the primary AlFeMnSi phases particles formation in the solidifying alloy and their final morphology were shown as influenced by cooling rate and alloy chemical composition.

  19. Experimental cation redistribution in the tourmaline lucchesiite, CaFe2 + 3Al6(Si6O18)(BO3)3(OH)3O

    Science.gov (United States)

    Bosi, Ferdinando; Skogby, Henrik; Hålenius, Ulf; Ciriotti, Marco E.

    2018-02-01

    Natural Mg-rich lucchesiite was thermally treated in air and hydrogen atmosphere up to 800 °C to study potential changes in Fe-, Mg- and Al ordering over the octahedrally coordinated Y- and Z-sites, and to explore possible applications to intracrystalline geothermometry based on tourmaline. Overall, the experimental data (structural refinement, Mössbauer, infrared and optical absorption spectroscopy) show that thermal treatment of lucchesiite results in an increase of Fetot contents at Z balanced by an increase of Mg and Al at Y. This process is accompanied by a significant deprotonation of the O3 anion site. The Fe order-disorder reaction depends more on temperature, than on redox conditions. During heat treatment in H2, reduction of Fe3+ to Fe2+ was not observed despite strongly reducing conditions, indicating that the f O2 conditions do not exclusively control the Fe oxidation state at the present experimental conditions. On the basis of this and previous studies, the intersite order-disorder process induced by thermal treatment indicates that Fe redistribution is an important factor for Fe-Mg-Al-exchange and is significant at temperatures around 800 °C. As a result, Fe-Mg-Al intersite order-disorder is sensitive to temperature variations, whereas geothermometers based solely on Mg-Al order-disorder appear insensitive and involve large uncertainties. The presented findings are important for interpretation of the post-crystallization history of both tourmaline and tourmaline host rocks, and indicate that successful tourmaline geothermometers may be developed by thermal calibration of the Fe-Mg-Al order-disorder reaction.

  20. 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.

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

    Science.gov (United States)

    Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

    2016-06-30

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

  2. 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.

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

    Science.gov (United States)

    Zhao, Xianming; Shen, Yongfeng; Qiu, Lina; Liu, Yandong; Sun, Xin; Zuo, Liang

    2014-12-09

    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.

  4. 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.

  5. Equilibria of Gold and Silver between Molten Copper and FeOx-SiO2-Al2O3 Slag in WEEE Smelting at 1300 °C

    Science.gov (United States)

    Avarmaa, Katri; O'Brien, Hugh; Taskinen, Pekka

    Waste Electrical and Electronic Equipment (WEEE) offers a significant resource for precious metals such as gold and silver. To maximize precious metal recoveries and sustainable use their behavior during WEEE smelting with copper as the collector metal needs to be characterized. This study experimentally determines the distributions of gold and silver between metallic copper and FeOx-SiO2-Al2O3 slag (LCu/s[Me] = [Me]Copper/[Me]Slag) in alumina-saturation over the oxygen potential range of 10-5-10-10 atm at 1300 °C. The experiments were conducted employing equilibration / quenching followed by major element analysis by Electron Probe Micro-Analysis (EPMA) and trace element analysis by Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS) techniques. Our results show silver distribution increased exponentially from 30 to 1000 as a function of decreasing oxygen partial pressure. Gold distribution was 105 at pO2 = 10-5 atm and >106 at pO2 = 10-6-10-10 atm.

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

    Directory of Open Access Journals (Sweden)

    S.A. Shokry

    2014-06-01

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

  7. Electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Guezlane, M. [Department of Physics, Faculty of Science, University of Batna, 05000 Batna (Algeria); Baaziz, H., E-mail: baaziz_hakim@yahoo.fr [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); El Haj Hassan, F., E-mail: hassan.f@ul.edu.lb [Université Libanaise, Faculté des Sciences (I), Laboratoire de Physique et d’Electronique (LPE), Elhadath, Beirut (Lebanon); Charifi, Z. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Djaballah, Y. [Laboratoire d’étude Physico-Chimique des Matériaux, Département de Physique, Faculté des Sciences, Université de Batna, Rue Chahid Boukhlouf, 05000 Batna (Algeria)

    2016-09-15

    Density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method is used to investigate the structural, electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) full Heusler alloys, with L2{sub 1} structure. The structural properties and spin magnetic moments are investigated by the generalized gradient approximations (GGA) minimizing the total energy. For band structure calculations, GGA, the Engel–Vosko generalized gradient approximation (EVGGA) and modified Becke–Johnson (mBJ) schemes are used. Results of density of states (DOS) and band structures show that these alloys are half-metallic ferromagnets (HMFS). A regular-solution model has been used to investigate the thermodynamic stability of the compounds Co{sub 2}Cr{sub x}Fe{sub 1−x}X that indicates a phase miscibility gap. The thermal effects using the quasi-harmonic Debye model are investigated within the lattice vibrations. The temperature and pressure effects on the heat capacities, Debye temperatures and entropy are determined from the non-equilibrium Gibbs functions. - Highlights: • We present electronic, magnetic and thermal properties of Co{sub 2}Cr{sub x}Fe{sub 1−x}X (X=Al, Si) Heusler alloys. • The calculated phase diagram indicates a significant phase miscibility gap. • The computed band structures of ternary compounds using GGA, EVGGA and mBJ schemes indicate an indirect band gap (Γ-X) for the ternary compounds Co{sub 2}FeAl, Co{sub 2}CrAl, Co{sub 2}FeSi and Co{sub 2}CrSi while both alloys have a direct band gap. • The quasi-harmonic Debye model is successfully applied to determine the thermal properties.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  9. First principles investigation of high pressure behavior of FeOOH-AlOOH-phase H (MgSiO4H2) system.

    Science.gov (United States)

    Tsuchiya, J.; Thompson, E. C.; Tsuchiya, T.; Nishi, M.; Kuwayama, Y.

    2017-12-01

    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) in the descending cold plate. A numbers of researches have been conducted so far about the high pressure behaviors of DHMSs. In recent years, we found new DHMS, phase H, at lower mantle pressure condition and the solid solution between phase H and d-AlOOH has been proposed as the most important carrier of water in the deepest part of Earth's mantle (Tsuchiya 2013 GRL, Nishi et al. 2014 Nature Geo., Ohira et al. 2014 EPSL). However, those hydrous minerals are actually not denser than surrounding (dry) mantle minerals (Tsuchiya and Mookherjee 2015 Scientific Reports) and the gravitational stability in deeper part of the Earth is questionable. Therefore, the effects of denser element such as Fe on the stability of DHMS are intimately connected to the ability of transportation of water into Earth's deep interiors. In order to assess the effect of Fe on the phase relation of phase H and d-AlOOH, we first investigated the high pressure behavior of the end-member composition of this system, the e-FeOOH. We have found the new high pressure transformation of FeOOH in the lower mantle conditions both theoretically and experimentally(Nishi et al. 2017 Nature). Here we show high pressure structures and the physical properties of FeOOH-AlOOH-phase H system using first principles calculation and discuss the possible geophysical implications of these phases.

  10. Morphology and the magnetic and conducting properties of heterogeneous layered magnetic structures [(Co45Fe45Zr10)35(Al2O3)65/ a-Si:H]36

    Science.gov (United States)

    Dyadkina, E. A.; Vorobiev, A. A.; Ukleev, V. A.; Lott, D.; Sitnikov, A. V.; Kalinin, Yu. E.; Gerashchenko, O. V.; Grigoriev, S. V.

    2014-03-01

    The morphology and the magnetic and conducting properties of an amorphous multilayer nanosystem [(Co45Fe45Zr10)35(Al2O3)65/ a-Si:H]36 consisting of (Co45Fe45Zr10)35(Al2O3)65 magnetic layers and semiconducting hydrogenated amorphous silicon ( a-Si:H) layers of various thicknesses have been studied. Using a combination of methods (including polarized neutron reflectometry and grazing incidence small-angle X-ray scattering), it is shown that the magnetic and electrical properties of these multilayer structures are determined by their morphology. It is established that the magnetization and electric resistance of a sample is a nonmonotonic function of the a-Si:H layer thickness. Both characteristics are at a minimum for a structure with a semiconductor layer thickness of 0.4 nm. Samples with silicon layer thicknesses below 0.4 nm represent a three-dimensional structure of Co45Fe45Zr10 grains weakly ordered in space, while in samples with silicon layer thicknesses above 0.4 nm, these grains are packed in layers alternating in the vertical direction. The average lateral distance between nanoparticles in the layer plane has been determined, from which the dimensions of metal grains in each sample have been estimated.

  11. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  12. Current–voltage studies on β-FeSi2/Si heterojunction

    Indian Academy of Sciences (India)

    Ar + H2 ambient. Some samples were annealed at 750°C for 2 h. XRD analysis confirmed the formation of poly- crystalline β-FeSi2. The ohmic contact on back side was done by depositing Al by thermal evaporation technique. Some identical samples were sorted out and the junctions were pulse laser irradiated. Excimer ...

  13. Moessbauer effect in pure and impurity doped FeSi2

    International Nuclear Information System (INIS)

    Blaauw, C.; Hanson, H.; Woude, F. van der

    1975-01-01

    Numerical values of the calculated and experimentally determined Moessbauer parameters for pure β-FeSi 2 and α-FeSi 2 are given. Temperature dependence of isomer shift and quadrupole splitting for the two Fe positions in β-FeSi 2 is presented. For α-FeSi 2 only average values are given. Spectra of Co- and Al-doped FeSi 2 recorded at 80, 293, 557 and 788 K were analyzed in the same manner as those of undoped FeSi 2 . The average values of isomer shift and quadrupole splitting in Co- and Al-doped β-FeSi 2 (α-Fesi 2 ) were compared to those found in undoped β-FeSi 2 (α-FeSi 2 ). All data were based on the room temperature spectra. Changes in Moessbauer parameters of doped samples relative to undoped ones were generally small, being of the order of hundredths of mm/sec. (Z.S.)

  14. Microstructural and Fracture Behavior of Phosphorus-Containing Fe-30Mn-9Al-1Si-0.9C-0.5Mo Alloy Steel

    Science.gov (United States)

    Howell, Ryan A.; Van Aken, David C.

    2015-08-01

    Five different phosphorus (P)-containing heat-treated Fe-Mn-Al-C alloys were tested in accordance with ASTM E 23 Charpy V-notch Energy (CVNE) standards. Room temperature CVNE of solution treated and quenched specimens revealed ductile fracture for 0.001 and 0.006 wt pct (pct P-containing alloys). Brittle cleavage fracture dominated the 0.043 and 0.07 pct P-containing alloys. A hard brittle P eutectic phase was observed in the 0.07 pct P-containing alloy.

  15. Correlation between impurities in Fe-Si amorphous layers synthesized by Fe implantation and photoluminescence property of {beta}-FeSi{sub 2} precipitates in Si

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C.M. [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China)], E-mail: cmsun@ee.cuhk.edu.hk; Tsang, H.K.; Wong, S.P.; Ke, N. [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China); Hark, S.K. [Department of Physics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China)

    2008-11-15

    Completely amorphous Fe-Si layers are formed by Fe implantation into Si substrate at a dosage of 5x10{sup 15} cm{sup -2} using a metal vapor vacuum arc (MEVVA) ion source under 80 kV extraction voltage and cryogenic temperature. After thermal annealing, {beta}-FeSi{sub 2} precipitates are formed in Si matrix. The influence of impurities in these amorphous Fe-Si layers on the photoluminescence (PL) from {beta}-FeSi{sub 2} precipitates is investigated. PL is found to be significantly enhanced by optimizing the impurity concentration and annealing scheme. After 60 s of rapid thermal annealing (RTA) at 900 deg. C, {beta}-FeSi{sub 2} precipitates in medium boron-doped Si substrate give the strongest PL intensity without boron out-diffusion from them.

  16. Influence of modifier on base Al and Si on structure and elongation Al-7%Si alloy

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2008-08-01

    Full Text Available A homogenous modifier with Al and Si obtained by the rapid solidification at a cooling rate equal to v=200 K/s was applied to the modification of the Al-7%Si alloy. The different modifiers were obtained by means of the Al-Si alloys. The components Al, Al-7%Si and Al-12%Si were put into crucible containing the liquid Al-7%Si alloy and kept for one minute to obtain a new homogenous alloy which after break-up was homogenous modifier. Both, effect of cooling rate applied to obtain modifier and weight in weight modifier concentration in the melt on structure and elongations of Al-7%Si alloy are determined. A structural, and elongations resulting from the Al-7%Si alloy treatment by modifiers are studied in details.

  17. Lattice sites of implanted Fe in Si

    CERN Document Server

    Wahl, Ulrich; Rita, E; Araújo, João Pedro; Carvalho-Soares, José

    2005-01-01

    The angular distribution of $\\beta^{-}$-particles emitted by the radioactive isotope $^{59}$Fe was monitored following implantation into Si single crystals at fluences from $1.4 \\times 10^{12}$ cm$^{-2}$ to $1 \\times 10^{14}$ cm$^{-2}$. We identified Fe on three distinct sites: ideal substitutional, displaced substitutional and displaced tetrahedral interstitial. Whereas displaced substitutional Fe was dominating for annealing temperatures below 500 °C, annealing between 500-700 °C caused the majority of Fe to occupy displaced tetrahedral interstitial sites. Ideal substitutional positions were increasingly populated following annealing at 800 °C and above. A comparison of the emission channeling results to Mössbauer and electron paramagnetic resonance experiments is given.

  18. A viscosity model for fully liquid coal ash slags in the Al{sub 2}O{sub 3}-CaO-'FeO'-MgO-SiO{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    A. Kondratiev; P.C. Hayes; E. Jak [University of Queensland, St. Lucia, Qld. (Australia). Pyrometallurgy Research Centre

    2005-07-01

    A general viscosity model for fully liquid coal ash slags in the Al{sub 2}O{sub 3}-CaO-'FeO'-MgO-SiO{sub 2} system in reducing conditions has been developed. The present model links the coal ash slag viscosity with the internal structure of the molten slags described by the thermodynamic quasi-chemical model. The model describes slag viscosities over the whole compositional range, including all unary, binary, ternary and higher-order sub-systems. The overall agreement between the critically assessed experimental data in the Al{sub 2}O{sub 3}-CaO-'FeO'-MgO-SiO{sub 2} slag system at metallic iron saturation and the quasi-chemical viscosity model is within 19.5 per cent. The present viscosity model can now be used to assist in a number of coal industrial issues such as analysis of coal suitability for different slagging gasifiers, coal fluxing and blending, modelling of slag flow in slagging gasifiers and adhesion of ash particles to reactor walls etc. The application of the model in the coal gasification field will be demonstrated in the paper. 24 refs., 6 figs., 1 tab.

  19. Computer aided cooling curve analysis for Al-5Si and Al-11Si alloys

    African Journals Online (AJOL)

    user

    1. Introduction. Aluminium-Silicon (Al-Si) alloys are considered as the most important cast alloys due to their excellent casting characteristics, good corrosion resistance, and good weldability. The fluidity of the Al-Si alloy increases up to eutectic composition (12.5% Si), further, presence of Si reduces hot cracking tendencies ...

  20. 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.

  1. Upgrade Recycling of Cast Iron Scrap Chips towards β-FeSi2 Thermoelectric Materials

    Science.gov (United States)

    Laila, Assayidatul; Nanko, Makoto; Takeda, Masatoshi

    2014-01-01

    The upgrade recycling of cast-iron scrap chips towards β-FeSi2 thermoelectric materials is proposed as an eco-friendly and cost-effective production process. By using scrap waste from the machining process of cast-iron components, the material cost to fabricate β-FeSi2 is reduced and the industrial waste is recycled. In this study, β-FeSi2 specimens obtained from cast iron scrap chips were prepared both in the undoped form and doped with Al and Co elements. The maximum figure of merit (ZT) indicated a thermoelectric performance of approximately 70% in p-type samples and nearly 90% in n-type samples compared to β-FeSi2 prepared from pure Fe and other published studies. The use of cast iron scrap chips to produce β-FeSi2 shows promise as an eco-friendly and cost-effective production process for thermoelectric materials. PMID:28788193

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

    Directory of Open Access Journals (Sweden)

    Brodarac Zovko Z.

    2014-01-01

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

  3. Behavior of U3Si2 Fuel and FeCrAl Cladding under Normal Operating and Accident Reactor Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States); Barani, Tommaso [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pizzocri, Davide [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pastore, Giovanni [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    As part of the Department of Energy's Nuclear Energy Advanced Modeling and Simulation program, an Accident Tolerant Fuel High Impact Problem was initiated at the beginning of fiscal year 2015 to investigate the behavior of \\usi~fuel and iron-chromium-aluminum (FeCrAl) claddings under normal operating and accident reactor conditions. The High Impact Problem was created in response to the United States Department of Energy's renewed interest in accident tolerant materials after the events that occurred at the Fukushima Daiichi Nuclear Power Plant in 2011. The High Impact Problem is a multinational laboratory and university collaborative research effort between Idaho National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory, and the University of Tennessee, Knoxville. This report primarily focuses on the engineering scale research in fiscal year 2016 with brief summaries of the lower length scale developments in the areas of density functional theory, cluster dynamics, rate theory, and phase field being presented.

  4. Release of Si from Silicon, a Ferrosilicon (FeSi) Alloy and a Synthetic Silicate Mineral in Simulated Biological Media

    Science.gov (United States)

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

    2014-01-01

    Unique quantitative bioaccessibility data has been generated, and the influence of surface/material and test media characteristics on the elemental release process were assessed for silicon containing materials in specific synthetic body fluids at certain time periods at a fixed loading. The metal release test protocol, elaborated by the KTH team, has previously been used for classification, ranking, and screening of different alloys and metals. Time resolved elemental release of Si, Fe and Al from particles, sized less than 50 µm, of two grades of metallurgical silicon (high purity silicon, SiHG, low purity silicon, SiLG), an alloy (ferrosilicon, FeSi) and a mineral (aluminium silicate, AlSi) has been investigated in synthetic body fluids of varying pH, composition and complexation capacity, simple models of for example dermal contact and digestion scenarios. Individual methods for analysis of released Si (as silicic acid, Si(OH)4) in synthetic body fluids using GF-AAS were developed for each fluid including optimisation of solution pH and graphite furnace parameters. The release of Si from the two metallurgical silicon grades was strongly dependent on both pH and media composition with the highest release in pH neutral media. No similar effect was observed for the FeSi alloy or the aluminium silicate mineral. Surface adsorption of phosphate and lactic acid were believed to hinder the release of Si whereas the presence of citric acid enhanced the release as a result of surface complexation. An increased presence of Al and Fe in the material (low purity metalloid, alloy or mineral) resulted in a reduced release of Si in pH neutral media. The release of Si was enhanced for all materials with Al at their outermost surface in acetic media. PMID:25225879

  5. Low Gilbert damping in Co2FeSi and Fe2CoSi films

    Science.gov (United States)

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

    2016-08-01

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

  6. 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

  7. Effect of FSW welding speed on microstructure and microhardness of Al-0.84Mg-0.69Si-0.76Fe alloy at moderate rotational tool velocity

    Science.gov (United States)

    Chand, Suresh; Vineetha, S.; Madhusudhan, D.; Sai Krishna, CH; Kusuma Devi, G.; Bhawani; Hemarao, K.; Ganesh Naidu, G.

    2018-03-01

    The plate of 7.0 mm thickness was double side welded using friction stir welding is investigated. The rotational velocity of friction stir welding tool is used 1400 rpm. The influence of welding speed on the microstructure and microhardness values of Al-0.84Mg-0.69Si-0.76Fe aluminum alloy is presented. Two welding speeds 25 mm/min and 31.5 mm/min are used. The microhardness values of friction stir weld are measured at various locations from the weld interface. The microhardness values in stir zone of weld are found larger than lower welding speed at constant rotational velocity of 1400 rpm of friction stir welding tool. The similar effects on microhardness values are found in the thermo-mechanically affected zone and heat affected zone. The fine microstructure is observed at 31.5 mm/min welding speed compared to the 25 mm/min welding speed at 1400 rpm.

  8. Computer aided cooling curve analysis for Al-5Si and Al-11Si alloys ...

    African Journals Online (AJOL)

    The effect of grain refiner, modifier, and combination of grain refiner cum modifier was studied on Al-5Si and Al-11Si alloys using computer aided cooling curve analysis. For combined grain refinement and modification effect, Al-Ti-B-Sr single master alloy was developed that acted as both grain refiner and modifier.

  9. Fabrication of FeSi and Fe{sub 3}Si compounds by electron beam induced mixing of [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers grown by focused electron beam induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Porrati, F.; Sachser, R.; Huth, M. [Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Gazzadi, G. C. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); Frabboni, S. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy)

    2016-06-21

    Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO){sub 5}, and neopentasilane, Si{sub 5}H{sub 12} as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way, we are able to fabricate FeSi and Fe{sub 3}Si binary compounds from [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

  10. Perpendicular magnetic anisotropy in Mo/Co2FeAl0.5Si0.5/MgO/Mo multilayers with optimal Mo buffer layer thickness

    Science.gov (United States)

    Saravanan, L.; Raja, M. Manivel; Prabhu, D.; Pandiyarasan, V.; Ikeda, H.; Therese, H. A.

    2018-05-01

    Perpendicular Magnetic Anisotropy (PMA) was realized in as-deposited Mo(10)/Co2FeAl0.5Si0.5(CFAS)(3)/MgO(0.5)/Mo multilayer stacks with large perpendicular magnetic anisotropy energy (Keff). PMA of this multilayer is found to be strongly dependent on the thickness of the individual CFAS (tCFAS), Mo (tMo) and MgO (tMgO) layers and annealing temperatures. The interactions at the Mo/CFAS/MgO interfaces are critical to induce PMA and are tuned by the interfacial oxidation. The major contribution to PMA is due to iron oxide at the CFAS/MgO interface. X-ray diffraction (XRD) and infrared spectroscopic (FT-IR) studies further ascertain this. However, an adequate oxidation of MgO and the formation of (0 2 4) and (0 1 8) planes of α-Fe2O3 at the optimal Mo buffer layer thickness is mainly inducing PMA in Mo/CFAS/MgO/Mo stack. Microstructural changes in the films are observed by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) demonstrates the oxidation of CFAS/MgO interface and the formation of Fe-O bonds confirming that the real origin of PMA in Mo/CFAS/MgO is due to hybridization of Fe (3dz2) and O (2pz) orbitals and the resulted spin-orbit interaction at their interface. The half-metallic nature CFAS with Mo layer exhibiting PMA can be a potential candidate as p-MTJs electrodes for the new generation spintronic devices.

  11. 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.

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

    International Nuclear Information System (INIS)

    Jemmali, M.; Walha, S.; Pasturel, M.; Tougait, O.; Ben Hassen, R.; Noel, H.

    2010-01-01

    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 o C. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe 12-x Al x with 5 ≤ x ≤ 8 (ThMn 12 -type), ErFe 1+x Al 1-x with -0.2 ≤ x ≤ 0.75 (MgZn 2 -type), ErFe 3-x Al x with 0.5 2 Al-type), Er 2 Fe 17-x Al x with 4.74 ≤ x ≤ 5.7 (TbCu 7 -type) and Er 2 Fe 17-x Al x with 5.7 2 Zn 17 -type), seven extensions of binaries into the ternary system; ErFe x Al 3-x with x 3 Cu-type), ErFe x Al 2-x with x ≤ 0.68 (MgCu 2 -type), Er 2 Fe x Al 1-x with x ≤ 0.25 (Co 2 Si-type), ErFe 2-x Al x with x ≤ 0.5 (MgCu 2 -type), ErFe 3-x Al x with x ≤ 0.5 (Be 3 Nb-type), Er 6 Fe 23-x Al x with x ≤ 8 (Th 6 Mn 23 -type), and Er 2 Fe 17-x Al x with x ≤ 4.75 (Th 2 Ni 17 -type) and one intermetallic compound; the ErFe 2 Al 10 (YbFe 2 Al 10 -type).

  13. Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

    Directory of Open Access Journals (Sweden)

    Hongzhou Lu

    2017-07-01

    Full Text Available It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

  14. 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)

  15. Si/Fe flux ratio influence on growth and physical properties of polycrystalline β-FeSi2 thin films on Si(100) surface

    Science.gov (United States)

    Tarasov, I. A.; Visotin, M. A.; Aleksandrovsky, A. S.; Kosyrev, N. N.; Yakovlev, I. A.; Molokeev, M. S.; Lukyanenko, A. V.; Krylov, A. S.; Fedorov, A. S.; Varnakov, S. N.; Ovchinnikov, S. G.

    2017-10-01

    This work investigates the Si/Fe flux ratio (2 and 0.34) influence on the growth of β-FeSi2 polycrystalline thin films on Si(100) substrate at 630 °C. Lattice deformations for the films obtained are confirmed by X-ray diffraction analysis (XRD). The volume unit cell deviation from that of β-FeSi2 single crystal are 1.99% and 1.1% for Si/Fe =2 and Si/Fe =0.34, respectively. Absorption measurements show that the indirect transition ( 0.704 eV) of the Si/Fe =0.34 sample changes to the direct transition with a bandgap value of 0.816 eV for the sample prepared at Si/Fe =2. The absorption spectrum of the Si/Fe =0.34 sample exhibits an additional peak located below the bandgap energy value with the absorption maximum of 0.36 eV. Surface magneto-optic Kerr effect (SMOKE) measurements detect the ferromagnetic behavior of the β-FeSi2 polycrystalline films grown at Si/Fe =0.34 at T=10 K, but no ferromagnetism was observed in the samples grown at Si/Fe =2. Theoretical calculations refute that the cell deformation can cause the emergence of magnetization and argue that the origin of the ferromagnetism, as well as the lower absorption peak, is β-FeSi2 stoichiometry deviations. Raman spectroscopy measurements evidence that the film obtained at Si/Fe flux ratio equal to 0.34 has the better crystallinity than the Si/Fe =2 sample.

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

    International Nuclear Information System (INIS)

    Polcar, Tomas; Cavaleiro, Albano

    2011-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  18. Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al ...

    Indian Academy of Sciences (India)

    Unknown

    Diffusivity of Al and Fe near the diffusion bonding interface of Fe3Al with low carbon steel. LI YAJIANG*†, WANG JUAN†, YIN YANSHENG† and MA HAIJUN†. *Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China. †National Key Lab of Advanced Welding ...

  19. Ferrofluids based on Co-Fe-Si-B amorphous nanoparticles

    Science.gov (United States)

    Wang, Tianqi; Bian, Xiufang; Yang, Chuncheng; Zhao, Shuchun; Yu, Mengchun

    2017-03-01

    Magnetic Co-Fe-Si-B amorphous nanoparticles were successfully synthesized by chemical reduction method. ICP, XRD, DSC, and TEM were used to investigate the composition, structure and morphology of Co-Fe-Si-B samples. The results show that the Co-Fe-Si-B samples are amorphous, which consist of nearly spherical nanoparticles with an average particle size about 23 nm. VSM results manifest that the saturation magnetization (Ms) of Co-Fe-Si-B samples ranges from 46.37 to 62.89 emu/g. Two kinds of ferrofluids (FFs) were prepared by dispersing Co-Fe-Si-B amorphous nanoparticles and CoFe2O4 nanoparticles in kerosene and silicone oil, respectively. The magnetic properties, stability and viscosity of the FFs were investigated. The FFs with Co-Fe-Si-B samples have a higher Ms and lower coercivity (Hc) than FFs with CoFe2O4 sample. Under magnetic field, the silicone oil-based FFs exhibit high stability. The viscosity of FFs under different applied magnetic fields was measured by a rotational viscometer, indicating that FFs with Co-Fe-Si-B particles present relative strong response to an external magnetic field. The metal-boride amorphous alloy nanoparticles have potential applications in the preparation of magnetic fluids with good stability and good magnetoviscous properties.

  20. The thermal evolution and dynamo generation of Mercury with an Fe-Si core

    Science.gov (United States)

    Knibbe, Jurrien

    2017-04-01

    The present day partially liquid (as opposed to fully solidified) Fe-rich core of Mercury is traditionally explained by assuming a substantial amount of S to be present in the core (e.g. Grott et al., 2011), because S lowers the core's melting temperature. However, this assumption has problematic implications: Mercury's large Fe-rich core and measured low FeO surface content are indicative of an oxygen poor bulk composition, which is consistent with the volatile-poor material that is expected to have condensed from the solar nebula close to the Sun. In contrast, S is a moderately volatile element. Combined with the high S content of Mercury's crust and (likely) mantle, as indicated by the measured high S/Si surface fraction, the resulting high planetary S abundance is difficult to reconcile with a volatile poor origin of the planet. Additionally, the observed low magnetic field strength is most easily explained if compositional buoyancy fluxes are absent [Manglik et al., 2010], yet such fluxes are produced upon solidifying a pure Fe inner core from Fe-S liquid. Alternatively, both Mercury's high S/Si and Mg/Si surface ratios (Nittler et al., 2011) may indicate that a siderophile fractionation of Si and lithophile fractionation of S took place during Mercury's core-mantle differentiation. This fractionation behaviour of these elements is supported by metal/silicate partitioning experiments that have been performed at the low oxygen conditions inferred for Mercury [e.g. Chabot et al., 2014]. Mercury's bulk composition, in terms of S/Si and Fe/Si ratios, would also approach that of meteorites that are considered as potential building blocks of the planet if the core is Si-rich and S-poor. Here we simulate the thermal evolution of Mercury with an Fe-Si core. Results show that an Fe-Si core can remain largely molten until present, without the need for S. An Fe-Si core also has interesting implications for Mercury's core-convection regime and magnetic field generation

  1. Post-magmatic solid solutions of CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-bearing epidote in miarolitic pegmatites of Permian Baveno granite (Verbania, central-southern alps, Italy)

    Science.gov (United States)

    Guastoni, Alessandro; Nestola, Fabrizio; Schiazza, Mariangela

    2017-06-01

    CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and rare earth element (REE)-bearing epidote occur as globular aggregates and platy prismatic crystals in miarolitic cavities in a niobium, yttrium, fluorine (NYF) granitic pegmatite at Baveno, Verbania, Southern Alps, Italy. These samples were investigated by means of an electron probe micro-analyser (EPMA) and single-crystal X-ray diffraction. Our EPMA results show that the globular aggregates have the highest REE content in the core portion and decreases to REE-bearing epidote towards the rim whereas the prismatic crystals are characterized by marked oscillatory zoning that have the highest REE contents at the rim of the crystal. The unit-cell parameters of "allanites" have an intermediate unit-cell between CaCeAl2(Fe3+ 2/3□1/3)[Si2O7][SiO4]O(OH), allanite-(Ce) and REE-free epidote, because reflect the strong chemical heterogeneity of the samples which form complete solid solutions. Hydrothermal fluids control the activity and precipitation of incompatible elements like high field strength elements (HFSE), Sc and REE by hydrous F-rich fluids below the critical temperature which allow to deposit accessory minerals in the cavities with decreasing temperature. The source of REE and Y are the sheet and REE-silicates like siderophyllite-annite, and gadolinite-(Y) which underwent partial to complete decomposition by the activity of aggressive F-rich hydrothermal fluids.

  2. A remanent Fe/Si supermirror transmission polarizer

    CERN Document Server

    Stahn, J

    2002-01-01

    In order to develop a neutron spin polarizer on the basis of magnetically remanent supermirrors, we produced a first Fe/Si supermirror (m=2, q=0.044 A sup - sup 1) giving polarizations of 96% to 98%. The addition of the reactive gases O sub 2 and N sub 2 to Si reduced the stress in the supermirror and improved the matching of Si and Fe for spin-down neutrons. (orig.)

  3. Abrasive wear resistance and microstructure of Ni-Cr-B-Si hardfacing alloys with additions of Al, Nb, Mo, Fe, Mn and C

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.; Theisen, W.

    1987-01-01

    The development of new Ni-base hardfacing alloys for filler wire welding or metal spraying should result in materials with a good resistance against high temperature corrosion and abrasive wear. The first step is to design microstructures, which obtain a satisfactory abrasive wear behaviour at room temperature. Thus, different alloys are melted and scrutinized as to their microstructure and their abrasive wear resistance in laboratory. Compared to commercial Ni-base hardfacing alloys they show a higher volume fraction of coarse hard phases due to the additional, initial solidification of Nb-carbides and Cr-, and Mo-borides. Thus, the abrasive wear resistance is improved. For hard abrasive particles, such as corundum, the Ni-base alloys are more wear resistant than harder Fe-base alloys investigate earlier. This is due to the tougher Ni metal matrix that results in microcracking not to be the most significantly acting wear mechanism

  4. Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

    Science.gov (United States)

    Dolejš, David; Wagner, Thomas

    2008-01-01

    We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic

  5. Microstructural Evolution in AlMgSi Alloys during Solidification under Electromagnetic Stirring

    Directory of Open Access Journals (Sweden)

    Piotr Mikolajczak

    2017-03-01

    Full Text Available Equiaxed solidification of AlMgSi alloys with Fe and Mn was studied by electromagnetic stirring to understand the effect of forced flow. The specimens solidified with a low cooling rate, low temperature gradient, and forced convection. Stirring induced by a coil system around the specimens caused a transformation from equiaxed dendritic to rosette morphology with minor dendrites and, occasionally, spheroids. This evolution was quantitatively observed with specific surface Sv. The precipitation sequence of the phases was calculated using the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry technique. Melt flow decreased secondary dendrite arm spacing λ2 in the AlSi5Fe1.0 alloy, while λ2 increased slightly in Mg-containing alloys. The length of detrimental β-Al5FeSi phases decreased only in AlSi5Fe1.0 alloy under stirring, whereas in Mg-containing alloys, changes to the β-Al5FeSi phase were negligible; however, in all specimens, the number density increased. The modification of Mn-rich phases, spacing of eutectics, and Mg2Si phases was analyzed. It was found that the occurrence of Mg2Si phase regions reduced fluid flow in the late stages of solidification and, consequentially, reduced shortening of β-Al5FeSi, diminished secondary arm-ripening caused by forced convection, and supported diffusive ripening. However, the Mg2Si phase was found to have not disturbed stirring in the early stage of solidification, and transformation from dendrites to rosettes was unaffected.

  6. Effect of the magnetic prehistory on the low-temperature heat capacity of the La(Fe{sub 0.88}Al{sub 0.12-x}Si{sub x}){sub 13} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Podgornykh, S M [Institute of Metal Physics, Ekaterinburg (Russian Federation); Chirkova, I M, E-mail: sp@imp.uran.r [Ural State University, Ekaterinburg (Russian Federation)

    2010-01-01

    The measured heat capacity C of solids is thought in general to involve the change of the internal energy which is a state property. Therefore the electron density of states at the Fermi level is derived from the low-temperature data C={gamma} T + {beta} T{sup 3}. The La(Fe{sub 0.88}Al{sub 0.12-x}Si{sub x}){sub 13} compounds are the antiferromagnets (AFM) T{sub N}=200 K with 0

  7. Photoluminescence properties of {beta}-FeSi{sub 2} grains on Si with coating Au layer

    Energy Technology Data Exchange (ETDEWEB)

    Akiyama, K; Kaneko, S; Hirabayashi, Y [Kanagawa Industrial Technology Center, 705-1 Shimoimaizumi, Edina, Kanagawa, 243-0435 (Japan); Yokomizo, K; Itakura, M, E-mail: akiyama@kanagawa-iri.go.jp [Department of Applied Science for Electronics and Materials, Kyusyu University, 6- 1 Kasuga, Fukuoka 816-8580 (Japan)

    2011-10-29

    We have investigated the growth of {beta}-FeSi{sub 2} grains on Si(001) substrates with 90-nm-thick gold layer and its photoluminescence (PL) property. X-ray diffraction and scanning electron microscopy observations revealed that coarse island {beta}-FeSi{sub 2} grains with sizes from several to tens of micrometers were formed on the Si surface. A clear PL spectrum for the {beta}-FeSi{sub 2} grains was observed on as deposited sample by argon-ion laser irradiation to the Si substrate side. The values of the activation energy for a non-radiative recombination path were large, and indicated the formation of high-crystal-quality {beta}-FeSi{sub 2} with a low-level non-radiative center without post-annealing.

  8. Self organization of FeGe/FeSi/FeGe layered structures on Ge and their electrical conduction properties

    Science.gov (United States)

    Matsukura, B.; Hiraiwa, Y.; Nakajima, T.; Narumi, K.; Sakai, S.; Sadoh, T.; Miyao, M.; Maeda, Y.

    We have investigated self organization of novel FeGe/FeSi/FeGe layered structures on Ge(111) and their electrical conduction properties. From analyses of compositional change, diffusion dynamics analyses and microstructure observations, it was revealed that the self organization of the layered structures was enhanced by spinodal decomposition which may be induced by pronounced compositional changes associating to inhomogeneous interdiffusion. The electrical conduction showed singular temperature dependence which obviously reflected natureof Kondo insulator FeSi.

  9. Plastic deformation of Al13Fe4 particles in Al-Al13Fe4 by high-speed compression

    International Nuclear Information System (INIS)

    Yoneyama, N.; Mizoguchi, K.; Kumai, S.; Sato, A.; Kiritani, M.

    2003-01-01

    Spray-formed Al-Fe alloys having undergone high-speed deformation were examined under a high-voltage electron microscope. Two types of specimens were examined; one containing fine Al 13 Fe 4 particles, and the other containing large particles. In the former specimen, deformation is found to proceed in three patterns, depending on specimen thickness and strain rate: (1) without deformation of the Al 13 Fe 4 ; (2) breaking of the Al 13 Fe 4 ; or (3) melting of the Al 13 Fe 4 . Local melting is found to alter some of the Al 13 Fe 4 particles, to impart five-fold symmetry in diffraction or an amorphous structure. In the latter specimen, introduction of glide dislocations enabled us to determine a shear system in the mc102 monoclinic c2/m crystal of Al 13 Fe 4 . On the bases of these observations, the mechanism of high-speed deformation is discussed while taking into account the highly stressed and/or heated states of Al 13 Fe 4 embedded in Al matrix

  10. Electronic and magnetic properties of AlFe3 and AlFe3N nitride

    International Nuclear Information System (INIS)

    Kuhnen, C.A.; Santos, A.V. dos

    2004-01-01

    Self-consistent band structure calculations were performed for the metal aluminide AlFe 3 (in the fcc structure) and the nitride AlFe 3 N (perovskite-like nitride) at several lattice parameters in order to obtain the electronic structure and magnetic properties of these compounds. In this study we have employed the full potential linear augmented plane wave (FPLAPW) and the linear muffin-tin orbital (LMTO-ASA) methods. Our results show that the modeled AlFe 3 is ferromagnetic (FM) with 2.07μ B as the magnetic moment at Fe sites. On the other hand, AlFe 3 N is non-magnetic (NM) contrary to other perovskite nitrides that show magnetic order. Hence as the stable phase of AlFe 3 is magnetic with DO 3 structure a crystallographic transformation occurs accompanied by a magnetic transition from a non-magnetic perovskite structure to a magnetic DO 3 structure as AlFe 3 N lose nitrogen atoms. The LMTO and FPLAPW total energy calculations give the equilibrium volume for both compounds. For AlFe 3 N, the FPLAPW calculations give the equilibrium volume that agrees well with the experimental lattice spacing, which is not achieved by LMTO calculations within the same accuracy. The calculated magnetic moment as function of the lattice parameter for the AlFe 3 shows a collapse of the magnetism at certain critical lattice parameter whose FPLAPW value (2.962 A) differs only slightly from the LMTO value (3.041 A)

  11. Electroluminescence of erbium in Al/α-Si:H(Er)/p-c-Si/Al structure

    International Nuclear Information System (INIS)

    Kon'kov, I.O.; Kuznetsov, A.N.; Pak, P.E.; Terukov, E.I.; Granitsyna, L.S.

    2001-01-01

    It is informed for the first time on the observation of the erbium intensive electroluminescence from the amorphous hydrated silicon layer by application of the Al/α-Si:H(Er)/p-c-Si/Al structure in the direct shift mode. The above structure is the n-p-heterostructure with the barrier values of 0.3-0.4 eV for the electrons and 0.9-1.1 eV for the holes. The electroluminescence efficiency is evaluated at the level ∼ 2 x 10 -5 . The electroluminescence effect in the Al/α-Si:H(Er)/p-c-Si/Al structure is connected with the hole tunneling from the crystal silicon by the amorphous silicon localized states with the subsequent release into the valent zone [ru

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    A single crystal of a natural orthopyroxene with composition M2[Fe2+0.818Mg0.156Ca0.010Mn0.016]M1[Fe2+0.081 Mg0.767Al0.084Fe3+0.068]TA[Si]TB[Si0.848Al0.152]O6 and space group Pbca (sample S95) was investigated at high pressure by X-ray diffraction using a diamond-anvil cell up to 9.56 GPa. No phase...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-08-01

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

  14. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China)], E-mail: wyy532001@163.com; Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602, Shandong (China); Jiang Binggang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Huang Chuanzhen [School of Mechanical Engineering, Shandong University, Jinan 250061 (China)

    2009-05-27

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  15. 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.

  16. 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.

  17. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    The passivation behaviour of binary cast Fe–Si alloys tested in phthalate buffer solution has shown that low Si alloys do not form a thick SiO2 layer and only iron oxide layer forms. In case of Si-rich alloys, formation of a stable SiO2 layer leads to improved corrosion resistance (Wolff et al 2001). The stability of the passive ...

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  19. Metalorganic chemical vapor deposition of {beta}-FeSi{sub 2} on {beta}-FeSi{sub 2} seed crystals formed on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Suzuno, Mitsushi; Akutsu, Keiichi; Kawakami, Hideki [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8573 (Japan); Akiyama, Kensuke [Kanagawa Industrial Technology Center 705-1 Shimoizumi, Ebina, Kanagawa 243-0435 (Japan); Suemasu, Takashi, E-mail: suemasu@bk.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba, Ibaraki 305-8573 (Japan)

    2011-10-03

    We have fabricated a {beta}-FeSi{sub 2} film by metalorganic chemical vapor deposition on a Si(001) substrate with {beta}-FeSi{sub 2} seed crystals grown by molecular beam epitaxy, and investigated the crystallinity, surface morphology and temperature dependence of photoresponse properties of the {beta}-FeSi{sub 2} film. The surface of the grown {beta}-FeSi{sub 2} film was atomically flat, and step-and-terrace structure was clearly observed. Multi-domain structure of {beta}-FeSi{sub 2} whose average size was approximately 200 nm however was revealed. The photoresponse was obtained in an infrared light region ({approx} 0.95 eV) at temperatures below 200 K. The external quantum efficiency reached a maximum, being as large as 25% at 100 K when a bias voltage was 2.0 V.

  20. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    Passivation behaviour of nanocrystalline coating (Fe80Si20) obtained by in situ mechanical alloying route is studied and compared with that of the commercial pure iron and cast Fe80Si20 in sodium borate buffer solution at two different pH values (7.7 and 8.4). The coating reveals single passivation at a pH of 7.7 and ...

  1. Development of an efficient grain refiner for Al-7Si alloy and its modification with strontium

    Energy Technology Data Exchange (ETDEWEB)

    Kori, S.A.; Murty, B.S.; Chakraborty, M. [Indian Inst. of Technol., Kharagpur (India). Dept. of Metall. and Mater. Eng.

    2000-05-15

    The grain refining response of Al and Al-7Si alloy has been studied with various Al-Ti, Al-B and Al-Ti-B master alloys at different addition levels. The results show that Al-B and B rich Al-Ti-B master alloys cannot grain refine Al, while they are efficient grain refiners to Al-7Si alloy. The level of grain refinement saturates after 0.03% of Ti or B for most of the master alloys studied both at short and long holding times. The grain refining efficiency of some elements other than Ti and B on Al-7Si alloy has also been studied. Interestingly, all the elements studied (B, Cr, Fe, Mg, Ni, Ti and Zr) have resulted in some grain refinement of Al-7Si alloy at short holding time and have shown fading/poisoning on long holding, which increased in the order of B (no poisoning), Ti, Cr, Ni, Fe, Mg, Zr. Sr (0.02%) has been found to provide complete modification of the eutectic in Al-7Si alloy within 2 min, which is not lost even after long holding up to 120 min. Significant improvements in the mechanical properties have been obtained by a combination of grain refinement and modification to an extent that was not possible by either of them alone. (orig.)

  2. Forging of FeAl intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-09-01

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

  3. Upgrade Recycling of Cast Iron Scrap Chips towards β-FeSi2 Thermoelectric Materials

    Directory of Open Access Journals (Sweden)

    Assayidatul Laila

    2014-09-01

    Full Text Available The upgrade recycling of cast-iron scrap chips towards β-FeSi2 thermoelectric materials is proposed as an eco-friendly and cost-effective production process. By using scrap waste from the machining process of cast-iron components, the material cost to fabricate β-FeSi2 is reduced and the industrial waste is recycled. In this study, β-FeSi2 specimens obtained from cast iron scrap chips were prepared both in the undoped form and doped with Al and Co elements. The maximum figure of merit (ZT indicated a thermoelectric performance of approximately 70% in p-type samples and nearly 90% in n-type samples compared to β-FeSi2 prepared from pure Fe and other published studies. The use of cast iron scrap chips to produce β-FeSi2 shows promise as an eco-friendly and cost-effective production process for thermoelectric materials.

  4. Growth and magnetic study of sputtered Fe/Al multilayers

    International Nuclear Information System (INIS)

    Cherif, S.M.; Bouziane, K.; Roussigne, Y.; Al-Busaidy, M.

    2007-01-01

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)] x18 and deposited under different negative DC bias voltages (V b = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm (±0.05 nm) by increasing V b from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V b . The same trend upon V b was observed for the perpendicular and in-plane anisotropies

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

    Directory of Open Access Journals (Sweden)

    Pisarek B. P.

    2013-09-01

    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.

  6. Growth and magnetic study of sputtered Fe/Al multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, S.M. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Bouziane, K. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France) and Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)]. E-mail: bouzi@squ.edu.om; Roussigne, Y. [LPMTM (CNRS-UPR 9001), Universite Paris 13, 99 Av. J.B. Clement, 93430 Villetaneuse (France); Al-Busaidy, M. [Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khodh 123 (Oman)

    2007-03-15

    Brillouin light scattering (BLS) and vibrating sample magnetometry (VSM) were used to study the effect of interfacial intermixing and microstructure on the magnetic properties of DC magnetron sputtered Fe/Al multilayers (MLs) on Si(1 0 0) substrate. Three samples with nominal composition [Al (4 nm)/Fe (3.7 nm)]{sub x18} and deposited under different negative DC bias voltages (V {sub b} = -50, -200 and -400 V) have been investigated. The X-ray diffraction results indicate that the FeAl MLs have a poor crystallinity with no evidence of the absence of B2 phase. The grazing X-ray reflectivity results suggest that the interfacial roughness and intermixing were gradually reduced from 0.7 to 0.5 nm ({+-}0.05 nm) by increasing V {sub b} from -50 to -400 V. The magnetization measurements demonstrate the presence of in-plane uniaxial anisotropy and magnetically dead interfacial layers. The BLS results reveal spin-wave surface modes whose frequencies also depend on the applied V{sub b}. The same trend upon V {sub b} was observed for the perpendicular and in-plane anisotropies.

  7. Tunneling magnetoresistance in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Tao, L. L.; Liang, S. H.; Liu, D. P.; Wei, H. X.; Han, X. F., E-mail: xfhan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Jian [Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong (China)

    2014-04-28

    We present a theoretical study of the tunneling magnetoresistance (TMR) and spin-polarized transport in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junction (MTJ). It is found that the spin-polarized conductance and bias-dependent TMR ratios are rather sensitive to the structure of Fe{sub 3}Si electrode. From the symmetry analysis of the band structures, we found that there is no spin-polarized Δ{sub 1} symmetry bands crossing the Fermi level for the cubic Fe{sub 3}Si. In contrast, the tetragonal Fe{sub 3}Si driven by in-plane strain reveals half-metal nature in terms of Δ{sub 1} state. The giant TMR ratios are predicted for both MTJs with cubic and tetragonal Fe{sub 3}Si electrodes under zero bias. However, the giant TMR ratio resulting from interface resonant transmission for the former decreases rapidly with the bias. For the latter, the giant TMR ratio can maintain up to larger bias due to coherent transmission through the majority-spin Δ{sub 1} channel.

  8. Magnetostrictive properties of FeAl/polyester and FeAl/silicone composites

    Energy Technology Data Exchange (ETDEWEB)

    Riesgo, G. [Dpto. de Ciencias y Técnicas de la Navegación, Universidad de Oviedo, Campus universitario de Gijón, 33203 Gijón (Spain); Carrizo, J. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Elbaile, L., E-mail: elbaile@uniovi.es [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Crespo, R.D. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Sepúlveda, R. [Dpto. de Ingeniería Mecánica y de los Materiales, Universidad de Sevilla, Isla Cartuja, 41092 Sevilla (Spain); García, J.A. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2017-01-15

    Highlights: • Nanocrystalline powders of FeAl have been obtained from the Fe{sub 81}Al{sub 19} ribbon produced by melt spinning. • The method allows the obtainment of a FeAl solid solution from the starting process. • The microstructure and magnetic properties of the powders were investigated. • Composites with a magnetostriction of 45 ppm have been obtained. - Abstract: Ribbons of composition Fe{sub 81}Al{sub 19} obtained by the melt spinning method have been used to yield powder by mechanical milling. Using this method, a rapid nanocrystallization and a FeAl solid solution phase was obtained from the start of the process. The microstructural and magnetic properties as well as the XRD patterns of the powders were studied in function of the milling time. Grain refinement and an increase of the coercive field were the main transformations resulting from increasing the milling time. Two sets of magnetostrictive composites were produced from the 100 h-milled powder. In one of them polyester was used as matrix and in the other one silicone. In the case of the silicone composites cured in a magnetic field of 140 mT in the longitudinal direction a saturation magnetostriction as high as 45 ppm was obtained.

  9. Catalytic Methane Decomposition over Fe-Al2O3

    KAUST Repository

    Zhou, Lu

    2016-05-09

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

  10. Characterization of Coatings on Grey Cast Iron Fabricated by Hot-dipping in Pure Al, AlSi11 and AlTi5 Alloys

    Directory of Open Access Journals (Sweden)

    Mola R.

    2014-03-01

    Full Text Available Flake graphite cast iron was hot-dip coated with pure aluminium or aluminium alloys (AlSi11 and AlTi5. The study aimed at determining the influence of bath composition on the thickness, microstructure and phase composition of the coatings. The analysis was conducted by means of an optical microscope and a scanning electron microscope with an EDS spectrometer. It was found that the overall thickness of a coating was greatly dependent on the chemical composition of a bath. The coatings consisted of an outer layer and an inner intermetallic layer, the latter with two zones and dispersed graphite. In all the cases considered, the zone in the inner intermetallic layer adjacent to the cast iron substrate contained the Al5Fe2 phase with small amount of silicon; the interface between this phase and the cast iron substrate differed substantially, depending on the bath composition. In the coatings produced by hot-dipping in pure aluminium the zone adjacent to the outer layer had a composition similar to that produced from an AlTi5 bath, the Al3Fe phase was identified in this zone. The Al3Fe also contained silicon but its amount was lower than that in the Al5Fe2. In the coatings produced by hot-dipping in AlSi11, the zone adjacent to the outer layer contained the Al3FeSi phase. The analysis results showed that when AlSi11 alloy was applied, the growth mode of the inner layer changed from inwards to outwards. The interface between the Al5Fe2 phase and the cast iron substrate was flat and the zone of this phase was very thin. Locally, there were deep penetrations of the Al5FeSi phase into the outer layer, and the interface between this phase and the outer layer was irregular. Immersion in an AlTi5 bath caused that the inner intermetallic layer was thicker than when pure aluminium or AlSi11 alloy baths were used; also, some porosity was observed in this layer; and finally, the interface between the inner layer and the cast iron substrate was the most

  11. Surface charges and Np(V) sorption on amorphous Al- and Fe- silicates

    International Nuclear Information System (INIS)

    Del Nero, M.; Assada, A.; Barillon, R.; Duplatre, G.; Made, B.

    2005-01-01

    Full text of publication follows: Sorption onto Si-rich alteration layers of crystalline minerals and nuclear glasses, and onto amorphous secondary silicates of rocks and soils, are expected to retard the migration of actinides in the near- and far-field of HLW repositories. We present experimental and modeling studies on the effects of silicate structure and bulk chemistry, and of solution chemistry, on charges and adsorption of neptunyl ions at surfaces of synthetic, amorphous or poorly ordered silica, Al-silicates and Fe-silicates. The Al-silicates display similar pH-dependent surface charges characterized by predominant Si-O - Si sites, and similar surface affinities for neptunyl ions, irrespective to their Si/Al molar ratio (varying from 10 to 4.3). Such experimental features are explained by incorporation of Al atoms in tetrahedral position in the silicate lattice, leading to only trace amounts of high-affinity Al-OH surface groups due to octahedral Al. By contrast, the structure of the Fe-silicates ensures the occurrence of high-affinity Fe-OH surface groups, whose concentration is shown by proton adsorption measurements to increase with decreasing of the silicate Si/Fe molar ratio (from 10 to 2.3). Nevertheless, experimental data of the adsorption of neptunyl and electrolyte ions show unexpectedly weak effect of the Si/Fe ratio, and suggest predominant Si-OH surface groups. A possible explanation is that aqueous silicate anions, released by dissolution, adsorb at OH Fe - surface groups and / or precipitate as silica gel coatings, because experimental solutions were found at near-equilibrium with respect to amorphous silica. Therefore, the environmental sorption of Np(V) onto Si-rich, amorphous or poorly ordered Al-silicates may primarily depend on pH and silicate specific surface areas, given the low overall chemical affinity of such phases for dissolved metals. By contrast, the sorption of Np(V) on natural, amorphous or poorly ordered Fe-silicates may be a

  12. X-ray spectra, chemical bonding, and electron structure of ScM2Si2 (M = Fe, Co, Ni)

    International Nuclear Information System (INIS)

    Shcherba, I.D.; Kotur, B.Ya.

    1990-01-01

    In a study of the interaction of the components in the ternary systems Sc-M-Si (where M is a 3d transition metal) it was established that there are compounds of the empirical formula ScM 2 Si 2 (M = Fe, Co, Ni). They crystallize in two structural types, HfFe 2 Si 2 (the compound ScFe 2 Si 2 ) and CeGa 2 Al 2 (ScCo 2 Si 2 and ScNi 2 Si 2 ) (ref. 1), leading to different coordination environment of the atoms in the structures of the compounds. With the aim of investigating the electron structure and the type ofin these compounds, they authors made a systematic x-ray spectral investigation with simultaneous analysis of the crystal structures of ScM 2 Si 2

  13. Structural and magnetic stability of Fe2NiSi

    International Nuclear Information System (INIS)

    Gupta, Dinesh C.; Bhat, Idris Hamid; Chauhan, Mamta

    2014-01-01

    Full-potential ab-initio calculations in the stable F-43m phase have been performed to investigate the structural and magnetic properties of Fe 2 NiSi inverse Heusler alloys. The spin magnetic moment distributions show that present material is ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancy in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. It is found that the main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for present alloy

  14. 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.

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

    Science.gov (United States)

    Kolel-Veetil, Manoj K.; Keller, Teddy M.

    2010-01-01

    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, α-FeSi2 and β-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 β-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.

  16. Microstructure and properties of FeSiCr/PA6 composites by injection molding using FeSiCr powders by phosphating and coupling treatment

    Science.gov (United States)

    Wang, Lulu; Qiao, Liang; Zheng, Jingwu; Cai, Wei; Ying, Yao; Li, Wangchang; Che, Shenglei; Yu, Jing

    2018-04-01

    FeSiCr/PA6 composites were prepared by injection molding using the FeSiCr powders modified by different phosphating agents and KH550 coupling agent. The resistivity, impact strength, magnetic permeability and magnetic loss of the FeSiCr/PA6 composites were measured. The morphologies of different FeSiCr powders and the FeSiCr/PA6 composites were also observed by scanning electron microscope (SEM). The results showed that 1-Hydroxyethylidene-1,1-diphosphonic acid, phytic acid and H3PO4 could improve the electrical resistivity of FeSiCr powders by forming the dense phosphating layer except diphenylphosphinic acid. However, the resistivity of FeSiCr/PA6 composites using the FeSiCr powders treated by all the four phosphating agents had no obvious increase though the phosphating layer on the surface of FeSiCr powder came into being. The nylon insulation layer had much stronger influence than the phosphating layer on electrical resistivity of the composites. After adding appropriate KH550 coupling agent, the impact strengths of FeSiCr/PA6 composites were significantly improved, which may be associated with the tiny gap between FeSiCr powder and PA6 matrix. The effects of the phosphating agents on the magnetic permeability and loss of the FeSiCr/PA6 were small and the mechanism were also discussed.

  17. Thermodynamic modeling of the Fe-Mg-Si system

    Directory of Open Access Journals (Sweden)

    Du Y.

    2007-01-01

    Full Text Available A thermo dynamic modeling for the Fe-Mg-Si system is conducted. All of the experimental phase diagram and thermodynamic data available from the literature are critically reviewed and assessed using thermo dynamic models for the Gibbs energies of individual phases. The thermodynamic parameters for ternary liquid as well as binary phases αFeSi, (high-temperature form of FeSi2 and FeSi showing noticeable solubilities for Mg are evaluated in the optimization. Comparisons between the calculated and measured phase diagrams show that the measured isothermal six-lions at 1600°, 1454°, 727° and 710°C, the observed regions of primary phases are satisfactorily accounted for by the thermodynamic description. The limited thermodynamic data concerning the activity of Mg in liquid at 1350°C are found to be inconsistent with the well established phase relations. The liquidus projection and reaction scheme for the entire Fe-Mg-Si system are also presented. .

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

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2015-03-01

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

  19. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 36; Issue 7. Properties of porous FeAlO/FeAl ceramic matrix composite influenced by mechanical activation of FeAl powder. V Usoltsev S Tikhov A Salanov V Sadykov G Golubkova O Lomovskii. Volume 36 Issue 7 December 2013 pp 1195-1200 ...

  20. Microstructure and Properties of Fe3Al-Fe3AlC x Composite Prepared by Reactive Liquid Processing

    Science.gov (United States)

    Verona, Maria Nalu; Setti, Dalmarino; Paredes, Ramón Sigifredo Cortés

    2018-04-01

    A Fe3Al-Fe3AlC x composite was prepared using reactive liquid processing (RLP) through controlled mixture of carbon steel and aluminum in the liquid state. The microstructure and phases of the composite were assessed using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, optical microscopy, and differential scanning calorimetry. In addition, the density, hardness, microhardness, and elastic modulus were evaluated. The Fe3Al-Fe3AlC x composite consisted of 65 vol pct Fe3Al and 35 vol pct Fe3AlC x ( κ). The κ phase contained 10.62 at. pct C, resulting in the stoichiometry Fe3AlC0.475. The elastic modulus of the Fe3Al-Fe3AlC0.475 composite followed the rule of mixtures. The RLP technique was shown to be capable of producing Fe3Al-Fe3AlC0.475 with a microstructure and properties similar to those achieved using other processing techniques reported in the literature.

  1. Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

    International Nuclear Information System (INIS)

    Rivas Mercury, J.M.; Pena, P.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

    2007-01-01

    Partially deuterated Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x hydrates prepared by a reaction in the presence of D 2 O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29 Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x was followed by 27 Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 5 environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data

  2. Studies on magneto conductance of nickel substituted FeSi

    Science.gov (United States)

    Krishnan, M.; Mishra, Ashish; Singh, Durgesh; Yadam, Sankararao; Venkatesh, R.; Gangrade, Mohan; Ganesan, V.

    2018-02-01

    Structural and electrical transport properties of Nickel (Ni) doped FeSi at low temperatures in the presence of zero and high magnetic fields are investigated systematically and reported. FeSi is a material known for its high thermoelectric power. Metal-Insulator Transition in FeSi is always an exotic one with different ground states depending upon the substituent. Changes in Magneto Resistance (MR) at low temperatures are explained by invoking an interplay between Weak Localization (WL) and enhanced Electron-Electron Interaction (EEI) that evolved upon varying the nickel concentrations. Competing interactions between WL and EEI along with Kondo hybridization scenario may classify this system into an exotic one among doped semiconductors. Temperature dependent zero field resistivity is analyzed in the light of various scattering mechanism in different doping regimes at low temperatures. Different crossover regimes are explained by invoking carriers and magnetic moments induced by the Ni impurity in an otherwise non-magnetic Kondo Insulator (KI).

  3. Electroless siliconizing Fe-3% Cr-3% Si alloy

    International Nuclear Information System (INIS)

    Nurlina, Enung; Darmono, Budy; Purwadaria, Sunara

    2000-01-01

    In this research Fe-3%Cr-3%Mo-3%Si and Fe-3%Cr-3%Cu-3%Si alloys had been coated by silicon metal without electricity current which knows as electroless siliconizing. Coating was conducted by immersed sampler into melt fluoride-chloride salt bath at temperature of 750 o C for certain period. The layer consisted of Fe3Si phase. Observation by microscope optic and EDAX showed that the silicide layer were thick enough, adherent, free for crack and had silicon content on the surface more than 15%. The growth rate of silicide layer followed parabolic rate law, where the process predominantly controlled by interdiffusion rate in the solid phase. Key words : electroless siliconizing, the melt fluoride- chloride salt mix, silicide layer

  4. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li Jinlong; Mao Shoudong; Sun Kefei [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Li Xiaomin [Shanghai Institute of Ceramics Chinese Academy of Sciences, Shanghai 200050 (China); Song Zhenlun [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)], E-mail: songzhenlun@nimte.ac.cn

    2009-11-15

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  5. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Li Jinlong; Mao Shoudong; Sun Kefei; Li Xiaomin; Song Zhenlun

    2009-01-01

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  6. Growth, structure and luminescence properties of multilayer Si/{beta}-FeSi{sub 2}NCs/Si/.../Si nanoheterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Galkin, Nikolay G., E-mail: ngalk@iacp.dvo.ru [Institute of Automation and Control Processes, FEB of RAS, Radio Str. 5, Vladivostok, 690041 (Russian Federation); Chusovitin, Evgeniy A. [Institute of Automation and Control Processes, FEB of RAS, Radio Str. 5, Vladivostok, 690041 (Russian Federation); Shamirsaev, Timur S.; Gutakovski, Anton K.; Latyshev, Alexander V. [Institute of Semiconductor Physics, SB of RAS, Academician Lavrentiev, 13, Novosibirsk, 630090 (Russian Federation)

    2011-10-03

    Multilayer structures (up to 15 layers) with {beta}-FeSi{sub 2} nanocrystallites (NCs) buried in silicon crystalline lattice were grown by successive repetition of reactive deposition epitaxy (RDE) or solid phase epitaxy (SPE) of thin iron film on Si(100) or Si(111) substrates and silicon molecular beam epitaxy (MBE) (100-200 nm). Cross-section high resolution transmission electron microscopy (HR TEM) images and ex situ optical and Raman spectroscopy data prove that NCs formed in silicon matrix have the structure and optical properties of {beta}-FeSi{sub 2}. The growth conditions provide no dislocations in silicon lattice were found in the course of TEM analysis. Two types of NCs depth distribution were observed: (i) layered that corresponds to iron RDE and (ii) uniform that occurs in the case of iron SPE. The uniform NCs distribution points out the fact that during a growth process NCs moves up to the surface. In spite of small nanocrystallites size (5-50 nm) and their distribution in silicon cap layers the significant photoluminescence (PL) signal at 0.8 eV was observed for all grown samples.

  7. Phonon properties of β-FeSi2 and photoluminescence

    Science.gov (United States)

    Maeda, Y.; Nakajima, T.; Matsukura, B.; Ikeda, T.; Hiraiwa, Y.

    We have investigated phonon properties of some β-FeSi2 crystals with characteristic light emission properties by using measurements of far-infrared absorption and photoluminescence in order to discuss a correlation between them. It has been found that there is a systematic correlation between phonon states and light emission efficiency and that the phonons above the energy of more than ∼44 meV may be effectively coupled to the optical indirect transition for the IR light emission from β-FeSi2 crystals.

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

    International Nuclear Information System (INIS)

    Kuo, Chin-Guo

    2010-01-01

    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 FeAl 2 O 4 curve. Then the Al 2 O 3 curve appears and replaces the FeAl 2 O 4 curve, where the interconnection point of the two curves is the coexistence point of FeAl 2 O 4 and Al 2 O 3 phases. When %Al is increased to 0.4%, the %O decreases to 6.35 ppm, which is the lowest point of the Al 2 O 3 curve. The solubility of oxygen in Fe-Al alloys is about 6.35 ppm with 0.4 wt.% aluminum at 1873 K. Liquid FeO-Al 2 O 3 , hercynite (FeAl 2 O 4 ), and alumina (Al 2 O 3 ) are three possible products during the deoxidation process. Based on thermodynamic calculation, the value of the interaction coefficient of e o Al was determined as -0.75 at 1873 K. This value is in good agreement with experimental curves in the literature.

  9. 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

  10. Mechanochemically synthesized Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Khodaei, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)], E-mail: ena78@cc.iut.ac.ir; Karimzadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-01-07

    Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite powder was successfully synthesized by mechanochemical route starting from Fe{sub 2}O{sub 3} and Al powder mixture. The resulting nanocomposite powder was consolidated at 1400 deg. C for 1 h. The phase transformation and microstructural characterization during mechanochemical reaction and sintering were investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results showed that during ball milling the Fe{sub 2}O{sub 3}-Al combustion reaction directly produces the Fe{sub 3}Al-Al{sub 2}O{sub 3} nanocomposite. The consolidated Fe{sub 3}Al-Al{sub 2}O{sub 3} part had an ultrafine uniform structure without 'core-rim' feature consisting of an interconnected network of Fe{sub 3}Al and Al{sub 2}O{sub 3} phases.

  11. Fe Isotopic Composition of Presolar SiC Mainstream Grains

    Science.gov (United States)

    Tripa, C. E.; Pellin, M. J.; Savina, M. R.; Davis, A. M.; Lewis, R. S.; Clayton, R. N.

    2002-01-01

    Iron isotopic distribution was measured in SiC mainstream grains from the Murchison meteorite by time-of-flight resonance ionization mass spectrometry. All grains exhibit 54Fe depletions of 50 to 200, lower than what are predicted by calculations of s-process nucleosynthesis in AGB stars. Additional information is contained in the original extended abstract.

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

    Science.gov (United States)

    Lu, Xin; Miki, Takahiro; Nagasaka, Tetsuya

    2017-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Podprocká R.

    2017-09-01

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

  14. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    Abstract. Porous ceramic matrix composites FeAlOy/FeAlx 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.

  15. Surface sputtering in high-dose Fe ion implanted Si

    International Nuclear Information System (INIS)

    Ishimaru, Manabu

    2007-01-01

    Microstructures and elemental distributions in high-dose Fe ion implanted Si were characterized by means of transmission electron microscopy and Rutherford backscattering spectroscopy. Single crystalline Si(0 0 1) substrates were implanted at 350 deg. C with 120 keV Fe ions to fluences ranging from 0.1 x 10 17 to 4.0 x 10 17 /cm 2 . Extensive damage induced by ion implantation was observed inside the substrate below 1.0 x 10 17 /cm 2 , while a continuous iron silicide layer was formed at 4.0 x 10 17 /cm 2 . It was found that the spatial distribution of Fe projectiles drastically changes at the fluence between 1.0 x 10 17 and 4.0 x 10 17 /cm 2 due to surface sputtering during implantation

  16. Silicon-Mediated Alleviation of Aluminum Toxicity by Modulation of Al/Si Uptake and Antioxidant Performance in Ryegrass Plants

    Directory of Open Access Journals (Sweden)

    Paula Cartes

    2017-04-01

    Full Text Available Silicon (Si has been well documented to alleviate aluminum (Al toxicity in vascular plants. However, the mechanisms underlying these responses remain poorly understood. Here, we assessed the effect of Si on the modulation of Si/Al uptake and the antioxidant performance of ryegrass plants hydroponically cultivated with Al (0 and 0.2 mM in combination with Si (0, 0.5, and 2.0 mM. Exposure to Al significantly increased Al concentration, mainly in the roots, with a consequent reduction in root growth. However, Si applied to the culture media steadily diminished the Al concentration in ryegrass, which was accompanied by an enhancement in root dry matter production. A reduced concentration of Si in plant tissues was also observed when plants were simultaneously supplied with Al and Si. Interestingly, Si transporter genes (Lsi1 and Lsi2 were down-regulated in roots after Si or Al was applied alone; however, both Lsi1 and Lsi2 were up-regulated as a consequence of Si application to Al-treated plants, denoting that there is an increase in Si requirement in order to cope with Al stress in ryegrass. Whereas Al addition triggered lipid peroxidation, Si contributed to an attenuation of Al-induced oxidative stress by increasing phenols concentration and modulating the activities of superoxide dismutase (SOD, catalase, peroxidase, and ascorbate peroxidase antioxidant enzymes. Differential changes in gene expression of SOD isoforms (Mn-SOD, Cu/Zn-SOD, and Fe-SOD and the profile of peroxide (H2O2 generation were also induced by Si in Al-stressed plants. This, to the best of our knowledge, is the first study to present biochemical and molecular evidence supporting the effect of Si on the alleviation of Al toxicity in ryegrass plants.

  17. Room temperature luminescence and ferromagnetism of AlN:Fe

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-06-01

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

  18. 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

  19. Effects of Strain Rate on Compressive Properties in Bimodal 7075 Al-SiCp Composite

    Science.gov (United States)

    Lee, Hyungsoo; Choi, Jin Hyeok; Jo, Min Chul; Jo, Ilguk; Lee, Sang-Kwan; Lee, Sunghak

    2018-03-01

    A 7075 Al alloy matrix composite reinforced with SiC particulates (SiCps) whose sizes were 10 and 30 μm, i.e., a bimodal Al-SiCp composite, was made by a liquid pressing process, and its quasi-static and dynamic compressive properties were evaluated by using a universal testing machine and a split Hopkinson pressure bar, respectively. Mg-Si-, Al-Fe-, and Cu-rich intermetallic compounds existed inside the Al matrix, but might not deteriorate compressive properties because of their low volume fraction (about 2.6%) which was much lower than that of SiCp. The dynamic compressive strength was higher than the quasi-static strength, and was higher in the specimen tested at 2800 s-1 than in the specimen tested at 1400 s-1 according to the strain-rate hardening. For explaining the strain data, the blocking extent of crack propagation by the Al matrix was quantitatively examined. The melting of Al matrix occurred by adiabatic heating was favorable for the improvement in compressive strain because it favorably worked for activating the shear band formation and for blocking the crack propagation, thereby leading to the excellent compressive strain (10.9-11.6%) as well as maximum compressive strength (1057-1147 MPa). Thus, the present bimodal 7075 Al-SiCp composite provides a promise for new applications to high-performance armor plates.

  20. A pulse synthesis of beta-FeSi sub 2 layers on silicon implanted with Fe sup + ions

    CERN Document Server

    Batalov, R I; Terukov, E I; Kudoyarova, V K; Weiser, G; Kuehne, H

    2001-01-01

    The synthesis of thin beta-FeSi sub 2 films was performed by means of the Fe sup + ion implantation into Si (100) and the following nanosecond pulsed ion treatment of implanted layer. Using the beta-FeSi sub 2 beta-FeSi sub 2 e X-ray diffraction it is shown that the pulsed ion treatment results in the generation of the mixture of two phases: FeSi and beta-FeSi sub 2 with stressed crystal lattices. The following short-time annealing leads to the total transformation of the FeSi phase into the beta-FeSi sub 2 one. The Raman scattering data prove the generation of the beta-FeSi sub 2 at the high degree of the silicon crystallinity. The experimental results of the optical absorption testify to the formation of beta-FeSi sub 2 layers and precipitates with the straight-band structure. The photoluminescence signal at lambda approx = 1.56 mu m observes up to 210 K

  1. Stress-induced indirect to direct band gap transition in β-FeSi2 nanocrystals embedded in Si

    Science.gov (United States)

    Shevlyagin, A. V.; Goroshko, D. L.; Chusovitin, E. A.; Balagan, S. A.; Dotsenko, S. A.; Galkin, K. N.; Galkin, N. G.; Shamirzaev, T. S.; Gutakovskii, A. K.; Iinuma, M.; Terai, Y.

    2017-09-01

    Embedded in silicon β-FeSi2 nanocrystals (NCs) were grown on Si(111) by solid phase epitaxy of a thin iron film followed by Si molecular beam epitaxy. After solid phase epitaxy, a mixture of β-FeSi2 and ɛ-FeSi nanocrystals is formed on the surface, sometimes β and ɛ phases coexist inside one nanocrystal. During initial stage of Si molecular beam epitaxy all ɛ-FeSi transforms into β-FeSi2. β-FeSi2 nanocrystals tend to move following Si growth front. By adjusting growth condition, we manage to prevent the nanocrystals from moving and to fabricate 7-layer n-Si(111)/β-FeSi2_NCs/p+-Si silicon heterostructure with embedded β-FeSi2 NCs. An epitaxial relationship and a stress induced in the nanocrystals by silicon matrix were found to be suitable for indirect to direct band gap transition in β-FeSi2. Of the heterostructure, a n-i-p avalanche photodetector and a light-emitting diode were formed. They have shown relatively good performance: ultrabroadband photoresponse from the visible (400 nm) to short-wavelength infrared (1800 nm) ranges owing to quantum-confined Stark effect in the nanocrystals and optical emission power of up to 25 µW at 9 A/cm2 with an external quantum efficiency of 0.009% at room temperature owing to a direct fundamental transition in stressed β-FeSi2 nanocrystals.

  2. Study of ion beam sputtered Fe/Si interfaces as a function of Si layer thickness

    Science.gov (United States)

    Kumar, Anil; Brajpuriya, Ranjeet; Singh, Priti

    2018-01-01

    The exchange interaction in metal/semiconductor interfaces is far from being completely understood. Therefore, in this paper, we have investigated the nature of silicon on the Fe interface in the ion beam deposited Fe/Si/Fe trilayers keeping the thickness of the Fe layers fixed at 3 nm and varying the thickness of the silicon sandwich layer from 1.5 nm to 4 nm. Grazing incidence x-ray diffraction and atomic force microscopy techniques were used, respectively, to study the structural and morphological changes in the deposited films as a function of layer thickness. The structural studies show silicide formation at the interfaces during deposition and better crystalline structure of Fe layers at a lower spacer layer thickness. The magnetization behavior was investigated using magneto-optical Kerr effect, which clearly shows that coupling between the ferromagnetic layers is highly influenced by the semiconductor spacer layer thickness. A strong antiferromagnetic coupling was observed for a value of tSi = 2.5 nm but above this value an unexpected behavior of hysteresis loop (step like) with two coercivity values is recorded. For spacer layer thickness greater than 2.5 nm, an elemental amorphous Si layer starts to appear in the spacer layer in addition to the silicide layer at the interfaces. It is observed that in the trilayer structure, Fe layers consist of various stacks, viz., Si doped Fe layers, ferromagnetic silicide layer, and nonmagnetic silicide layer at the interfaces. The two phase hysteresis loop is explained on the basis of magnetization reversal of two ferromagnetic layers, independent of each other, with different coercivities. X-ray photo electron spectroscopy technique was also used to study interfaces characteristics as a function of tSi.

  3. Positive magnetoresistance in Co40Fe40B20/SiO2/Si heterostructure

    KAUST Repository

    Zhang, Y.

    2016-07-20

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

  4. Effect of Si/Fe ratio on the boron and phosphorus doping efficiency of β-FeSi2 by magnetron sputtering

    International Nuclear Information System (INIS)

    Xu Jiaxiong; Yao Ruohe

    2011-01-01

    Boron-doped or phosphorus-doped β-FeSi 2 thin films have been prepared on silicon substrate by magnetron sputtering. Effects of Si/Fe ratio on the boron and phosphorus doping efficiencies have been studied from the resistivities of doped β-FeSi 2 thin films and current-voltage characteristics of doped β-FeSi 2 /Si heterojunctions. The experimental results reveal that the carrier concentration and doping efficiency of boron or phosphorus dopants at the Fe-rich side are higher than that at the Si-rich side. The effect of Si/Fe ratio can be deduced from the comparison of the formation energies under two extreme conditions. At the Fe-rich limit condition, the formation energy of boron or phosphorous doping is lower than that at the Si-rich condition. Therefore, the activation of impurities is more effective at the Fe-rich side. These results demonstrate that the boron-doped and phosphorous-doped β-FeSi 2 thin films should be kept at the Fe-rich side to avoid the unexpected doping sites and low doping efficiency.

  5. Layer magnetization canting in {sup 57}Fe/FeSi multilayer observed by synchrotron Moessbauer reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Bottyan, L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Dekoster, J. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Deak, L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Baron, A.Q.R. [European Synchrotron Radiation Facility (France); Degroote, S.; Moons, R. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Nagy, D.L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Langouche, G. [University of Leuven, Instituut voor Kern- en Stralingsfysica (Belgium)

    1998-08-15

    Synchrotron Moessbauer reflectometry and CEMS results on a [{sup 57}Fe(2.55 nm)/FeSi(1.57 nm)]{sub 10} multilayer (ML) on a Zerodur substrate are reported. CEMS spectra are satisfactorily fitted by {alpha}-Fe and an interface layer of random {alpha}-(Fe, Si) alloy of 20% of the {sup 57}Fe layer thickness on both sides of the individual Fe layers. Kerr loops show a fully compensated AF magnetic layer structure. Prompt X-ray reflectivity curves show the structural ML Bragg peak and Kiessig oscillations corresponding to a bilayer period and total film thickness of 4.12 and 41.2 nm, respectively. Grazing incidence nuclear resonant {theta}-2{theta} scans and time spectra (E = 14.413 keV, {lambda} = 0.0860 nm) were recorded in different external magnetic fields (0 < B{sup ext} < 0.95 T) perpendicular to the scattering plane. The time integral delayed nuclear {theta}-2{theta} scans reveal the magnetic ML period doubling. With increasing transversal external magnetic field, the antiferromagnetic ML Bragg peak disappears due to Fe layer magnetization canting, the extent of which is calculated from the fit of the time spectra and the {theta}-2{theta} scans using an optical approach. In a weak external field the Fe layer magnetization directions are neither parallel with nor perpendicular to the external field. We suggest that the interlayer coupling in [Fe/FeSi]{sub 10} varies with the distance from the substrate and the ML consists of two magnetically distinct regions, being of ferromagnetic character near substrate and antiferromagnetic closer to the surface.

  6. Characterization of a-FeSi2/c-Si heterojunctions for photovoltaic applications

    International Nuclear Information System (INIS)

    Antwis, L; Gwilliam, R; Smith, A; Jeynes, C; Homewood, K

    2012-01-01

    Amorphous iron disilicide (a-FeSi 2 ) shows potential as a photovoltaic material due to its bandgap of ∼0.9 eV and high absorption coefficient. We present a detailed characterization of a-FeSi 2 , with particular emphasis on the electrical properties of a-FeSi 2 /c-Si heterostructures, under both dark and illuminated conditions. The samples were prepared on quartz and silicon substrates using RF co-sputtering of an iron/silicon target. Optical transmission spectroscopy was used to confirm the bandgap of the samples. Van der Pauw measurements and current–voltage analysis techniques were used to determine the carrier type and conduction mechanisms of the samples. The results show that a-FeSi 2 forms a rectifying p–n heterojunction on p-type crystalline silicon. The silicide is characterized by very high carrier concentrations, resulting in the depletion region being almost entirely formed within the silicon substrate. Initial J–V results suggest carrier recombination within the silicide to be the dominant contribution to the conduction across the junction, with photovoltaic effects having been observed under AM1.5 conditions. (paper)

  7. Fe-Al-Nb phase diagram investigation and directional growth of the (Fe, Al){sub 2}Nb-(Fe, Al, Nb){sub ss} eutectic system

    Energy Technology Data Exchange (ETDEWEB)

    Mota, M.A. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Coelho, A.A. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Bejarano, J.M.Z. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Gama, S. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil); Caram, R. [State University of Campinas, C.P. 6122, 13083-970 Campinas, SP (Brazil)]. E-mail: rcaram@fem.unicamp.br

    2005-08-16

    An attractive alternative method for the manufacture of high temperature structural materials may be achieved from a eutectic transformation found in the Fe-Al-Nb system, which generates the (Fe, Al){sub 2}Nb and (Fe, Al, Nb){sub ss} solid phases. Eutectic and off-eutectic samples from the Fe-Al-Nb system were prepared by arc melting under argon atmosphere, which were subsequently directionally solidified using a vertical Bridgman crystal growth unit. The ingots obtained were investigated using optical and electron scanning microscopy with the purpose to evaluate the effect of the growth condition on the microstructure. Primarily, the growth mode of the (Fe, Al){sub 2}Nb/(Fe, Al, Nb) eutectic was considered by examining off-eutectic samples. The solidification experiments carried out under different conditions revealed that the microstructure of this system is very sensitive to a growth rate variation. At a low growth rate, the eutectic microstructure was regular, even though several types of defects were found. As the growth rate was increased, a transition from lamellar to fibrous morphology was observed. Some aspects of this transition were also evaluated.

  8. 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.

  9. The thermal evolution of Mercury's Fe-Si core

    Science.gov (United States)

    Knibbe, Jurriën Sebastiaan; van Westrenen, Wim

    2018-01-01

    We have studied the thermal and magnetic field evolution of planet Mercury with a core of Fe-Si alloy to assess whether an Fe-Si core matches its present-day partially molten state, Mercury's magnetic field strength, and the observed ancient crustal magnetization. The main advantages of an Fe-Si core, opposed to a previously assumed Fe-S core, are that a Si-bearing core is consistent with the highly reduced nature of Mercury and that no compositional convection is generated upon core solidification, in agreement with magnetic field indications of a stable layer at the top of Mercury's core. This study also present the first implementation of a conductive temperature profile in the core where heat fluxes are sub-adiabatic in a global thermal evolution model. We show that heat migrates from the deep core to the outer part of the core as soon as heat fluxes at the outer core become sub-adiabatic. As a result, the deep core cools throughout Mercury's evolution independent of the temperature evolution at the core-mantle boundary, causing an early start of inner core solidification and magnetic field generation. The conductive layer at the outer core suppresses the rate of core growth after temperature differences between the deep and shallow core are relaxed, such that a magnetic field can be generated until the present. Also, the outer core and mantle operate at higher temperatures than previously thought, which prolongs mantle melting and mantle convection. The results indicate that S is not a necessary ingredient of Mercury's core, bringing bulk compositional models of Mercury more in line with reduced meteorite analogues.

  10. FeSiBP bulk metallic glasses with high magnetization and excellent magnetic softness

    Energy Technology Data Exchange (ETDEWEB)

    Makino, Akihiro [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)], E-mail: amakino@imr.tohoku.ac.jp; Kubota, Takeshi; Chang, Chuntao [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan); Makabe, Masahiro [Makabe R and D Co., Ltd., 3-1-25 Nagatake, Sendai 983-0036 (Japan); Inoue, Akihisa [Tohoku University, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2008-10-15

    Fe-based amorphous alloy ribbons are one of the major soft magnetic materials, because of their superior magnetic properties such as the relatively high saturation magnetization (J{sub s}) of 1.5-1.6 T and good magnetic softness. However, the preparation of the ordinary amorphous magnetic alloys requires cooling rates higher than 10{sup 4} K/s due to the low glass-forming ability (GFA) and thus restricts the material outer shape. Recently, Fe-metalloid-based bulk metallic glasses (BMGs) containing glass-forming elements such as Al, Ga, Nb, Mo, Y and so forth have been developed. These alloys have high GFA, leading to the formation of BMG rod with diameters of mm-order. However, the glass-forming metal elements in BMGs result in a remarkable decrease in magnetization. Basically, J{sub s} depends on Fe content; hence, high J{sub s} requires high Fe content in the Fe-based amorphous alloys or BMGs. On the other hand, high GFA requires a large amount of glass-forming elements in the alloys, which results in lower Fe content. Therefore, in substances, the coexistence of high J{sub s} and high GFA is difficult. Since this matter should be immensely important from academia to industry in the material field, a great deal of effort has been devoted; however, it has remained unsolved for many years. In this paper, we present a novel Fe-rich FeSiBP BMG with high J{sub s} of 1.51 T comparable to the ordinary Fe-Si-B amorphous alloy now in practical use as well as with high GFA leading to a rod-shaped specimen of 2.5 mm in diameter, obtained by Cu-mold casting in air.

  11. 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.

  12. Electronic properties of beta-FeSi sub 2 under pressure

    CERN Document Server

    Takarabe, K; Oinuma, J; Mori, Y

    2002-01-01

    We have investigated for the first time the high-pressure optical absorption of beta-FeSi sub 2 thin films (90 nm in thickness) prepared from Si/Fe multilayers on Si(001) with a template and SiO sub 2 capping. The pressure coefficient for the direct band gap of beta-FeSi sub 2 is determined as 15.9 meV GPa sup - sup 1. This small coefficient is due to the negative deformation potential of the valence band maximum, and the large bulk modulus of beta-FeSi sub 2.

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

    Directory of Open Access Journals (Sweden)

    J. Wysocki

    2009-04-01

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

  15. Strength anomaly in B2 FeAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, K.; Hanada, S.; Yoo, M.H. [Oak Ridge National Lab., TN (United States); Matsumoto, N. [Tohoku Univ. (Japan). Graduate School

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  16. Chemical leaching of rapidly solidified Al-Si binary alloys

    International Nuclear Information System (INIS)

    Yamauchi, I.; Takahara, K.; Tanaka, T.; Matsubara, K.

    2005-01-01

    Various particulate precursors of Al 100-x Si x (x = 5-12) alloys were prepared by a rapid solidification process. The rapidly solidified structures of the precursors were examined by XRD, DSC and SEM. Most of Si atoms were dissolved into the α-Al(fcc) phase by rapid solidification though the solubility of Si in the α-Al phase is negligibly small in conventional solidification. In the case of 5 at.% Si alloy, a single α-Al phase was only formed. The amount of the primary Si phase increased with increase of Si content for the alloys beyond 8 at.% Si. Rapid solidification was effective to form super-saturated α-Al precursors. These precursors were chemically leached by using a basic solution (NaOH) or a hydrochloric acid (HCl) solution. All Al atoms were removed by a HCl solution as well as a NaOH solution. Granules of the Si phase were newly formed during leaching. The specific surface area was about 50-70 m 2 /g independent of Si content. The leaching behavior in both solutions was slightly different. In the case of a NaOH solution, the shape of the precursor often degenerated after leaching. On the other hand, it was retained after leaching by a HCl solution. Fine Si particles precipitated in the α-Al phase by annealing of as-rapidly solidified precursors at 773 K for 7.2 x 10 3 s. In this case, it was difficult to obtain any products by NaOH leaching, but a few of Si particles were obtained by HCl leaching. Precipitated Si particles were dissolved by the NaOH solution. The X-ray diffraction patterns of leached specimens showed broad lines of the Si phase and its lattice constant was slightly larger than that of the pure Si phase. The microstructures of the leached specimens were examined by transmission electron microscopy. It showed that the leached specimens had a skeletal structure composed of slightly elongated particles of the Si phase and quite fine pores. The particle size was about 30-50 nm. It was of comparable order with that evaluated by Scherer

  17. Photoabsorption properties of {beta}-FeSi{sub 2} nanoislands grown on Si(111) and Si(001): Dependence on substrate orientation studied by nano-spectroscopic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Naruse, Nobuyasu, E-mail: naruse@sanken.osaka-u.ac.jp [Institute of Scientific and Industrial Research (ISIR), Ibaraki, Osaka University, Osaka 567-0047 (Japan); Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Toyonaka, Osaka University, Osaka 560-8531 (Japan); Mera, Yutaka; Ichikawa, Masakazu; Maeda, Koji [Department of Applied Physics, School of Engineering, University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2011-10-03

    Photoabsorption properties of {beta}-FeSi{sub 2} nanoislands epitaxially grown on Si(111) and Si(001) have been discussed using photoabsorption nano-spectroscopy based on scanning tunneling microscope. The obtained spectra exhibit clear features around 0.86-0.91 eV and around 0.71-0.74 eV, which are explained as a direct and an indirect photoabsorption edge of {beta}-FeSi{sub 2}, respectively. We also observed a blue shift of spectrum obtained from {beta}-FeSi{sub 2} nanoislands on Si(111) substrates, compared to those on Si(001) substrates. We attributed the dependence on Si-substrate orientation not to a quantum confinement effect but to an effect of elastic strain in the {beta}-FeSi{sub 2} nanoislands epitaxially grown on the substrate.

  18. Aqueous processing of carbothermally prepared Ca- α -SiAlON and β -SiAlON Powders : Powder and suspension characterisation

    NARCIS (Netherlands)

    Kudyba-Jansen, A.; Almeida, M.; Laven, J.; Heijde, J.C.T. van der; Hintzen, H.T.; Metselaar, R.

    1999-01-01

    Properties of carbothermally prepared Ca-α-SiAlON and β-SiAlON powders and aqueous suspensions thereof were determined. The isoelectric points of Ca-α-SiAlON and β-SiAlON were 3·4 and 4·6. After addition of deflocculant, Dolapix CE64, the behaviour of both suspensions is nearly identical. The

  19. Two-Zone Microstructures in Al-18Si Alloy Powders

    Science.gov (United States)

    Spinelli, J. E.; Bogno, A.-A.; Henein, H.

    2018-02-01

    Hypereutectic Al-18 wt pct Si alloy is widely used in automotive industry as a wear-resistant alloy for engine components. However, in the last few years, this traditional composition is being considered for processing by different rapid solidification methods. Positive points include its low thermal expansion and uniform distribution of surface oxides. Nevertheless, the microstructural aspects of Al-Si powders of 18 wt pct Si are still need to be addressed, such as, the eutectic Si morphology, size, and distribution generated by different process conditions during rapid solidification. Based on a detailed quantitative analysis of the microstructures of rapid solidified Al-18 wt pct Si in this work, solidification conditions that yield specific Si morphologies, Si spacing, and thermal cooling conditions are outlined. The focus is determining the solidification conditions that will yield a specified shape of eutectic Si. It is shown that Si morphology is dependent on a combination of growth velocity (based on modified JH model) and temperature gradient. Furthermore, the highest hardness is achieved with globular morphologies of Si. The processing conditions required to achieve these properties are outlined.

  20. Point defects in B.C.C. Fe-Al, Fe-Co, and Fe-Co-V ordered alloys

    International Nuclear Information System (INIS)

    Riviere, J.P.; Dinhut, J.F.

    1982-01-01

    Radiation damage produced at 20 K by 2.5 MeV electrons is studied in three B 2 type Fe-40 at % Al, Fe-Co, Fe-Co-V ordered alloys. The resistivity damage in Fe-40 at % Al ordered single crystals is found less effective in the directions. The results suggest that replacement collision chains are difficult to propagate along the direction. Frenkel pair creation superimposed with disordering can account for the resistivity damage in the initially ordered Fe-Co alloy. Informations concerning replacement collision sequences in direction are derived. During the recovery of all the alloys, three main stages are observed and an ordering enhancement occurs. (author)

  1. Electronic structure, metamagnetism and thermopower of LaSiFe12 and interstitially doped LaSiFe12

    Science.gov (United States)

    Gercsi, Z.; Fuller, N.; Sandeman, K. G.; Fujita, A.

    2018-01-01

    We present a systematic investigation of the effect of H, B, C, and N interstitials on the electronic, lattice and magnetic properties of La(Fe,Si)13 using density functional theory. The parent LaSiFe12 alloy has a shallow, double-well free energy function that is the basis of itinerant metamagnetism. On increasing the dopant concentration, the resulting lattice expansion causes an initial increase in magnetisation for all interstitials that is only maintained at higher levels of doping in the case of hydrogen. Strong s-p band hybridisation occurs at high B,C and N concentrations. We thus find that the electronic effects of hydrogen doping are much less pronounced than those of other interstitials, and result in the double-well structure of the free energy function being least sensitive to the amount of hydrogen. This microscopic picture accounts for the vanishing first order nature of the transition by B,C, and N dopants as observed experimentally. We use our calculated electronic density of states for LaSiFe12 and the hydrogenated alloy to infer changes in magneto-elastic coupling and in phonon entropy on heating through T C by calculating the fermionic entropy due to the itinerant electrons. Lastly, we predict the electron thermopower in a spin-mixing, high temperature limit and compare our findings to recent literature data.

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

    Science.gov (United States)

    Çolak, O.; Yünlü, L.

    2017-06-01

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

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

    International Nuclear Information System (INIS)

    Brown, P J; Kainuma, R; Kanomata, T; Okubo, A; Neumann, K-U; Umetsu, R Y; Ziebeck, K R A

    2013-01-01

    The magnetization distribution in Co 2 FeSi which has the largest moment per formula unit ∼6 μ B 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 L1 2 structure giving μ Fe = 3.10(3) μ B and μ Co = 1.43(2) μ B , 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 e g 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 Co 2 FeSi is not a perfect half-metallic ferromagnet. (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-27

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

  5. Study of the ternary alloy systems Al-Ni-Fe and Al-Cu-Ru with special regard to quasicrystalline phases

    International Nuclear Information System (INIS)

    Lemmerz, U.

    1996-07-01

    Two ternary alloy-systems, the Al-Ni-Fe system and the Al-Cu-Ru system were studied with special regard to quasicrystalline phases. Isothermal sections were established in both systems in the stoichiometric area of the quasicrystalline phase. In the Al-Ni-Fe system a new stable decagonal phase was found. Its stoichiometric range is very small around Al 71.6 Ni 23.0 Fe 5.4 . The temperature range in which it is stable lies between 847 and 930 C. The decagonal phase undergoes a eutectoid reaction to the three crystalline phases Al 3 Ni 2 , Al 3 Ni and Al 13 Fe 4 at 847 C. It melts peritectically at 930 C forming Al 13 Fe 4 , Al 3 Ni 2 and a liquid. The investigations in the Al-Cu-Ru system concentrated on the phase equilibria between the icosahedral phase and its neighbouring phases in a temperature range between 600 and 1000 C. The icosahedral phase was observed in the whole temperature range. The investigated stoichiometric area extends down to Al contents of 45%, which allows the fields of existence to be determined for the ternary phases α-AlCuRu, the icosahedral phase and Al 7 Cu 2 Ru. Binary phases were determined down to the upper (high Al content) border of AlRu. No hitherto unknown phase was observed in the investigated area. Rietveld analyses were carried out on α-AlCuRu and Al 7 Cu 2 Ru showing some discrepancies from the α-AlMnSi structure taken as a base for α-AlCuRu and confirming the Al 7 Cu 2 Fe structure for Al 7 Cu 2 Ru. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Suárez-Peña, B.

    2007-10-01

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

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-01

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

  8. High silicon steel production through hot-dipping in Al-Si-alloy and diffusion annealing

    International Nuclear Information System (INIS)

    Ros-Yanez, T.; Houbaert, Y.; Schneeweis, O.; Asensio-Lozano, J.; Prado-Garcia, M.

    2000-01-01

    It is difficult to process steel sheet with a high Si content (>3,5%Si), mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a hot-dip simulator using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that: Intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram. With a double dipping primary silicon crystals are formed in the surface layer. the ordered DO 3 structure is present if the dipping and/or diffusion time is long enough. Homogeneous silicon gradients in the whole substrate thickness have not yet been achieved. Theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour. (Author) 17 refs

  9. Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

    Indian Academy of Sciences (India)

    The interface of Fe3Al/Q235 dissimilar materials joint, which was made by vacuum diffusion welding, combines excellently. There are Fe3Al, FeAl phases and -Fe (Al) solid solution at the interface of Fe3Al/Q235. Aluminum content decreases from 28% to 1.5% and corresponding phase changes from Fe3Al with DO3 type ...

  10. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    The lower load-bearing capacity of graphite flakes in localized region was found to increase the wear rate of the alloy. The carbides such as Fe 3 AlC 0.5 , TiC and ZrC are embedded in the matrix after sliding wear without destruction or delamination. This significantly affects the wear resistance of FeAl-based alloys.

  11. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    The carbides such as Fe3AlC0.5, TiC and ZrC are embedded in the matrix after sliding wear ... to formation of TiC/ZrC, thus forming a composite with the. FeAl matrix. ... s. −1 at room temperature. The dry sliding wear tests were carried out using a ball- on-disc apparatus. Specimens with size of 12 × 12 × 5 mm3 were used.

  12. Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

    Indian Academy of Sciences (India)

    Abstract. 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 ...

  13. Interlayer exchange coupling, crystalline and magnetic structure in Fe/CsCl-FeSi multilayers grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Dekoster, J.; Degroote, S.; Meersschaut, J.; Moons, R.; Vantomme, A. [K.U. Leuven, Instituut voor Kern- en Stralingsfysica (Belgium); Bottyan, L.; Deak, L.; Szilagyi, E.; Nagy, D.L. [KFKI Research Institute for Particle and Nuclear Physics (Hungary); Baron, A.Q.R. [European Synchrotron Radiation Facility (France); Langouche, G. [K.U. Leuven, Instituut voor Kern- en Stralingsfysica (Belgium)

    1999-09-15

    Crystalline and magnetic structure as well as the interlayer exchange coupling in MBE grown Fe/FeSi multilayers are investigated. From conversion electron Moessbauer spectroscopy and ion beam channeling measurements the spacer FeSi material is found to be stabilized in a crystalline metastable metallic FeSi phase with the CsCl structure. Strong non-oscillatory interlayer exchange coupling is identified with magnetometry and synchrotron Moessbauer reflectometry. From the fits of the time spectrum and the resonant {phi}-{phi} scans a model for the sublayer magnetization of the multilayer is deduced.

  14. Al(Fe,Ti,Si)-mobility and secondary mineralization implications: A case study of the karst unconformity diasporite-type bauxite horizons in Milas (Muğla), Turkey

    Science.gov (United States)

    Hatipoğlu, Murat

    2011-05-01

    The Paleogene aged metabauxite deposit in the Upper Cretaceous-Early Paleogene aged marble sequence within the southwestern Menderes Massif in the İlbir Mountains of the Milas (Muğla) region of SW Turkey comprises many initially karst unconformity-type bauxite horizons with unusual Al-mobility. Thus, it displays singular geochemical and mineralogical implications. The settling down of these horizons was syngenetic with limestone sedimentation, as evidenced by their lithologic associations. In the region, they are mainly found as karst unconformity diasporite-type upper bauxite horizons due to lower-graded burial metamorphism in the Küçükçamlık and Büyükçamlık hills, and also found as emery type lower bauxite horizons due to higher-graded burial metamorphism in the Meneviş and Kure streams. The main focus of this study was the upper bauxite horizons because they contain significant secondary Al- and Fe(Ti)-rich mineralization in the structurally-controlled open spaces (fracture zones) crosscutting the brittle bauxite horizons. This secondary mineralization is unique worldwide because the fracture zones contain coarse crystals of secondary minerals, such as gem-quality diaspore, muscovite, specular hematite, ilmenite, goethite, and chloritoid. These secondary metamorphic minerals were formed by high-temperature hydrothermal activity involving metamorphic remobilized reactions of extraction, mobilization, migration and re-crystallization, from the primary metamorphic mineral constituents in the metabauxite ore bodies. Thus, within the well known Mediterranean Bauxite Belt (MBB) in southern Europe trending from Portugal through Turkey, the metabauxite deposit in the İlbir Mountains is noteworthy for the coexistence of two serial phases of metamorphic mineralization which occurred when the metabauxite deposit was modified by late-stage Alpine tectono-metamorphism in the Menderes Massif. This study is mainly focused on the original primary metamorphic

  15. Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

    International Nuclear Information System (INIS)

    Andoh, A.

    1997-01-01

    The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

  16. 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.

  17. Understanding the magnetic anisotropy in Fe-Si amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, J.; Hamdan, N.M.; Jalil, P.; Hussain, Z.; Valvidares, S.M.; Alameda, J.M.

    2002-08-01

    The origin of the magnetic anisotropy in a very disordered Fe-Si alloy has been investigated. The alloy containing 40 percent at. Si was prepared in the form of a thin film in a DC magnetron sputtering chamber. Structural disorder was obtained from Extended X-ray Absorption Fine Structure spectroscopy. The uniformity and lack of inhomogeneities at a microscopic level was checked by measuring their transverse magnetic susceptibility and hysteresis loops. The orbital component of the magnetic moment was measured by X-ray Magnetic Circular Dichroism spectroscopy. The orbital moment was extraordinary high, 0.4mB. Such a high value contrasted with the relatively small uniaxial anisotropy energy of the thin film (2kJ/m3). This suggests that the cause of the magnetic anisotropy in this alloy was a small degree of correlation in the orientation of the local orbital moments along a preferential direction.

  18. Understanding the magnetic anisotropy in Fe-Si amorphous alloys

    International Nuclear Information System (INIS)

    Diaz, J.; Hamdan, N.M.; Jalil, P.; Hussain, Z.; Valvidares, S.M.; Alameda, J.M.

    2002-01-01

    The origin of the magnetic anisotropy in a very disordered Fe-Si alloy has been investigated. The alloy containing 40 percent at. Si was prepared in the form of a thin film in a DC magnetron sputtering chamber. Structural disorder was obtained from Extended X-ray Absorption Fine Structure spectroscopy. The uniformity and lack of inhomogeneities at a microscopic level was checked by measuring their transverse magnetic susceptibility and hysteresis loops. The orbital component of the magnetic moment was measured by X-ray Magnetic Circular Dichroism spectroscopy. The orbital moment was extraordinary high, 0.4mB. Such a high value contrasted with the relatively small uniaxial anisotropy energy of the thin film (2kJ/m3). This suggests that the cause of the magnetic anisotropy in this alloy was a small degree of correlation in the orientation of the local orbital moments along a preferential direction

  19. Synthesis, characterization and magnetic properties of Fe-Al nanopins

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Zhang, Z.D.

    2005-01-01

    We report the synthesis of Fe-Al nanopins using arc discharge. The morphology and chemical composition of the Fe-Al nanopins were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). The nanopins are composed of a spherical base of about 20-100 nm and a needle-like tip of about several hundred nanometers. EDX and HRTEM studies indicate that the spherical base is mainly composed of α-Fe and FeAl core coated with a thin Al 2 O 3 layer, while the needle-like part contains only Al and O and corresponds to Al 2 O 3 . The formation mechanism of the nanopins is suggestive of a vapor-liquid-solid (VLS) growth process. The as-prepared Fe-Al nanopins show ferromagnetic properties. The temperature dependence of the magnetization at high temperatures indicates the existence of some phase transformations

  20. Consolidation of partially amorphous Al-Fe-Zr alloys

    International Nuclear Information System (INIS)

    Rodrigues, C.A.D.; Leiva, D.R.; Kiminami, C.S.; Botta F., W.J.

    2002-01-01

    We present in this work the preparation of partially amorphous Al-Fe-Zr alloy powders by mechanical alloying and their consolidation by hot-extrusion. Elemental powder mixture corresponding to the composition Al 90 Fe 7 Zr 3 was mechanically alloyed with milling power of 10:1 and time varying from 5 h to 100 h. Milling for 60 h resulted in a powder alloy microstructure composed mostly of nanocrystalline Al and amorphous phase. Heat treatment of such powder resulted in the formation of Al and also the equilibrium intermetallic Al 3 Zr and Al 13 Fe 4 phases. The alloy powders have been hot extruded at 450 C and the microstructure of the consolidated alloy was very fine and composed also by the three equilibrium phases; Al, Al 3 Zr and Al 13 Fe 4 . This fine microstructure resulted in yield stress values in compression tests at room temperature in the range of 780MPa, associated with elongation to fracture of 10%. (orig.)

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

    International Nuclear Information System (INIS)

    Courbiere, M.; Mocellin, A.

    1993-01-01

    Hypereutectic AlSiFe spray-cast alloys exhibit properties similar to those of metal-matrix composite (MMC's) : high Young's modulus and a low coefficient of thermal expansion. These physical properties can be adjusted by changing the Si content of the alloy. The refinement of the microstructure is produced by formation of a large amount of nuclei in the spray. Consolidation done by extrusion (bars, tubes or profiles) and/or forging leads to high mechanical properties, especially very good dynamic properties. High fatigue properties coupled with high modulus, good high temperature behaviour and low thermal expansion, allow their use for applications in the automotive industry. In opposition to MMC's, these materials present the advantage of easy recycling and easy machinability as it is the case for the conventional AlSi alloys. The low oxygen content allows quality joining with conventional arc welding techniques. (orig.)

  2. Effect of Al and AlP on the microstructure of Mn-30 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

    2008-04-15

    Effect of Al and AlP particles on the microstructure of near eutectic Mn-Si alloy (Mn-30 wt.%Si) was studied by Electron Probe Micro-analyzer (EPMA) and Differential Scanning Calorimeter (DSC). Crystal lattice correspondence analyses show that both Al and AlP have good lattice matching coherence relationships with MnSi phase, and the addition of Al and AlP particles results in an abnormal eutectic structure, i.e. the eutectic constitution MnSi and Mn{sub 5}Si{sub 3} precipitate separately: MnSi precipitates firstly, and then the Mn{sub 5}Si{sub 3} phase.

  3. Effect of strontium addition on silicon phase and mechanical properties of Zn-27Al-3Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Feng; Chen, Fei; Yan, Guangyuan [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Tongmin, E-mail: tmwang@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Cao, Zhiqiang, E-mail: caozq@dlut.edu.cn [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116024 (China)

    2015-02-15

    Highlights: • The nodular primary Si is observed in Zn-27Al-3Si alloy by addition of 0.2 wt% Sr. • Fibrous FE eutectic Si and rod-like CE eutectic Si are found after Sr modification. • EPMA mapping shows that Sr element is enriched in the primary Si. • The UTS and EI increase by 62.6% and 162% by addition of 0.1 wt% Sr. - Abstract: The evolution of silicon phase and mechanical properties of Zn-27Al-3Si alloy with Sr addition were investigated. The results showed that primary Si crystals were gradually modified from polygonal, plate-like and star-like to larger nodular with increasing the addition contents of Sr. A bimodal distribution of eutectic Si crystals was found. One was the coarse eutectic (CE) Si nucleating and growing from the primary Si crystals, the other was the fine eutectic (FE) Si nucleating at other sites (not primary Si). The average size and aspect ratio of FE Si crystals significantly decreased and whose morphology was transformed from a coarser plate-like structure to a fine fibrous structure with more branches with increasing Sr content. Through electron probe microanalysis mapping (EPMA) and cooling curves, it was concluded that the nodular primary Si crystals nucleated and grew by producing a large undercooling (about 40 °C) and preferential attachment of Sr to silicon phase. The mechanical properties were investigated by tensile test with various concentration of Sr. It was found that the ultimate tensile strength (UTS) and elongation (EI) increased by 62.6% and 162%, respectively. The improvements in UTS and EI were attributed to the morphology change of silicon phase as well as the improved feeding solidification shrinkage.

  4. Post-annealing recrystallization and damage recovery process in Fe ion implanted Si

    International Nuclear Information System (INIS)

    Naito, Muneyuki; Hirata, Akihiko; Ishimaru, Manabu; Hirotsu, Yoshihiko

    2007-01-01

    We have investigated ion-beam-induced and thermal annealing-induced microstructures in high fluence Fe implanted Si using transmission electron microscopy. Si(1 1 1) substrates were irradiated with 120 keV Fe ions at 120 K to fluences of 0.4 x 10 17 and 4.0 x 10 17 cm -2 . A continuous amorphous layer was formed on Si substrates in both as-implanted samples. After thermal annealing at 1073 K for 2 h, β-FeSi 2 fine particles buried in a polycrystalline Si layer were observed in the low fluence sample, while a continuous β-FeSi 2 layer was formed in the high fluence sample. We discuss the relationship between ion fluence and defects recovery process in Fe ion implanted Si

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

    International Nuclear Information System (INIS)

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

    2012-01-01

    Self-assembled α-FeSi 2 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-FeSi 2 island phase, in an α-FeSi 2 { 112} ∥ Si{ 111} orientation. Superconducting quantum interference device magnetometry showed considerable superparamagnetism, with ∼1.9 μ B /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 μ B /Fe atom. Such anomalous magnetic behavior, particularly for the low Fe-coverage case, is radically different from the non-magnetic bulk α-FeSi 2 phase, and may open new pathways to high-density magnetic memory storage devices. (paper)

  6. 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.

  7. Characterisation of NdFeB thin films prepared on (100)Si substrates with SiO2 barrier layers

    International Nuclear Information System (INIS)

    Sood, D.K.; Muralidhar, G.K.

    1998-01-01

    This work presents a systematic study of the deposition and characterization of NdFeB films on substrates of Si(100) and of SiO2 layer thermally grown on Si(100) held at RT, 360 deg C or 440 deg C. The post-deposition annealing is performed at 600 or 800 deg C in vacuum. The films are characterised using the analytical techniques of RBS, SIMS, XRD, OM and SEM. Results indicate that SiO2 is, in deed, an excellent diffusion barrier layer till 600 deg C but becomes relatively less effective at 800 deg C. Without this barrier layer, interdiffusion at the Si-NdFeB film interface leads to formation of iron silicides, α-Fe and B exclusion from the diffusion zone, in competition with the formation of the magnetic NdFeB phase. (authors)

  8. Experimental Liquidus Studies of the Pb-Fe-Si-O System in Equilibrium with Metallic Pb

    Science.gov (United States)

    Shevchenko, M.; Jak, E.

    2018-02-01

    Phase equilibria of the Pb-Fe-Si-O system have been investigated at 943 K to 1773 K (670 °C to 1500 °C) for oxide liquid in equilibrium with liquid Pb metal and solid oxide phases: (a) quartz, tridymite, or cristobalite; (b) (fayalite + tridymite) or (fayalite + spinel); (c) spinel (Fe3O4); (d) complex lead-iron silicates (melanotekite PbO·FeO1.5·SiO2, barysilite 8PbO·FeO·6SiO2, 5PbO·FeO1.5·SiO2, and 6PbO·FeO1.5·SiO2); (e) lead silicates (Pb2SiO4, Pb11Si3O17); (f) lead ferrites (magnetoplumbite Pb1+ x Fe12- x O19- x solid solution range); and (g) lead oxide (PbO, massicot). High-temperature equilibration on primary phase or iridium substrates, followed by quenching and direct measurement of Pb, Fe, and Si concentrations in the phases with the electron probe X-ray microanalysis, has been used to accurately characterize the system in equilibrium with Pb metal. All results are projected onto the PbO-"FeO"-SiO2 plane for presentation purposes. The present study is the first systematic characterization of liquidus over a wide range of compositions in this system in equilibrium with metallic Pb.

  9. 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.

  10. Fe{sub 3}Si nanodots epitaxially grown on Si(111) substrates using ultrathin SiO{sub 2} film technique

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Fukuda, Kenjiro; Amari, Shogo; Ichikawa, Masakazu [Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2011-10-03

    Ultrahigh density (> 10{sup 12} cm{sup -2}) Fe{sub 3}Si nanodots (NDs) are epitaxially grown on Si(111) substrates by codeposition of Fe and Si on the ultrathin SiO{sub 2} films with ultrahigh density nanovoids. We used two kinds of methods for epitaxial growth: molecular beam epitaxy (MBE) and solid phase epitaxy. For MBE, low temperature (< 300 deg. C) growth of the Fe{sub 3}Si NDs is needed to suppress the interdiffusion between Fe atoms deposited on the surfaces and Si atoms in the substrate. These epitaxial NDs exhibited the ferromagnetism at low temperatures, which were expected in terms of the application to the magnetic memory device materials.

  11. 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

    2015-10-05

    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 × 10(9) cm × Hz(1/2)/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.

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

    Directory of Open Access Journals (Sweden)

    Lenka HURTALOVÁ

    2012-09-01

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

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

    International Nuclear Information System (INIS)

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

    2001-01-01

    The constitution of alloys and the liquidus surface in the Al-rich corner of the Al-Si-Sm ternary system were determined by the examination of controlled heated and cooled specimens, as well as heat-treated specimens by means of optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential thermal analysis and X-ray diffraction. The Al-rich corner of the Al-Si-Sm ternary system comprises five regions of primary crystallisation (α Al , β Si , Al 3 Sm, Al 2 Si 2 Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L → α Al + β Si + Al 2 Si 2 Sm, and two liquidus transition reactions, i. e., L + Al 3 Sm → α Al + AlSiSm, and L + AlSiSm → α Al + Al 2 Si 2 Sm. Along with the position of ternary eutectic and both interstitial points in the Al-rich corner of the Al-Si-Sm ternary system, the temperatures for each reaction were determined. (orig.)

  14. Surface morphology evolution of amorphous Fe-Si layers upon thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Sun, C M; Tsang, H K; Wong, S P; Ke, N [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China); Hark, S K [Department of Physics, Chinese University of Hong Kong, Shatin, NT, Hong Kong (China)], E-mail: cmsun@ee.cuhk.edu.hk

    2008-04-21

    Changes in the surface morphology of ion-beam-synthesized amorphous Fe-Si layers after rapid thermal annealing (RTA) and furnace annealing (FA) were investigated using atomic force microscopy and transmission electron microscopy. Completely amorphous Fe-Si layers were formed by Fe implantation at a dosage of 5 x 10{sup 15} cm{sup -2} using a metal vapour vacuum arc ion source under 80 kV extraction voltage and cryogenic temperature. After RTA at 850 deg. C, {beta}-FeSi{sub 2} precipitates in Si are completely aggregated from this amorphous Fe-Si layer and the surface of the implanted layer remains flat. To date, no obvious photoluminescence (PL) spectrum has been reported from RTA treated {beta}-FeSi{sub 2} precipitates. However, after annealing at 850 deg. C for 40 s, high-quality {beta}-FeSi{sub 2} precipitates in Si are obtained which clearly show 1.5 {mu}m PL at 80 K for the first time. Even though additional long-term FA at 850 deg. C can enhance PL intensity to a limited extent, the longer thermal treatment induces the outdiffusion of {beta}-FeSi{sub 2} precipitates and degrades the surface flatness.

  15. Synthesis of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 ...

    Indian Academy of Sciences (India)

    The adsorption performance of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of an anionic dye (Congo Red, CR) from aqueous solution was investigated. The results showed that MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres are particularly efficient in removing CR.

  16. 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.

  17. Creep behavior of a nanocrystalline Fe-B-Si alloy

    International Nuclear Information System (INIS)

    Xiao, M.; Kong, Q.P.

    1997-01-01

    The research of nanocrystalline materials has attracted much attention in the world. In recent years, there have been several studies on their creep behavior. Among these, the authors have studied the tensile creep of a nanocrystalline Ni-P alloy (28 nm) at temperatures around 0.5 Tm (Tm is the melting point). The samples were prepared by the method of crystallization of amorphous ribbon. Based on the data of stress exponent and activation energy, they suggested that the creep was controlled by boundary diffusion; while the creep of the same alloy with a larger grain size (257 nm) was controlled by a different mechanism. In the present paper, the authors extend the research to the creep of a nanocrystalline Fe-B-Si alloy. The samples are also prepared by crystallization of amorphous ribbon. The samples such prepared have an advantage that the interfaces are naturally formed without artificial compaction and porosity

  18. Photoluminescence properties of ion-beam-synthesized β-FeSi2 nanocrystals in Si

    Science.gov (United States)

    Nakajima, T.; Ichikawa, T.; Matsukura, B.; Maeda, Y.

    We have investigated photoluminescence (PL) properties of β-FeSi2 nanocrystals in Si crystals. The PL spectrum could be separated into three major A, B and C bands and some minor bands. The B and C band (side band) spectra with a Gaussian function shape could be deduced from subtraction of the A band spectra with a Lorentzian function shape from the whole PL spectrum observed. It was found that the temperature dependence of the C band emission was quite different from that of the intrinsic band (A band) emission which follows a Varshini empirical formula. The C band emission may be originated from two competition processes which are switched at 70 K.

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

    Directory of Open Access Journals (Sweden)

    Xiao-Lu Zhou

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

  20. Effects of Al substitution in Nd2Fe17 studied by first-principles calculations

    International Nuclear Information System (INIS)

    Huang, M.; Ching, W.Y.

    1994-01-01

    We have studied the effect of Al substitution in Nd 2 Fe 17 compound by means of first-principles calculations. We first obtain the site-decomposed potentials for Fe from self-consistent calculation on Y 2 Fe 17 and the atomiclike potentials in the crystalline environment for Al and Nd. Calculations are carried out for a single Al substituting one Fe at four different Fe sites (6c), (9d), (18f ), and (18h), two Al substituting two Fe (18h), and four Al substituting three Fe (18h) and one Fe (18f ). Our results show that the Al moment is oppositely polarized to Fe. The average moment per Fe atom actually increases for Al substituting Fe (18h) and Fe (18f ) is about the same for Al substituting Fe (6c), and is drastically reduced when replacing Fe (9d). Experimentally, Al is shown to be excluded from the (9d) sites because of the small Wigner--Seitz volume. When two Fe atoms are replaced by two Al atoms, the total moment is only slightly less than when only one Fe atom is replaced, and the M s per Fe site actually increases, in agreement with the Moessbauer data. These results are analyzed in terms of the local atomic geometry and the charge transfer effect from the neighboring Fe to Al

  1. Microstructure and Hot Oxidation Resistance of SiMo Ductile Cast Irons Containing Si-Mo-Al

    Science.gov (United States)

    Ibrahim, Mervat M.; Nofal, Adel; Mourad, M. M.

    2017-04-01

    SiMo ductile cast irons are used as high-temperature materials in automotive components, because they are microstructurally stable at high operating temperatures. The effect of different amounts of Si and Mo as well as the addition of 3 wt pct Al on the microstructure, high-temperature oxidation, and mechanical properties of SiMo ductile cast iron was studied. Dilatometric measurements of SiMo ductile iron exhibited obvious differences in the transformation temperature A 1 due to presence of Al and the increase of Si. The microstructure of the SiMo alloys without Al addition showed outstanding nodularity and uniform nodule distribution. However, by adding 3 wt pct Al to low Si-SiMo ductile iron, some compacted graphite was observed. The results of oxidation experiments indicated that high Si-SiMo ductile iron containing 4 and 4.9 wt pct Si had superior resistance to lower Si-SiMo and SiMo ductile iron containing 3 wt pct Al. The results showed also that with increasing Si up to 4.9 wt pct or by replacing a part of Si with 3 wt pct Al, tensile strength increased while elongation and impact toughness decreased.

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

    OpenAIRE

    Orth, Andreas

    2013-01-01

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

  3. Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

    Indian Academy of Sciences (India)

    Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres. K C BARICK and D BAHADUR*. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay,. Mumbai 400 076, India. Abstract. The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 ...

  4. Cluster-based bulk metallic glass formation in Fe-Si-B-Nb alloy systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, C L; Wang, Q; Li, F W; Li, Y H; Wang, Y M; Dong, C [State Key Laboratory of Materials Modification, Dalian University of Technology (DUT), Dalian 116024 (China); Zhang, W; Inoue, A, E-mail: dong@dlut.edu.c [Institute for Materials Research (IMR), Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

    2009-01-01

    Bulk metallic glass formations have been explored in Fe-B-Si-Nb alloy system using the so-called atomic cluster line approach in combination with minor alloying guideline. The atomic cluster line refers to a straight line linking binary cluster to the third element in a ternary system. The basic ternary compositions in Fe-B-Si system are determined by the inetersection points of two cluster lines, namely Fe-B cluster to Si and Fe-Si cluster to B, and then further alloyed with 3-5 at. % Nb for enhancing glass forming abilities. BMG rods with a diameter of 3 mm are formed under the case of minor Nb alloying the basic intersecting compositions of Fe{sub 8}B{sub 3}-Si with Fe{sub 12}Si-B and Fe{sub 8}B{sub 2}-Si with Fe{sub 9}Si-B. The BMGs also exhibit high Vickers hardness (H{sub v}) of 1130-1164 and high Young's modulous (E) of 170-180 GPa

  5. Irradiation behaviour of U-Si-Al with peripheral voidage

    International Nuclear Information System (INIS)

    Fehrenbach, P.J.; Feraday, M.A.; Cotnam, K.D.; Morel, P.A.

    1977-12-01

    Peripheral voidage in the form of longitudinal slots on the surface of the fuel is effective in accommodating the irradiation induced swelling of U-Si-Al rods clad in cold-worked Zr-2.5 wt% Nb. Diametral increases in elements operated at steady powers between 50 and 80 kW/m to a burnup of 240 MW.h/kg U were less than 1.25%. Similar to U 3 Si elements, lower sheath strength or higher temperatures resulted in greater diametral increases. An oxide or graphite interlayer between the fuel and sheath was shown to be effective in preventing the development of a fuel/sheath bond. The ability of U-Si-Al elements to successfully survive a power increase from 35 to 70 kW/m after appreciable burnup at the lower power has also been demonstrated. (author)

  6. Y-Si-Al-O-N Glass Fibers.

    Science.gov (United States)

    The excellent mechanical properties and outstanding water corrosion resistance of Y -Si-Al-O- N glasses indicate that they are attractive candidate...materials for forming into high performance glass fibers. Fibers of glasses containing, respectively,3.2 and 6.6 wt% N were drawn freehand in air, and

  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. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    International Nuclear Information System (INIS)

    Kumar, Santosh; Deepika; Tripathi, Malvika; Vaibhav, Pratyush; Kumar, Aman; Kumar, Ritesh; Choudhary, R.J.; Phase, D.M.

    2016-01-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn 0.97 Al 0.03 O, Zn 0.95 Fe 0.05 O and Zn 0.92 Al 0.03 Fe 0.05 O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

  9. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Santosh, E-mail: skphysics@yahoo.co.in [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Deepika [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Tripathi, Malvika [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Vaibhav, Pratyush [Jaypee University of Engineering and Technology, Guna 473226, Madhya Pradesh (India); Kumar, Aman [Indian Institute of Technology, Roorkee (India); Kumar, Ritesh [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Choudhary, R.J., E-mail: ram@csr.res.in [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Phase, D.M. [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India)

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn{sub 0.97}Al{sub 0.03}O, Zn{sub 0.95}Fe{sub 0.05}O and Zn{sub 0.92}Al{sub 0.03}Fe{sub 0.05}O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

  10. Effect of interleaved Si layer on the magnetotransport and semiconducting properties of n-Si/Fe Schottky junctions

    Science.gov (United States)

    Das, Sudhansu Sekhar; Kumar, M. Senthil

    2017-12-01

    Heterostructure films of the form n-Si/Si(tSi)/Fe(800 Å) were prepared by DC magnetron sputtering. In these films, the Si and Fe (800 Å) films were deposited onto n-Si(100) substrates. Substrates with different doping concentration ND were used. The thickness tSi of the interleaved Si layer is varied. For tSi = 0, the heterostructures form n-Si/Fe Schottky junctions. Structural studies on the samples as performed through XRD indicate the polycrystalline nature of the films. The magnetization data showed that the samples have in-plane easy axis of magnetization. The coercivity of the samples is of the order of 90 Oe. The I-V measurements on the samples showed nonlinear behavior. The diode ideality factor η = 2.6 is observed for the junction with ND = 1018 cm-3. The leakage current I0 increases with the increase of ND. Magnetic field has less effect on the electrical properties of the junctions. A positive magnetoresistance in the range 1 - 10 % was observed for the Si/Fe Schottky junctions in the presence of magnetic field of strength 2 T. The origin of the MR is analyzed using a model where the ratio of the currents across the junctions with and without the applied magnetic field, IH=2T/IH=0 is studied as a function of the bias voltage Vbias. The ratio IH=2T/IH=0 shows a decreasing trend with the Vbias, suggesting that the contribution to the MR in our n-Si/Fe Schottky junctions due to the spin dependent scattering is very less as compared to that due to the suppression of the impact ionization process.

  11. Dissipative collision studies in 11B + 28Si, 12C + 27Al, 12C + 28Si

    International Nuclear Information System (INIS)

    Kundu, S.; Bhattacharya, C.; Rana, T.K.; Banerjee, K.; Dey, A.; Ghosh, T.K.; Mukherjee, G.; Bhattacharya, S.; Meena, J.K.; Banerjee, S.R.; Mukhopadhyay, S.; Pandit, D.; Mali, P.; Gupta, D.; Shrivastava, A.; Kumar, Suresh; Chatterjee, A.; Ramachandran, K.; Banerjee, P.

    2011-01-01

    It has been observed that the energy damped yield of the fragments emitted in the reactions 28 Si + 12 C at energies 29.5 c.m 11 B (64 MeV) + 28 Si and 12 C (73 MeV) + 27 Al with the aim to see how the fragment emission mechanism changes as one moves to nearest non-alpha cluster system. Here, the dissipative collision studies for these reactions have been reported

  12. Effect of Si on the reversibility of stress-induced martensite in Fe-Mn-Si shape memory alloys

    International Nuclear Information System (INIS)

    Stanford, N.; Dunne, D.P.

    2010-01-01

    Fe-Mn-Si is a well-characterized ternary shape memory alloy. Research on this alloy has consistently shown that the addition of 5-6 wt.% Si is desirable to enhance the reversibility of stress-induced martensite vis-a-vis shape memory. This paper examines the effect of Si on the morphology and the crystallography of the martensite in the Fe-Mn-Si system. It is concluded that the addition of Si increases the c/a ratio of the martensite, reduces the transformation volume change and decreases the atomic spacing difference between the parallel close-packed directions in the austenite-martensite interface (habit) plane. It is proposed that, in addition to austenite strengthening, Si enhances reversibility by reducing the volume change and the interfacial atomic mismatch between the martensite and the austenite. Although shape memory is improved, transformation reversibility remains limited by the necessary misfit dislocations that accommodate the atomic spacing differences in the interface.

  13. Structural characterization of amorphous Fe-Si and its recrystallized layers

    International Nuclear Information System (INIS)

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

    2006-01-01

    We have synthesized amorphous Fe-Si thin layers and investigated their microstructure using transmission electron microscopy (TEM). Si single crystals with (1 1 1) orientation were irradiated with 120 keV Fe + ions to a fluence of 4.0 x 10 17 cm -2 at cryogenic temperature (120 K), followed by thermal annealing at 1073 K for 2 h. A continuous amorphous layer with a bilayered structure was formed on the topmost layer of the Si substrate in the as-implanted specimen: the upper layer was an amorphous Fe-Si, while the lower one was an amorphous Si. After annealing, the amorphous bilayer crystallized into a continuous β-FeSi 2 thin layer

  14. Single-phase {beta}-FeSi{sub 2} thin films prepared on Si wafer by femtosecond laser ablation and its photoluminescence at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lu Peixiang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)]. E-mail: lupeixiang@mail.hust.edu.cn; Zhou Youhua [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China) and Physics and Information School, Jianghan University, Wuhan 430056 (China)]. E-mail: yhzhou@jhun.edu.cn; Zheng Qiguang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Yang Guang [State Key Laboratory of Laser Technology and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2006-02-06

    Single-phase {beta}-FeSi{sub 2} thin films were prepared on Si(100) and Si(111) wafers by using femtosecond laser deposition with a FeSi{sub 2} alloy target for the first time. X-ray diffraction (XRD), field scanning electron microscopy (FSEM), scanning probe microscopy (SPM), electron backscattered diffraction pattern (EBSD), and Fourier-transform Raman infrared spectroscopy (FTRIS) were used to characterize the structure, composition, and properties of the {beta}-FeSi{sub 2}/Si films. The orientation of {beta}-FeSi{sub 2} grains was found to depend on the orientation of the Si substrates, and photoluminescence at wavelength of 1.53 {mu}m was observed from the single-phase {beta}-FeSi{sub 2}/Si thin film at room temperature (20 {sup o}C)

  15. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    resistance of FeAl-based alloys is found to be significantly improved on addition of Ti/Zr. This is attributed to the ... exhibit superior wear resistance due to higher hardness of ..... This research has been supported by the Department of Sci- ence and Technology, New Delhi, and we are thankful for the financial support.

  16. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    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.

  17. Vacancy-induced hardening in Fe-Al alloys

    Czech Academy of Sciences Publication Activity Database

    Lukáč, F.; Čížek, J.; Procházka, I.; Jirásková, Yvonna; Janičkovič, D.; Anwand, W.; Brauer, G.

    2013-01-01

    Roč. 443, č. 1 (2013), 012025 ISSN 1742-6588. [International Conference on Positron Annihilation /16./. Bristol, 19.08.2012-24.08.2012] R&D Projects: GA ČR(CZ) GAP108/11/1350 Institutional support: RVO:68081723 Keywords : Vacancy * Hardening * Fe-Al alloy Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Electrical discharge machining studies on reactive sintered FeAl

    Indian Academy of Sciences (India)

    Unknown

    MS received 7 November 2005. Abstract. Electrical discharge machining (EDM) studies on reactive sintered FeAl were carried out with differ- ... electric breakdown process spreads at an explosive rate, resulting in the formation of a .... of cutting fluid takes place which would give out a car- bon residue. The visual black layer ...

  19. Processing and properties of FeAl-bonded composites

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J.H.; Subramanian, R.; Alexander, K.B.; Becher, P.F. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1996-12-31

    Iron aluminides are thermodynamically compatible with a wide range of ceramics such as carbides, borides, oxides, and nitrides, which makes them suitable as the matrix in composites or cermets containing fine ceramic particulates. For ceramic contents varying from 30 to 60 vol.%, composites of Fe-40 at. % Al with WC, TiC, TiB{sub 2}, and ZrB{sub 2} were fabricated by conventional liquid phase sintering of powder mixtures. For ceramic contents from 70 to 85 vol.%, pressureless melt infiltration was found to be a more suitable processing technique. In FeAl-60 vol.% WC, flexure strengths of up to 1.8 GPa were obtained, even though processing defects consisting of small oxide clusters were present. Room temperature fracture toughnesses were determined by flexure testing of chevron-notched specimens. FeAl/WC and FeAl/TiC composites containing 60 vol.% carbide particles exhibited K{sub Q} values around 20 MPa m{sup 1/2}. Slow crack growth measurements carried out in water and in dry oxygen suggest a relatively small influence of water-vapor embrittlement. It appears therefore that the mechanical properties of iron aluminides in the form of fine ligaments are quite different from their bulk properties. Measurements of the oxidation resistance, dry wear resistance, and thermal expansion of iron aluminide composites suggest many potential applications for these new materials.

  20. 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

  1. 26Al and 60Fe from supernova explosions

    International Nuclear Information System (INIS)

    Timmes, F.X.; Woosley, S.E.; Hartmann, D.H.; Hoffman, R.D.; Weaver, T.A.; Matteucci, F.

    1995-01-01

    Using recently calculated yields for Type II supernovae, along with models for chemical evolution and the distribution of mass in the interstellar medium, the current abundances and spatial distributions of two key gamma-ray radioactivities, 26 Al and 60 Fe, are determined. The estimated steady state production rates are 2.0±1.0 M circle-dot Myr -1 for 26 Al and 0.75±0.4 M circle-dot Myr -1 for 60 Fe. This corresponds to 2.2±1.1 M circle-dot of 26 Al and 1.7±0.9 M circle-dot of 60 Fe in the present interstellar medium. Sources of uncertainty are discussed, one of the more important being the current rate of core collapse supernovae in the Galaxy. Our simple model gives three per century, but reasonable changes in the star formation rate could easily accommodate a core collapse rate one-half as large, and thus one-half the yields. When these stellar and chemical evolution results are mapped into a three-dimensional model of the Galaxy, the calculated 1809 keV gamma-ray flux map is consistent with the Compton Gamma Ray Observatory observations of a steep decline in the flux outside a longitude of ±50 degree from the Galactic center, and the slight flux enhancements observed in the vicinity of spiral arms. Other potential stellar sources of 26 Al and 60 Fe are mentioned, especially the possibility of 60 Fe synthesis in Type Ia supernovae. Predictions for the 60 Fe mass distribution, total mass, and flux map are given. copyright 1995 The American Astronomical Society

  2. Insights into Mercury's Core Evolution from the Thermodynamic Properties of Fe-S-Si

    Science.gov (United States)

    Edgington, A.; Vocadlo, L.; Stixrude, L. P.; Wood, I. G.; Lord, O. T.

    2015-12-01

    The structure, composition and evolution of Mercury, the innermost planet, are puzzling, as its high uncompressed density implies a body highly enriched in metallic iron, whilst the existence of Mercury's magnetic field and observations of its longitude librations [1] suggest at least a partially molten core. This study uses a combination of experimental and ab-initio computer simulation techniques to determine the properties of Fe-S-Si (relative atomic percentages, 80:10:10) throughout the conditions of the interior of the planet Mercury, and evaluates the implications of this material for the structure and evolution of the planet's core. Previous studies have considered the addition of sulphur to the pure iron system, as this can significantly depress the melting curve of iron, and so may possibly allow Mercury's core to remain molten to the present day [2]. However, important constraints placed by the MESSENGER spacecraft on Mercury's surface abundance of iron [3] suggest that the planet formed in highly reduced conditions, in which significant amounts of silicon could have also dissolved into the core [4]. First-principles molecular dynamics simulations of the thermodynamic properties of liquid Fe-S-Si, alongside laser-heated diamond-anvil-cell experiments to determine the melting behaviour of the same composition, reveal the slopes of the adiabatic gradient and melting curve respectively, which together may allow insight into the evolution of our solar system's smallest planet. [1] Margot, J. L. et al. (2007) Science, 316: 710-714[2] Schubert, G. et al. (1988) in 'Mercury' 429-460[3] Nittler, L. R. et al. (2011) Science, 333, 1847-1850[4] Malavergne, V. et al. (2010) Icarus, 206:199-209

  3. Influence of n$^{+}$ and p$^{+}$ doping on the lattice sites of implanted Fe in Si

    CERN Document Server

    Silva, Daniel José; Correia, João Guilherme; Araújo, João Pedro

    2013-01-01

    We report on the lattice location of implanted $^{59}$Fe in n$^{+}$ and p$^{+}$ type Si by means of emission channeling. We found clear evidence that the preferred lattice location of Fe changes with the doping of the material. While in n$^{+}$ type Si Fe prefers displaced bond-centered (BC) sites for annealing temperatures up to 600°C, changing to ideal substitutional sites above 700°C, in p$^{+}$ type Si, Fe prefers to be in displaced tetrahedral interstitial positions after all annealing steps. The dominant lattice sites of Fe in n$^{+}$ type Si therefore seem to be well characterized for all annealing temperatures by the incorporation of Fe into vacancy-related complexes, either into single vacancies which leads to Fe on ideal substitutional sites, or multiple vacancies, which leads to its incorporation near BC sites. In contrast, in p$^{+}$ type Si, the major fraction of Fe is clearly interstitial (near-T or ideal T) for all annealing temperatures. The formation and possible lattice sites of Fe in FeB...

  4. Phase relations in the SiC-Al2O3-Pr2O3 system

    International Nuclear Information System (INIS)

    Pan, W.; Wu, L.; Jiang, Y.; Huang, Z.

    2016-01-01

    Phase relations in the Si-Al-Pr-O-C system, including the SiC-Al 2 O 3 -Pr 2 O 3 , the Al 2 O 3 -Pr 2 O 3 -SiO 2 and the SiC-Al 2 O 3 -Pr 2 O 3 -SiO 2 subsystems, were determined by means of XRD phase analysis of solid-state-reacted samples fabricated by using SiC, Al 2 O 3 , Pr 2 O 3 and SiO 2 powders as the starting materials. Subsolidus phase diagrams of the systems were presented. Two Pr-aluminates, namely PrAlO 3 (PrAP) and PrAl 11 O 18 (β(Pr) β-Al 2 O 3 type) were formed in the SiC-Al 2 O 3 -Pr 2 O 3 system. SiC was compatible with both of them. Pr-silicates of Pr 2 SiO 5 , Pr 2 Si 2 O 7 and Pr 9.33 Si 6 O 26 (H(Pr) apatite type) were formed owing to presence of SiO 2 impurity in the SiC powder. The presence of the SiO 2 extended the ternary system of SiC-Al 2 O 3 -Pr 2 O 3 into a quaternary system of SiC-Al 2 O 3 -SiO 2 -Pr 2 O 3 (Si-Al-Pr-O-C). SiC was compatible with Al 2 O 3 , Pr 2 O 3 and the Pr-silicates. The effect of SiO 2 on the phase relations and liquid phase sintering of SiC ceramics was discussed.

  5. Endotaxially stabilized B2-FeSi nanodots in Si (100) via ion beam co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Cassidy, Cathal, E-mail: c.cassidy@oist.jp; Singh, Vidyadhar; Grammatikopoulos, Panagiotis [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Onna-Son, Okinawa 904-0495 (Japan); Kioseoglou, Joseph [Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Lal, Chhagan [Department of Physics, University of Rajasthan, Jaipur, Rajasthan 302005 (India); Sowwan, Mukhles, E-mail: mukhles@oist.jp [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Onna-Son, Okinawa 904-0495 (Japan); Nanotechnology Research Laboratory, Al-Quds University, East Jerusalem, P.O. Box 51000, Palestine (Country Unknown)

    2014-04-21

    We report on the formation of embedded B2-FeSi nanodots in [100]-oriented Si substrates, and investigate the crystallographic mechanism underlying the stabilization of this uncommon, bulk-unstable, phase. The nanodots were approximately 10 nm in size, and were formed by iron thin film deposition and subsequent annealing. Cross-sectional transmission electron microscopy, energy loss spectroscopy mapping, and quantitative image simulation and analysis were utilized to identify the phase, strain, and orientational relationship of the nanodots to the host silicon lattice. X-ray photoelectron spectroscopy was utilized to analyze the surface composition and local bonding. Elasticity calculations yielded a nanodot residual strain value of −18%. Geometrical phase analysis graphically pinpointed the positions of misfit dislocations, and clearly showed the presence of pinned (11{sup ¯}1{sup ¯}){sub Si}//(100){sub FeSi}, and unpinned (2{sup ¯}42){sub Si}//(010){sub FeSi}, interfaces. This partial endotaxy in the host silicon lattice was the mechanism that stabilized the B2-FeSi phase.

  6. Raman spectroscopic features of Al- Fe3+- poor magnesiochromite and Fe2+- Fe3+- rich ferrian chromite solid solutions

    Science.gov (United States)

    Kharbish, Sherif

    2017-08-01

    Naturally occurring Al- Fe3 +- poor magnesiochromite and Fe2+- Fe3 +- rich ferrian chromite solid solutions have been analyzed by micro-Raman spectroscopy. The results reflect a strong positive correlation between the Fe3 + # [Fe3+/(Fe3 ++Cr + Al)] and the positions of all Raman bands. A positive correlation of the Raman band positions with Mg# [Mg/(Mg + Fe2 +)] is less stringent. Raman spectra of magnesiochromite and ferrian chromite show seven and six bands, respectively, in the spectral region of 800 - 100 cm- 1. The most intense band in both minerals is identified as symmetric stretching vibrational mode, ν 1(A 1g ). In the intermediate Raman-shift region (400-600 cm- 1), the significant bands are attributed to the ν 3(F 2g ) > ν 4(F 2g ) > ν 2(E g ) modes. The bands with the lowest Raman shifts (< 200 cm- 1) are assigned to F 2g (trans) translatory lattice modes. Extra bands in magnesiochromite (two bands) and in ferrian chromite (one weak band) are attributed to lowering in local symmetry and order/disorder effects.

  7. Neural network potential for Al-Mg-Si alloys

    Science.gov (United States)

    Kobayashi, Ryo; Giofré, Daniele; Junge, Till; Ceriotti, Michele; Curtin, William A.

    2017-10-01

    The 6000 series Al alloys, which include a few percent of Mg and Si, are important in automotive and aviation industries because of their low weight, as compared to steels, and the fact their strength can be greatly improved through engineered precipitation. To enable atomistic-level simulations of both the processing and performance of this important alloy system, a neural network (NN) potential for the ternary Al-Mg-Si has been created. Training of the NN uses an extensive database of properties computed using first-principles density functional theory, including complex precipitate phases in this alloy. The NN potential accurately reproduces most of the pure Al properties relevant to the mechanical behavior as well as heat of solution, solute-solute, and solute-vacancy interaction energies, and formation energies of small solute clusters and precipitates that are required for modeling the early stage of precipitation and mechanical strengthening. This success not only enables future detailed studies of Al-Mg-Si but also highlights the ability of NN methods to generate useful potentials in complex alloy systems.

  8. Ti doped amorphous carbon (Al/Ti-a:C/p-Si/Al) photodiodes for optoelectronic applications

    Science.gov (United States)

    Aslan, Naim; Koç, Mümin Mehmet; Dere, Ayşegül; Arif, Bilal; Erkovan, Mustafa; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed A.; Yakuphanoglu, Fahrettin

    2018-03-01

    Electrochemical deposition technique was used to fabricate titanium doped amorphous carbon (Ti doped a:C) Al/Ti-a:C/p-Si/Al photodiode. The effects of illumination on the current-voltage (I-V) characteristics of the Al/a:C/p-Si/Al doped Ti diode for optoelectronic applications were investigated. The reverse current of the diode increased with the increasing illumination intensities when the bias voltage was applied. By using the forward bias I-V characteristics, the ideality factor (n) and barrier height (Φb) of Al/Ti-a:C/p-Si photodiode structure was found as 1,84 and 0,50 eV, respectively. In addition, the capacitance-voltage (C-V) and conductance-voltage (G-V) measurements of the diode were studied in the frequency range of 100 kHz-600 kHz. The measured values of the capacitance decreased with the increasing frequency. The photoelectrical properties of Al/Ti-a:C/p-Si/Al device indicates that the photodiode investigated in this paper has great potential to be used in optoelectronic device applications and in industry.

  9. Structural study on nickel doped Li{sub 2}FeSiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Jaén, Juan A., E-mail: juan.jaen@up.ac.pa [Universidad de Panamá, Departamento de Química Física, CITEN, Edificio de Laboratorios Científicos-VIP (Panama); Jiménez, Miguel [Universidad de Panamá, Departamento de Física (Panama); Flores, Eibar [Universidad de Panamá, Escuela de Física (Panama); Muñoz, Alcides [Universidad de Panamá, Departamento de Física (Panama); Tabares, Jesús A.; Pérez Alcázar, Germán A. [Universidad del Valle, Departamento de Física (Colombia)

    2015-06-15

    The effect of nickel doping on the structure of Li{sub 2}FeSiO{sub 4} is examined by X-ray diffraction, Mössbauer spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometer, and magnetization measurements. Both, the pristine and nickel doped Li{sub 2}FeSiO{sub 4}, crystallize in a monoclinic structure with (P2{sub 1}/n) symmetry. Their lattice parameters are similar, which suggests that Ni{sup 2+} doesn’t destroy the lattice structure. Some small amounts of Fe{sup 3+} impurity phases and unreacted Li{sub 2}SiO{sub 3} are detected. Samples doped with more than 10 mol% contain some magnetic impurity of Fe-Ni alloy. Magnetic measurements indicated that Li{sub 2}FeSiO{sub 4} is paramagnetic and becomes antiferromagnetic below 23 K. Nickel dopant does not modify the paramagnetic nature of this material.

  10. Si segregation at Fe grain boundaries analyzed by ab initio local energy and local stress

    International Nuclear Information System (INIS)

    Bhattacharya, Somesh Kr; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori

    2014-01-01

    Using density-functional theory calculations combined with recent local-energy and local-stress schemes, we studied the effects of Si segregation on the structural, mechanical and magnetic properties of the Σ3(1 1 1) and Σ11(3 3 2) Fe GBs formed by rotation around the [1 1 0] axis. The segregation mechanism was analyzed by the local-energy decomposition of the segregation energy, where the segregation energy is expressed as a sum of the following four terms: the local-energy change of Si atoms from the isolated state in bulk Fe to the GB segregated state, the stabilization of replaced Fe atoms from the GB to the bulk, the local-energy change of neighboring Fe atoms from the pure GB to the segregated GB and the local-energy change of neighboring Fe atoms from the system of an isolated Si atom in the bulk Fe to the pure bulk Fe. The segregation energy and value of each term greatly depends on the segregation site and Si concentration. The segregation at interface Fe sites with higher local energies in the original GB configurations naturally leads to higher segregation-energy gains, while interface sites with lower local energies can lead to larger energy gains if stronger Si–Fe interactions occur locally in the final segregated configurations. The high Si concentration reduces the segregation-energy gain per Si atom due to the local-energy increases of Si atoms neighboring to each other or through the reduction in the number of stabilized Fe atoms per Si atom as observed in a Si dimer in bulk Fe. In the Si-segregated GBs, Si–Fe bonds enhance local Young’s moduli and tend to suppress the interface weakening, while the GB adhesion is slightly reduced. And Fe atoms contacting Si atoms have reduced magnetic moments, due to Si–Fe sp-d hybridization interactions. (paper)

  11. Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kee Ahn [School of Advanced Materials Engineering, Andong National University, Andong 760-749 (Korea, Republic of)]. E-mail: keeahn@andong.ac.kr; Kim, Yong Chan [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Jung Han [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Lee, Chong Soo [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Namkung, Jung [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Moon Chul [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of)

    2007-03-25

    The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys.

  12. Investigation of Fe-Si-N films as magnetic overcoat for high density recording disk drives

    International Nuclear Information System (INIS)

    Gauvin, M.; Talke, F. E.; Fullerton, E. E.

    2010-01-01

    A 50-nm-thick Fe-Si-N films were deposited via reactive magnetron cosputtering of independent Fe and Si targets, in Ar/N 2 gas mixture, under different dc Fe target power conditions. Magnetic properties, mechanical hardness and tribological properties were characterized as a function of the Fe target power by magnetometry, nanoindentation, and nanoscratch testing, respectively. Deposited samples were found to be ferromagnetic with a coercivity of approximately 20 Oe and a saturation magnetization increasing from 200 to 1100 emu/cm 3 as a function of Fe sputter power, i.e., values typical of soft magnetic materials. The mechanical hardness was found to be between 50% and 70% of the hardness of a pure SiN x film. Nanotribological properties of films deposited with a Fe target power ≥80 W degraded rapidly.

  13. RETRACTED ARTICLE: Microstructures and morphologies of B2-Ordered NiAl(Co) and FeAl(Co)

    Science.gov (United States)

    Oh, Chang-Sup; Han, Chang-Suk

    2013-03-01

    Fine dispersion of disordered phases is obtained in a Ni-Al-Co and Fe-Al-Co ternary system. A transmission electron microscopy investigation has been performed in the present work on the precipitation of supersaturated B2-ordered (Ni,Co)Al and α-Fe in B2-ordered FeAl(Co) with different stoichiometries. Precipitation behavior and hardening were investigated by measuring the hardness variation. The hardness of (Ni,Co)Al and B2-FeAl(Co) increased appreciably by the fine precipitation of (Ni,Co)2Al, α-Fe, and overage softening occurred after prolonged aging. In case of B2-ordered (Ni,Co)Al, the (Ni,Co)2Al phase had a hexagonal structure and took a rod-like shape with the long axis of the rod parallel to the directions of the B2 matrix. By aging at temperatures below 873 K, a long period superlattice structure appeared in the hexagonal (Ni,Co)2Al phase. The orientation relationship between the (Ni,Co)2Al precipitates and the B2-(Ni,Co)Al matrix was (0001)p//(111)B2 and [bar 12bar 10]_p //[bar 110]_{B2}, where the suffix p and B2 denote the (Ni,Co)2Al precipitate and the B2-(Ni,Co)Al matrix, respectively. (Ni,Co)Al hardened appreciably by the fine precipitation of the (Ni,Co)2Al phase. On the other hand, in case of B2-FeAl(Co), the disordered α-Fe phase was present as a precipitate in a B2-FeAl(Co) matrix and had a cubic-cubic orientation with the matrix. At the early aging periods, prismatic dislocation loops formed in the B2-FeAl(Co) matrix. B2-FeAl(Co) matrix was typically hardened by the precipitation of α-Fe.

  14. Magnetoresistance of rolled-up Fe3Si nanomembranes.

    Science.gov (United States)

    Schumann, J; Lisunov, K G; Escoffier, W; Raquet, B; Broto, J M; Arushanov, E; Mönch, I; Makarov, D; Deneke, C; Schmidt, O G

    2012-06-29

    Magnetotransport of individual rolled-up Fe(3)Si nanomembranes is investigated in a broad temperature range from 4.2 K up to 300 K in pulsed magnetic fields up to 55 T. The observed magnetoresistance (MR) has the following pronounced features: (i) MR is negative in the investigated intervals of temperature and magnetic field; (ii) its magnitude increases linearly with the magnetic field in a low-field region and reveals a gradual trend to saturation when the magnetic field increases; (iii) the MR effect becomes more pronounced with increasing temperature. These dependences of MR on the magnetic field and temperature are in line with predictions of the spin-disorder model of the spin-flip s-d interaction assisted with creation or annihilation of magnons, which is expected above a certain critical temperature. Comparison of the MR features in rolled-up and planar samples reveals a substantial increase of the critical temperature in the rolled-up tube, which is attributed to a new geometry and internal strain arising in the rolled-up nanomembranes, influencing the electronic and magnetic properties of the material.

  15. Fabrication of MgAl2Si2O8

    Indian Academy of Sciences (India)

    Abstract. Five new MgAl2Si2O8 : M0.01 (M = Ni2+, Cu2+, Pd2+, Pt2+ and Ru3+) materials were developed for the reduction of nitroarenes as catalysts by conventional solid state reaction at 1300◦C. The prepared materials were characterized by thermal analysis, Fourier transform infrared spectroscopy, X-ray powder ...

  16. Joining Thick Section Aluminum to Steel with Suppressed FeAl Intermetallic Formation via Friction Stir Dovetailing

    Energy Technology Data Exchange (ETDEWEB)

    Reza E Rabby, MD; Ross, Kenneth A.; Overman, Nicole R.; Olszta, Matthew J.; Mcdonnell, Martin; Whalen, Scott A.

    2018-04-17

    A new solid-phase technique called friction stir dovetailing (FSD) has been developed for joining thick section aluminum to steel. In FSD, mechanical interlocks are formed at the aluminum-steel interface and are reinforced by metallurgical bonds where intermetallic growth has been uniquely suppressed. Lap shear testing shows superior strength and extension at failure compared to popular friction stir approaches where metallurgical bonding is the only joining mechanism. High resolution microscopy revealed the presence of a 40-70 nm interlayer having a composition of 76.4 at% Al, 18.4 at% Fe, and 5.2 at% Si, suggestive of limited FeAl3 intermetallic formation.

  17. Hydrometallurgical extraction of Al and Si from kaolinitic clays

    Directory of Open Access Journals (Sweden)

    Eliana G. Pinna

    Full Text Available Abstract Herein is presented the results of a study on the hydrometallurgic extraction and recovery of aluminum and silicon by leaching of kaolinitic clays with HF. The studied extraction parameters were: temperature, reaction time, solid/liquid ratio, concentration, and precipitating agent mass. In the leaching process, mineral dissolutions near 100% were obtained when working at 348 K, solid/liquid ratio 2% w/v, HF 12% v/v, for 120 minutes. The HF leach liquor generated from the dissolution of kaolinitic clays contains H2SiF6and H3AlF6. Studies were conducted to recover the two valuable fluorides as K2SiF6and Na3AlF6by precipitation with alkaline salts from the leach liquor. Phases of precipitated fluorides were identified by XRD and surface morphology by SEM. The purity of the K2SiF6precipitate was 98.8%, whereas for Na3AlF6, it was 89.3%. Also, both synthesized solids are of high commercial value due to their industrial applications.

  18. High temperature neutron diffraction (time-of-flight) in Si-Al-O-N compounds

    International Nuclear Information System (INIS)

    Cartz, L.; Roult, G.; Billy, M.

    1977-01-01

    The Si-Al-O-N compounds, intermediate between the Al 2 O 3 -Si 3 N 4 -AlN or SiO 2 phase, can be used as refractory compounds. The resistance to thermal shocks essentially depends on the coefficients of anisotropic thermal expansion, that explains their experimental determination for Si 2 N 2 O by time-of-flight neutron diffraction at high temperature. The nature of the anisotropies was shown to correspond to a crystal structure of Si 2 N 2 O involving Si-O-Si bounds along the x axis, and Si-N bounds in the y-z plane [fr

  19. Properties of porous FeAlOy/FeAlx ceramic matrix composite ...

    Indian Academy of Sciences (India)

    hydrothermal treatment and calcination). Accord- ing to the thermal analysis data in the air flow (not presented for brevity), the relative weight gain of FeAl alloys after. MA and HTT under high temperature oxidizing treatment decreased from 28 to 17 wt%, ...

  20. Phosphorus Equilibrium Between Liquid Iron and CaO-SiO2-MgO-Al2O3-FeO-P2O5 Slag Part 1: Literature Review, Methodology, and BOF Slags

    Science.gov (United States)

    Assis, Andre N.; Tayeb, Mohammed A.; Sridhar, Seetharaman; Fruehan, Richard J.

    2015-10-01

    Although the phosphorus reaction in steelmaking has been extensively studied, it continues to be a relevant topic as low phosphorus iron sources become less available and more expensive, necessitating the need for more accurate predictions of the partitioning of phosphorous as function of slag composition and temperature. The current study revisits some of the relevant literature on the topic and details the methodology and experimental setup used in recent studies on phosphorus equilibrium between liquid iron and slags. New data for BOF-type slags are presented, where equilibrium was approached from both metal and slag sides i.e., phosphorus was transferred from metal to slag and vice versa. It was found that slags with basicities higher than 2.5 and FeO contents around 20 to 25 wt pct can promote extensive dephosphorization, and high L P, ((pct P)/[pct P]), values were observed i.e., greater than 500.

  1. High-pressure crystal structure investigation of synthetic Fe2SiO4 spinel

    DEFF Research Database (Denmark)

    Nestola, F.; Balic Zunic, Tonci; Koch-Müller, M.

    2011-01-01

    The crystal structure of Fe2SiO4 spinel at room temperature was investigated at seven different pressures by X-ray diffraction, using a diamond anvil cell to examine the influence of Fe substitution on ringwoodite behaviour at high pressure. The results compared with those of a pure Mg endmember...... show that the substitution of Fe into the spinel structure causes only small changes in the compression rate of coordination polyhedra and the distortion of the octahedron. The data show that the compression rate for the octahedron and tetrahedron in (Mg,Fe)2SiO4 can be considered statistically equal...

  2. Aluminum coprecipitates with Fe (hydr)oxides: Does isomorphous substitution of Al 3+ for Fe 3+ in goethite occur?

    Science.gov (United States)

    Bazilevskaya, Ekaterina; Archibald, Douglas D.; Aryanpour, Masoud; Kubicki, James D.; Martínez, Carmen Enid

    2011-08-01

    Iron (hydr)oxides are common in natural environments and typically contain large amounts of impurities, presumably the result of coprecipitation processes. Coprecipitation of Al with Fe (hydr)oxides occurs, for example, during alternating reduction-oxidation cycles that promote dissolution of Fe from Fe-containing phases and its re-precipitation as Fe-Al (hydr)oxides. We used chemical and spectroscopic analyses to study the formation and transformation of Al coprecipitates with Fe (hydr)oxides. In addition, periodic density functional theory (DFT) computations were performed to assess the structural and energetic effects of isolated or clustered Al atoms at 8 and 25 mol% Al substitution in the goethite structure. Coprecipitates were synthesized by raising the pH of dilute homogeneous solutions containing a range of Fe and Al concentrations (100% Fe to 100% Al) to 5. The formation of ferrihydrite in initial suspensions with ⩽20 mol% Al, and of ferrihydrite and gibbsite in initial suspensions with ⩾25 mol% Al was confirmed by infrared spectroscopic and synchrotron-based X-ray diffraction analyses. While base titrations showed a buffer region that corresponded to the hydrolysis of Fe in initial solutions with ⩽25 mol% Al, all of the Al present in these solutions was retained by the solid phases at pH 5, thus indicating Al coprecipitation with the primary Fe hydroxide precipitate. In contrast, two buffer regions were observed in solutions with ⩾30 mol% Al (at pH ˜2.25 for Fe 3+ and at pH ˜4 for Al 3+), suggesting the formation of Fe and Al (hydr)oxides as two separate phases. The Al content of initial coprecipitates influenced the extent of ferrihydrite transformation and of its transformation products as indicated by the presence of goethite, hematite and/or ferrihydrite in aged suspensions. DFT experiments showed that: (i) optimized unit cell parameters for Al-substituted goethites (8 and 25 mol% Al) in clustered arrangement (i.e., the formation of diaspore

  3. Welding technology of the intermetallic Fe3 Al phase

    Directory of Open Access Journals (Sweden)

    K. Garbala

    2010-01-01

    Full Text Available This paper presents the analyses of the welding terms and estimation of the welded joints quality for intermetallic Fe3Al. Materials, on the base which, joints were made and some welding technologies has been examined. Results of that investigations let one to type welding methods and materials that gives the best physicochemical effects of the joints. Regarding to the specific properties of the welded material especially its quite high hardness and fragility, it has been proposed that when joining intermetallic Fe3Al advisable would be welding in an argon cover with using Es9CrNiB electrode optionally electrowelding with Es 9CrNiB electrode. Welds made that way are thought to have the best properties within methods and welding materials being tested.

  4. Wear deformation of ordered Fe-Al intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E. (US Bureau of Mines, Albany Research Center, OR (United States)); Wilson, R.D. (US Bureau of Mines, Albany Research Center, OR (United States)); Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))

    1993-04-13

    The Bureau of Mines conducted abrasive wear research on DO[sub 3] ordered and disordered Fe[sub 3]Al intermetallics. The effect of abrasion on these alloys was studied through mixroscopy, X-ray diffraction and hardness measurements. The region near the wear surface undergoes dynamic recrystallization, i.e. the original microstructural morphology of micron-size grains is replaced by one with nanosize grains. Abrasion of the Fe[sub 3]Al alloys also results in a loss of the DO[sub 3] ordering in the wear surface region. The bulk temperature rise of the specimen during abrasion was approximately 28 C which is insufficient to cause recrystallization in these alloys. Therefore, the flash temperature due to interface frictional heating is considered more important than the bulk temperature when considering dynamic recrystallization as the transformation mechanism in the near wear surface region. (orig.)

  5. A General Perspective of Fe-Mn-Al-C Steels

    OpenAIRE

    Zambrano, O. A.

    2017-01-01

    During the last years, the scientific and industrial community has focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~15% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength (UTS) ~1 Gpa) and at the same time ductilities above 60%. The increase of the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which...

  6. Welding technology of the intermetallic Fe3 Al phase

    OpenAIRE

    K. Garbala; A. Patejuk

    2010-01-01

    This paper presents the analyses of the welding terms and estimation of the welded joints quality for intermetallic Fe3Al. Materials, on the base which, joints were made and some welding technologies has been examined. Results of that investigations let one to type welding methods and materials that gives the best physicochemical effects of the joints. Regarding to the specific properties of the welded material especially its quite high hardness and fragility, it has been proposed that when j...

  7. Plasma spraying of Fe-Cr-Al alloy powder

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

    2008-01-01

    Roč. 46, č. 1 (2008), s. 17-25 ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

  8. Creep of cast Fe-36Al-2Ti alloy

    Czech Academy of Sciences Publication Activity Database

    Dobeš, Ferdinand; Kratochvíl, P.; Milička, Karel

    2006-01-01

    Roč. 14, 10-11 (2006), s. 1199-1203 ISSN 0966-9795. [EUROMAT 2005. Praha, 05.09.2005-08.09.2005] R&D Projects: GA ČR(CZ) GA106/05/0409 Institutional research plan: CEZ:AV0Z20410507 Keywords : iron aluminides, based on FeAl * creep * mechanical testing Subject RIV: JG - Metallurgy Impact factor: 1.943, year: 2006

  9. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

  10. Optimization of the boron content in FeAl (40 at. % Al) alloys

    International Nuclear Information System (INIS)

    Webb, G.; Juliet, P.; Lefort, A.

    1993-01-01

    FeAl intermetallic alloys are of interest for several high temperature applications due to excellent oxidation resistance, low density, and relatively low cost. Attempts to further increase the ductility of iron-rich FeAl have met with, at best, marginal success. Of the ductilization techniques employed, B doping appears to be a promising method for obtaining enhanced ductility and high strength in iron rich FeAl. Boron additions enhance the ductility of these alloys by increasing the grain boundary cohesive strength which reduces the tendency for intergranular fracture. The goal of the present work was to determine the optimum B concentration for increasing ambient temperature ductility. To accomplish this, a series of three iron rich FeAl alloys of similar Fe stoichiometries were doped with different levels of B (0,12, and 80 wppm). Secondary ion mass spectrometry (SIMS) was conducted on these alloys for evaluation of the B partitioning after consolidation by extrusion. Ambient temperature tensile testing and SEM fractography were then used to evaluate the effect of such additions on ambient temperature ductility in air. The results of these experiments indicate that optimum ductility is obtained from a homogeneous distribution of boron in which boride precipitation is limited

  11. Leaching of rapidly quenched Al65Cu20Fe15 quasicrystalline ribbons

    Indian Academy of Sciences (India)

    2017-12-06

    Dec 6, 2017 ... softening tendency and high hardness. When prepared by conventional melting and casting, the QC phase in Al–Cu–. Fe system exhibits a peritectic reaction among AlFe, Al3Fe ... stability, easy forming ability of the metallic nanoparticles on ... Fe3O4 (magnetite, JCPDS Number 65-3107), with lattice.

  12. Hydrothermal Fe-Si-Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

    International Nuclear Information System (INIS)

    Sun Zhilei; Zhou Huaiyang; Yang Qunhui; Sun Zhixue; Bao Shenxu; Yao Huiqiang

    2011-01-01

    Highlights: → The Fe-Mn crust in the HHF has seawater contribution, whereas the Fe-Si oxide in the MHF is dominated by hydrothermal fluid → The Nd isotope of diffuse flow Fe-Si-Mn deposits indicates the obvious hydrothermal origin. → The Mn/Fe ratio in hydrothermal deposit may be a good indicator of propagating activities of the Valu Fa Ridge. - Abstract: A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe-Si-Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Moessbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe-Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ΣREE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe-Si-Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.

  13. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  14. Investigation of the Electrical Characteristics of Al/p-Si/Al Schottky Diode

    International Nuclear Information System (INIS)

    Şenarslan, Elvan; Güzeldir, Betül; Sağlam, Mustafa

    2016-01-01

    In this study, p-type Si semiconductor wafer with (100) orientation, 400 μm thickness and 1-10 Ω cm resistivity was used. The Si wafer before making contacts were chemically cleaned with the Si cleaning procedure which for remove organic contaminations were ultrasonically cleaned at acetone and methanol for 10 min respectively and then rinsed in deionized water of 18 MΩ and dried with high purity N 2 . Then respectively RCA1(i.e., boiling in NH 3 +H 2 O 2 +6H 2 O for 10 min at 60°C ), RCA2 (i.e., boiling in HCl+H 2 O 2 +6H 2 O for 10 min at 60°C ) cleaning procedures were applied and rinsed in deionized water followed by drying with a stream of N 2 . After the cleaning process, the wafer is immediately inserted in to the coating unit. Ohmic contact was made by evaporating of Al on the non-polished side of the p-Si wafer pieces under ∼ 4,2 10 -6 Torr pressure. After process evaporation, p-Si with omic contac thermally annealed 580°C for 3 min in a quartz tube furnace in N 2 . Then, the rectifier contact is made by evaporation Al metal diameter of about 1.0 mm on the polished surface of p-Si in turbo molecular pump at about ∼ 1 10 -6 Torr. Consequently, Al/p-Si/Al Schottky diode was obtained. The I–V measurements of this diode performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C–V measurements were performed with HP 4192A (50–13 MHz) LF Impedance Analyzer at room temperature and in dark. (paper)

  15. Investigation of the Electrical Characteristics of Al/p-Si/Al Schottky Diode

    Science.gov (United States)

    Şenarslan, Elvan; Güzeldir, Betül; Sağlam, Mustafa

    2016-04-01

    In this study, p-type Si semiconductor wafer with (100) orientation, 400 μm thickness and 1-10 Ω cm resistivity was used. The Si wafer before making contacts were chemically cleaned with the Si cleaning procedure which for remove organic contaminations were ultrasonically cleaned at acetone and methanol for 10 min respectively and then rinsed in deionized water of 18 MΩ and dried with high purity N2. Then respectively RCA1(i.e., boiling in NH3+H2O2+6H2O for 10 min at 60°C ), RCA2 (i.e., boiling in HCl+H2O2+6H2O for 10 min at 60°C ) cleaning procedures were applied and rinsed in deionized water followed by drying with a stream of N2. After the cleaning process, the wafer is immediately inserted in to the coating unit. Ohmic contact was made by evaporating of Al on the non-polished side of the p-Si wafer pieces under ~ 4,2 10-6 Torr pressure. After process evaporation, p-Si with omic contac thermally annealed 580°C for 3 min in a quartz tube furnace in N2. Then, the rectifier contact is made by evaporation Al metal diameter of about 1.0 mm on the polished surface of p-Si in turbo molecular pump at about ~ 1 10-6 Torr. Consequently, Al/p-Si/Al Schottky diode was obtained. The I-V measurements of this diode performed by the use of a KEITLEY 487 Picoammeter/Voltage Source and the C-V measurements were performed with HP 4192A (50-13 MHz) LF Impedance Analyzer at room temperature and in dark.

  16. Ferromagnetic glass ceramics and glass fibers based on the composition of SiO{sub 2}-CaO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Fe{sub 2}O{sub 3} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianan, E-mail: lja@qlu.edu.cn; Zhu, Chaofeng; Zhang, Meimei; Zhang, Yanfei; Yang, Xuena

    2017-03-15

    Ferromagnetic glass-ceramics and glass fibers were obtained by the melt-method from the glass system SiO{sub 2}-CaO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Fe{sub 2}O{sub 3} without performing any nucleation and crystallization heat treatments. Glass-ceramics and glass fibers were characterized by x-ray diffraction, scanning and transmission electron microscopy, magnetic measurements, and thermal expansion instrument. The influence of alumina content on the spontaneous crystallization of magnetite, magnetism properties and thermal expansion performances in glass were investigated. We examined the crystallization behavior of the glasses and found that the spontaneous crystallization capacity of magnetite and magnetism properties in base glass increases with increasing the content of alumina. The ferromagnetic glass fibers containing magnetite nano-crystals are also obtained. - Highlights: • Magnetite nano-crystals are formed spontaneously in the investigated glass systems. • The crystallization behavior of the glasses with the alumina content is examined. • Ferromagnetic glass fibers containing magnetite nano-crystals are obtained.

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

    Directory of Open Access Journals (Sweden)

    K. A. Ramesh Kumar

    2014-09-01

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

  18. Wear Behaviour of Nanocrystalline Fe88Si12 Alloy in Water Environment

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2014-01-01

    Full Text Available Wear behaviour of nanocrystalline Fe88Si12 alloy has been investigated in water environment compared with the coarse grained counterpart. The friction coefficient of the Fe88Si12 alloy changes slightly with the grain size. The wear resistance is enhanced as the grain size decreases first and then reduces when the grain size continues to decrease, although the hardness of the Fe88Si12 alloy decreases monotonically with the grain size. It is contrary to the predications of Archard’s formula. The best wear resistance of Fe88Si12 alloy with grain size of 40 nm in our present work is attributed to the proper grain boundary volume fraction and composite phase structures of disordered B2 and ordered D03.

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

    Directory of Open Access Journals (Sweden)

    Lorella Ceschini

    2018-04-01

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

  20. Fine structure at the diffusion welded interface of Fe3Al/Q235 ...

    Indian Academy of Sciences (India)

    Unknown

    DO3 type body centred cubic (bcc) structure to α-Fe (Al) solid solution with B2 type bcc structure. ... the diffusion of alloy elements causes the transitional zone ... Table 1. Chemical composition and thermophysical properties of Fe3Al intermetallic compound. Chemical composition (wt%). Fe. Al. Cr. Nb. Zr. Mn. B. Ce. 81⋅02.

  1. High silicon steel production through hot-dipping in Al-Si-alloy and diffusion annealing; Acero de alto silicio producido por enmersion en Al-Si y recocido de difusion

    Energy Technology Data Exchange (ETDEWEB)

    Ros-Yanez, T.; Houbaert, Y. [Ghent University. Belgica (Belgium); Schneeweis, O. [Institute of Physical of Materials. Czech Republic (Czech Republic); Asensio-Lozano, J.; Prado-Garcia, M. [Universidad de Oviedo (Spain)

    2000-07-01

    It is difficult to process steel sheet with a high Si content (>3,5%Si), mainly because of its brittleness and the appearance of cracks during rolling and oxidation. However, there is a market for this steel in electrical applications because of the favourable influence of Si on magnetostriction and electrical resistivity. As an alternative process, 3% Si-steel substrates were coated with hypereutectic Al-Si-alloys in a hot-dip simulator using different preheating and dipping times. The obtained layers were characterised by SEM and EDS analysis. Diffusion annealing experiments were performed to obtain sufficient amount of Si in the steel. It was observed that: Intermetallic phases appear in the coating layers as according to the ternary Fe-Si-Al diagram. With a double dipping primary silicon crystals are formed in the surface layer. the ordered DO{sub 3} structure is present if the dipping and/or diffusion time is long enough. Homogeneous silicon gradients in the whole substrate thickness have not yet been achieved. Theoretic calculations show that Si-gradient, also have beneficial effects on magnetic behaviour. (Author) 17 refs.

  2. Study on Formation Mechanism of Fayalite (Fe2SiO4) by Solid State Reaction in Sintering Process

    Science.gov (United States)

    Wang, Zhongbing; Peng, Bing; Zhang, Lifeng; Zhao, Zongwen; Liu, Degang; Peng, Ning; Wang, Dawei; He, Yinghe; Liang, Yanjie; Liu, Hui

    2017-12-01

    The sintering behaviors among SiO2, FeS and Fe3O4 were detected to reveal the formation mechanism of Fe2SiO4. The results indicated that the formation mechanism is divided into five steps: (1) migration of O2- induced by S2- under a reducing atmosphere; (2) formation of Fe3O4-β ; (3) migration of Fe(II) into a ferrite cluster structure to gain oxygen and form Fe3-x O4; (4) Fe(II) invaded the silicon atomic position and released Si(IV); and (5) formation of the stable structure of Fe2SiO4 through chemical diffusion between cations of Fe(II) and Si(IV). These findings can provide theoretical support for controlling the process of the recovery of valuable metals in copper slag through the combined roasting modification-magnetic separation process.

  3. Study on Formation Mechanism of Fayalite (Fe2SiO4) by Solid State Reaction in Sintering Process

    Science.gov (United States)

    Wang, Zhongbing; Peng, Bing; Zhang, Lifeng; Zhao, Zongwen; Liu, Degang; Peng, Ning; Wang, Dawei; He, Yinghe; Liang, Yanjie; Liu, Hui

    2018-04-01

    The sintering behaviors among SiO2, FeS and Fe3O4 were detected to reveal the formation mechanism of Fe2SiO4. The results indicated that the formation mechanism is divided into five steps: (1) migration of O2- induced by S2- under a reducing atmosphere; (2) formation of Fe3O4- β ; (3) migration of Fe(II) into a ferrite cluster structure to gain oxygen and form Fe3- x O4; (4) Fe(II) invaded the silicon atomic position and released Si(IV); and (5) formation of the stable structure of Fe2SiO4 through chemical diffusion between cations of Fe(II) and Si(IV). These findings can provide theoretical support for controlling the process of the recovery of valuable metals in copper slag through the combined roasting modification-magnetic separation process.

  4. Coercivity Recovery Effect of Sm-Fe-Cu-Al Alloy on Sm2Fe17N3 Magnet

    Science.gov (United States)

    Otogawa, Kohei; Asahi, Toru; Jinno, Miho; Yamaguchi, Wataru; Takagi, Kenta; Kwon, Hansang

    2018-03-01

    The potential of a Sm-Fe-Cu-Al binder for improvement of the magnetic properties of Sm2Fe17N3 was examined. Transmission electron microscope (TEM) observation of a Sm-Fe-Cu-Al alloy-bonded Sm2Fe17N3 magnet which showed high coercivity revealed that the Sm-Fe-Cu-Al alloy had an effect of removing the surface oxide layer of the Sm2 Fe17N3 grains. However, the Sm-Fe-Cu-Al binder was contaminated by carbon and nitrogen, which originated from the organic solvent used as the milling medium during pulverization. To prevent carbon and nitrogen contamination, the Sm-Fe- Cu-Al alloy was added directly on the surface of the Sm2Fe17N3 grains by sputtering. Comparing the recovered coercivity per unit amount of the added binder the uncontaminated binder-coated sample had a higher coercivity recovery effect than the milled binder-added sample. These results suggested that sufficient addition of the contamination-free Sm-Fe-Cu-Al binder has the possibility to reduce the amount of binder necessary to produce a high coercive Sm2Fe17N3 magnet.

  5. Semiconducting {beta}-FeSi{sub 2} towards optoelectronics and photonics

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Yoshihito [Department of Energy Science and Technology, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)], E-mail: ymaeda@zenon.energy.kyoto-u.ac.jp

    2007-08-15

    This article explains some recent studies on a mechanism of luminescence from {beta}-FeSi{sub 2} and its applications to optoelectronics and photonics. A luminescence at 0.805 eV (i.e. the A-band) can be understood to be originated from dissolution process of indirect excitons. Photonic crystals using {beta}-FeSi{sub 2} with a high refractive index are one of the promising applications to realize high performance photonic circuits.

  6. Internal Friction of Austenitic Fe-Mn-C-Al Alloys

    Science.gov (United States)

    Lee, Young-Kook; Jeong, Sohee; Kang, Jee-Hyun; Lee, Sang-Min

    2017-12-01

    The internal friction (IF) spectra of Fe-Mn-C-Al alloys with a face-centered-cubic (fcc) austenitic phase were measured at a wide range of temperature and frequency ( f) to understand the mechanisms of anelastic relaxations occurring particularly in Fe-Mn-C twinning-induced plasticity steels. Four IF peaks were observed at 346 K (73 °C) (P1), 389 K (116 °C) (P2), 511 K (238 °C) (P3), and 634 K (361 °C) (P4) when f was 0.1 Hz. However, when f increased to 100 Hz, whereas P1, P2, and P4 disappeared, only P3 remained without the change in peak height, but with the increased peak temperature. P3 matches well with the IF peak of Fe-high Mn-C alloys reported in the literature. The effects of chemical composition and vacancy (v) on the four IF peaks were also investigated using various alloys with different concentrations of C, Mn, Al, and vacancy. As a result, the defect pair responsible for each IF peak was found as follows: a v-v pair for P1, a C-v pair for P2, a C-C pair for P3, and a C-C-v complex (major effect) + a Mn-C pair (minor effect) for P4. These results showed that the IF peaks of Fe-Mn-C-Al alloys reported previously were caused by the reorientation of C in C-C pairs, not by the reorientation of C in Mn-C pairs.

  7. Karakterisasi Paduan AlMgSi Untuk Kelongsong Bahan Bakar U3Si2/Al Dengan Densitas Uranium 5,2 gU/cm3

    Directory of Open Access Journals (Sweden)

    Aslina Br. Ginting

    2018-03-01

    Full Text Available Meningkatnya densitas uranium dari 2,96 gU/cm3 menjadi 5,2 gU/cm3 bahan bakar U3Si2/Al harus diikuti dengan penggunaan kelongsong yang kompatibel. Bahan bakar berdensitas tinggi mempunyai kekerasan yang tinggi, sehingga bila menggunakan paduan AlMg2 sebagai kelongsong dapat menyebabkan terjadi dogbone pada saat perolan. Selain fenomena dogbone, pada saat bahan bakar tersebut digunakan di reaktor dapat terjadi swelling karena meningkatnya hasil fisi maupun burn up. Oleh karena itu, perlu dicari pengganti bahan kelongsong untuk bahan bakar U3Si2/Al densitas tinggi. Pada penelitian ini telah dilakukan karakterisasi paduan AlMgSi sebagai kandidat pengganti kelongsong AlMg2. Karakterisasi yang dilakukan meliputi analisis termal, kekerasan, mikrostruktur dan laju korosi. Analisis termal dilakukan menggunakan DTA (Differential Thermal Analysis dan DSC (Differential Scanning Calorimetry. Analisis kekerasan menggunakan alat uji kekerasan mikro, mikrostruktur menggunakan SEM (Scanning Electron Microscope dan analisis laju korosi dilakukan dengan pemanasan pada temperatur 150 oC selama 77 jam di dalam autoclave. Hasil analisis menunjukkan bahwa kelongsong AlMgSi maupun AlMg2 mempunyai kompatibilitas panas dengan bahan bakar U3Si2/Al cukup stabil hingga temperatur 650 oC. Kelongsong AlMgSi mempunyai kekerasan sebesar 115 HVN dan kelongsong AlMg2 sebesar 70,1 HVN. Sementara itu, analisis mikrostruktur menunjukkan bahwa morfologi ikatan antarmuka (interface bonding kelongsong AlMgSi lebih baik dari kelongsong AlMg2, demikian halnya dengan laju korosi bahwa kelongsong AlMgSi mempunyai laju korosi lebih kecil dibanding kelongsong AlMg2. Hasil karakterisasi termal, kekerasan, mikrostruktur dan laju korosi menunjukkan bahwa PEB U3Si2/Al densitas 5,2 gU/cm3 menggunakan kelongsong AlMgSi lebih baik dibanding PEB U3Si2/Al  densitas 5,2 gU/cm3  menggunakan kelongsong AlMg2. Kata kunci: U3Si2/Al, densitas 5,2 gU/cm3, kelongsong AlMgSi dan AlMg2.

  8. Martensitic Transformations and Mechanical and Corrosion Properties of Fe-Mn-Si Alloys for Biodegradable Medical Implants

    Science.gov (United States)

    Drevet, Richard; Zhukova, Yulia; Malikova, Polina; Dubinskiy, Sergey; Korotitskiy, Andrey; Pustov, Yury; Prokoshkin, Sergey

    2018-01-01

    The Fe-Mn-Si alloys are promising materials for biodegradable metallic implants for temporary healing process in the human body. In this study, three different compositions are considered (Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si, all in wt pct). The phase composition analysis by XRD reveals ɛ-martensite, α-martensite, and γ-austenite in various proportions depending on the manganese amount. The DSC study shows that the starting temperature of the martensitic transformation (M s) of the alloys decreases when the manganese content increases (416 K, 401 K, and 323 K (143 °C, 128 °C, and 50 °C) for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). Moreover, mechanical compression tests indicate that these alloys have a much lower Young's modulus (E) than pure iron (220 GPa), i.e., 145, 133, and 118 GPa for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively. The corrosion behavior of the alloys is studied in Hank's solution at 310 K (37 °C) using electrochemical experiments and weight loss measurements. The corrosion kinetics of the Fe-Mn-Si increases with the manganese content (0.48, 0.59, and 0.80 mm/year for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). The alloy with the highest manganese content shows the most promising properties for biomedical applications as a biodegradable and biomechanically compatible implant material.

  9. Martensitic Transformations and Mechanical and Corrosion Properties of Fe-Mn-Si Alloys for Biodegradable Medical Implants

    Science.gov (United States)

    Drevet, Richard; Zhukova, Yulia; Malikova, Polina; Dubinskiy, Sergey; Korotitskiy, Andrey; Pustov, Yury; Prokoshkin, Sergey

    2018-03-01

    The Fe-Mn-Si alloys are promising materials for biodegradable metallic implants for temporary healing process in the human body. In this study, three different compositions are considered (Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si, all in wt pct). The phase composition analysis by XRD reveals ɛ-martensite, α-martensite, and γ-austenite in various proportions depending on the manganese amount. The DSC study shows that the starting temperature of the martensitic transformation ( M s) of the alloys decreases when the manganese content increases (416 K, 401 K, and 323 K (143 °C, 128 °C, and 50 °C) for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). Moreover, mechanical compression tests indicate that these alloys have a much lower Young's modulus ( E) than pure iron (220 GPa), i.e., 145, 133, and 118 GPa for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively. The corrosion behavior of the alloys is studied in Hank's solution at 310 K (37 °C) using electrochemical experiments and weight loss measurements. The corrosion kinetics of the Fe-Mn-Si increases with the manganese content (0.48, 0.59, and 0.80 mm/year for the Fe23Mn5Si, Fe26Mn5Si, and Fe30Mn5Si alloys, respectively). The alloy with the highest manganese content shows the most promising properties for biomedical applications as a biodegradable and biomechanically compatible implant material.

  10. Metal organic vapor phase epitaxy growth of (Al)GaN heterostructures on SiC/Si(111) templates synthesized by topochemical method of atoms substitution

    DEFF Research Database (Denmark)

    Rozhavskaya, Mariia M.; Kukushkin, Sergey A.; Osipov, Andrey V.

    2017-01-01

    crystalline interfaces with epitaxial relationship between SiC/Si and AlN/SiC layers. Optimization of SiC morphology and AlN seed layer thickness facilitates the growth of GaN layers free of pits (v-defects). It is also found that Si doping eliminates these defects in the case of growth on SiC templates...

  11. Mössbauer spectroscopy study of surfactant sputtering induced Fe silicide formation on a Si surface

    Energy Technology Data Exchange (ETDEWEB)

    Beckmann, C.; Zhang, K. [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Hofsäss, H., E-mail: hans.hofsaess@phys.uni-goettingen.de [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Brüsewitz, C.; Vetter, U. [2nd Institute of Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany); Bharuth-Ram, K. [Physics Department, Durban University of Technology, Durban 4001 (South Africa)

    2015-12-01

    Highlights: • We study the formation of self-organized nanoscale dot and ripple patterns on Si. • Patterns are created by keV noble gas ion irradiation and simultaneous {sup 57}Fe co-deposition. • Ion-induced phase separation and the formation of a-FeSi{sub 2} is identified as relevant process. - Abstract: The formation of Fe silicides in surface ripple patterns, generated by erosion of a Si surface with keV Ar and Xe ions and simultaneous co-deposition of Fe, was investigated with conversion electron Mössbauer spectroscopy, atomic force microscopy and Rutherford backscattering spectrometry. For the dot and ripple patterns studied, we find an average Fe concentration in the irradiated layer between 6 and 25 at.%. The Mössbauer spectra clearly show evidence of the formation of Fe disilicides with Fe content close to 33 at.%, but very little evidence of the formation of metallic Fe particles. The results support the process of ion-induced phase separation toward an amorphous Fe disilicide phase as pattern generation mechanism. The observed amorphous phase is in agreement with thermodynamic calculations of amorphous Fe silicides.

  12. Al-matrix composite materials reinforced by Al-Cu-Fe particles

    International Nuclear Information System (INIS)

    Bonneville, J; Laplanche, G; Joulain, A; Gauthier-Brunet, V; Dubois, S

    2010-01-01

    Al-matrix material composites were produced using hot isostatic pressing technique, starting with pure Al and icosahedral (i) Al-Cu-Fe powders. Depending on the processing temperature, the final reinforcement particles are either still of the initial i-phase or transformed into the tetragonal ω-Al0 0.70 Cu 0.20 Fe 0.10 crystalline phase. Compression tests performed in the temperature range 293K - 823K on the two types of composite, i.e. Al/i and Al/ω, indicate that the flow stress of both composites is strongly temperature dependent and exhibit distinct regimes with increasing temperature. Differences exist between the two composites, in particular in yield stress values. In the low temperature regime (T ≤ 570K), the yield stress of the Al/ω composite is nearly 75% higher than that of the Al/i composite, while for T > 570K both composites exhibit similar yield stress values. The results are interpreted in terms of load transfer contribution between the matrix and the reinforcement particles and elementary dislocation mechanisms in the Al matrix.

  13. Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hu, Xunxiang [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-30

    The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

  14. Growth of uniform lath-like α-(Fe,Al)OOH and disc-like α-(Fe,Al)2O3 nanoparticles in a highly alkaline medium

    International Nuclear Information System (INIS)

    Krehula, Stjepko; Music, Svetozar

    2010-01-01

    The effects of aluminium (Al 3+ )-dopant on the precipitation of uniform lath-like α-FeOOH particles, the obtention and growth of α-(Fe,Al)OOH and α-(Fe,Al) 2 O 3 solid solutions, particle size and shape were investigated using X-ray powder diffraction, Moessbauer and Fourier transform infrared spectroscopies, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. Acicular α-FeOOH particles, precipitated in a highly alkaline medium with the addition of tetramethylammonium hydroxide (TMAH), were used as reference material. The influence of Al-dopant was investigated by adding varying amounts of Al 3+ ions to the initial FeCl 3 solution. In the presence of lower concentrations of aluminium ions (up to 11.11 mol%) α-(Fe,Al)OOH as a single phase was formed, whereas higher concentrations led to an additional obtention and growth of α-(Fe,Al) 2 O 3 . Al-for-Fe substitution in the α-FeOOH and α-Fe 2 O 3 structures was confirmed by a decrease in the unit-cell dimensions, a decrease in the hyperfine magnetic field and an increase in the wave number of the infrared absorption bands. The presence of lower concentrations of aluminium ions (up to 11.11 mol%) in the precipitation system did not affect the size and shape of the α-(Fe,Al)OOH particles, whereas higher concentrations influenced a decrease in the length and aspect ratio. In the presence of 42.86 mol% Al 3+ ions fairly uniform disc-shaped α-(Fe,Al) 2 O 3 were formed.

  15. X-ray photoelectron spectroscopy studies on single crystalline β-FeSi{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Wei, E-mail: mao@nuclear.jp [The Micro Analysis Laboratory, Tandem Accelerator, The University Museum, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Udono, Haruhiko [Department of Electrical and Electronic Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Yamaguchi, Kenji [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai, Naka, Ibaraki 319-1195 (Japan); Terai, Takayuki [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Matsuzaki, Hiroyuki [The Micro Analysis Laboratory, Tandem Accelerator, The University Museum, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-05-01

    In order to realize the photoluminescence of semiconducting β-FeSi{sub 2} homoepitaxial films, surface preparation of single crystalline β-FeSi{sub 2} is of critical importance. An atomically flat and clean substrate surface of β-FeSi{sub 2} was prepared by sputtering with 2 keV Ar{sup +} ions or by heating at 850 °C. The structure of the native surface oxide and the removal of this layer were investigated though X-ray photoelectron spectroscopy measurements. No significant deviation of the stoichiometry was detected in the surface region. Our results suggest that a surface prepared in this way is an eligible substrate for homoepitaxy of β-FeSi{sub 2}. - Highlights: • A clean surface of single crystalline (beta)-FeSi{sub 2} was prepared by Ar{sup +} sputtering or by heating. • The removal of surface oxide during the surface treatment is elucidated. • The native surface oxides are identified as SiO{sub 2} on top and SiO{sub x} as the inner layer. • There is no significant deviation of surface stoichiometry on the clean surface.

  16. Cu-segregation at the Q'/α-Al interface in Al-Mg-Si-Cu alloy

    International Nuclear Information System (INIS)

    Matsuda, Kenji; Teguri, Daisuke; Uetani, Yasuhiro; Sato, Tatsuo; Ikeno, Susumu

    2002-01-01

    Cu segregation was detected at the Q ' /α-Al interface in an Al-Mg-Si-Cu alloy by energy-filtered transmission electron microscopy. By contrast, in a Cu-free Al-Mg-Si alloy no segregation was observed at the interface between the matrix and Type-C precipitate

  17. Improving the characteristics of foundry alloys AlSiCuMg during manufacturing

    Science.gov (United States)

    Fragoso, Bruno Filipe Marques

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

  18. Influence of the doping on the lattice sites of Fe in Si

    CERN Document Server

    Silva, Daniel; Wahl, Ulrich; Martins Correia, Joao; Esteves De Araujo, Araujo Joao Pedro

    2014-01-01

    We report on the lattice location and thermal stability of Fe in n+- and p+-type silicon. By means of emission channeling we have observed Fe on ideal substitutional sites, sites located in between bond-centered (BC) and substitutional sites, and sites displaced from tetrahedral towards anti-bonding sites. Here, we focus our analysis on the identification of Fe displaced 0.4-0.6 Å from BC sites and the influence of the doping on the stability of these sites. Fe on near-BC sites is found to be more thermally stable in n+-type Si than in low doped or p+-type Si, and seems to be related to multiple vacancy defects. We suggest that the complexes which trap Fe near BC sites, as well as the formation of substitutional Fe, may play a crucial role in P-diffusion gettering.

  19. Electrical performance of multilayer MoS2 transistors on high-κ Al2O3 coated Si substrates

    Directory of Open Access Journals (Sweden)

    Tao Li

    2015-05-01

    Full Text Available The electrical performance of MoS2 can be engineered by introducing high-κ dielectrics, while the interactions between high-κ dielectrics and MoS2 need to be studied. In this study, multilayer MoS2 field-effect transistors (FETs with a back-gated configuration were fabricated on high-κ Al2O3 coated Si substrates. Compared with MoS2 FETs on SiO2, the field-effect mobility (μFE and subthreshold swing (SS were remarkably improved in MoS2/Al2O3/Si. The improved μFE was thought to result from the dielectric screening effect from high-κ Al2O3. When a HfO2 passivation layer was introduced on the top of MoS2/Al2O3/Si, the field-effect mobility was further enhanced, which was thought to be concerned with the decreased contact resistance between the metal and MoS2. Meanwhile, the interface trap density increased from 2.4×1012 eV−1cm−2 to 6.3×1012 eV−1cm−2. The increase of the off-state current and the negative shift of the threshold voltage may be related to the increase of interface traps.

  20. Fe diffusion in amorphous Si studied using x-ray standing wave technique

    Directory of Open Access Journals (Sweden)

    Parasmani Rajput

    2012-03-01

    Full Text Available Diffusion of Fe impurity in amorphous Si at the intermediate concentration range of 25 at.% Fe has been studied. A combination of x-ray standing wave technique and secondary ion mass spectrometry provides unambiguous determination of the concentration profiles of the constituent species with sub-nanometer depth resolution. X-ray standing waves are generated using total external reflection from an underlying W layer. It is found that up to 573 K, Fe diffusivity is less than 10−23m2/s. This is in stark contrast to isolated Fe impurity diffusion in Si or to the interdiffusion at Fe/Si interface, which are orders of magnitude higher. An interesting phenomenon is observed, when a Pt buffer layer is used instead of W for generating standing waves: With thermal annealing, as the Pt atoms move into Si layer and cross the marker layer containing Fe atoms, Fe atoms also move along. This results in an upwards shift of the concentration profile of Fe.

  1. Thermodynamic Phase Relations in the MgO-FeO-SiO2 System in the Lower Mantle

    Science.gov (United States)

    Wolf, A. S.; Caracas, R.; Asimow, P. D.

    2008-12-01

    The perovskite (Pv) to post-perovskite (PPv) phase transition at pressures near the Earth's core-mantle boundary (CMB) is currently the favored candidate for explaining most, if not all, of the peculiarities of the D" layer (~200 km region above core) [1, 2]. Additionally, the pressure- and temperature-dependence of this phase boundary in the Earth provides the possibility of an important new thermo-barometer at the bottom of the convecting mantle. The post-perovskite phase boundary in pure MgSiO3 is fairly well known, but the experimental and calculated results on the partitioning of Fe among the stable coexisting phases and its influence on the transition pressure are currently contradictory [3, 4, 5, 6]. Using density functional theory (DFT), we investigate the MgO-FeO-SiO2 ternary system over the temperatures and pressures relevant to the core-mantle boundary. We use DFT to calculate the energies of the relevant stable phases (Pv, PPv, (Mg,Fe)O magnesio-wustite, and SiO2 stishovite) for a range of Fe compositions along the Mg-Fe binary. These results are fit with a Vinet equation of state, allowing us to parameterize the effect of both pressure and Fe composition. The effect of temperature is modeled using a Grüneisen thermal correction, where the vibrational heat capacities are determined using DFT perturbation calculations and the quasi-harmonic approximation. These pressure-, temperature-, and composition-dependent equations of state are then used to explore the predicted phase relations. The results of this investigation are a complete thermodynamic description of the stable phases for this simplified chemistry and a theoretical prediction for iron partioning in the lower mantle. In particular, we find that there may be a coincidence point (azeotrope) on the Pv-PPv phase loop, across which the sense of Fe-partitioning changes sign, as well as significant immiscibility between Mg-rich and Fe-rich post-perovskite. These findings help explain many of the

  2. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyong June [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  3. Synthesis and characterization of pillared bentonite with Al, AL/Fe and impregnated with Pd; Sintese e caracterizacao de bentonitas pilarizadas com Al, AL/Fe e impregnadas com Pd

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcus Vinicius Costa; Pizarro, Alejandro Herrero; Molina, Carmen Belen, E-mail: marcus.ufpa@yahoo.com.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Instituto de Tecnologia. Faculdade de Engenharia Quimica; Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madri (Spain)

    2017-10-01

    In this work, a north american bentonite was pillared with Al and Al/Fe, creating the Al-PILC and Al-Fe-PILC, respectively. Then the Pd was impregnated in the materials, generating Pd-Al-PILC and Pd-Al-Fe-PILC, respectively. The samples were characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and N{sub 2} adsorption at 77 K to determine the specific surface area by BET method (Brunauer - Emmett - Teller). There was an increase in the basal spacing of bentonite from 12.4Å in the original sample to 17.81Å in the Al-Fe-PILC, 17.20Å in Pd-Al-PILC and 17.05Å in the Pd-Al-Fe-PILC. The specific surface area increased from 19.05m{sup 2}/g in the original sample to 173.49m{sup 2}/g in Al-Fe-PILC, 101.31m{sup 2}/g to Pd-Al-PILC and 92m{sup 2}/g in Pd-Al-Fe-PILC. The pillaring process was successful and the synthesized materials have great potential for use as catalysts. (author)

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

    Science.gov (United States)

    Finkelstein, Arkady; Schaefer, Arseny; Chikova, Оlga; Borodianskiy, Konstantin

    2017-07-11

    One of the main goals of modern materials research is obtaining different microstructures and studying their influence on the mechanical properties of metals; aluminum alloys are particularly of interest due to their advanced performance. Traditionally, their required properties are obtained by alloying process, modification, or physical influence during solidification. The present work describes a saturation of the overheated AlSi₇Fe₁ casting alloy by oxides using oxygen blowing approach in overheated alloy. Changes in metals' microstructural and mechanical properties are also described in the work. An Al 10 SiFe intermetallic complex compound was obtained as a preferable component to Al₂O₃ precipitation on it, and its morphology was investigated by scanning electron microscopy. The mechanical properties of the alloy after the oxygen blowing treatment are discussed in this work.

  5. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification; Analisis elemental del intermetalico Al-Fe preparado por solidificacion rapida

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2003-07-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  6. Microstructures after processing by aging and ECAP for Al-Mg{sub 2}Si alloys containing excess Si or Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, K.; Kaneko, K.; Horita, Z. [Dept. of Materials Science and Engineering, Faculty of Engineering, Kyushu Univ., Fukuoka (Japan); Fujita, T. [Center for Solid State Science, Arizona State Univ., Tempe (United States); Oh-ishi, K. [Dept. of Mechanical Engineering, Naval Postgraduate School, Monterey, CA (United States); Langdon, T.G. [Dept. of Aerospace and Mechanical Engineering and Materials Science, Univ. of Southern California, Los Angeles, CA (United States)

    2005-07-01

    In this study, severe plastic straining through equal-channel angular pressing (ECAP) is imposed on age-hardenable Al-Mg-Si alloys having two different compositions of excess Si or Mg in the Al-Mg{sub 2}Si pseudo-binary system. Thereafter, the alloys are subjected to aging and the microstructures are examined using transmission electron microscopy. It is shown that the precipitation behavior is significantly changed through application of ECAP. (orig.)

  7. Low-temperature pyrolysis of oily sludge: roles of Fe/Al-pillared bentonites

    Directory of Open Access Journals (Sweden)

    Jia Hanzhong

    2017-09-01

    Full Text Available Pyrolysis is potentially an effective treatment of oily sludge for oil recovery, and the addition of a catalyst is expected to affect its pyrolysis behavior. In the present study, Fe/Al-pillared bentonite with various Fe/Al ratios as pyrolysis catalyst is prepared and characterized by XRD, N2 adsorption, and NH3-TPD. The integration of Al and Fe in the bentonite interlayers to form pillared clay is evidenced by increase in the basal spacing. As a result, a critical ratio of Fe/Al exists in the Fe/Al-pillared bentonite catalytic pyrolysis for oil recovery from the sludge. The oil yield increases with respect to increase in Fe/Al ratio of catalysts, then decreases with further increasing of Fe/Al ratio. The optimum oil yield using 2.0 wt% of Fe/Al 0.5-pillared bentonite as catalyst attains to 52.46% compared to 29.23% without catalyst addition in the present study. In addition, the addition of Fe/Al-pillared bentonite catalyst also improves the quality of pyrolysis-produced oil and promotes the formation of CH4. Fe/Al-pillared bentonite provides acid center in the inner surface, which is beneficial to the cracking reaction of oil molecules in pyrolysis process. The present work implies that Fe/Al-pillared bentonite as addictive holds great potential in industrial pyrolysis of oily sludge.

  8. Zero thermal expansion in NaZn13-type La(Fe,Si)13 compounds.

    Science.gov (United States)

    Wang, Wei; Huang, Rongjin; Li, Wen; Tan, Jie; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-01-28

    A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| linear thermal expansion) over a broad temperature range (15-150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

  9. The Effect of Ultrasonic Melt Treatment on the Microstructure and Mechanical Properties of Al-7Si-0.35Mg Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soo-Bae; Cho, Young-Hee; Lee, Jung-Moo; Jung, Jae-Gil [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Su Gun [Gyeongsang National University, Jinju (Korea, Republic of)

    2017-04-15

    The effect of ultrasonic melt treatment (UST) on the microstructure and mechanical properties of Al-7Si-0.35Mg (A356) casting alloys was investigated. The particular aim of this study was to analyze the mechanism involved in the strengthening of the A356 alloys when fabricated by UST. The UST had little effect on the sizes of the α-Al grain and eutectic Si at a melt temperature of 750 ℃, and the yield strength of the A356 alloy was increased by UST by approximately 16%. After T6 heat treatment, however, both alloys prepared with and without UST had similar levels of yield strength. These results are possibly associated with a change in the type and the volume fraction of intermetallics due to UST. UST greatly reduced the volume fractions of the intermetallics which were formed upon solidification, resulting in alloys with predominantly β-Al{sub 5}FeSi instead of π-Al{sub 8}FeMg{sub 3}Si{sub 6}. However, T6 heat treatment, especially a solid solution treatment at 530 ℃ for 8 hours, led to the dissolving of intermetallics such as Mg{sub 2}Si and π -Al{sub 8}FeMg{sub 3}Si{sub 6} and as a result their volume fractions were further reduced to similar levels in both alloys with and without UST.

  10. A study of a stable Al-Cu-Fe quasicrystal in solid and liquid state

    International Nuclear Information System (INIS)

    Chen Lifan; Chen Xishen

    1992-01-01

    A stable Al 65 Cu 20 Fe 15 quasicrystal with an icosahedral structure is studied in solid and liquid state. It is found that the icosahedral phase in Al 65 Cu 20 Fe 15 alloy does not grow directly from the pure liquid state, but rather forms between monoclinic Al 13 Fe 4 and residual liquid state at 865degC. The melting point of the Al 65 Cu 20 Fe 15 icosahedral quasicrystal occurs at 865degC and that of the Al 65 Cu 20 Fe 15 alloy occurs at 1008degC. Moreover, the monoclinic Al 13 Fe 4 is transformed into the icosahedral phase easily at the temperature of 845degC. The icosahedral quasicrystal in Al 65 Cu 20 Fe 15 alloy has a high thermal stability even at 950degC. Above 950degC, the icosahedral structure tends to an amorphous structure. (orig.)

  11. Aleaciones cuasicristalinas Al93Fe3Cr2Ti2

    Directory of Open Access Journals (Sweden)

    García-Escorial, Asunción

    2015-12-01

    Full Text Available Aluminium alloy powder having a nominal composition of Al93Fe3Cr2Ti2 (at% has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nanometre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 °C. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases.Se ha obtenido por atomización por gas polvo de la aleación Al93Fe3Cr2Ti2 (at%. Este polvo presenta una microestructura de una matriz de aluminio reforzada por precipitados icosaédricos de tamaño nanométrico. El polvo fue consolidado por extrusión en forma de barras cilíndricas. La microestructura de las barras retiene la microestructura cuasicristalina de las partículas de polvo. El material consolidado presenta propiedades mecánicas prometedoras, como un límite elástico de 280 MPA a 300 °C. Con los tratamientos térmicos, la microestructura evoluciona hacia el equilibrio. Esta evolución se estudia por difracción de rayos x, calorimetría diferencial de barrido, microscopías electrónicas de barrido y de transmisión. A la luz de los resultados obtenidos se propone que la transformación de las fases con el tiempo de tratamiento térmico ocurre en dos pasos. Primeramente, tiene lugar la descomposición de la

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  13. The formation mechanism of mechanically alloyed Fe-20 at% Al powder

    Energy Technology Data Exchange (ETDEWEB)

    Hadef, F., E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Otmani, A. [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Universite 20 Aout 1955, BP 26, Route d' El-Hadaiek, Skikda 21000 (Algeria); Djekoun, A. [Laboratoire de Magnetisme et Spectroscopie des Solides, LM2S, Universite Badji Mokhtar, BP 12 Annaba 23000 (Algeria); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans (France)

    2013-01-15

    The formation mechanism of the mechanically alloyed Fe-20 at% Al, from elemental Fe and Al powders, has been investigated. The experimental results indicate the formation of a nanocrystalline bcc {alpha}-Fe(Al) solid solution with a lattice parameter close to a{sub {alpha}-Fe(Al)}=0.2890 nm, where each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere. The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Aluminum particles undergo an important refinement to the nanometer scale and then they stick on Fe particles of large sizes. A large number of clear Al/Fe interface areas were generated. The short diffusion path and the presence of high concentration of defects accelerated the solid state reaction. - Highlights: Black-Right-Pointing-Pointer A nanocrystalline bcc {alpha}-Fe(Al) solid solution is formed from elemental Fe and Al powders. Black-Right-Pointing-Pointer The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Black-Right-Pointing-Pointer Each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere.

  14. Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α-Fe-Si alloys

    Science.gov (United States)

    Nandipati, Giridhar; Jiang, Xiujuan; Vemuri, Rama S.; Mathaudhu, Suveen; Rohatgi, Aashish

    2018-01-01

    Diffusion of Si atom and vacancy in the A2-phase of α-Fe-Si alloys in the ferromagnetic state, with and without magnetic order and in various temperature ranges, are studied using AKSOME, an on-lattice self-learning KMC code. Diffusion of the Si atom and the vacancy are studied in the dilute limit and up to 12 at.% Si, respectively, in the temperature range 350-700 K. Local Si neighborhood dependent activation energies for vacancy hops were calculated on-the-fly using a broken-bond model based on pairwise interaction. The migration barrier and prefactor for the Si diffusion in the dilute limit were obtained and found to agree with published data within the limits of uncertainty. Simulations results show that the prefactor and the migration barrier for the Si diffusion are approximately an order of magnitude higher, and a tenth of an electron-volt higher, respectively, in the magnetic disordered state than in the fully ordered state. However, the net result is that magnetic disorder does not have a significant effect on Si diffusivity within the range of parameters studied in this work. Nevertheless, with increasing temperature, the magnetic disorder increases and its effect on the Si diffusivity also increases. In the case of vacancy diffusion, with increasing Si concentration, its diffusion prefactor decreases while the migration barrier more or less remained constant and the effect of magnetic disorder increases with Si concentration. Important vacancy-Si/Fe atom exchange processes and their activation barriers were identified, and the effect of energetics on ordered phase formation in Fe-Si alloys are discussed.

  15. (FeCo)3Si-SiOx core-shell nanoparticles fabricated in the gas phase

    International Nuclear Information System (INIS)

    Bai Jianmin; Xu Yunhao; Thomas, John; Wang Jianping

    2007-01-01

    A method of fabricating core-shell nanoparticles by using an integrated nanoparticle deposition technique in the gas phase is reported. The principle of the method is based on nanoparticle growth from the vapour phase, during which elements showing lower surface energies prefer to form the shells and elements showing higher surface energies prefer to stay in the cores. This method was applied successfully to the Fe-Co-Si ternary system to fabricate core-shell-type nanoparticles. The nanoparticles were exposed in air after collection to achieve oxidation. The analysis results based on transmission electron microscopy (TEM), Auger electron spectroscopy (AES), x-ray diffraction (XRD), and a superconducting quantum interference device (SQUID) showed that the core parts are magnetic materials of body-centred cubic (bcc) structured (FeCo) 3 Si of 15 nm in diameter, and the shell parts are amorphous SiO x of 2 nm in thickness. These core-shell-type nanoparticles show a magnetic anisotropy constant of about 7 x 10 5 erg cm -3 and a saturation magnetization of around 1160 emu cm -3 , which is much higher than that of iron oxide. After annealing at 300 deg. C in air (FeCo) 3 Si-SiO x core-shell-type nanoparticles showed a little bit of a drop in magnetic moment, while pure FeCo nanopariticles totally lost their magnetic moment. This means that the shells of SiO x are dense enough to prevent the magnetic cores from oxidation

  16. Plastic deformation of FeSi at high pressures: implications for planetary cores

    Science.gov (United States)

    Kupenko, Ilya; Merkel, Sébastien; Achorner, Melissa; Plückthun, Christian; Liermann, Hanns-Peter; Sanchez-Valle, Carmen

    2017-04-01

    The cores of terrestrial planets is mostly comprised of a Fe-Ni alloy, but it should additionally contain some light element(s) in order to explain the observed core density. Silicon has long been considered as a likely candidate because of geochemical and cosmochemical arguments: the Mg/Si and Fe/Si ratios of the Earth does not match those of the chondrites. Since silicon preferentially partition into iron-nickel metal, having 'missing' silicon in the core would solve this problem. Moreover, the evidence of present (e.g. Mercury) or ancient (e.g. Mars) magnetic fields on the terrestrial planets is a good indicator of (at least partially) liquid cores. The estimated temperature profiles of these planets, however, lay below iron melting curve. The addition of light elements in their metal cores could allow reducing their core-alloy melting temperature and, hence, the generation of a magnetic field. Although the effect of light elements on the stability and elasticity of Fe-Ni alloys has been widely investigated, their effect on the plasticity of core materials remains largely unknown. Yet, this information is crucial for understanding how planetary cores deform. Here we investigate the plastic deformation of ɛ-FeSi up to 50 GPa at room temperature employing a technique of radial x-ray diffraction in diamond anvil cells. Stoichiometric FeSi endmember is a good first-order approximation of the Fe-FeSi system and a good starting material to develop new experimental perspectives. In this work, we focused on the low-pressure polymorph of FeSi that would be the stable phase in the cores of small terrestrial planets. We will present the analysis of measured data and discuss their potential application to constrain plastic deformation in planetary cores.

  17. Electrical investigation of the Al/porous Si/p{sup +}-Si heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, A. [Universite de Sousse, Laboratoire Energie-Materiaux, Ecole Superieure des Sciences et de la Technologie, Rue Lamine Abessi 4011, Hammam Sousse (Tunisia); Jomni, S. [Laboratoire Materiaux, Organisation et Proprietes, Faculte des Sciences de Tunis (Tunisia); Hannachi, R. [Universite de Sousse, Laboratoire Energie-Materiaux, Ecole Superieure des Sciences et de la Technologie, Rue Lamine Abessi 4011, Hammam Sousse (Tunisia); Laboratoire Materiaux, Organisation et Proprietes, Faculte des Sciences de Tunis (Tunisia); Universite de Sousse, Equipe de recherche caracterisations optoelectronique et spectroscopique des materiaux et nanomateriaux pour les telecommunications et capteurs, ISITCOM 4011, Hammam Sousse (Tunisia); and others

    2013-01-15

    Porous silicon based Al/porous Si/p{sup +}-Si heterojunction with porous silicon layer was fabricated on low-resistivity crystalline silicon substrate by electrochemical anodisation. Measurements of the current-voltage I(V) characteristics and capacitance-voltage C(V) at various frequencies were used for the investigation of the electrical properties of this heterojunction. The forward bias I(V) dependencies exhibited a high value of the quality factor close to 7. This was attributed to the existence of interfacial layer and interface states which cause the forward I(V) characteristic not to obey the ideal Schottky diode characteristic. Therefore, it was demonstrated that the current has a square root dependence on the forward bias and it was governed by the Richardson-Schottky conduction mechanism. Furthermore, an ideality factor near the unity has been obtained in the reverse current and the I(V) characteristics were governed by the porous Si/Si heterojunction. The C(V) measurement was performed at different frequencies and revealed that the capacitance behavior was typical of material with interface states. The density of interface states was found to vary from 2 Multiplication-Sign 10{sup 10} eV{sup -1}cm{sup -2} to 1.1 Multiplication-Sign 10{sup 11} eV{sup -1}cm{sup -2} as a function of the interface states energy level position in the band gap of the porous silicon.

  18. Analysis of the High Conversion Efficiencies β-FeSi2 and BaSi2 n-i-p Thin Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Jung-Sheng Huang

    2014-01-01

    Full Text Available Both β-FeSi2 and BaSi2 are silicides and have large absorption coefficients; thus they are very promising Si-based new materials for solar cell applications. In this paper, the dc I-V characteristics of n-Si/i-βFeSi2/p-Si and n-Si/i-BaSi2/p-Si thin film solar cells are investigated by solving the charge transport equations with optical generations. The diffusion current densities of free electron and hole are calculated first. Then the drift current density in the depletion regions is obtained. The total current density is the sum of diffusion and drift current densities. The conversion efficiencies are obtained from the calculated I-V curves. The optimum conversion efficiency of n-Si/i-βFeSi2/p-Si thin film solar cell is 27.8% and that of n-Si/i-BaSi2/p-Si thin film solar cell is 30.4%, both are larger than that of Si n-i-p solar cell (η is 20.6%. These results are consistent with their absorption spectrum. The calculated conversion efficiency of Si n-i-p solar cell is consistent with the reported researches. Therefore, these calculation results are valid in this work.

  19. MICROSTRUCTURAL ANALYSIS OF Al-Mg-Si-Zn ALLOY

    Directory of Open Access Journals (Sweden)

    SERGIO VALADEZ

    2010-01-01

    Full Text Available En un esfuerzo por desarrollar una nueva aleación con aplicación estructural, se ha desarrollado una aleación base Aluminio aleada con magnesio, silicio y zinc. La investigación pretende correlacionar la microestructura y con el tratamiento térmico. La aleación AlMgSiZn, fue elegida para ese propósito debido a la presencia de precipitados tanto en la matriz del aAl, como en los límites de grano, los cuales permiten una excelente relación entre la dureza y la resistencia mecánica. En lo que respecta a la microestructura, esta fue caracterizada bajo condición de colada y después de ser tratada térmicamente por envejecimiento. Este tratamiento fue realizado en dos etapas, la primera a 450ºC durante 3 horas que corresponde al tratamiento de homogeneización: y la segunda al proceso de envejecimiento artificial llevado a cabo a 160ºC durante 1hr. Los resultados indican la presencia de dendritas de aAl, además un eutéctico binario y partículas de Mg7Zn3 adentro de las regiones interdendríticas. El eutéctico y las partículas fueron modificados por el tratamiento de envejecido. Las observaciones realizadas con el microscopio electrónico de transmisión en especímenes con y sin tratamientos térmicos, demostraron una distribución uniforme de precipitados con diversas morfologías, tales como cúbico, esférico y plaqueta: para la matriz de aAl, los cuales no fueron detectados durante las observaciones en el microscopio electrónico de barrido.

  20. Visible and IR photoluminescence of c-FeSi@a–Si core–shell nano-fibres produced by vapour transport

    Energy Technology Data Exchange (ETDEWEB)

    Thabethe, Sibongiseni [DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001 (South Africa); Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Linganiso, Ella; Motaung, David; Mashapa, Matete G.; Nkosi, Steven [DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001 (South Africa); Arendse, Christopher J. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Mwakikunga, Bonex W., E-mail: bmwakikunga@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, PO Box 395, Pretoria 0001 (South Africa); Department of Physics and Biochemical Sciences, University of Malawi, The Polytechnic, Private Bag 303, Chichiri, Blantyre 3 (Malawi)

    2013-11-15

    The procedures for the synthesis of amorphous ε-FeSi/Si core–shell nanofibres by vapour transport in a CVD configuration are reported. Crystallite studies by the Williamson-Hall method show the sizes to be typically about 8.0 nm which agrees with TEM value of 7.9 nm fibre diameter with a compressive strain of about 0.04. Features in the photoluminescence of these FeSi core–shells in both visible and IR are at 410 nm, 1062 nm, 1414 nm and 1772 nm and absorption feature at 1000 cm{sup −1} from FTIR are explained from density functional theory (DFT) ab initio calculations. PL confirms the intra-band transition whereas FTIR agrees perfectly with the band-to-band transition whose band gap energy is 0.13 eV for FeSi. FTIR also unveils inter-band transition which DFT calculation could not predict. Raman spectroscopy data confirm FeSi and nano-Si presence. -- Highlights: • New PL data has been obtained for the c-FeSi@a–Si nano-fibres in the range (0.7–3.1 eV). • FTIR unveils the band-to-band transition within this narrow band gap FeSi. • The new data are explained through electronic energy band structure and density of states of FeSi. • Intra-band transitions as well as quantum confinement are responsible for blue shifts.

  1. Solid-state {sup 27}Al and {sup 29}Si NMR investigations on Si-substituted hydrogarnets

    Energy Technology Data Exchange (ETDEWEB)

    Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Pena, P. [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)]. E-mail: ppena@icv.csic.es; Aza, A.H. de [Instituto de Ceramica y Vidrio, CSIC, Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, CSIC, Serrano Galvache, 4, 28033 Madrid (Spain); Sobrados, I. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain); Sanz, J. [Instituto de Ciencia de Materiales, CSIC, Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

    2007-02-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} hydrates prepared by a reaction in the presence of D{sub 2}O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by {sup 29}Si and {sup 27}Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The {sup 29}Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x} was followed by {sup 27}Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.

  2. Size dependent structural, vibrational and magnetic properties of BiFeO3 and core-shell structured BiFeO3@SiO2 nanoparticles

    International Nuclear Information System (INIS)

    Chauhan, Sunil; Kumar, Manoj; Chhoker, Sandeep; Katyal, S. C.

    2014-01-01

    Bulk BiFeO 3 , BiFeO 3 nanoparticles and core-shell structured BiFeO 3 @SiO 2 nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO 2 shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO 3 @SiO 2 nanoparticles with BiFeO3 core ∼50-90 nm and SiO 2 shell ∼16 nm. X-ray diffraction and FTIR spectroscopy results showed the presence of distorted rhombohedral structure with R3c space group in all three samples. The magnetic measurement indicated the existence of room-temperature weak ferromagnetism in core-shell BiFeO 3 @SiO 2 nanoparticles and BiFeO3 nanoparticles, whereas bulk BiFeO 3 showed antiferromagnteic nature. Electron Spin Resonance results confirmed the enhancement in magnetic properties of coreshell structured BiFeO 3 @SiO 2 nanoparticles in comparison with BiFeO 3 nanoparticles and bulk BiFeO 3

  3. Ultra-reduced phases in Apollo 16 regolith: Combined field emission electron probe microanalysis and atom probe tomography of submicron Fe-Si grains in Apollo 16 sample 61500

    Science.gov (United States)

    Gopon, Phillip; Spicuzza, Michael J.; Kelly, Thomas F.; Reinhard, David; Prosa, Ty J.; Fournelle, John

    2017-09-01

    The lunar regolith contains a variety of chemically reduced phases of interest to planetary scientists and the most common, metallic iron, is generally ascribed to space weathering processes (Lucey et al. ). Reports of silicon metal and iron silicides, phases indicative of extremely reducing conditions, in lunar samples are rare (Anand et al. ; Spicuzza et al. ). Additional examples of Fe-silicides have been identified in a survey of particles from Apollo 16 sample 61501,22. Herein is demonstrated the utility of low keV electron probe microanalysis (EPMA), using the Fe Ll X-ray line, to analyze these submicron phases, and the necessity of accounting for carbon contamination. We document four Fe-Si and Si0 minerals in lunar regolith return material. The new Fe-Si samples have a composition close to (Fe,Ni)3Si, whereas those associated with Si0 are close to FeSi2 and Fe3Si7. Atom probe tomography of (Fe,Ni)3Si shows trace levels of C (60 ppma and nanodomains enriched in C, Ni, P, Cr, and Sr). These reduced minerals require orders of magnitude lower oxygen fugacity and more reducing conditions than required to form Fe0. Documenting the similarities and differences in these samples is important to constrain their formation processes. These phases potentially formed at high temperatures resulting from a meteorite impact. Whether carbon played a role in achieving the lower oxygen fugacities—and there is evidence of nearby carbonaceous chondritic material—it remains to be proven that carbon was the necessary component for the unique existence of these Si0 and iron silicide minerals.

  4. Structural and magnetic stability of Fe{sub 2}NiSi

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dinesh C., E-mail: idu.idris@gmail.com; Bhat, Idris Hamid, E-mail: idu.idris@gmail.com; Chauhan, Mamta, E-mail: idu.idris@gmail.com [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior - 474011 (India)

    2014-04-24

    Full-potential ab-initio calculations in the stable F-43m phase have been performed to investigate the structural and magnetic properties of Fe{sub 2}NiSi inverse Heusler alloys. The spin magnetic moment distributions show that present material is ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancy in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. It is found that the main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for present alloy.

  5. Enhancing Corrosion and Wear Resistance of AA6061 by Friction Stir Processing with Fe78Si9B13 Glass Particles

    Directory of Open Access Journals (Sweden)

    Lingyu Guo

    2015-08-01

    Full Text Available The AA6061-T6 aluminum alloy samples including annealed Fe78Si9B13 particles were prepared by friction stir processing (FSP and investigated by various techniques. The Fe78Si9B13-reinforced particles are uniformly dispersed in the aluminum alloy matrix. The XRD results indicated that the lattice parameter of α-Al increases and the preferred orientation factors F of (200 plane of α-Al reduces after friction stir processing. The coefficient of thermal expansion (CTE for FSP samples increases at first with the temperature but then decreases as the temperature further increased, which can be explained by the dissolving of Mg and Si from β phase and Fe78Si9B13 particles. The corrosion and wear resistance of FSP samples have been improved compared with that of base metal, which can be attributed to the reduction of grain size and the CTE mismatch between the base metal and reinforced particles by FSP, and the lubrication effect of Fe78Si9B13 particles also plays a role in improving wear resistance. In particular, the FSP sample with reinforced particles in amorphous state exhibited superior corrosion and wear resistance due to the unique metastable structure.

  6. Increasing strength of a biomedical Ti-Nb-Ta-Zr alloy by alloying with Fe, Si and O.

    Science.gov (United States)

    Stráský, Josef; Harcuba, Petr; Václavová, Kristína; Horváth, Klaudia; Landa, Michal; Srba, Ondřej; Janeček, Miloš

    2017-07-01

    Low-modulus biomedical beta titanium alloys often suffer from low strength which limits their use as load-bearing orthopaedic implants. In this study, twelve different Ti-Nb-Zr-Ta based alloys alloyed with Fe, Si and O additions were prepared by arc melting and hot forging. The lowest elastic modulus (65GPa) was achieved in the benchmark TNTZ alloy consisting only of pure β phase with low stability due to the 'proximity' to the β to α'' martensitic transformation. Alloying by Fe and O significantly increased elastic modulus, which correlates with the electrons per atom ratio (e/a). Sufficient amount of Fe/O leads to increased yield stress, increased elongation to fracture and also to work hardening during deformation. A 20% increase in strength and a 20% decrease in the elastic modulus when compared to the common Ti-6Al-4V alloy was achieved in TNTZ-Fe-Si-O alloys, which proved to be suitable for biomedical use due to their favorable mechanical properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Production of Al-Si-Fe-Xalloys by Powder Mettalurgy

    Czech Academy of Sciences Publication Activity Database

    Školáková, A.; Novák, P.; Vojtěch, D.; Kubatík, Tomáš František

    2014-01-01

    Roč. 14, č. 3 (2014), s. 437-441 ISSN 1213-2489. [Mezinárodní konference „Mikroskopie a nedestruktivní zkoušení materiálů/3./. Litoměřice, 22.10.2014-24.10.2014] Institutional support: RVO:61389021 Keywords : Aluminium alloys * powder metallurgy * NiTi * mechanical alloying * reactive sintering Subject RIV: JG - Metallurgy http://journal.strojirenskatechnologie.cz/templates/obalky_casopis/XIV_2014-3.pdf

  8. CHARACTERIZATION OF PHASES IN SECONDARY AlZn10Si8Mg CAST ALLOY

    Directory of Open Access Journals (Sweden)

    Eva Tillová

    2011-04-01

    Full Text Available Using recycled aluminium cast alloys is profitable in many aspects. Requiring only 5 % of the energy to produce secondary metal as compared to primary metal and generates only 5 % of the green house gas emissions, the recycling of aluminium is therefore beneficial of both environmental and economical point of view. Secondary AlZn10Si8Mg (UNIFONT® - 90 cast alloy are used for engine and vehicle constructions, hydraulic unit and mouldmaking without heat treatment. Properties include good castability, very good mechanical strength and elongation, light weight, good wear resistance, low thermal expansion and very good machining. Improved mechanical properties are strongly dependent upon the morphologies, type and distribution of the secondary phases, which are in turn a function of alloy composition and cooling rate. The presence of additional elements as Mg, Mn, Fe, or Cu allows many complex intermetallic phases to form, which make characterisation non-trivial. These include, for example, Mg2Si, Al2CuMg and AlFeMn phases, all of which may have some solubility for additional elements. Phase’s identification in aluminium alloys is often non-trivial due to the fact that some of the phases have either similar crystal structures or only subtle changes in their chemistries. A combination different analytical techniques (light microscopy upon black-white and colour etching, scanning electron microscopy (SEM upon deep etching, energy dispersive X-ray analysis (EDX and HV 0.01 microhardness measurement were therefore been used for the identification of the various phase.

  9. Investigation of the 600 C isothermal section of the Fe-Al-Ce ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huiyun; Yin, Fucheng [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Li, Zhi [Xiangtan Univ., Hunan (China). School of Materials Science and Engineering; Xiangtan Univ., Hunan (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province; Xiangtan Univ., Hunan (China). Key Laboratory of Key Film Materials and Application for Equipment (Hunan province); Ji, Li [South China University of Technology, Guangdong (China). School of Materials Science and Engineering

    2017-01-15

    The isothermal section of the Fe-Al-Ce system at 600 C was determined by means of scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray powder diffraction. Twenty three-phase regions were confirmed experimentally, and two three-phase regions could be deduced in this section. Five ternary compounds, i. e., τ{sub 1}, τ{sub 2}, τ{sub 3}, τ{sub 5}, and τ{sub 6}, exist at 600 C. The Fe{sub 2}Ce phase contains 6.6 at.% Al in the Fe-Al-Ce system. The Fe solubility in α-Al, αAl{sub 11}Ce{sub 3}, αAl{sub 3}Ce, Al{sub 2}Ce, AlCe, and AlCe{sub 3} is approximately 1.7 at.%, 1.1 at.%, 1.2 at.%, 1.3 at.%, 5.8 at.%, and 0.1 at.%, respectively, and the solubility of Ce in α-Al, FeAl{sub 3}, Fe{sub 2}Al{sub 5}, FeAl{sub 2}, and FeAl is approximately 0.1 at.%, 1.2 at.%, 1.9 at.%, 0.9 at.%, and 3.7 at.%, respectively.

  10. Study on Microstructure and Mechanical Properties of Hypereutectic Al-18Si Alloy Modified with Al-3B.

    Science.gov (United States)

    Gong, Chunjie; Tu, Hao; Wu, Changjun; Wang, Jianhua; Su, Xuping

    2018-03-20

    An hypereutectic Al-18Si alloy was modified via an Al-3B master alloy. The effect of the added Al-3B and the modification temperature on the microstructure, tensile fracture morphologies, and mechanical properties of the alloy were investigated using an optical microscope, Image-Pro Plus 6.0, a scanning electron microscope, and a universal testing machine. The results show that the size of the primary Si and its fraction decreased at first, and then increased as an additional amount of Al-3B was added. When the added Al-3B reached 0.2 wt %, the fraction of the primary Si in the Al-18Si alloy decreased with an increase in temperature. Compared with the unmodified Al-18Si alloy, the tensile strength and elongation of the alloy modified at 850 °C with 0.2 wt % Al-3B increased by 25% and 81%, respectively. The tensile fracture of the modified Al-18Si alloy exhibited partial ductile fracture characteristics, but there were more areas with ductile characteristics compared with that of the unmodified Al-18Si alloy.

  11. A study on the microstructural characteristics of rapidly solidified Al-Fe alloys(I)

    International Nuclear Information System (INIS)

    Kim, D.H.; Lee, H.I.

    1991-01-01

    Solidification microstructures and phases in rapidly solidified Al-5, 10wt% Fe alloys have been investigated by TEM bright field and dark field imaging techniques and electron and x-ray diffraction techniques. Rapid solidification of Al-5, 10wt%Fe alloys produces various metastable and stable phases, such as Al m Fe, Al 6 Fe and Al 13 Fe 4 . In addition to these phases, clusters of randomly oriented few nm scale particles exist in the form of fine cellular network with α-Al or primary spherical particles. Solidification microstructures of the rapidly solidified Al-5, 10wt%Fe alloys consist of various combination of primary phases such as Al 13 Fe 4 , Al m Fe and cluster of nm scale particles, and cellular/dendritic structures such as fine cellular network structure of nm scale particle clusters and α-Al and cellular structure of Al m Fe and α-Al, depending upon alloy compositions and local cooling rates. (Author)

  12. Coarsening kinetics of coherent precipitates in Ni-Al-Mo and Fe-Ni-Al alloys

    International Nuclear Information System (INIS)

    Calderon, H.A.; Dorantes, H.J.; Cruz, J.J.; Cabanas-Moreno, J.G.

    1997-01-01

    The late stage coarsening kinetics of coherent γ' and β' have been investigated in single crystalline specimens of Ni-14.5 at.% Al-5.9 at.% Mo and Fe-10 at.% Ni-15 at.% Al after aging at 1453 K for the Ni alloy and 1233 K for the Fe alloy. Scanning electron microscopy (SEM) shows that early in the coarsening regime there is particle splitting in the Ni-base alloy. Continued aging changes the spatial distribution of particles giving rise to the formation of groups of many particles. In the Fe-base alloy, formation of particle groups is seen earlier. Longer aging treatments produce large particles that split forming plate like precipitates. Particle migration is evident in both alloys. The coarsening kinetics of particles in the Ni-base alloy show deviations from the usual linear behavior between the cube of the average particle radius and the aging time. There is a reduction of the coarsening rate and in addition broader particle size distributions are obtained. In the Fe-base alloy, direct measurements of particle areas on SEM images show a linear dependence of the cube of the average particle radius with the aging time. However, after correcting for particle shape an increase of the coarsening rate is suggested. (orig.)

  13. Coarsening kinetics of coherent precipitates in Ni-Al-Mo and Fe-Ni-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, H.A.; Dorantes, H.J.; Cruz, J.J.; Cabanas-Moreno, J.G. [ESIQIE-IPN, Mexico (Mexico). Dept. de Ingenieria Metalurgica; Kostorz, G.; Qu, Y.Y. [ETH Zuerich, Institut fuer Angewandte Physik, Zuerich CH-8093 (Switzerland)

    1997-10-30

    The late stage coarsening kinetics of coherent {gamma}` and {beta}` have been investigated in single crystalline specimens of Ni-14.5 at.% Al-5.9 at.% Mo and Fe-10 at.% Ni-15 at.% Al after aging at 1453 K for the Ni alloy and 1233 K for the Fe alloy. Scanning electron microscopy (SEM) shows that early in the coarsening regime there is particle splitting in the Ni-base alloy. Continued aging changes the spatial distribution of particles giving rise to the formation of groups of many particles. In the Fe-base alloy, formation of particle groups is seen earlier. Longer aging treatments produce large particles that split forming plate like precipitates. Particle migration is evident in both alloys. The coarsening kinetics of particles in the Ni-base alloy show deviations from the usual linear behavior between the cube of the average particle radius and the aging time. There is a reduction of the coarsening rate and in addition broader particle size distributions are obtained. In the Fe-base alloy, direct measurements of particle areas on SEM images show a linear dependence of the cube of the average particle radius with the aging time. However, after correcting for particle shape an increase of the coarsening rate is suggested. (orig.) 19 refs.

  14. Bonding of WC with an iron aluminide (FeAl) intermetallic

    Energy Technology Data Exchange (ETDEWEB)

    Schneibel, J.H.; Subramanian, R.

    1996-08-01

    FeAl, which has high oxidation and sulfidation resistance, was shown to be thermodynamically compatible with WC. Calculations indicate that soly. of WC in liq. Fe-40at.%Al at 1450 C is about 2 at.%. Since liquid FeAl wets WC very well, the WC/FeAl system lends itself to liquid-phase sintering, resulting in close to theoretical densities. Almost fully dense cermets with 20.6 wt% FeAl binder were produced. With one-step infiltration, 98% dense cermets with only 7 wt% FeAl binder were fabricated. RT bend strengths and fracture toughness for WC-20.6 wt% FeAl reached 1680 MPa and 22 MPa{center_dot}m{sup 1/2}. Ductile binder fracture was observed on the fracture surfaces. Pores containing oxide inclusions were found, suggesting that improvements in processing are likely to further improve the mechanical properties. Insufficient process control may explain why WC/FeAlNi cermets did not show improved mechanical properties, although Ni strengthens FeAl. For WC bonded with FeAl, mechanical properties were measured at RT and 800 C. Bend strengths at 800 C in air increased with WC volume fraction, and fracture toughness were higher than at RT.

  15. Investigation of the Lattice Dynamics of α-Fe and Fe3al by Neutron Inelastic Scattering. RCN Report

    International Nuclear Information System (INIS)

    Dijk, C. van

    1970-09-01

    This report describes the study of the lattice dynamics of α-Fe and ordered Fe 3 Al by means of inelastic neutron scattering using a triple-axis crystal spectrometer. Detailed phonon dispersion relations both for α-Fe and Fe 3 Al are presented. A Born-von Kármán model is used to analyse the experimental data. For α-Fe interactions out to fifth neighbours are included, while for Fe 3 Al interactions out to third neighbours are taken into account. The obtained force constants are used for the calculation of the frequency distribution functions, from which related thermodynamic quantities and Debye temperatures are deduced. The analysis of the lattice dynamics of the more complex system of Fe 3 Al was facilitated by a group-theoretical treatment. The blocks for the different irreducible representations of the block-diagonalised dynamical matrix together with their symmetry adapted eigenvectors are presented. Reduced inelastic structure factors are given for normal modes in the symmetry directions. From the force constants for ordered FegAl values for those of partly disordered (CsCl-type) Fe 3 Al were estimated. The latter were used for the calculation of phonon dispersion relations, frequency distribution functions and some other related properties. (author)

  16. High-Temperature Corrosion of AlCrSiN Film in Ar-1%SO2 Gas

    Directory of Open Access Journals (Sweden)

    Poonam Yadav

    2017-03-01

    Full Text Available AlCrSiN film with a composition of 29.1Al-17.1Cr-2.1Si-51.7N in at. % was deposited on a steel substrate by cathodic arc ion plating at a thickness of 1.8 μm. It consisted of nanocrystalline hcp-AlN and fcc-CrN, where a small amount of Si was dissolved. Corrosion tests were carried out at 800 °C for 5–200 h in Ar-1%SO2 gas. The major corrosion reaction was oxidation owing to the high oxygen affinity of Al and Cr in the film. The formed oxide scale consisted primarily of (Al,Cr2O3, within which Fe, Si, and S were dissolved. Even after corrosion for 200 h, the thickness of the scale was about 0.7–1.2 μm, indicating that the film had good corrosion resistance in the SO2-containing atmosphere.

  17. The Co-60 gamma-ray irradiation effects on the Al/HfSiO4/p-Si/Al MOS capacitors

    Science.gov (United States)

    Lok, R.; Kaya, S.; Karacali, H.; Yilmaz, E.

    2017-12-01

    In this work, the initial interface trap density (Nit) to examine device compability for microelectronics and then the Co-60 gamma irradiation responses of Al/HfSiO4/p-Si/Al (MOS) capacitors were investigated in various dose ranges up to 70 Gy. Pre-irradiation response of the devices was evaluated from high frequency (HF) and low frequency (LF) capacitance method and the Nit was calculated as 9.91 × 1011 cm-2 which shows that the HfSiO4/p-Si interface quality is convenient for microelectronics applications. The irradiation responses of the devices were carried out from flat-band and mid-gap voltage shifts obtained from stretch of capacitance characteristics prior to and after irradiation. The results show that the flat band voltages very slightly shifted to positive voltage values demonstrating the enhancement of negative charge trapping in device structure. The sensitivity of the Al/HfSiO4/p-Si/Al MOS capacitors was found to be 4.41 mV/Gy for 300 nm-thick HfSiO4 gate dielectrics. This value approximately 6.5 times smaller compared to the same thickness conventional SiO2 based MOS devices. Therefore, HfSiO4 exhibits crucial irradiation tolerance in gamma irradiation environment. Consequently, HfSiO4 dielectrics may have significant usage for microelectronic technology as a radiation hard material where radiation field exists such as in space applications.

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

    Science.gov (United States)

    Alyaldin, Loay

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

  19. Structure and wear behavior of AlCrSiN-based coatings

    Science.gov (United States)

    Chen, Yun; Du, Hao; Chen, Ming; Yang, Jun; Xiong, Ji; Zhao, Haibo

    2016-05-01

    AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC-Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N2 mixtures. Al0.6Cr0.4, Al0.6Cr0.3Si0.1, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiNx peak were formed in the AlCrSiN/MexN coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H3/E2 ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  20. Influence of substrate treatment on the growth of advanced core–shell alloys and compounds of FeSi@SiO2 and SiO2 nanowires

    CSIR Research Space (South Africa)

    Thabethe, S

    2014-12-01

    Full Text Available stream_source_info Thabethe_2014_ABSTRACT ONLY.pdf.txt stream_content_type text/plain stream_size 1199 Content-Encoding UTF-8 stream_name Thabethe_2014_ABSTRACT ONLY.pdf.txt Content-Type text/plain; charset=UTF-8 Journal... of Alloys and Compounds 616 (2014) 221–226 Influence of substrate treatment on the growth of advanced core–shell alloys and compounds of FeSi@SiO2 and SiO2 nanowires Sibongiseni Thabethe a,b, Christopher J. Arendse b, Bonex W. Mwakikunga a,c, a...

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

    Directory of Open Access Journals (Sweden)

    Ahmed M. Nabawy

    2016-05-01

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

  2. Formation of metastable phases and nanocomposite structures in rapidly solidified Al-Fe alloys

    International Nuclear Information System (INIS)

    Nayak, S.S.; Chang, H.J.; Kim, D.H.; Pabi, S.K.; Murty, B.S.

    2011-01-01

    Highlights: → Structures of nanocomposites in rapidly solidified Al-Fe alloys were investigated. → Nanoquasicrystalline, amorphous and intermetallics phases coexist with α-Al. → Nanoquasicrystalline phase was observed for the first time in the dilute Al alloys. → Thermodynamic driving force plays dominant role in precipitation of Fe-rich phases. → High hardness (3.57 GPa) was observed for nanocomposite of Al-10Fe alloy. - Abstract: In the present work the structure and morphology of the phases of nanocomposites formed in rapidly solidified Al-Fe alloys were investigated in details using analytical transmission electron microscopy and X-ray diffraction. Nanoquasicrystalline phases, amorphous phase and intermetallics like Al 5 Fe 2 , Al 13 F 4 coexisted with α-Al in nanocomposites of the melt spun alloys. It was seen that the Fe supersaturation in α-Al diminished with the increase in Fe content and wheel speed indicating the dominant role of the thermodynamic driving force in the precipitation of Fe-rich phases. Nanoquasicrystalline phases were observed for the first time in the dilute Al alloys like Al-2.5Fe and Al-5Fe as confirmed by high resolution TEM. High hardness (3.57 GPa) was measured in nanocomposite of Al-10Fe alloy, which was attributed to synergistic effect of solid solution strengthening due to high solute content (9.17 at.% Fe), dispersion strengthening by high volume fraction of nanoquasicrystalline phase; and Hall-Petch strengthening from finer cell size (20-30 nm) of α-Al matrix.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-01-01

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

  4. A new technique to modify hypereutectic Al-24%Si alloys by a Si-P master alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yaping; Wang Shujun; Li Hui [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

    2009-05-27

    The modification effect of a Si-P master alloy on Al-24%Si alloy was investigated by using electron probe micro-analyzer (EPMA) and optical microscopy (OM). The dissolution problem of the Si-P master alloys was solved by changing the sequence of addition. When the Si-P master alloy was added into Al melt before the addition of silicon, the best modification effect could be achieved. The modification parameters of the master alloy on Al-24%Si alloy were optimized through designing and analyzing the orthogonal experiment, and their influences on the modification effect were discussed. The results show that the influence of temperature on the modification effect is the greatest, followed by the addition level, and the holding time is the least. The optimized modification parameters are the modification temperature of 810 deg. C, the addition level of 0.35 wt.%, the holding time of 30 min + 50 min whose meaning is that the Si-P master alloy is added firstly to the molten Al, and silicon is added 30 min later, then holding another 50 min. In addition, the modification mechanism of the Si-P master alloy on Al-24%Si alloy was also discussed.

  5. Positron annihilation studies of the AlOx/SiO2/Si interface in solar cell structures

    Science.gov (United States)

    Edwardson, C. J.; Coleman, P. G.; Li, T.-T. A.; Cuevas, A.; Ruffell, S.

    2012-03-01

    Film and film/substrate interface characteristics of 30 and 60 nm-thick AlOx films grown on Si substrates by thermal atomic layer deposition (ALD), and 30 nm-thick AlOx films by sputtering, have been probed using variable-energy positron annihilation spectroscopy (VEPAS) and Doppler-broadened spectra ratio curves. All samples were found to have an interface which traps positrons, with annealing increasing this trapping response, regardless of growth method. Thermal ALD creates an AlOx/SiOx/Si interface with positron trapping and annihilation occurring in the Si side of the SiOx/Si boundary. An induced positive charge in the Si next to the interface reduces diffusion into the oxides and increases annihilation in the Si. In this region there is a divacancy-type response (20 ± 2%) before annealing which is increased to 47 ± 2% after annealing. Sputtering seems to not produce samples with this same electrostatic shielding; instead, positron trapping occurs directly in the SiOx interface in the as-deposited sample, and the positron response to it increases after annealing as an SiO2 layer is formed. Annealing the film has the effect of lowering the film oxygen response in all film types. Compared to other structural characterization techniques, VEPAS shows larger sensitivity to differences in film preparation method and between as-deposited and annealed samples.

  6. AES study of the reaction between a thin Fe-film and β-SiC (100) surface

    International Nuclear Information System (INIS)

    Mizokawa, Yusuke; Nakanishi, Shigemitsu; Miyase, Sunao

    1989-01-01

    The solid state reaction between thin Fe-films and β-SiC(100) in UHV has been studied using AES. Even at room temperature, the reaction between the thin Fe-film and SiC occurred and formed Fe-silicide and graphite with a minor product of Fe-carbide (Fe 3 C). The reaction proceeded with an increase of Fe-coverage to some extent. With annealing of 15 A-Fe-film/SiC below 540degC, the Fe-silicide formation was accelerated, but because the amount of available Fe was small, the dissolved carbon atoms were forced to form not the Fe-carbide but the graphite phase. Above 640degC, the Fe-silicide started to decompose and the carbon atoms diffused to the surface and formed surface graphite layers. With annealing at 1080degC, the free-Si segregats at the surface and formed Si-Si bonds, as well as the Si-C bonds consuming the surface graphite phase. (author)

  7. Microstructure and magnetic properties of FePt:Ag nanocomposite films on SiO2/Si(1 0 0)

    International Nuclear Information System (INIS)

    Wang Hao; Yang, F.J.; Wang, H.B.; Cao, X.; Xue, S.X.; Wang, J.A.; Gao, Y.; Huang, Z.B.; Yang, C.P.; Chiah, M.F.; Cheung, W.Y.; Wong, S.P.; Li, Q.; Li, Z.Y.

    2006-01-01

    FePt:Ag nanocomposite films were prepared by pulsed filtered vacuum arc deposition system and subsequent rapid thermal annealing on SiO 2 /Si(1 0 0) substrates. The microstructure and magnetic properties were investigated. A strong dependence of coercivity and ordering of the face-central tetragonal structure on both Ag concentration and annealing temperature was observed. With Ag concentration of 22% in atomic ratio, the coercivity got to 6.0 kOe with a grain size of 6.7 nm when annealing temperature was 400 deg. C

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

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Choonho [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Morphological evolution and selection of angular primary silicon is investigated in near-eutectic Al-Si alloys. Angular silicon arrays are grown directionally in a Bridgman furnace at velocities in the regime of 10-3 m/sec and with a temperature gradient of 7.5 x 103 K/m. Under these conditions, the primary Si phase grows as an array of twinned bicrystalline dendrites, where the twinning gives rise to a characteristic 8-pointed star-shaped primary morphology. While this primary Si remains largely faceted at the growth front, a complex structure of coherent symmetric twin boundaries enables various adjustment mechanisms which operate to optimize the characteristic spacings within the primary array. In the work presented here, this primary silicon growth morphology is examined in detail. In particular, this thesis describes the investigation of: (1) morphological selection of the twinned bicrystalline primary starshape morphology; (2) primary array behavior, including the lateral propagation of the starshape grains and the associated evolution of a strong <100> texture; (3) the detailed structure of the 8-pointed star-shaped primary morphology, including the twin boundary configuration within the central core; (4) the mechanisms of lateral propagation and spacing adjustment during array evolution; and (5) the thermosolutal conditions (i.e. operating state) at the primary growth front, including composition and phase fraction in the vicinity of the primary tip.

  9. Study of Ni/Si(1 0 0) solid-state reaction with Al addition

    International Nuclear Information System (INIS)

    Huang Yifei; Jiang Yulong; Ru Guoping; Li Bingzong

    2008-01-01

    The characteristics of Ni/Si(1 0 0) solid-state reaction with Al addition (Ni/Al/Si(1 0 0), Ni/Al/Ni/Si(1 0 0) and Al/Ni/Si(1 0 0)) is studied. Ni and Al films were deposited on Si(1 0 0) substrate by ion beam sputtering. The solid-state reaction between metal films and Si was performed by rapid thermal annealing. The sheet resistance of the formed silicide film was measured by four-point probe method. The X-ray diffraction (XRD) was employed to detect the phases in the silicide film. The Auger electron spectroscopy was applied to reveal the element profiles in depth. The influence of Al addition on the Schottky barrier heights of the formed silicide/Si diodes was investigated by current-voltage measurements. The experimental results show that NiSi forms even with the addition of Al, although the formation temperature correspondingly changes. It is revealed that Ni silicidation is accompanied with Al diffusion in Ni film toward the film top surface and Al is the dominant diffusion species in Ni/Al system. However, no Ni x Al y phase is detected in the films and no significant Schottky barrier height modulation by the addition of Al is observed

  10. Formation of Fe2SiO4 thin films on Si substrates and influence of substrate to its thermoelectric transport properties

    Science.gov (United States)

    Choi, Jeongyong; Nguyen, Van Quang; Duong, Van Thiet; Shin, Yooleemi; Duong, Anh Tuan; Cho, Sunglae

    2018-03-01

    Fe2SiO4 thin films have been grown on n-type, p-type and semi-insulating Si(100) substrates by molecular beam epitaxy. When Fe-O thin films were deposited on Si(100) substrate at 300 °C, the film reacted with Si, resulting in a Fe2SiO4 film because of the high reactivity between Fe and Si. The electrical resistance and Seebeck coefficient of Fe2SiO4 thin films grown were different in different doping states. On n-type and p-type Si(100), the electrical resistance decreased suddenly and increased again at 350 and 250 K, respectively, while on semi-insulating Si(100), it exhibited typical semiconducting resistance behavior. We observed similar crossovers at 350 and 250 K in temperature dependent Seebeck coefficients on n-type and p-type Si(100), respectively. These results suggest that the measured electrical and thermoelectric properties originate from Si substrate.

  11. Spin correlations in (Mn,Fe2(P,Si magnetocaloric compounds above Curie temperature

    Directory of Open Access Journals (Sweden)

    X.F. Miao

    2016-06-01

    Full Text Available The longitudinal-field muon-spin relaxation (LF-μSR technique was employed to study the spin correlations in (Mn,Fe2(P,Si compounds above the ferromagnetic transition temperature (TC. The (Mn,Fe2(P,Si compound under study is found to show itinerant magnetism. The standard deviation of the magnetic field distribution of electronic origin increases with a decrease in temperature, which is attributed to the development of spin correlations. The anomalously low magnetic fluctuation rate is suggested to be another signature of the spin correlations. The development of pronounced magnetic fluctuations is in agreement with the observed deviation of the paramagnetic susceptibility from Curie–Weiss behavior. Our study sheds light on the magneto-elastic transition and the mixed magnetism in (Mn,Fe2(P,Si compounds.

  12. Stresses related to the shape memory effect in Fe-Mn-Si-based shape memory alloys

    International Nuclear Information System (INIS)

    Caenegem, N. van; Duprez, L.; Verbeken, K.; Segers, D.; Houbaert, Y.

    2008-01-01

    The shape memory behaviour of two Fe-Mn-Si-based alloys has been investigated. Two compositions were studied, i.e. Fe29Mn7Si and Fe29Mn7Si5Cr (numbers indicate mass%). Characterizations of the martensitic transformation and the different structural constituents were performed using optical microscopy and X-ray diffraction methods. Transformation temperatures were determined by thermodilatometry on undeformed and deformed samples. The shape recovery was quantified by means of bending tests and dilatometry experiments on compressed samples. A procedure was designed to measure the recovery stresses caused by the dimensional changes of the sample due to the shape memory effect. The recovery stress is defined as the stress that is generated when the recovery of deformation is impeded under constraint. The mechanical results are discussed on the basis of the underlying transformation and deformation processes

  13. Lattice anharmonicity and thermal properties of strongly correlated Fe1- x Co x Si alloys

    Science.gov (United States)

    Povzner, A. A.; Nogovitsyna, T. A.; Filanovich, A. N.

    2015-10-01

    The temperature dependences of the thermal and elastic properties of strongly correlated metal alloys Fe1- x Co x Si ( x = 0.1, 0.3, 0.5) with different atomic chiralities have been calculated in the framework of the self-consistent thermodynamic model taking into account the influence of lattice anharmonicity. The lattice contributions to the heat capacity and thermal expansion coefficient of the alloys have been determined using the experimental data. It has been demonstrated that the invar effect in the thermal expansion of the lattice observed in the magnetically ordered region of Fe0.7Co0.3Si and Fe0.5Co0.5Si is not related to the lattice anharmonicity, even though its appearance correlates with variations in the atomic chirality.

  14. A Comparative Study of Carbon Nanotubes Synthesized from Co/Zn/Al and Fe/Ni/Al Catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel Dixon Dikio

    2011-01-01

    Full Text Available The catalyst systems Fe/Ni/Al and Co/Zn/Al were synthesized and used in the synthesis of carbon nanotubes. The carbon nanotubes produced were characterized by Field Emission Scanning Electron Microscope (FE-SEM, Energy Dispersive x-ray Spectroscopy (EDS, Raman spectroscopy, Thermogravimetric Analysis (TGA and Transmission Electron Microscope (TEM. A comparison of the morphological profile of the carbon nanotubes produced from these catalysts indicates the catalyst system Fe/Ni/Al to have produced higher quality carbon nanotubes than the catalyst system Co/Zn/Al.

  15. Annealing Behavior of Al-Implantation-Induced Disorder in 4H-SiC

    International Nuclear Information System (INIS)

    Zhang, Yanwen; Weber, William J.; Jiang, Weilin; Shutthanandan, V.; Thevuthasan, Suntharampillai; Janson, Martin; Hallen, Anders

    2004-01-01

    Single crystal 4H-SiC films were implanted at 150 K with 1.1 MeV Al 2 2+ and subsequently annealed at elevated temperatures. Rutherford backscattering spectrometry (RBS) results indicate that the relative Si disorder at the damage peak recovers significantly as the annealing temperature increases. However, the residual Si disorder is more resistant to high-temperature annealing in the region of the implanted Al. The maximum concentration of Al profile measured by secondary ion mass spectroscopy (SIMS) is a factor of 1000 lower than the level of the residual Si disorder at the same region. Analysis of these results indicates that the excess residual Si disorder around the implanted Al projected range cannot be accounted for by just the Al interstitials; instead, it appears that each implanted Al stabilizes or inhibits recovery for an equivalent of a few hundred Si interstitials under the current experimental conditions

  16. The preferential orientation and lattice misfit of the directionally solidified Fe-Al-Ta eutectic composite

    Science.gov (United States)

    Cui, Chunjuan; Wang, Pei; Yang, Meng; Wen, Yagang; Ren, Chiqiang; Wang, Songyuan

    2018-01-01

    Fe-Al intermetallic compound has been paid more attentions recently in many fields such as aeronautic, aerospace, automobile, energy and chemical engineering, and so on. In this paper Fe-Al-Ta eutectic was prepared by a modified Bridgman directional solidification technique, and it is found that microstructure of the Fe-Al-Ta eutectic alloy transforms from the broken-lamellar eutectic to cellular eutectic with the increase of the solidification rate. In the cellular eutectic structure, the fibers are parallel to each other within the same grain, but some fibers are deviated from the original orientation at the grain boundaries. To study the crystallographic orientation relationship (OR) between the two phases, the preferential orientation of the Fe-Al-Ta eutectic alloy at the different solidification rates was studied by Selected Area Electron Diffraction (SAED). Moreover, the lattice misfit between Fe2Ta(Al) Laves phase and Fe(Al,Ta) matrix phase was calculated.

  17. Structural investigation of the (010) surface of the Al13 Fe4 catalyst.

    Science.gov (United States)

    Ledieu, J; Gaudry, É; Loli, L N Serkovic; Villaseca, S Alarcón; de Weerd, M-C; Hahne, M; Gille, P; Grin, Y; Dubois, J-M; Fournée, V

    2013-02-15

    We have investigated the structure of the Al(13)Fe(4)(010) surface using both experimental and ab initio computational methods. The results indicate that the topmost surface layers correspond to incomplete puckered (P) planes present in the bulk crystal structure. The main building block of the corrugated termination consists of two adjacent pentagons of Al atoms, each centered by a protruding Fe atom. These motifs are interconnected via additional Al atoms referred to as "glue" atoms which partially desorb above 873 K. The surface structure of lower atomic density compared to the bulk P plane is explained by a strong Fe-Al-Fe covalent polar interaction that preserves intact clusters at the surface. The proposed surface model with identified Fe-containing atomic ensembles could explain the Al(13)Fe(4) catalytic properties recently reported in line with the site-isolation concept [M. Armbrüster et al., Nat. Mater. 11, 690 (2012)].

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

    DEFF Research Database (Denmark)

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

    1995-01-01

    The control of the interfacial reaction between the matrix and the SiC reinforcement in Al-SiC metal matrix composites (MMCs) is an important production parameter. The reaction causes degradation of the reinforcement, weakening of the interface and a decrease of the mechanical properties...... of the products. Much recent work has been carried out to characterize the Al/SiC interface and to control the interfacial reaction. The present paper describes and compares the effects of surface coatings on two interface properties, the wettability of SiC in pure A1 and the interface reaction of the same SiC...... for uncoated SiC particles....

  19. Mechanochemical synthesis of (Fe,Ti){sub 3}Al-Al{sub 2}O{sub 3} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Rafiei, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Enayati, M.H., E-mail: ena78@cc.iut.ac.i [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Karimzadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-11-20

    Formation mechanism of (Fe,Ti){sub 3}Al-Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying of Fe, Al and TiO{sub 2} with molar ratio of 6:7:3 was studied. The structural changes of powder particles during mechanical alloying were investigated by X-ray diffractometery. Morphology and microstructure of powder particles were characterized by scanning electron microscopy. It was found that during mechanical alloying Al first reacts with TiO{sub 2} leading to the gradual formation of crystalline Ti and amorphous Al{sub 2}O{sub 3} phases. In the second stage Ti and remaining Al diffuse into the Fe lattice and as a result a Fe(Al,Ti) solid solution develops. This structure transformed to (Fe,Ti){sub 3}Al intermetallic compound at longer milling times. Heat treatment of this structure led to the crystallization of Al{sub 2}O{sub 3} and ordering of (Fe,Ti){sub 3}Al phases.

  20. Modification of the Fe-environment in Fe2O3 glass/glass ceramic systems containing Pb, Na and Si

    International Nuclear Information System (INIS)

    Pinakidou, F.; Katsikini, M.; Paloura, E.C.; Kavouras, P.; Kalogirou, O.; Komninou, Ph.; Karakostas, Th.

    2006-01-01

    The effect of composition and casting temperature on the microstructure and the oxidation state of Fe in a series of glass/glass ceramic materials that contain Fe 2 O 3 , PbO, Na 2 O and SiO 2 is studied by means of X-ray fluorescence mapping (XRF), micro- (μ-) and conventional X-ray absorption fine structure (XAFS) and 75 Fe Moessbauer spectroscopies. The Moessbauer results reveal that the majority of Fe exists in the Fe 3+ state. Divalent Fe is detected only in small amounts (2.1-5.7 at.%) in the ternary samples consisting of Fe 2 O 3 , SiO 2 and Na 2 O. The XRF mapping demonstrates that the ternary samples Fe 2 O 3 -Na 2 O-SiO 2 that contain more than 40 wt.% of Fe 2 O 3 develop Fe-rich islands. According to the combined μ-EXAFS and EXAFS results, 44 wt.% of the Fe atoms belong to those Fe-rich microcrystalline islands, where they are octahedrally coordinated, while the rest belong to the vitreous matrix where they are tetrahedrally coordinated. The Fe-O distance is found equal to 0.188 nm and 0.193 nm in the vitreous and microcrystalline regions, respectively. The differences in the NEXAFS spectra, due to the different local environment of Fe embedded in the vitreous or microcrystalline regions, are also discussed

  1. Thermal Conductivity of the Molten CaO-SiO2-FeO x System

    Science.gov (United States)

    Kang, Youngjo; Nomura, Kiyoshi; Tokumitsu, Kazuto; Tobo, Hiroyuki; Morita, Kazuki

    2012-12-01

    Thermal conductivity measurements were carried out on synthetic steelmaking slag using the hot-wire method. Furthermore, local structure analysis in the melts was carried out in order to investigate the relationship with the composition dependence. The thermal conductivity of the CaO-SiO2-FeO x melts significantly decreased as the content of FeO x increases, particularly at lower basicity. Both chemical analysis and the observation show that the amount of Fe2+ increases when CaO/SiO2 is smaller, implying more basic behavior of FeO than FeO1.5. According to further analyses by Mössbauer spectroscopy, the degree of basicity of FeO1.5 remains virtually unchanged in the composition range of interest. From the experimental results, it could be concluded that the thermal conductivity of the silicate melt containing iron oxide is highly dependent on the valence of the Fe ion and comparatively independent of the amphoteric behavior of FeO1.5.

  2. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    International Nuclear Information System (INIS)

    Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

    2016-01-01

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the AlCoFe

  3. An abrasive wear study of ordered Fe[sub 3]Al. [Fe[sub 73]Al[sub 27], Fe[sub 76]Al[sub 24], Fe[sub 77]Al[sub 23

    Energy Technology Data Exchange (ETDEWEB)

    Maupin, H.E.; Wilson, R.D.; Hawk, J.A. (US Bureau of Mines, Albany Research Center, OR (United States))

    1992-12-01

    Abrasive wear research has been conducted on ordered iron aluminide intermetallics. Pin-on-drum abrasive wear tests were performed on samples of varying long-range order. Wear surfaces were examined with optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy and X-ray diffraction. The wear mechanism consisted of microplowing, micromachining and microfracture. Compositional variation near Fe[sub 3]Al and the degree of long-range ordering had only minor effects on the abrasive wear rates of iron aluminide samples. TEM analysis of the wear surfaces indicated that significant plastic deformation and recrystallization had occurred. The abrasive wear rates were compared with those of well-known abrasive wear-resistant materials. (orig.).

  4. Magnetism and disorder in BCC AlCuFe intermetallics

    International Nuclear Information System (INIS)

    Meyer, M.; Sanchez, F.; Mendoza-Zelis, L.

    2007-01-01

    We present here a systematic study of the structural and magnetic properties of a series of alloys around a central composition Al 50 Cu 20 Fe 30 , obtained by mechanical alloying. The samples have BCC crystalline structure with partial B2 order. Thermal annealing, through differential scanning calorimetry measurements, just removes some defects but does not change the crystalline structure. AC susceptibility measurements show that in spite of their structural similarity these samples have quite different magnetic behaviors. Furthermore, most of the samples show a complex magnetic evolution with temperature. Some samples have a cluster glass-like behavior at low temperatures and a superparamagnetic-like one at higher temperatures. A model of magnetic clusters originating in composition fluctuations across the alloy is proposed to explain the observed magnetic properties

  5. Local Structure and Magnetic Properties of Fe 50 Cr 40 Si 10 Nanocrystalline Alloys

    Science.gov (United States)

    Tarigan, K.; Sebayang, D.; Yu, S. C.; Yang, D. S.

    2018-03-01

    The structural and the magnetic properties of nanocrystalline Fe 50 Cr 40 Si 10 alloys were prepared via mechanical alloying by using Fe, Cr, and Si elements with 1- to 24 hrs milling times. Structural analysis based on X-ray diffraction and Extended X-ray absorption fine structure spectroscopy. Concerning the magnetic behavior, the data obtained from a vibrating sample magnetometer at 300 K shows that both the magnetic saturation and the coercivity are dependent strongly on the milling time and the crystallite size. By adjusting the milling time, both appropriate structural transformation and magnetization values are obtained.

  6. Improvement of shape memory effect in Fe-Mn-Si alloy by slight tantalum addition

    International Nuclear Information System (INIS)

    Yang, Cheng-Hsiu; Lin, Hsin-Chih; Lin, Kun-Ming

    2009-01-01

    The effects of slight tantalum (Ta) addition on the microstructures, precipitates, martensitic transformation and shape memory performance of Fe-30Mn-6Si-based alloys were investigated. Experimental results show that the slight Ta addition will increase the c/a ratio of ε martensite, reduce the M s temperature and improve the alloy's shape recovery ability. After TMT at 650 deg. C, the alloy's M s temperature is reduced and lots of (Fe, Mn) 3 Si and TaC precipitates form. The effective nuclei and well-aligned precipitates within the grain interior after TMT will improve significantly the alloy's shape memory performance.

  7. Spin Texture And Magnetic Properties Of Fe-Si-Co Alloys

    International Nuclear Information System (INIS)

    Schneeweiss, O.; Zak, T.; Jiraskova, Y.; Havlicek, S.; Solyom, A.; Marko, P.

    1998-01-01

    The Fe-13at.%Si alloys with 1, 3, and 5 at.% of Co were investigated. Spin texture, atomic configuration, and Curie temperature were studied in dependence on chemical composition and heat treatment. Data on atomic arrangements derived form Moessbauer spectra and Curie temperatures showed that Co atoms substituted regular positions of Fe atoms in the bcc lattice. Spin texture was found to be only slightly dependent on the chemical composition of the alloys, however, it varies with heat treatment considerably. (Authors)

  8. Mixing induced by swift heavy ion irradiation at Fe/Si interface

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The present work deals with the mixing of metal and silicon by swift heavy ions in high-energy range. Threshold value for the defect creation in metal Fe calculated was found to be ~ 40 keV/nm. A thin film of Fe (10 nm) was deposited on Si (100) at a pressure of 4 × 10–8 Torr and was irradiated with 95 MeV Au ions ...

  9. Characterization of FeOOH Nanoparticles and Amorphous Silica Matrix in an FeOOH-SiO2 Nanocomposite

    Directory of Open Access Journals (Sweden)

    Guido Ennas

    2008-01-01

    Full Text Available A nanocomposite with an FeOOH/SiO2 ratio equal to 17.7 wt% and the pertinent matrix, obtained by etching away the nanoparticles through reaction with hydrochloric acid, were investigated by XRD, TGA-DTA, heliostereopicnometry, BET, and TEM techniques. The study shows the presence in the nanocomposite of ferrihydrite nanoparticles phase with average dimensions around 4 nm. The FeOOH nanoparticles structure was analyzed by synchrotron X-ray diffraction data using the distribution difference curve method. The porous structure of the matrix resulting by etching away the nanoparticles differs significantly from that of a pure SiO2 sample obtained by hydrolysis of TEOS under the same operative conditions followed in the nanocomposite preparation.

  10. CoFe2O4-SiO2 Composites: Preparation and Magnetodielectric Properties

    Directory of Open Access Journals (Sweden)

    T. Ramesh

    2016-01-01

    Full Text Available Cobalt ferrite (CoFe2O4 and silica (SiO2 nanopowders have been prepared by the microwave hydrothermal (M-H method using metal nitrates as precursors of CoFe2O4 and tetraethyl orthosilicate as a precursor of SiO2. The synthesized powders were characterized by XRD and FESEM. The (100-x (CoFe2O4 + xSiO2 (where x = 0%, 10%, 20%, and 30% composites with different weight percentages have been prepared using ball mill method. The composite samples were sintered at 800°C/60 min using the microwave sintering method and then their structural and morphological studies were investigated using X-ray diffraction (XRD, Fourier transformation infrared (FTIR spectra, and scanning electron microscopy (SEM, respectively. The effect of SiO2 content on the magnetic and electrical properties of CoFe2O4/SiO2 nanocomposites has been studied via the magnetic hysteresis loops, complex permeability, permittivity spectra, and DC resistivity measurements. The synthesized nanocomposites with adjustable grain sizes and controllable magnetic properties make the applicability of cobalt ferrite even more versatile.

  11. Characterization of Si particles and their effects on and recrystallization in a nanostructured cold rolled Al-1%Si alloy

    DEFF Research Database (Denmark)

    Huang, T.L.; Wu, G.L.; Huang, Xiaoxu

    2015-01-01

    An Al-1.08 vol.% Si alloy was cold rolled to a reduction of 98% (εvM = 4.5) and then annealed at different temperatures up to 210°C (0.52 Tm) for different times. The deformed structure is characterized by a nanoscale lamellar structure with the presence of Si particles of coarse (> 1 μm), medium...

  12. Nanostructure evolution in joining of Al and Fe nanoparticles with femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Jiao, Z.; Huang, H.; Zhou, Y.; Liu, L.; Hu, A.; Duley, W.; He, P.

    2014-01-01

    The joining of Al-Fe nanoparticles (NPs) by femtosecond (fs) laser irradiation is reported in this paper. Fe and Al NPs were deposited on a carbon film in vacuum via fs laser ablation. Particles were then exposed to multiple fs laser pulses at fluences between 0.5 and 1.3 mJ/cm 2 . Transmission Electron Microscopy (TEM) and Electron Diffraction X-ray observations indicate that Al and Fe NPs bond to each other under these conditions. For comparison, bonding of Al to Al and Fe to Fe NPs was also investigated. The nanostructure, as observed using TEM, showed that individual Al NPs were monocrystalline while individual Fe NPs were polycrystalline prior to joining and that these structures are retained after the formation of Al-Al and Fe-Fe NPs. Al-Fe NPs produced by fs laser joining exhibited a mixed amorphous and crystalline phase at the interface. Bonding is suggested to originate from intermixing within a region of high field intensity between particles

  13. Formation of Al70Cu20Fe10 icosahedral quasicrystal by mechanically alloyed method

    International Nuclear Information System (INIS)

    Yin Shilong; Bian Qing; Qian Liying; Zhang Aimei

    2007-01-01

    The structural evolutions of the mechanically alloyed ternary Al 70 Cu 20 Fe 10 powders with the milling time and the annealing treatment have been studied by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and X-ray absorption fine-structure spectroscopy (XAFS) techniques. Results show that an Al 2 Cu compound forms with short-time milling, while a Cu 9 Al 4 compound forms with long-time milling. Fe can react with Al-Cu alloy by annealing treatment. Al 7 Cu 2 Fe compound with tetragonal structure or Al (Cu, Fe) solid solution with cubic structure may form at lower temperature, while a quasicrystal phase of Al 65 Cu 20 Fe 15 alloy may form at higher temperature

  14. First-principle study of the AlP/Si interfacial adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Dai Hongshang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Du Jing [School of Science, Shandong Jianzhu University, Jinan 250101 (China); Wang Li; Peng Chuanxiao [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Liu Xiangfa, E-mail: xfliu@sdu.edu.c [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Shandong Binzhou Bohai Piston Co. Ltd., Binzhou 256602, Shandong (China)

    2010-01-15

    AlP is heterogeneous nucleation substrate of primary Si in hypereutectic Al-Si alloys, while studies on the nucleation mechanism at atomic level are absent. The pseudopotential-based DFT calculations have been carried out to investigate the atomic and electronic structure, bonding and adhesion of the AlP/Si interface. In total, eight geometries have been investigated, in which the interfacial stacking sequence is different. The favorable interfaces can be deduced for the reason that adhesive interface energies (W{sub ad}) are different, which cannot be obtained from the traditional mismatch theory. The interfacial density of states and Mulliken population are also investigated. It is found that the main bond between AlP and Si is covalent Al-Si or P-Si bond, accompanying some ionic characteristic.

  15. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    Energy Technology Data Exchange (ETDEWEB)

    Lollobrigida, V. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Torino (Italy); Borgatti, F. [CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), I-40129 Bologna (Italy); Torelli, P.; Panaccione, G. [CNR, Istituto Officina dei Materiali (IOM), Lab. TASC, I-34149 Trieste (Italy); Tortora, L. [Laboratorio di Analisi di Superficie, Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Ingegneria Meccanica, Università Tor Vergata, I-00133 Rome (Italy); Stefani, G.; Offi, F. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy)

    2014-05-28

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  16. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    International Nuclear Information System (INIS)

    Lollobrigida, V.; Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F.; Borgatti, F.; Torelli, P.; Panaccione, G.; Tortora, L.; Stefani, G.; Offi, F.

    2014-01-01

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  17. Rare earth concentration in the primary Si crystal in rare earth added Al-21 wt. % Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.Y.; Kim, G.H. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Moon, I.G.; Choi, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering

    1998-07-03

    Al-Si alloys containing more than about 12 wt. % Si exhibit a hypereutectic microstructure, normally consisting of a primary silicon phase in an eutectic matrix. The primary silicon in normal hypereutectic alloys is usually very coarse and thus leads to poor properties to these alloys. Therefore, alloys with a predominantly coarse primary silicon crystal must be modified to ensure adequate mechanical strength and ductility. Further improvement of mechanical properties of these alloys can be achieved by the modification of eutectic microstructure. Therefore, development of a modifier or refiner that can produce both fine primary and eutectic Si is a major factor which can lead to significant enhancement of mechanical properties in hypereutectic Al-Si alloys. Refinement of primary silicon is usually achieved by the addition of phosphor to the melt. On the other hand, it is reported that the rare earth (RE) elements are capable of modifying the eutectic structure of cast Al-Si alloys. According to the literature, Phosphor acts as a heterogeneous nucleation site of Si crystal by forming AlP intermetallic particles at high temperature, i.e., above liquidus temperature of Al-Si alloy. Unlike phosphor, RE was not known to form a stable compound with Al that can act as a nucleation site at high temperature. Therefore, the role of RE as a refiner should be considered by examining the behavior of RE as a solute in the melt. The distribution of RE within the primary Si and in the matrix of the alloy will provide a clue to the role of RE on the modification of primary Si during solidification.

  18. Electrical Investigation of Nanostructured Fe2O3/p-Si Heterojunction Diode Fabricated Using the Sol-Gel Technique

    Science.gov (United States)

    Mansour, Shehab A.; Ibrahim, Mervat M.

    2017-11-01

    Iron oxide (α-Fe2O3) nanocrystals have been synthesized via the sol-gel technique. The structural and morphological features of these nanocrystals were studied using x-ray diffraction, Fourier transform-infrared spectroscopy and transmission electron microscopy. Colloidal solution of synthesized α-Fe2O3 (hematite) was spin-coated onto a single-crystal p-type silicon (p-Si) wafer to fabricate a heterojunction diode with Mansourconfiguration Ag/Fe2O3/p-Si/Al. This diode was electrically characterized at room temperature using current-voltage (I-V) characteristics in the voltage range from -9 V to +9 V. The fabricated diode showed a good rectification behavior with a rectification factor 1.115 × 102 at 6 V. The junction parameters such as ideality factor, barrier height, series resistance and shunt resistance are determined using conventional I-V characteristics. For low forward voltage, the conduction mechanism is dominated by the defect-assisted tunneling process with conventional electron-hole recombination. However, at higher voltage, I-V ohmic and space charge-limited current conduction was became less effective with the contribution of the trapped-charge-limited current at the highest voltage range.

  19. Fast diffusion in the intermetallics Ni3Sb and Fe3Si: a neutron scattering study

    International Nuclear Information System (INIS)

    Randl, O.G.

    1994-02-01

    We present the results of neutron scattering experiments designed to elucidate the reason for the extraordinarily fast majority component diffusion in two intermetallic alloys of DO 3 structure, Fe 3 Si and Ni 3 Sb: We have performed diffraction measurements in order to determine the crystal structure and the state of order of both alloys as a function of composition and temperature. The results on Fe 3 Si essentially confirm the classical phase diagram: The alloys of a composition between 16 and 25 at % Si are DO 3 -ordered at room temperature and disorder at high temperatures. The high-temperature phase Ni 3 Sb also crystallizes in the DO 3 structure. Vacancies are created in one Ni sublattice at Sb contents beyond 25 at %. In a second step the diffusion mechanism in Ni 3 Sb has been studied by means of quasielastic neutron scattering. The results are reconcileable with a very simple NN jump model between the two different Ni sublattices. Finally, the lattice dynamics of Fe 3 Si and Ni 3 Sb has been studied by inelastic neutron scattering in dependence of temperature (both alloys) and alloy composition (Fe 3 Si only). The results on Fe 3 Si indicate clearly that phonon enhancement is not the main reason for fast diffusion in this alloy. In Ni 3 Sb no typical signs of phonon-enhanced diffusion have been found either. As a conclusion, fast diffusion in DO 3 intermetallics is explained by extraordinarily high vacancy concentrations (several atomic percent) in the majority component sublattices. (author)

  20. Response of Si- and Al-doped graphenes toward HCN: A computational study

    International Nuclear Information System (INIS)

    Rastegar, Somayeh F.; Peyghan, Ali Ahmadi; Hadipour, Nasser L.

    2013-01-01

    Highlights: ► Sensitivity of Si- and Al-doped graphene (SiG and AlG) toward HCN is investigated. ► The electronic properties of AlG are significantly changed in the presence of HCN. ► It is established that AlG can be a good sensor for HCN molecule. - Abstract: Sensitivity of Si- and Al-doped graphenes (SiG and AlG) toward toxic HCN has been investigated using density functional theory (DFT) in terms of energetic, geometric and electronic properties. Optimized configurations corresponding to physisorption and, subsequently, chemisorption of HCN on each surface have been identified. It is found that HCN molecule can be adsorbed on impurity atoms with adsorption energies about −27.20 and −38.75 kcal/mol on the SiG and the AlG, respectively. By comparing to HCN adsorption on SiG, it can be inferred that molecular HCN adsorbed on AlG can induce significant change in AlG conductivity. On the basis of calculated changes in the HOMO/LUMO energy gap it is found that electronic properties of AlG are sensitive toward adsorption of HCN and the reverse is correct for SiG, suggesting that the AlG may be a promising sensor for HCN.

  1. Defect evolution during annealing of deformed FeSi alloys studied by positron annihilation spectroscopy

    Science.gov (United States)

    Mostafa, K. M.; Cámara, F. González; Petrov, Roumen; Calvillo, P. Rodríguez; De Grave, E.; Segers, D.; Houbaert, Y.

    2011-04-01

    High silicon steel is widely used in electrical appliances. Alloying iron with silicon improves its magnetic performance. A silicon content up to 6.5 wt. % gives excellent magnetic properties such as high saturation magnetization, near zero magnetostriction and low iron loss in high frequencies. Their workability is greatly reduced by the appearance of ordered structures, namely B2 and D03, as soon as the Si content becomes higher than 3.5 wt. %. This limits the mass production by conventional rolling to this maximum percentage of Si. In this work a series of FeSi (7.5 wt. % Si) samples with different degrees of deformation are investigated with positron annihilation spectroscopy and optical microscopy (OM). The influence of annealing on the concentration of defects of different deformed FeSi alloys has been investigated by positron annihilation lifetime spectroscopy and Doppler broadening of the annihilation radiation. OM is used to investigate the microstructure of deformed samples before and after annealing. The values of the S parameter present a decrease for all studied FeSi alloys with the increase of the annealing temperature, being attributed to a decrease of the concentration of defects. A sudden increase of the S-parameter value at 600 °C was observed for all samples, which could be related to the change of the ordering of the FeSi alloys at that temperature. At 700 °C, the values of the S parameter decreased drastically and starting from 900 °C, they became constant. The microstructures of the alloys, investigated by OM, show that recrystallization is completed at 900 °C and the samples are mainly free of defects, which is in agreement with the positron annihilation lifetime data.

  2. Influence of powder particle injection velocity on the microstructure of Al-12Si/SiCp coatings produced by laser cladding

    NARCIS (Netherlands)

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

    2009-01-01

    The influence of powder particle injection velocity on the microstructure of coatings consisting of an Al-Si matrix reinforced with SiC particles prepared by laser cladding from mixtures of powders of Al-12 wt.% Si alloy and SiC was investigated both experimentally and by modeling. At low injection

  3. Structure and wear behavior of AlCrSiN-based coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Du, Hao [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Ming, E-mail: mchen@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Jun [Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Xiong, Ji [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhao, Haibo [The Analysis and Testing Centre, Sichuan University, Chengdu 610065 (China)

    2016-05-01

    Graphical abstract: - Highlights: • AlCrSiN based coating showed amorphous structure. • AlCrSiN/Me{sub x}N coatings obtained better wear resistance. • Molybdenum and niobium increased the coating hardness and wear resistance. - Abstract: AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC–Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N{sub 2} mixtures. Al{sub 0.6}Cr{sub 0.4}, Al{sub 0.6}Cr{sub 0.3}Si{sub 0.1}, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiN{sub x} peak were formed in the AlCrSiN/Me{sub x}N coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H{sup 3}/E{sup 2} ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  4. Manipulating NiFe/AlOx interfacial chemistry for the spin-polarized electrons transport

    International Nuclear Information System (INIS)

    Zhao, Chong-Jun; Sun, Li; Ding, Lei; Li, Jian-Wei; Zhang, Jing-Yan; Cao, Yi; Yu, Guang-Hua

    2013-01-01

    Through vacuum annealing, interfacial chemical composition of sputter-deposited AlO x /NiFe/AlO x can be controlled for electron transport manipulation. Chemical status change at the NiFe/AlO x interface was quantified by X-ray photoelectron spectroscopy and correlated to the structure and electron transport properties of the heterostructure. It is found that elemental Al existed in the insulting AlO x after annealing at intermediate temperature can improve the AlO x /NiFe interface and thus favor the electronic transport. Annealing at higher temperature will result in native AlO x formation and degrade transport properties due to the NiFe/AlO x interfaces deterioration caused by significant difference in thermal expansion coefficients of the two materials.

  5. Elemental analysis of the Al-Fe intermetallic prepared by fast solidification

    International Nuclear Information System (INIS)

    Sandoval J, R.A.; Lopez M, J.; Ramirez T, J.J.; Aspiazu F, J.; Villasenor S, P.

    2003-01-01

    Applying the PIXE technique samples of the Al-Fe intermetallic prepared by fast solidification, obtained starting from Al recycled were analyzed. The concentrations of the found elements are given. (Author)

  6. Pitting susceptibility of chromium modified passive films of a B2-FeAl intermetallic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frangini, S. [ENEA Casaccia (Italy). Settore Nuovi Materiali; Lascovich, J. [ENEA Casaccia (Italy). Settore Nuovi Materiali; De Cristofaro, N. [ENEA Casaccia (Italy). Settore Nuovi Materiali

    1995-11-01

    The effect of chromium on the pitting corrosion resistance of an iron aluminide B2-FeAl alloy (40 at/o Al) has been evaluated in chloride borate solutions. Chromium was permanently incorporated into the passive film of FeAl by repetitive oxidation-reduction cycles from alkaline chromate solution. Although the Cr-modified passive FeAl surface was found to have a pitting behaviour comparable to that of stainless Fe-Cr steels containing Cr in the range 12-24 at/o, the XPS analysis showed that Cr enrichment within the passive film of FeAl was not as high suggesting that the protective properties of the film would be due to a synergistic effect between Cr and Al. The use of the Kirchheim model allowed to predict the ternary alloy composition in equilibrium with the Cr-modified passive film one. (orig.)

  7. Determination of the structure of a new tetragonal U2FeAl20 phase

    International Nuclear Information System (INIS)

    Meshi, L.; Munitz, A.; Talianker, M.

    2008-01-01

    The atomic structure of a new ternary U 2 FeAl 20 phase appearing in the Al-rich corner of a U-Fe-Al system was solved using electron crystallography and X-ray powder diffraction techniques (XRD). The positions of U atoms were determined from crystallographically processed high-resolution electron microscopy (HRTEM) images. These positions were used as a starting set for determining the coordinates of Fe and Al atoms by difference-Fourier synthesis technique. The U 2 FeAl 20 phase is tetragonal and belongs to the I4-bar 2m space group. Its unit cell contains 80 Al, 4 Fe, and 8 U atoms. The lattice parameters obtained after Rietveld refinement are: a = 12.4138 A, c = 10.3014 A. The reliability factors characterizing the Rietveld refinement procedure are: R p = 8.65%, R wp = 11.2% and R b = 5.93%

  8. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    KAUST Repository

    Balasamy, Rabindran J.

    2010-12-20

    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  9. Fabrication and high frequency magnetic characterization of FeCoAl ternary thin films

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Yung-Wang [Center for Nanotechnology, Materials Science, and Microsystems, National Tsing Hua University, 101 Kuang-Fu Rd., Sec. 2, Hsinchu 300 (China); Wu, Fan-Bean [Department of Materials Science and Engineering, National United University, 1 Lein-Da, Kung-Ching Li, MiaoLi 360 (China); Li, Shandong [Center for Nanotechnology, Materials Science, and Microsystems, National Tsing Hua University, 101 Kuang-Fu Rd., Sec. 2, Hsinchu 300 (China); Department of Physics, Fujian Normal University, Fuzhou 35007 (China); Kuo, Cheng-Lun [Department of Materials Science and Engineering, National Tsing Hua University, 101 Kuang-Fu Rd., Sec. 2, Hsinchu 300 (China); Duh, Jenq-Gong [Center for Nanotechnology, Materials Science, and Microsystems, National Tsing Hua University, 101 Kuang-Fu Rd., Sec. 2, Hsinchu 300 (China); Department of Materials Science and Engineering, National Tsing Hua University, 101 Kuang-Fu Rd., Sec. 2, Hsinchu 300 (China)

    2007-12-15

    Integration of ferromagnetic materials with electronic components represents a key solution to the enhancement of high frequency characteristics for recent miniaturized communication devices. In this study, Al element was introduced into FeCo binary alloy to form a ternary FeCoAl magnetic thin film by co-sputtering technique followed by annealing in the presence of an external magnetic field. X-ray diffraction results revealed that the FeCoAl films exhibited a solid solution microstructure of FeCo matrix with Al as the solute element. The saturation magnetization (M{sub s}) of FeCoAl thin film still maintained a high value around 1780 emu/cm{sup 3}. It was found that the FeCoAl system possessed a high permeability around 1000 and an uni-axial anisotropic field (H{sub k}) of 50 Oe. In addition, with the incorporation of Al element, the resonance frequency of the FeCoAl film reached 2.1 GHz. Hence, it is suggested that the FeCoAl magnetic thin film is a potential candidate for high frequency devices operated in GHz bands. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Microstructural Evolution of Al-1Fe (Weight Percent) Alloy During Accumulative Continuous Extrusion Forming

    Science.gov (United States)

    Wang, Xiang; Guan, Ren-Guo; Tie, Di; Shang, Ying-Qiu; Jin, Hong-Mei; Li, Hong-Chao

    2018-04-01

    As a new microstructure refining method, accumulative continuous extrusion forming (ACEF) cannot only refine metal matrix but also refine the phases that exist in it. In order to detect the refinements of grain and second phase during the process, Al-1Fe (wt pct) alloy was processed by ACEF, and the microstructural evolution was analyzed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Results revealed that the average grain size of Al-1Fe (wt pct) alloy decreased from 13 to 1.2 μm, and blocky Al3Fe phase with an average length of 300 nm was granulated to Al3Fe particle with an average diameter of 200 nm, after one pass of ACEF. Refinement of grain was attributed to continuous dynamic recrystallization (CDRX), and the granulation of Al3Fe phase included the spheroidization resulting from deformation heat and the fragmentation caused by the coupling effects of strain and thermal effect. The spheroidization worked in almost the entire deformation process, while the fragmentation required strain accumulation. However, fragmentation contributed more than spheroidization. Al3Fe particle stimulated the formation of substructure and retarded the migration of recrystallized grain boundary, but the effect of Al3Fe phase on refinement of grain could only be determined by the contrastive investigation of Al-1Fe (wt pct) alloy and pure Al.

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

    Science.gov (United States)

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

    2011-10-01

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

  12. Cu clustering stage before the crystallization in Fe-Si-B-Nb-Cu amorphous alloys

    DEFF Research Database (Denmark)

    Ohnuma, M.; Hono, K.; Onodera, H.

    1999-01-01

    The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary...

  13. Ferromagnetic resonance investigation of nanocrystalline FeCuNbSiB

    Indian Academy of Sciences (India)

    The experimental studies [1–3] of nanocrystalline soft magnetic FeCuNbSiB alloys reported so far have mainly concentrated on the role of grain size in affecting magnetic hysteresis loop parameters, magnetic anisotropy and magnetostriction at room temperature. These studies have indicated that the magnetic softening in ...

  14. Crystallization processes in an amorphous Co-Fe-Cr-Si-B alloy under isothermal annealing

    Science.gov (United States)

    Fedorets, A. N.; Pustovalov, E. V.; Plotnikov, V. S.; Modin, E. B.; Kraynova, G. S.; Frolov, A. M.; Tkachev, V. V.; Tsesarskaya, A. K.

    2017-09-01

    Research present the crystallization processes investigation of the amorphous Co67Fe3Cr3Si15B12 alloy. In-situ experiments on heating in a transmission electron microscope (TEM) column were carried out. Critical temperatures influencing material structure are determined. The onset temperature of material crystallization was determined.

  15. Preparing Magnetocaloric LaFeSi Uniform Microstructures by Spark Plasma Sintering

    DEFF Research Database (Denmark)

    Vicente, N.; Ocanã, J.; Neves Bez, Henrique

    2014-01-01

    . This approaching aiming at improving the sample temperature distribution by deviating the electric current throughout the graphite die, since the electric current induces overheating by in situ Joule effect on powder. The LaFeSi powder with particles under 150 µm was obtained by mechanical milling of particles...

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

    Directory of Open Access Journals (Sweden)

    LI Xiao-qiang

    2016-09-01

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

  17. Effect of Co addition on crystallization and magnetic properties of FeSiBPCu alloy

    Directory of Open Access Journals (Sweden)

    Rui Xiang

    2014-12-01

    Full Text Available The effects of Co addition on the microstructure, crystallization processes and soft magnetic properties of (Fe1−xCox83Si4B8P4Cu1 (x=0.35, 0.5, 0.65 alloys were investigated. The experimental results demonstrated that the addition of Co decreased the thermal stability against crystallization of the amorphous phase, and thus improved the heat treatment temperature of this alloy. FeCoSiBPCu nanocrystalline alloys with a dispersed α′-FeCo phase were obtained by appropriately annealing the as-quenched ribbons at 763 K for 10 min. The α′-FeCo with grains size ranging from 9 to 28 nm was identified in primary crystallization. The coercivity (Hc markedly increased with increasing x and exhibited a minimum value at x=0.35, while the saturation magnetic flux density (Bs shows a slight decrease. The (Fe0.65Co0.3583Si4B8P4Cu1 nanocrystalline alloy exhibited a high saturation magnetic flux density Bs of 1.68 T, a low coercivity, Hc of 5.4 A/m and a high effective permeability µe of 29,000 at 1 kHz.

  18. First-principles investigation of Fe-doped MgSiO{sub 3}-ilmenite

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids, E-mail: arvids@utpl.edu.ec [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Rivera, Krupskaya [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Geologia y Minas, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Pinto, Henry P. [Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217-0510 (United States)

    2012-06-15

    First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO{sub 3} mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using {Delta}SCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO{sub 3}. Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe Rightwards-Double-Arrow Mg reaction can be described as substitutionally labile with Fe{sup 2+} complex being found in the high-spin state at low pressure MgSiO{sub 3}-ilmenite conditions.

  19. Sound velocities and density measurements of solid hcp-Fe and hcp-Fe-Si (9 wt.%) alloy at high pressure: Constraints on the Si abundance in the Earth's inner core

    Science.gov (United States)

    Antonangeli, Daniele; Morard, Guillaume; Paolasini, Luigi; Garbarino, Gaston; Murphy, Caitlin A.; Edmund, Eric; Decremps, Frédéric; Fiquet, Guillaume; Bosak, Alexei; Mezouar, Mohamed; Fei, Yingwei

    2018-01-01

    We carried out sound velocity and density measurements on solid hcp-Fe and an hcp-Fe-Si alloy with 9 wt.% Si at 300 K up to ∼170 and ∼140 GPa, respectively. The results allow us to assess the density (ρ) dependence of the compressional sound velocity (VP) and of the shear sound velocity (VS) for pure Fe and the Fe-Si alloy. The established VP-ρ and VS-ρ relations are used to address the effect of Si on the velocities in the Fe-FeSi system in the range of Si concentrations 0 to 9 wt.% applicable to the Earth's core. Assuming an ideal linear mixing model, velocities vary with respect to those of pure Fe by ∼ + 80 m / s for VP and ∼ - 80 m / s for VS for each wt.% of Si at the inner core density of 13 000 kg/m3. The possible presence of Si in the inner core and the quantification of its amount strongly depend on anharmonic effects at high temperature and on actual core temperature.

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

    Science.gov (United States)

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

    2018-01-01

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

  1. Literature review report on atomistic modeling tools for FeCrAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Martinez, Enrique [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-12-01

    This reports summarizes the literature review results on atomistic tools, particularly interatomic potentials used in molecular dynamics simulations, for FeCrAl ternary alloys. FeCrAl has recently been identified as a possible cladding concept for accident tolerant fuels for its superior corrosion resistance. Along with several other concepts, an initial evaluation and recommendation are desired for FeCrAl before it’s used in realistic fuels. For this purpose, sufficient understanding on the in-reactor behavior of FeCrAl needs to be grained in a relatively short timeframe, and multiscale modeling and simulations have been selected as an efficient measure to supplement experiments and in-reactor testing for better understanding on FeCrAl. For the limited knowledge on FeCrAl alloys, the multiscale modeling approach relies on atomistic simulations to obtain the missing material parameters and properties. As a first step, atomistic tools have to be identified and this is the purpose of the present report. It was noticed during the literature survey that no interatomic potentials currently available for FeCrAl. Here, we summarize the interatomic potentials available for FeCr alloys for possible molecular dynamics studies using FeCr as surrogate materials. Other atomistic methods such as lattice kinetic Monte Carlo are also included in this report. A couple of research topics at the atomic scale are suggested based on the literature survey.

  2. Effects of strontium impurity on the structure and dynamics of Al88Si12 liquid

    International Nuclear Information System (INIS)

    Yue, G Q; Wu, S; Shen, B; Wang, S Y; Chen, L Y; Wang, C Z; Ho, K M; Kramer, M J

    2013-01-01

    The effects of strontium modification on the structure and dynamics of Al 88 Si 12 liquid are studied by means of ab initio molecular dynamics simulations. By replacing 0.5% and 4.0% of Al with Sr, we show that the addition of Sr lowers the self-diffusion of Al and Si of the liquid and reduces the nearest-neighbor correlation between Si atoms. The simulation provides an explanation for the change in morphology of the eutectic phases observed in rapidly solidified Al–Si alloys modified with Sr. (paper)

  3. Synthesis of Fe-Al nanoparticles by hydrogen plasma-metal reaction

    CERN Document Server

    Liu Tong; Li Xing Guo

    2003-01-01

    Fe-Al nanoparticles of eight kinds have been prepared by hydrogen plasma-metal reaction. The morphology, crystal structure, and chemical composition of the nanoparticles obtained were investigated by transmission electron microscopy (TEM), x-ray diffractometry (XRD), and induction-coupled plasma spectroscopy. The particle size was determined by TEM and Brunaumer-Emmet-Teller gas adsorption. It was found that all the nanoparticles have spherical shapes, with average particle size in the range of 29-46 nm. The oxide layer in nanoparticles containing Al after passivation is not observable by XRD and TEM. The Al contents in Fe-Al ultrafine particles are about 1.2-1.5 times those in the master alloys. The evaporation speeds of Al and Fe in Fe-Al alloys are mutually accelerated at a certain composition. The crystal structures of the Fe-Al nanoparticles vary with the composition of the master alloys. Pure Fe sub 3 Al (D0 sub 3) and FeAl (B2) structures are successfully produced with 15 and 25 at.% Al in bulks, respe...

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

    Directory of Open Access Journals (Sweden)

    J. Mutwil

    2008-12-01

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

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

    International Nuclear Information System (INIS)

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

    1997-01-01

    This work shows the improvement obtained on tensile stress at room and high temperatures of hyper eutectic Al-Si alloys. These alloys are produced by a combination of spray-forming, extrusion and thixoforming process, in comparison with conventional casting alloys.Al-25% Si-5%Cu. Al-25%Si-5%Cu-2%Mg and Al-30%Si-5%Cu alloys have been studied relating their microstructural parameters with tensile stress obtained and comparing them with conventional Al-20%Si. Al-36%Si and Al-50%Si alloys. Al-25%Si-5%Cu alloy-was tested before and after semi-solid forming, in order to distinguish the different behaviour of this alloy due to the different microstructure. The properties obtained with these alloys were also related to Al-SiC composites formed by similar processes. (Author) 20 refs

  6. Study of magnetocaloric effect in LaFe11∙5Si1∙5 alloys prepared by ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. LaFe11∙5Si1∙5 alloys are annealed at 1503 K for 5 h and cooled down to room temperature by furnace cooling, air cooling and quenching in ice water, respectively. The main phases are 1:13 phases in those alloys. The impurity phases are α-Fe and the amount of LaFeSi phase is so small that it is hard to observe ...

  7. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Unknown

    It can be seen from [110] orienta- tion that fine structure of Fe3Al consists of dislocation walls which include several small regions. The produc- tion of Fe3Al dislocation walls is closely related to the .... Science Foundation of Shandong Province (Grant No. Y2003F05). The authors express their heartfelt thanks for this support.

  8. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Microstructure at the diffusion bonding interface between Fe3Al and steel including Q235 low carbon steel and Cr18–Ni8 stainless steel was analysed and compared by means of scanning electron micro- scopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe3Al/steel ...

  9. Magnetic phase transitions in TbFe sub 2 Al sub 1 sub 0 , HoFe sub 2 Al sub 1 sub 0 and ErFe sub 2 Al sub 1 sub 0

    CERN Document Server

    Reehuis, M; Krimmel, A; Scheidt, E W; Stüsser, N; Loidl, A; Jeitschko, W

    2003-01-01

    The magnetic order of the orthorhombic aluminides TbFe sub 2 Al sub 1 sub 0 , HoFe sub 2 Al sub 1 sub 0 and ErFe sub 2 Al sub 1 sub 0 (space group Cmcm) has been studied by specific heat and magnetic measurements, as well as by neutron powder diffraction down to 100 mK and in external fields up to 5 T. Only the rare-earth ions carry a magnetic moment. At T = 1.5 K the terbium moments in TbFe sub 2 Al sub 1 sub 0 show a square-wave modulated magnetic order with wavevector k = (0, 0.7977, 0) and a moment direction parallel to the a-axis. At a critical field of H sub c sub 1 = 0.9 T one of ten spins is forced to flip, going into an intermediate ferrimagnetic phase that is stable up to the critical field H sub c sub 2 = 1.8 T. Above this field finally all the rest of the spins flip, resulting in a ferromagnetic order of the terbium moments. ErFe sub 2 Al sub 1 sub 0 orders antiferromagnetically below T sub N 1.77(7) K with a similar magnetic structure characterized by a wavevector k (0, approx 0.8, 0). In contras...

  10. Inverse Tunnel Magnetocapacitance in Fe/Al-oxide/Fe3O4.

    Science.gov (United States)

    Kaiju, Hideo; Nagahama, Taro; Sasaki, Shun; Shimada, Toshihiro; Kitakami, Osamu; Misawa, Takahiro; Fujioka, Masaya; Nishii, Junji; Xiao, Gang

    2017-06-01

    Magnetocapacitance (MC) effect, observed in a wide range of materials and devices, such as multiferroic materials and spintronic devices, has received considerable attention due to its interesting physical properties and practical applications. A normal MC effect exhibits a higher capacitance when spins in the electrodes are parallel to each other and a lower capacitance when spins are antiparallel. Here we report an inverse tunnel magnetocapacitance (TMC) effect for the first time in Fe/AlO x /Fe 3 O 4 magnetic tunnel junctions (MTJs). The inverse TMC reaches up to 11.4% at room temperature and the robustness of spin polarization is revealed in the bias dependence of the inverse TMC. Excellent agreement between theory and experiment is achieved for the entire applied frequency range and the wide bipolar bias regions using Debye-Fröhlich model (combined with the Zhang formula and parabolic barrier approximation) and spin-dependent drift-diffusion model. Furthermore, our theoretical calculations predict that the inverse TMC effect could potentially reach 150% in MTJs with a positive and negative spin polarization of 65% and -42%, respectively. These theoretical and experimental findings provide a new insight into both static and dynamic spin-dependent transports. They will open up broader opportunities for device applications, such as magnetic logic circuits and multi-valued memory devices.

  11. Fe and Cu in Si: Lattice sites and trapping at implantation-related defects

    International Nuclear Information System (INIS)

    Wahl, U.; Correia, J.G.; Rita, E.; Araujo, J.P.; Soares, J.C.

    2006-01-01

    We have used the emission channeling technique in order to study the lattice sites of radioactive 59 Fe and 67 Cu following 60 keV ion implantation into Si single crystals at fluences around 10 12 -10 14 cm -2 . We find that in the room temperature as-implanted state in high-resistivity Si both Fe and Cu occupy mainly lattice sites displaced around 0.05 nm (0.5 A) from substitutional positions. Both are released from these positions during annealing at temperatures between 300 deg. C and 600 deg. C. Fe is then found mainly on near-tetrahedral interstitial sites and further annealing causes it to be increasingly incorporated on ideal substitutional sites, on which it is stable to around 800 deg. C. We have strong indications that during annealing around 600 deg. C, along with the dominance of interstitial Fe, a redistribution towards the surface takes place, suggesting that the subsequent formation of ideal substitutional Fe may be related to the trapping of Fe at R p /2, half of its implanted depth. Possible R p /2 trapping might also have taken place in our Cu experiments but appears to be less efficient since Cu tended to escape to the bulk of the samples

  12. Structural and magnetic properties of evaporated Fe thin films on Si(1 1 1), Si(1 0 0) and glass substrates

    International Nuclear Information System (INIS)

    Ghebouli, B.; Cherif, S.-M.; Layadi, A.; Helifa, B.; Boudissa, M.

    2007-01-01

    We present experimental results on the structural and magnetic properties of series of Fe thin films evaporated onto Si(1 1 1), Si(1 0 0) and glass substrates. The Fe thickness, t, ranges from 6 to110 nm. X-ray diffraction (XRD) and atomic force microscopy (AFM) have been used to study the structure and surface morphology of these films. The magnetic properties were investigated by means of the Brillouin light scattering (BLS) and magnetic force microscopy (MFM) techniques. The Fe films grow with (1 1 0) texture; as t increases, this (1 1 0) texture becomes weaker for Fe/Si, while for Fe/glass, the texture changes from (1 1 0) to (2 1 1). Grains are larger in Fe/Si than in Fe/glass. The effective magnetization, 4πM eff , inferred from BLS was found to be lower than the 4πM S bulk value. Stress induced anisotropy might be in part responsible for this difference. MFM images reveal stripe domain structure for the 110 nm thick Fe/Si(1 0 0) only

  13. Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

    Indian Academy of Sciences (India)

    Both beneficial as well as detrimental effects of the nanocrystalline coatings have been reported and the pro- perties of coating can be influenced by many factors such as grain size and its distribution, surface condition, adhe- rence to the substrate, reactivity with the medium and its pre- paration routes, etc (Szewieczek et al ...

  14. Investigations on Mechanical Behaviour of Micro Graphite Particulates Reinforced Al-7Si Alloy Composites

    Science.gov (United States)

    Nagaraj, N.; Mahendra, K. V.; Nagaral, Madeva

    2018-02-01

    Micro particulates reinforced metal matrix composites are finding wide range of applications in automotive and sports equipment manufacturing industries. In the present study, an attempt has been made to develop Al-7Si-micro graphite particulates reinforced composites by using liquid melt method. 3 and 6 wt. % of micro graphite particulates were added to the Al-7Si base matrix. Microstructural characterization was done by using scanning electron microscope and energy dispersive spectroscope. Mechanical behaviour of Al-7Si-3 and 6 wt. % composites were evaluated as per ASTM standards. Scanning electron micrographs revealed the uniform distribution of micro graphite particulates in the Al-7Si alloy matrix. EDS analysis confirmed the presence of B and C elements in graphite reinforced composites. Further, it was noted that ultimate tensile and yield strength of Al-7Si alloy increased with the addition of 3 and 6wt. % of graphite particulates. Hardness of graphite reinforced composites was lesser than the base matrix.

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

    Science.gov (United States)

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

    2015-12-01

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

  16. Pd-Fe/SiO{sub 2} catalysts in the hydrogenation of 2,4-dinitrotoluene

    Energy Technology Data Exchange (ETDEWEB)

    Pinna, F.; Selva, M.; Signoretto, M.; Strukel, G. [Universita di Venezia (Italy); Boccuzzi, F. [Unviersita di Torino (Italy); Benedetti, A.; Canton, P.; Fagherazzi, G. [Universita di Venezia (Italy)

    1994-12-01

    Pd-Fe/SiO{sub 2} bimetallic catalysts with a constant amount of Pd and a different Fe/Pd ratio were prepared by sequential wet impregnation and the hydrogenation of 2,4-dinitrotoluene was carried out at 25{degrees}C in a batch reactor. The presence of Fe enhances the Pd catalytic activity. The formation of a dispersed Pd-Fe alloy was evidenced through X-ray powder diffraction and is consistent with the data observed by FTIR analysis, TPR, and chemisorption features. The increase of the Fe total content of the catalysts results in the increase of the dispersion of the metallic phase and in the presence of partially oxidized Fe species. FTIR analysis shows that nitrocompounds chemisorb mainly on the support rather than on the metal surface. It is suggested that the Pd-Fe alloy formation is responsible for the increase of the catalytic activity because of a cooperative effect of Fe in the hydrogen transfer step. 48 refs., 12 figs., 4 tabs.

  17. Superplasticity in a lean Fe-Mn-Al steel.

    Science.gov (United States)

    Han, Jeongho; Kang, Seok-Hyeon; Lee, Seung-Joon; Kawasaki, Megumi; Lee, Han-Joo; Ponge, Dirk; Raabe, Dierk; Lee, Young-Kook

    2017-09-29

    Superplastic alloys exhibit extremely high ductility (>300%) without cracks when tensile-strained at temperatures above half of their melting point. Superplasticity, which resembles the flow behavior of honey, is caused by grain boundary sliding in metals. Although several non-ferrous and ferrous superplastic alloys are reported, their practical applications are limited due to high material cost, low strength after forming, high deformation temperature, and complicated fabrication process. Here we introduce a new compositionally lean (Fe-6.6Mn-2.3Al, wt.%) superplastic medium Mn steel that resolves these limitations. The medium Mn steel is characterized by ultrafine grains, low material costs, simple fabrication, i.e., conventional hot and cold rolling, low deformation temperature (ca. 650 °C) and superior ductility above 1300% at 850 °C. We suggest that this ultrafine-grained medium Mn steel may accelerate the commercialization of superplastic ferrous alloys.Research in new alloy compositions and treatments may allow the increased strength of mass-produced, intricately shaped parts. Here authors introduce a superplastic medium manganese steel which has an inexpensive lean chemical composition and which is suited for conventional manufacturing processes.

  18. Crystal field interactions in DyFe2Si2 and DyFe2Ge2

    Science.gov (United States)

    Chatterji, A.; Saha, D. P.; Chatterjee, Reba; Mitra, S.

    2009-11-01

    Two sets of crystal field (CF) parameters have been proposed for DyFe2Si2, none of which could provide a simultaneous explanation of the available experimental data, particularly at low temperatures (below 100 K). The set derived from magnetic studies could not even explain the thermal variation of the magnetic specific heat reported in the same work. Although the set of CF parameters, obtained from a fit to the Mossbauer spectra, could provide a fairly good explanation of the thermal variation of the magnetic susceptibilities along the c-axis, it could not explain the observed thermal variation of other reported experimental findings. In the present work, an appraisal of the CF parameters proposed earlier has been done and a set of CF parameters has been derived, which provide a simultaneous explanation of all the available experimental data. The effect of substitution of Ge for Si on the magnetic properties and the magnetic specific heat of DyFe2Si2 has been studied in the framework of one electron crystal field model. The inelastic neutron scattering studies and EPR measurements are required to check the predicted Stark energies and the paramagnetic resonance g-values.

  19. Corrosion behavior of Al-Fe-sputtering-coated steel, high chromium steels, refractory metals and ceramics in high temperature Pb-Bi

    International Nuclear Information System (INIS)

    Abu Khalid, Rivai; Minoru, Takahashi

    2007-01-01

    Corrosion tests of Al-Fe-coated steel, high chromium steels, refractory metals and ceramics were carried out in high temperature Pb-Bi at 700 C degrees. Oxygen concentrations in this experiment were 6.8*10 -7 wt.% for Al-Fe-coated steels and 5*10 -6 wt.% for high chromium steels, refractory metals and ceramics. All specimens were immersed in molten Pb-Bi in a corrosion test pot for 1.000 hours. Coating was done with using the unbalanced magnetron sputtering (UBMS) technique to protect the steel from corrosion. Sputtering targets were Al and SUS-304. Al-Fe alloy was coated on STBA26 samples. The Al-Fe alloy-coated layer could be a good protection layer on the surface of steel. The whole of the Al-Fe-coated layer still remained on the base surface of specimen. No penetration of Pb-Bi into this layer and the matrix of the specimen. For high chromium steels i.e. SUS430 and Recloy10, the oxide layer formed in the early time could not prevent the penetration of Pb-Bi into the base of the steels. Refractory metals of tungsten (W) and molybdenum (Mo) had high corrosion resistance with no penetration of Pb-Bi into their matrix. Penetration of Pb-Bi into the matrix of niobium (Nb) was observed. Ceramic materials were SiC and Ti 3 SiC 2 . The ceramic materials of SiC and Ti 3 SiC 2 had high corrosion resistance with no penetration of Pb-Bi into their matrix. (authors)

  20. Tensile Strength of the Al-9%Si Alloy Modified with Na, F and Cl Compounds

    Directory of Open Access Journals (Sweden)

    T. Lipiński

    2010-01-01

    Full Text Available The modification of the Al-9%Si alloy with the use of a complex modifier containing Na, F and Cl was investigated in the study. The modifier was composed of NaCl, Na3AlF6 and NaF compounds. The modifier and the liquid Al-Si alloy were kept in the crucible for 15 minutes. The modifier's effect relative to the weight of the processed alloy on its tensile strength was presented in graphic form. The results of the study indicate that the complex modifier altered the investigated properties of the eutectic Al-9%Si alloy.

  1. Al-doped single-crystalline SiC nanowires synthesized by pyrolysis of polymer precursors.

    Science.gov (United States)

    Yang, Weiyou; Gao, Fengmei; Fan, Yi; An, Linan

    2010-07-01

    Al-doped 6H-SiC nanowires are synthesized by catalyst-assisted pyrolysis of polymer precursors. The obtained nanowires were characterized using scanning electron microscopy, X-ray diffraction, transmission electron microscopy and selective area electron diffraction. We demonstrate that doping concentrations can be controlled by tailoring the Al concentrations in the precursors. We also find that Al-doping has a profound effect on the morphology and emission behavior of the SiC nanowires. The current results suggest a simple technique for synthesizing Al-doped SiC nanomaterials in a controlled manner, which are promising for applications in optical and electronic nanodevices.

  2. Preparation of mullite whiskers reinforced SiC/Al2O3 composites by microwave sintering

    Directory of Open Access Journals (Sweden)

    Wei Li

    2016-12-01

    Full Text Available Mullite whiskers reinforced SiC/Al2O3 composites were prepared by microwave sintering in a microwave chamber with TE666 resonant mode. Original SiC particles were coated with SiO2 using sol-gel processing and mixed with Al2O3 particles. Mullite was formed in the reaction between SiO2 and Al2O3. The isostatically pressed cylindrical pellets were sintered from 1350 °C to 1600 °C for 30 min. Physical and chemical responses were investigated by detecting changes in reflected power during the microwave sintering process. XRD was carried out to characterize the samples and showed that mullite could be formed at 1200 °C. Bridging of mullite whiskers between Al2O3 and SiC particles was observed by SEM and is due to a so-called local hot spot effect, which was the unique feature for microwave sintering. The optimized microwave sintering temperature was 1500 °C corresponding to the maximum amount of mullite whiskers within SiC/Al2O3 composites. The high electro-magnetic field enhanced the decomposition of mullite at higher temperatures above 1550 °C. The mechanical properties of mullite whiskers reinforced SiC/Al2O3 composites are much better than the SiC/Al2O3 composites without mullite whiskers.

  3. Effect of Fe content and microstructural features on the tensile and fatigue properties of the Al–Si10–Cu2 alloy

    International Nuclear Information System (INIS)

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Seifeddine, Salem; Svensson, Ingvar L.

    2012-01-01

    Highlights: ► The effect of different amounts of Fe and Mn on fatigue behaviour of the Al–Si10–Cu2 alloy was studied. ► Fatigue specimens were subjected to HIP to eliminate the internal pores. ► The effect of microstructural features on the fatigue propagation was studied. ► The presence of β-Al 5 FeSi induced only a slight increase on the fatigue resistance. ► The presence of the α-Al 15 (Fe,Mn) 3 Si increased the fatigue resistance of the alloy. -- Abstract: As the automotive industry has to meet the requirements of fuel efficiency and environmental concerns, the use of aluminium alloys is steadily increasing. A number of papers have been published about the correlation between microstructure and mechanical properties of the widely used A356/A357 aluminium alloys, while relatively few data are available on others hypoeutectic Al–Si alloys, such as Al–Si–Cu alloys with higher Si content. In this work the effect of different amounts of Fe and Mn on the tensile and fatigue behaviour of the Al–Si10–Cu2 casting alloy was studied. The reason of this study comes from the fact that cast components are mostly made by secondary Al alloys that inevitably contain Fe, which in turn forms intermetallic compounds, negatively affecting the mechanical behaviour of the alloy. Fatigue specimens were subjected to hot isostatic pressing (HIP) before tests, in order to eliminate the internal pores (gas pores and interdendritic shrinkages) and therefore to solely investigate the effect of microstructural features, rather than solidification defects, on the fatigue propagation stage. The microstructural characterisation of the alloy was carried out by optical and scanning electron microscopy. Proof and ultimate tensile strength, as well as fatigue life of the investigated alloy were greatly enhanced by high Fe and Mn content, which reduced the micro-crack propagation rate; on the contrary Fe, without Mn, negatively affected the elongation to failure.

  4. Microstructure of two phases alloy Al3Ti/Al3Ti0.75Fe0.25

    International Nuclear Information System (INIS)

    Angeles, C.; Rosas, G.; Perez, R.

    1998-01-01

    The titanium-aluminium system presents three intermetallic compounds from those Al 3 Ti is what less attention has received. The objective of this work is to generate and characterize the microstructure of multiphase alloys nearby to Al 3 Ti compound through Fe addition as alloying. This is because it has been seen that little precipitates of Al 2 Ti phase over Al 3 Ti intermetallic compound increases its ductility. (Author)

  5. Green synthesis and stable li-storage performance of FeSi(2)/Si@C nanocomposite for lithium-ion batteries.

    Science.gov (United States)

    Chen, Yao; Qian, Jiangfeng; Cao, Yuliang; Yang, Hanxi; Ai, Xinping

    2012-07-25

    Si-based alloy materials have received great attention as an alternative anode for high capacity and safe Li-ion batteries, but practical implementation of these materials is hindered by their poor electrochemical utilization and cyclability. To tackle this problem, we developed a core-shelled FeSi2/Si@C nanocomposite by a direct ball-milling of Fe and Si powders. Such a nanostructured composite can effectively buffer the volumetric change by alloying active Si phase with inactive FeSi2 matrix in its inner cores and prevent the aggregation of the active Si particles by outer graphite shells, so as to improve the cycling stability of the composite material. As a result, the FeSi2/Si@C composite exhibits a high Li-storage capacity of ∼1010 mA g(-1) and an excellent cyclability with 94% capacity retention after 200 cycles, showing a great promise for battery applications. More significantly, the synthetic method developed in this work possesses several advantages of low cost, zero emission, and operational simplicity, possibly to be extended for making other Li-storage alloys for large-scale applications in Li-ion batteries.

  6. Synthesis and adsorption properties of hierarchical Fe3O4@MgAl-LDH magnetic microspheres

    Science.gov (United States)

    Wu, Xiaoge; Li, Bo; Wen, Xiaogang

    2017-04-01

    In this study, Fe3O4 microspheres were prepared by a hydrothermal method, and then the synthesized Fe3O4 microspheres were used as template to prepare Fe3O4@MgAl-LDH composite microspheres by a coprecipitation process. Morphology, composition, and crystal structure of synthesized nanomaterials were characterized by X-ray powder diffractometry, scanning electron microscopy, and Fourier transform infrared spectroscopy technologies. The composite hierarchical microspheres are composed of inner Fe3O4 core and outer MgAl-LDH-nanoflake layer, and the average thickness of MgAl-LDH-nanoflake is about 70 nm. The adsorption property of the products toward congo red was also measured using UV-vis spectrometer. The result demonstrated that the Fe3O4@MgAl-LDH composite adsorbent could remove 99.8% congo red in 30 min, and the maximum adsorption capacity is about 404.6 mg/g, while congo red removal rate of pure MgAl-LDH and Fe3O4 are only 86.3 and 53.1% in 40 min, respectively, and their adsorption capacity are 345.72 and 220.56 mg/g, respectively. It indicates the composite Fe3O4@ MgAl-LDH nanomaterials have better adsorption performance than pure Fe3O4 and MgAl-LDH nanomaterials. In addition, the magnetic nanocomposites could be separated easily, and it demonstrated good cycle performance.

  7. Hyperfine electric parameters calculation in Si samples implanted with {sup 57}Mn→{sup 57}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Y., E-mail: yabreu@ceaden.edu.cu [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Cruz, C.M.; Piñera, I.; Leyva, A.; Cabal, A.E. [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Van Espen, P. [Departement Chemie, Universiteit Antwerpen, Middelheimcampus, G.V.130, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Van Remortel, N. [Departement Fysica, Universiteit Antwerpen, Middelheimcampus, G.U.236, Groenenborgerlaan 171, 2020 Antwerpen (Belgium)

    2014-07-15

    Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mössbauer spectroscopy in silicon materials implanted with {sup 57}Mn→{sup 57}Fe ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the {sup 57}Fe Mössbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the {sup 57}Fe hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of {sup 57}Fe ions in substitutional and interstitial sites is proposed.

  8. Determination of Al, Si and P in certified reference materials by Instrumental Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Noyori, Amanda; Saiki, Mitiko, E-mail: anoyori@gmail.com, E-mail: mitiko@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-11-01

    Neutron analysis activation is not commonly used for aluminum, phosphorus and silicon determination, due to the difficulty to obtain reliable results. In this study, Al was determined by measuring {sup 28}Al and the contribution of P and Si due to {sup 28}Al formed in {sup 31}P(n,α){sup 28}Al and {sup 28}Si(n,p){sup 28}Al reactions were corrected using correction factors determined experimentally. Phosphorus was determined by measuring {sup 32}P (pure beta emitter) formed in reaction {sup 31}P(n,γ){sup 32}P. Silicon was determined by epithermal neutron analysis activation (ENAA) and measuring {sup 29}Al radionuclide formed in {sup 29}Si(n,p){sup 29}Al reaction. Aliquots of certified reference materials (CRMs) and synthetic standards of the elements were irradiated together, using the pneumatic transfer station of IEA-R1 nuclear research reactor. Results obtained for biological and geological CRMs showed good precision and accuracy with |Z-score| < 2 for Al, P and Si determinations. The detection limits for Al, P and Si determinations CRMs were also evaluated. Results obtained in this study demonstrated the viability of applying INAA procedures in the determination of Al, P and Si. (author)

  9. Determination of Al, Si and P in certified reference materials by Instrumental Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Noyori, Amanda; Saiki, Mitiko

    2017-01-01

    Neutron analysis activation is not commonly used for aluminum, phosphorus and silicon determination, due to the difficulty to obtain reliable results. In this study, Al was determined by measuring 28 Al and the contribution of P and Si due to 28 Al formed in 31 P(n,α) 28 Al and 28 Si(n,p) 28 Al reactions were corrected using correction factors determined experimentally. Phosphorus was determined by measuring 32 P (pure beta emitter) formed in reaction 31 P(n,γ) 32 P. Silicon was determined by epithermal neutron analysis activation (ENAA) and measuring 29 Al radionuclide formed in 29 Si(n,p) 29 Al reaction. Aliquots of certified reference materials (CRMs) and synthetic standards of the elements were irradiated together, using the pneumatic transfer station of IEA-R1 nuclear research reactor. Results obtained for biological and geological CRMs showed good precision and accuracy with |Z-score| < 2 for Al, P and Si determinations. The detection limits for Al, P and Si determinations CRMs were also evaluated. Results obtained in this study demonstrated the viability of applying INAA procedures in the determination of Al, P and Si. (author)

  10. Microstructure and bonding mechanism of Al/Ti bonded joint using Al-10Si-1Mg filler metal

    International Nuclear Information System (INIS)

    Sohn, Woong H.; Bong, Ha H.; Hong, Soon H.

    2003-01-01

    The microstructures and liquid state diffusion bonding mechanism of cp-Ti to 1050 Al using an Al-10.0wt.%Si-1.0wt.%Mg filler metal with 100 μm in thickness have been investigated at 620 deg. C under 1x10 -4 Torr. The effects of bonding process parameters on microstructure of bonded joint have been analyzed by using an optical microscope, AES, scanning electron microscopy and EDS. The interfacial bond strength of Al/Ti bonded joints was measured by the single lap shear test. The results show that the bonding at the interface between Al and filler metal proceeds by wetting the Al with molten filler metal, and followed by removal of oxide layer on surface of Al. The interface between Al and filler metal moved during the isothermal solidification of filler metal by the diffusion of Si from filler metal into Al layer. The interface between Al and filler metal became curved in shape with increasing bonding time due to capillary force at grain boundaries. The bonding at the interface between Ti and filler metal proceeds by the formation of two different intermetallic compound layers, identified as Al 5 Si 12 Ti 7 and Al 12 Si 3 Ti 5 , followed by the growth of the intermetallic compound layers. The interfacial bond strength at Al/Ti joint increased with increasing bonding time up to 25 min at 620 deg. C. However, the interfacial bond strength of Al/Ti joint decreased after bonding time of 25 min at 620 deg. C due to formation of cavities in Al near Al/intermetallic interfaces

  11. First-principles investigation of Fe-doped MgSiO3-ilmenite

    International Nuclear Information System (INIS)

    Stashans, Arvids; Rivera, Krupskaya; Pinto, Henry P.

    2012-01-01

    First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO 3 mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using ΔSCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO 3 . Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe⇒Mg reaction can be described as substitutionally labile with Fe 2+ complex being found in the high-spin state at low pressure MgSiO 3 -ilmenite conditions.

  12. Preparation and Characterization of Promoted Fe-V/SiO2 Nanocatalysts for Oxidation of Alcohols

    Directory of Open Access Journals (Sweden)

    Hamid Reza Rafiee

    2013-01-01

    Full Text Available A series of SiO2 supported iron-vanadium catalysts were prepared using sol-gel and wetness impregnation methods. This research investigates the effects of V and Cu on the structure and morphology of Fe/SiO2 catalysts. The SiO2 supported catalyst with the highest specific surface area and pore volume was obtained when it is containing 40 wt.% Fe, 15 wt.% V, and 2 wt.% Cu. Characterization of prepared catalysts was carried out by powder X-ray diffraction (XRD, scanning electron microcopy (SEM, vibrating sample magnetometry (VSM, Fourier transform infrared (FT-IR spectrometry, temperature program reduction (TPR, N2 physisorption, and thermal analysis methods such as thermal gravimetric analysis (TGA and differential scanning calorimetry (DSC. The Fe-V/SiO2 catalyst promoted with 2 wt.% of Cu exhibited typical ferromagnetic behavior at room temperature with a saturation magnetization value of 11.44 emu/g. This character of catalyst indicated great potential for application in magnetic separation technologies. The prepared catalyst was found to act as an efficient recoverable nanocatalyst for oxidation reaction of alcohols to aldehydes and ketones in aqueous media under mild condition. Moreover, the catalyst was reused five times without significant degradation in catalytic activity and performance.

  13. Effect of Fe, Co, Si and Ge impurities on optical properties of graphene sheet

    Energy Technology Data Exchange (ETDEWEB)

    Kheyri, A. [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Nourbakhsh, Z., E-mail: z.nourbakhsh@sci.ui.ac.ir [Physics Department, Faculty of Science, University of Isfahan, Isfahan (Iran, Islamic Republic of); Darabi, E. [Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-08-01

    The electronic and linear optical properties of pure graphene and impurity-graphene (with Fe, Co, Si and Ge impurities) sheets are investigated by using the full potential linear augmented plane wave plus local orbital (FPLAPW + lo) in the framework of the density functional theory (DFT). The calculated results are obtained within the generalized gradient approximation using the Perdew–Burke–Ernzerhof scheme in the presence of spin-orbit interaction. The band structure, partial electron density of states, dielectric function, absorption coefficient, optical conductivity, extinction index, energy loss function, reflectivity and the refraction index of these sheets for parallel and perpendicular electromagnetic wave polarization to sheet are investigated. The optical conductivity of Si-graphene and Ge-graphene sheets for the parallel electromagnetic wave polarization to the sheet starts with a gap about 0.4 eV confirms that these sheets have semiconductor behavior. Also the optical spectra of these sheets are anisotropic along these two wave polarizations. The dielectric function in the static limit of pure graphene sheet for perpendicular electromagnetic wave polarization to sheet does not significant change in the presence of Si, Ge, Fe and Co impurities. The static refractive index of Fe-graphene and Co-graphene sheets for parallel electromagnetic wave polarization to sheet is much larger than the corresponding value of pure graphene sheet. - Highlights: • Graphene sheet with Fe and Co impurities is metal. • Graphene sheet with Si and Ge impurities is semiconductor with 0.2 eV energy band gap. • These sheets optical spectra have metallic behavior for perpendicular polarization. • These sheets optical spectra have semiconductor behavior for parallel polarization. • Graphene sheet with Si and Ge impurities can use for optoelectronic devices.

  14. Effect of Fe, Co, Si and Ge impurities on optical properties of graphene sheet

    International Nuclear Information System (INIS)

    Kheyri, A.; Nourbakhsh, Z.; Darabi, E.

    2016-01-01

    The electronic and linear optical properties of pure graphene and impurity-graphene (with Fe, Co, Si and Ge impurities) sheets are investigated by using the full potential linear augmented plane wave plus local orbital (FPLAPW + lo) in the framework of the density functional theory (DFT). The calculated results are obtained within the generalized gradient approximation using the Perdew–Burke–Ernzerhof scheme in the presence of spin-orbit interaction. The band structure, partial electron density of states, dielectric function, absorption coefficient, optical conductivity, extinction index, energy loss function, reflectivity and the refraction index of these sheets for parallel and perpendicular electromagnetic wave polarization to sheet are investigated. The optical conductivity of Si-graphene and Ge-graphene sheets for the parallel electromagnetic wave polarization to the sheet starts with a gap about 0.4 eV confirms that these sheets have semiconductor behavior. Also the optical spectra of these sheets are anisotropic along these two wave polarizations. The dielectric function in the static limit of pure graphene sheet for perpendicular electromagnetic wave polarization to sheet does not significant change in the presence of Si, Ge, Fe and Co impurities. The static refractive index of Fe-graphene and Co-graphene sheets for parallel electromagnetic wave polarization to sheet is much larger than the corresponding value of pure graphene sheet. - Highlights: • Graphene sheet with Fe and Co impurities is metal. • Graphene sheet with Si and Ge impurities is semiconductor with 0.2 eV energy band gap. • These sheets optical spectra have metallic behavior for perpendicular polarization. • These sheets optical spectra have semiconductor behavior for parallel polarization. • Graphene sheet with Si and Ge impurities can use for optoelectronic devices.

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

    Directory of Open Access Journals (Sweden)

    Birol Akyüz

    2016-09-01

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

  16. Physical and electrical properties of melt-spun Fe-Si (3–8 wt.%) soft magnetic ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Overman, Nicole R.; Jiang, Xiujuan; Kukkadapu, Ravi K.; Clark, Trevor; Roosendaal, Timothy J.; Coffey, Gregory; Shield, Jeffrey E.; Mathaudhu, Suveen N.

    2018-02-01

    Fe-Si alloys ranging from 3 to 8 wt% Si were rapidly solidified using melt spinning. Wheel speeds of 30 m/s and 40 m/s were employed to vary cooling rates. Mössbauer spectroscopic studies indicated the Si content significantly influenced the number of Fe sites, relative abundance of various Fe species, and internal magnetic fields/structural environments. Wheel speed altered Fe speciation only in the 3 wt% sample. Scanning electron microscopy confirmed that increasing the wheel speed refined both the ribbon thickness and grain size. Electron backscatter diffraction results suggest tailoring melt spinning process parameters and alloy chemistry may offer the ability to manipulate {001} texture development. Electrical resistivity measurements were observed to increase in response to elevated Si content. Increased hardness was correlated to elevated Si content and wheel speed.

  17. Oxidation of Ca-α-SiAlON Powders Prepared by Combustion Synthesis

    Science.gov (United States)

    Li, Jinfu; Li, Zhongmin; Wang, Enhui; Wang, Zhanjun; Yin, Xiaowei; Zhang, Zuotai

    2015-01-01

    The oxidation of Ca-α-SiAlON synthesized by the combustion synthesis (CS) method with different additives was investigated in air atmosphere using thermogravimetric (TG) analysis in a temperature range from 1453 K to 1653 K. The experimental results indicated that oxidation was controlled by mixed chemical and diffusion steps. The oxidation products by XRD analysis were composed of SiO2 and CaAl2Si2O8 at low oxidation temperature, whereas the SiO2-Al2O3-CaO ternary glassy phase was formed at elevated temperature. The deviation of oxidation resistance from each sample may be due to the morphological difference brought about by different additive additions. This study reveals the effects of additives on the oxidation resistance of synthesized Ca-α-SiAlON powders. PMID:28793657

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

    Directory of Open Access Journals (Sweden)

    M. Haghshenas

    2017-04-01

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

  19. Positive charge effects on the flatband voltage shift during avalanche injection on Al-SiO2-Si capacitors

    International Nuclear Information System (INIS)

    Fischetti, M.V.; Gastaldi, R.; Maggioni, F.; Modelli, A.

    1982-01-01

    Electron avalanche injection is performed at various temperatures on Al gate, wet oxide metal-oxide-semiconductor capacitors. The observed behavior of the flatband voltage shift versus injected charge is well represented by a phenomenological model which includes the buildup of positively charged defects at the Si-SiO 2 interface, their annealing, and their neutralization by ''trapped'' electrons. At high temperatures (T> or approx. =350 0 K) annealing is very efficient, while for T 0 K the positive charge is quickly neutralized. Thus the ''turn around'' is observable at room temperature only. The role of trivalent silicon defects and of Si-H bonds is discussed

  20. Heterogeneous Creep Deformations and Correlation to Microstructures in Fe-30Cr-3Al Alloys Strengthened by an Fe2Nb Laves Phase

    Science.gov (United States)

    Shassere, Benjamin; Yamamoto, Yukinori; Poplawsky, Jonathan; Guo, Wei; Babu, Sudarsanam Suresh

    2017-10-01

    A new Fe-Cr-Al (FCA) alloy system has been developed with good oxidation resistance and creep strength at high temperature. The alloy system is a candidate for use in future fossil-fueled power plants. The creep strength of these alloys at 973 K (700 °C) was found to be comparable with traditional 9 pct Cr ferritic-martensitic steels. A few FCA alloys with general composition of Fe-30Cr-3Al-.2Si- xNb ( x = 0, 1, or 2) with a ferrite matrix and Fe2Nb-type Laves precipitates were prepared. The detailed microstructural characterization of samples, before and after creep rupture testing, indicated precipitation of the Laves phase within the matrix, Laves phase at the grain boundaries, and a 0.5 to 1.5 μm wide precipitate-free zone (PFZ) parallel to all the grain boundaries. In these alloys, the areal fraction of grain boundary Laves phase and the width of the PFZ controlled the cavitation nucleation and eventual grain boundary ductile failure. A phenomenological model was used to compare the creep strain rates controlled by the effects of the particles on the dislocations within the grain and at grain boundaries. (The research sponsored by US-DOE, Office of Fossil Energy, the Crosscutting Research Program).

  1. Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

    International Nuclear Information System (INIS)

    Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

    2005-01-01

    In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

  2. Pendeo-epitaxy of stress-free AlN layer on a profiled SiC/Si substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bessolov, V.N. [Ioffe Physical Technical Institute, Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg, 194021 (Russian Federation); Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, V.O., Bolshoj pr., 61, St. Petersburg, 199178 (Russian Federation); Karpov, D.V. [St. Petersburg Academic University - Nanotechnology Research and Education Centre of the Russian Academy of Sciences (Academic University), Khlopina 8/3, St Petersburg, 194021 (Russian Federation); University of Eastern Finland, P.O. Box 111, Joensuu, 80101 (Finland); Konenkova, E.V. [Ioffe Physical Technical Institute, Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg, 194021 (Russian Federation); Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, V.O., Bolshoj pr., 61, St. Petersburg, 199178 (Russian Federation); Lipovskii, A.A. [St. Petersburg Academic University - Nanotechnology Research and Education Centre of the Russian Academy of Sciences (Academic University), Khlopina 8/3, St Petersburg, 194021 (Russian Federation); Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg, 195251 (Russian Federation); Osipov, A.V. [Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, V.O., Bolshoj pr., 61, St. Petersburg, 199178 (Russian Federation); St. Petersburg National Research University of Information Technologies, Mechanics and Optics, Kronverkskii pr. 49, St. Petersburg, 197101 (Russian Federation); Redkov, A.V. [Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, V.O., Bolshoj pr., 61, St. Petersburg, 199178 (Russian Federation); St. Petersburg Academic University - Nanotechnology Research and Education Centre of the Russian Academy of Sciences (Academic University), Khlopina 8/3, St Petersburg, 194021 (Russian Federation); Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg, 195251 (Russian Federation); and others

    2016-05-01

    A new approach to the pendeo-epitaxy of elastically-unstrained AlN films is developed. The AlN films are grown using chloride-hydride vapor phase epitaxy (HVPE) on a silicon substrate with specially synthesized and shaped buffer layer of nano-SiC (NSiC). This NSiC epitaxial layer is grown using a new technique based on the substitution of a part of silicon atoms by carbon ones in a 100–110 nm thick subsurface layer of the silicon substrate. The 2D array of ~ 200 nm in diameter wells with the depth of ~ 70 nm that is less than the NSiC layer thickness is formed on the NSiC surface using electron beam lithography followed by reactive ion etching, the period of the array is of 400 nm. In a single HVPE process we grew ~ 20 μm thick AlN film both on the shaped and smooth regions of the prepared substrate. The AlN films are examined with reflection high energy electron diffraction, X-ray diffractometry, Raman spectroscopy and scanning electron microscopy. We use the results of these measurements to compare residual elastic stresses in the AlN film grown on the shaped and smooth regions of the substrate. The film on the shaped part of the substrate is elastically-unstrained contrary to the smooth part where elastic stresses result in the formation of a textured AlN layer. The model of the AlN growth on shaped SiC/Si substrates prepared using the atomic substitution technique is proposed. - Highlights: • A new method for chloride-hydride vapor phase pendeo-epitaxy of AlN is proposed • Unstrained AlN layer is grown on a Si substrate with a nanoprofiled SiC buffer • SiC made by substitution of atoms is well suited for the growth of AlN • Dissolution of pores in silicon beneath the nano-SiC is revealed.

  3. Iron-based superconductivity extended to the novel silicide LaFeSiH

    Science.gov (United States)

    Bernardini, F.; Garbarino, G.; Sulpice, A.; Núñez-Regueiro, M.; Gaudin, E.; Chevalier, B.; Méasson, M.-A.; Cano, A.; Tencé, S.

    2018-03-01

    We report the synthesis and characterization of the novel silicide LaFeSiH displaying superconductivity with onset at 11 K. We find that this pnictogen-free compound is isostructural to LaFeAsO, with a similar low-temperature tetragonal to orthorhombic distortion. Using density functional theory we show that this system is also a multiband metal in which the orthorhombic distortion is likely related to single-stripe antiferromagnetic order. Electrical resistivity and magnetic susceptibility measurements reveal that these features occur side by side with superconductivity, which is suppressed by external pressure.

  4. Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys

    Directory of Open Access Journals (Sweden)

    Bae K.C.

    2017-06-01

    Full Text Available To investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the numb