Effect of Al substitution for Ga on the mechanical properties of directional solidified Fe-Ga alloys

Energy Technology Data Exchange (ETDEWEB)

Liu, Yangyang; Li, Jiheng; Gao, Xuexu, E-mail: gaox@skl.ustb.edu.cn

2017-02-01

Alloys of Fe{sub 82}Ga{sub 18−x}Al{sub x} (x=0, 4.5, 6, 9, 12, 13.5) were prepared by directional solidification technique and exhibited a <001> preferred orientation along the axis of alloy rods. The saturation magnetostriction value of the Fe{sub 82}Ga{sub 13.5}Al{sub 4.5} alloy was 247 ppm under no pre-stress. The tensile properties of alloys of Fe{sub 82}Ga{sub 18−x}Al{sub x} at room temperature were investigated. The results showed that tensile ductility of binary Fe-Ga alloy was significantly improved with Al addition. The fracture elongation of the Fe{sub 82}Ga{sub 18} alloy was only 1.3%, while that of the Fe{sub 82}Ga{sub 9}Al{sub 9} alloy increased up to 16.5%. Addition of Al increased the strength of grain boundary and cleavage, resulting in the enhancement of tensile ductility of the Fe-Ga-Al alloys. Analysis of deformation microstructure showed that a great number of deformation twins formed in the Fe-Ga-Al alloys, which were thought to be the source of serrated yielding in the stress-strain curves. The effect of Al content in the Fe-Ga-Al alloys on tensile ductility was also studied by the analysis of deformation twins. It indicated that the joint effect of slip and twinning was beneficial to obtain the best ductility in the Fe{sub 82}Ga{sub 9}Al{sub 9} alloy. - Highlights: • Tensile ductility of directional solidified Fe-Ga alloys was significantly improved with Al addition. • The fracture elongation of binary Fe{sub 82}Ga{sub 18} alloy was only 1.3% at room temperature. • The fracture elongation of Fe{sub 82}Ga{sub 9}Al{sub 9} alloy was 16.5% at room temperature. • A great number of deformation twins formed in the Fe-Ga-Al alloys during tensile tests at room temperature.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

OpenAIRE

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-01-01

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these allo...

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al-5Mg-Mn Alloys Solidified Under Near-Rapid Cooling.

Science.gov (United States)

Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

2016-01-29

Mn was an important alloying element used in Al-Mg-Mn alloys. However, it had to be limited to a low level (Al-5Mg-Mn alloy with low Fe content (Al₆(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al₆(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al-5Mg-Mn alloys (0.5 wt % Fe), intermetallic Al₆(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al₆(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al₆(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al₆(Fe,Mn) to become the primary phase at a lower Mn content.

Atomic site occupancies and magnetic properties of Ni-doped FeAl intermetallic compounds

CERN Document Server

Ko, K Y; Yoon, S

1999-01-01

Neutron and X-ray powder diffraction revealed FeAl sub 1 sub - sub x Ni sub x alloys to have the B2(CsCl) structure with a virtually constant lattice parameter of 2.91 A and with the Ni atoms preferring the Fe sites. The annealed specimens showed paramagnetism for x 0.25 whereas the rapidly solidified specimens showed superparamagnetism for x = 0.25. The magnetization increased as the Ni concentration (x) increased. The rapidly solidified specimens, in general, showed stronger magnetic properties than the annealed ones. The magnetic properties were explained in terms of the local environmental model for magnetic atoms.

Characterization of aluminium alloys rapidly solidified

International Nuclear Information System (INIS)

Monteiro, W.A.

1988-01-01

This paper discussed the investigation of the microstructural and mechanical properties of the aluminium alloys (3003; 7050; Al-9% Mg) rapidly solidified by melt spinning process (cooling rate 10 4 - 10 6 K/s). The rapidly solidification process of the studied aluminium alloys brought a microcrystallinity, a minimum presence of coarse precipitation and, also, better mechanical properties of them comparing to the same alloys using ingot process. (author) [pt

Cation distributions on rapidly solidified cobalt ferrite

Science.gov (United States)

De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

1990-01-01

The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

Formation of AlFeSi phase in AlSi12 alloy with Ce addition

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S. Kores

2012-04-01

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

Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy

Science.gov (United States)

Harf, F. H.; Tewari, S. N.

1977-01-01

Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.

Tensile behavior change depending on the microstructure of a Fe-Cu alloy produced from rapidly solidified powder

International Nuclear Information System (INIS)

Kakisawa, Hideki; Minagawa, Kazumi; Halada, Kohmei

2003-01-01

The relationship between consolidating temperature and the tensile behavior of iron alloy produced from Fe-Cu rapidly solidified powder is investigated. Fe-Cu powder fabricated by high-pressure water atomization was consolidated by heavy rolling at 873-1273 K. Microstructural changes were observed and tensile behavior was examined. Tensile behavior varies as the consolidating temperature changes, and these temperature-dependent differences depend on the morphology of the microstructure on the order of micrometers. The sample consolidated at 873 K shows a good strength/elongation balance because the powder microstructure and primary powder boundaries are maintained. The samples consolidated at the higher temperatures have a microstructure of recrystallized grains, and these recrystallized samples show the conventional relationship between tensile behavior and grain size in ordinal bulk materials

Microstructure of rapidly solidified Al2O3-dispersion-strengthened Type 316 stainless steel

International Nuclear Information System (INIS)

Megusar, J.; Arnberg, L.; Vander Sande, J.B.; Grant, N.J.

1981-01-01

An aluminum oxide dispersion strengthened 316 stainless steel was developed by surface oxidation. Surface oxidation was chosen as a preferred method in order to minimize formation of less stable chromium oxides. Ultra low C+N 316 stainless steel was alloyed with 1 wt % Al, rapidly solidified to produce fine powders and attrited to approximately 0.5 μm thick flakes to provide for surface oxidation. Oxide particles in the extruded material were identified mostly as Al oxides. In the preirradiated condition, oxide dispersion retarded crystallization and grain growth and had an effect on room temperature tensile properties. These structural modifications are expected to have an effect on the swelling resistance, structure stability and high temperature strength of austenitic stainless steels

High-temperature deformation behavior and mechanical properties of rapidly solidified Al-Li-Co and Al-Li-Zr alloys

International Nuclear Information System (INIS)

Sastry, S.M.L.; Oneal, J.E.

1984-01-01

The deformation behavior at 25-300 C of rapidly solidified Al-3Li-0.6Co and Al-3Li-0.3Zr alloys was studied by tensile property measurements and transmission electron microscopic examination of dislocation substructures. In binary Al-3Li and Al-3Li-Co alloys, the modulus normalized yield stress increases with an increase in temperature up to 150 C and then decreases. The yield stress at 25 C of Al-3Li-0.3Zr alloys is 180-200 MPa higher than that of Al-3Li alloys. However, the yield stress of the Zr-containing alloy decreases drastically with increasing temperatures above 75 C. The short-term yield stresses at 100-200 C of the Al-3Li-based alloys are higher than that of the conventional high-temperature Al alloys. The temperature dependences of the flow stresses of the alloys were analyzed in terms of the magnitudes and temperature dependences of the various strengthening contributions in the two alloys. The dislocation substructures at 25-300 C were correlated with mechanical properties. 19 references

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

Science.gov (United States)

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-11-05

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Phase formation kinetics, hardness and magnetocaloric effect of sub-rapidly solidified LaFe11.6Si1.4 plates during isothermal annealing

Science.gov (United States)

Dai, Yuting; Xu, Zhishuai; Luo, Zhiping; Han, Ke; Zhai, Qijie; Zheng, Hongxing

2018-05-01

High-temperature phase transition behavior and intrinsic brittleness of NaZn13-type τ1 phase in La-Fe-Si magnetocaloric materials are two key problems from the viewpoint of materials production and practical applications. In the present work, the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation was introduced to quantitatively characterize the formation kinetics of τ1 phase in sub-rapidly solidified LaFe11.6Si1.4 plates during the isothermal annealing process. Avrami index was estimated to be 0.43 (∼0.5), which suggests that the formation of τ1 phase is in a diffusion-controlled one-dimensional growth mode. Meanwhile, it is found that the Vickers hardness as a function of annealing time for sub-rapidly solidified plates also agrees well with the JMAK equation. The Vickers hardness of τ1 phase was estimated to be about 754. Under a magnetic field change of 30 kOe, the maximum magnetic entropy change was about 22.31 J/(kg·K) for plates annealed at 1323 K for 48 h, and the effective magnetic refrigeration capacity reached 191 J/kg.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

Directory of Open Access Journals (Sweden)

Andrea Školáková

2017-11-01

Full Text Available In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

Science.gov (United States)

Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

2016-01-01

Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (Al–5Mg–Mn alloy with low Fe content (Al6(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe), intermetallic Al6(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn) to become the primary phase at a lower Mn content. PMID:28787888

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al–5Mg–Mn Alloys Solidified Under Near-Rapid Cooling

Directory of Open Access Journals (Sweden)

Yulin Liu

2016-01-01

Full Text Available Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt % to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %, intermetallic Al6(Fe,Mn was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe, intermetallic Al6(Fe,Mn became the dominant phase, even in the alloy with low Mn content (0.39 wt %. Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn to become the primary phase at a lower Mn content.

The research of Ti-rich zone on the interface between TiCx and aluminum melt and the formation of Ti3Al in rapid solidified Al-Ti-C master alloys

International Nuclear Information System (INIS)

Jiang Kun; Ma Xiaoguang; Liu Xiangfa

2009-01-01

In the present work, the thermodynamic tendency of formation of Ti-rich zone on the interface between TiC x and aluminum melt is calculated and a high titanium concentration can exist in the zone according to the thermodynamic calculation. Rapid solidified Al-5Ti-0.5C master alloy is analyzed by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). The appearance of Ti 3 Al in the master alloy results from the existence of high-concentration Ti-rich zone.

Microstructural characterization of a rapidly solidified ultrahigh strength Al94.5Cr3Co1.5Ce1 alloy

International Nuclear Information System (INIS)

Ping, D.H.; Hono, K.; Inoue, A.

2000-01-01

The microstructure of a rapidly solidified Al 94.5 Cr 3 Co 1.5 Ce 1 alloy has been examined in detail by means of high resolution transmission electron microscopy (HRTEM) and atom probe field ion microscopy (APFIM). In the as-quenched microstructure, nanoscale particles of a solute-enriched amorphous phase and an Al-Cr compound are dispersed in randomly oriented fine grains of α-Al ( 200nm ). The interface between the Al grains and the amorphous particles is not smooth but irregular with atomic protrusions and concavities, suggesting that interfacial instability occurs during the solidification process. Nanoscale amorphous particles are formed as a result of solute trapping within the rapidly grown Al grains. After annealing at 400 C for 15 minutes grain growth occurs, and the interface of the Al grains is smoothed. The amorphous region trapped within the grains if crystallized to an Al-Cr compound, but no icosahedral phase has been confirmed. The APFIM results have revealed that Cr and Ce atoms have a similar partitioning behavior, i.e., they are rejected from the α-Al phase and partitioned into the trapped amorphous regions. On the other hand, Co atoms are not partitioned between the two phases in the as-quenched state but are partitioned into the α-Al grains in the annealed alloys being rejected from the Al compounds and finally form Al-Co compounds. Based on these microstructural characterization results, the origins of high strength of this alloy are discussed

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

OpenAIRE

Suárez-Rosales,Miguel Ángel; Pinto-Segura,Raúl; Palacios-Beas,Elia Guadalupe; Hernández-Herrera,Alfredo; Chávez-Alcalá,José Federico

2016-01-01

The combined processes; rapid solidification, addition of Cu3P compound and heat treatments to improve the mechanical properties of the hypereutectic Al-13Si, Al-20Si and Al-20Si-1.5Fe-0.7Mn alloys (in wt. %) was studied. Optical microscopy and scanning electron microscopy were used to characterize the microstructures. The mechanical properties were evaluated by tensile tests. It was found that the cooling rate (20-50°C/s) used to solidify the alloys plus the addition of Cu3P compound favored...

Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders

Science.gov (United States)

Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

2016-12-01

Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu6Sn5 phase during solidification. In this study, the number and size of Cu6Sn5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu6Sn5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu6Sn5 phases. Transitions in the Cu6Sn5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 103 to 104 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu6Sn5 nucleant relationship. In addition, little evidence of the formation or decomposition of the ternary- β phase in the solidified alloys was noted. Solidification pathways omitting the formation of the ternary- β phase agreed well with observed room temperature microstructures.

Microstructure and Mechanical Strengths of Metastable FCC Solid Solutions in Al-Ce-Fe System

OpenAIRE

A., Inoue; H., Yamaguchi; M., Kikuchi; T., Masumoto; Institute for Materials Research; Institute for Materials Research; Institute for Materials Research; Institute for Materials Research

1990-01-01

A metastable fcc solid solution (SS) with high mechanical strengths and good bending ductility was found to be formed in rapidly solidified Al-Ce-Fe alloys containing the solute elements below about 6 at%. The SS consists of equiaxed grains with a size of about 2μm and contains a high density of internal defects. The highest hardness (H_v) and tensile fracture strengtn (σ_f) are 440 and 860 MPa in the as-quenched state and remain almost unchanged up to about 600 K for 1 h, though fine compoun...

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.

Rapidly solidified aluminium for optical applications

NARCIS (Netherlands)

Gubbels, G.P.H.; Venrooy, B.W.H. van; Bosch, A.J.; Senden, R.

2008-01-01

This paper present the results of a diamond turning study of a rapidly solidified aluminium 6061 alloy grade, known as RSA6061. It is shown that this small grain material can be diamond turned to smaller roughness values than standard AA6061 aluminium grades. Also, the results are nearly as good as

Elevated temperature mechanical properties of a rapidly solidified A1-Fe-V-Si alloy

International Nuclear Information System (INIS)

Mitra, S.

1992-01-01

Dispersion strengthened Al alloys based on the Al-Fe-V-Si quartenary system have recently been developed using rapid solidification techniques. Rapid solidification techniques which resulted in the above mentioned alloys have also been used to manufacture another commercial alloy, FVS 1212, with 37 volume % of dispersoid. The alloy has shown excellent resistance to coarsening at high temperatures and to creep deformation. Elevated temperature exposure of FVS 1212, for times up to 100 hours, resulted in a significant loss in room temperature mechanical properties only beyond 500 degrees C while 1000 hours at 425 degrees C did not result in any degradation of mechanical but no detailed study of the tensile behavior of FVS 1212 at slow strain rates and elevated temperatures has been reported to date. This paper reports that the present study was undertaken to investigate the tensile behavior of FVS 1212 from room temperature to 400 degrees C at strain rates of 6.56 x 10 - 5/sec and 6.56 x 10 -6 /sec. The study focussed on dynamic strain aging effects and strain hardening behavior, while the effect of strain rate on the flow behavior at elevated temperatures was also evaluated

Solidification structure and dispersoids in rapidly solidified Ti-Al-Sn-Zr-Er-B alloys

International Nuclear Information System (INIS)

Rowe, R.G.; Broderick, T.F.; Koch, E.F.; Froes, F.H.

1986-01-01

The microstructure of melt extracted and melt spun titanium alloys containing erbium and boron revealed a duplex solidification structure of columnar grains leading to equiaxed and dendritic structures near the free surface of melt extracted and melt spun alloys. The solidification structure was revealed by apparent boride segregation to cellular, interdendritic and grain boundaries. Precipitation of needle or lath-like TiB particles occurred adjacent to Er/sub 2/O/sub 3/ dispesoid particles in as-rapidly solidified ribbon

Magnetostriction of the polycrystalline Fe80Al20 alloy doped with boron

International Nuclear Information System (INIS)

Bormio-Nunes, Cristina; Teodoro dos Santos, Claudio; Botani de Souza Dias, Mateus; Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael

2012-01-01

Highlights: ► Fe 80 Al 20 polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. ► B stabilizes α-FeAl phase and a coexistence of α-FeAl + Fe 3 Al improves magnetostriction. ► Presence of Fe 2 B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe 80 Al 20 polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic α-FeAl and/or Fe 3 Al and Fe 2 B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of α-FeAl and a correspondent decrease of the Fe 3 Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe 2 B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe 80 Al 20 alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the α-FeAl and Fe 3 Al phases could be reached.

Effect of Trace Ce on Microstructure and Properties of Near-rapidly Solidified Al-Zn-Mg-Cu Alloys

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HUANG Gao-ren

2018-03-01

Full Text Available Through using DSC, XRD, SEM, EDS, static tensile test and other analysis methods of materials, the effect of trace Ce on microstructure and properties of near-rapidly solidified Al-Zn-Mg-Cu alloy was studied in order to find out rational homogenizing heat treatment process. The results show that Ce plays a role of refining grain and purifying molten alloy. The addition of Ce reduces dendritic spacing, refines the grain structures, eliminates dispersed shrinkage. The addition of Ce reduces the initial melting point of low melting eutectic phases by 3℃, under the same homogenization conditions. Trace Ce promotes the dissolution of low melting eutectic phases into the matrix, which improves the effect of homogenization. Homogenization temperatures of alloy A should be lower than 480℃and alloy B should be lower than 470℃; the addition of Ce decreases the homogenization temperature and improves the homogenization effect. The addition of Ce also greatly increases the tensile strength of the alloys.

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.

Solidification Mechanism of the D-Gun Sprayed Fe-Al Particles

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Wołczyński W.

2017-12-01

Full Text Available The detonation gas spraying method is used to study solidification of the Fe-40Al particles after the D-gun spraying and settled on the water surface. The solidification is divided into two stages. First, the particle solid shell forms during the particle contact with the surrounding air / gas. Usually, the remaining liquid particle core is dispersed into many droplets of different diameter. A single Fe-Al particle is described as a body subjected to a rotation and finally to a centrifugal force leading to segregation of iron and aluminum. The mentioned liquid droplets are treated as some spheres rotated freely / chaotically inside the solid shell of the particle and also are subjected to the centrifugal force. The centrifugal force, and first of all, the impact of the particles onto the water surface promote a tendency for making punctures in the particles shell. The droplets try to desert / abandon the mother-particles through these punctures. Some experimental evidences for this phenomenon are delivered. It is concluded that the intensity of the mentioned phenomenon depends on a given droplet momentum. The droplets solidify rapidly during their settlement onto the water surface at the second stage of the process under consideration. A model for the solidification mechanism is delivered.

Rapidly solidified Ti-25Al-Nb alloys

International Nuclear Information System (INIS)

Ward, C.H.; Broderick, T.F.; Jackson, A.G.; Rowe, R.G.; Froes, F.H.

1987-01-01

Alloys based on the Ti-25Al-Nb intermetallic system were studied to determine the effects of rapid solidification on structure. Compositions ranging from 12 to 30 at% niobium which are beyond the α/sub 2/ single phase field were evaluated. Alloys were prepared using a melt spinning process. The resulting ribbons were characterized using transmission electron microscopy and x-ray diffraction. The alloys were all found to have a retained ordered B2 structure in the melt spun condition with an antiphase domain size that significantly decreased with increasing niobium content. ''Tweed-like'' striations, indicating planar shear strain, were observed in all compositions. The characteristic diffraction pattern of an ordered ''omega-type'' phase was found to occur in the patterns taken from the 12 at% niobium alloy

Microstructure and magnetic properties of rapidly solidified nanocrystalline Fe81Zr7B12 alloy

International Nuclear Information System (INIS)

Xiong, X.Y.; Muddle, B.C.; Finlayson, T.R.

2000-01-01

Full text: Nanocrystalline Fe-Zr-B alloys have aroused extensive research interest due to their high saturation magnetization. There have been several studies [Suzuki et al., 1994; Kim et al., 1994] of the effect of boron on the formation of nanocrystalline structure and magnetic properties, showing that the addition of boron to Fe-Zr alloys improves the glass-forming ability and refines the primary bcc α-Fe grains during crystallization. However, when the boron content is increased to 8 at.%, the magnetic permeability is observed to decrease. There has been no detailed work to date concerning the microstructural evolution and magnetic properties in those alloys with higher boron content

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

Directory of Open Access Journals (Sweden)

Yoshiki Tsunekawa

2014-07-01

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

Dispersion strengthening of precipitation hardened Al-Cu-Mg alloys prepared by rapid solidification and mechanical alloying

Science.gov (United States)

Gilman, P. S.; Sankaran, K. K.

1988-01-01

Several Al-4Cu-1Mg-1.5Fe-0.75Ce alloys have been processed from either rapidly solidified or mechanically alloyed powder using various vacuum degassing parameters and consolidation techniques. Strengthening by the fine subgrains, grains, and the dispersoids individually or in combination is more effective when the alloys contain shearable precipitates; consequently, the strength of the alloys is higher in the naturally aged rather than the artificially aged condition. The strengths of the mechanically alloyed variants are greater than those produced from prealloyed powder. Properties and microstructural features of these dispersion strengthened alloys are discussed in regards to their processing histories.

Magnetostriction of the polycrystalline Fe{sub 80}Al{sub 20} alloy doped with boron

Energy Technology Data Exchange (ETDEWEB)

Bormio-Nunes, Cristina, E-mail: cristina@demar.eel.usp.br [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Teodoro dos Santos, Claudio; Botani de Souza Dias, Mateus [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael [Institut fuer Festkoerperphysik, TU Dresden, D-01062 Dresden (Germany)

2012-10-25

Highlights: Black-Right-Pointing-Pointer Fe{sub 80}Al{sub 20} polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. Black-Right-Pointing-Pointer B stabilizes {alpha}-FeAl phase and a coexistence of {alpha}-FeAl + Fe{sub 3}Al improves magnetostriction. Black-Right-Pointing-Pointer Presence of Fe{sub 2}B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe{sub 80}Al{sub 20} polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic {alpha}-FeAl and/or Fe{sub 3}Al and Fe{sub 2}B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of {alpha}-FeAl and a correspondent decrease of the Fe{sub 3}Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe{sub 2}B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe{sub 80}Al{sub 20} alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the {alpha}-FeAl and Fe{sub 3}Al phases could be reached.

Rapidly solidified prealloyed powders by laser spin atomization

Science.gov (United States)

Konitzer, D. G.; Walters, K. W.; Heiser, E. L.; Fraser, H. L.

1984-01-01

A new technique, termed laser spin atomization, for the production of rapidly solidified prealloyed powders is described. The results of experiments involving the production of powders of two alloys, one based on Ni, the other on Ti, are presented. The powders have been characterized using light optical metallography, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Auger elec-tron spectroscopy, and these various observations are described.

Evolution of rapidly solidified NiAlCu(B) alloy microstructure.

Science.gov (United States)

Czeppe, Tomasz; Ochin, Patrick

2006-10-01

This study concerned phase transformations observed after rapid solidification and annealing at 500, 700 and 800 degrees C in 56.3 Ni-39.9 Al-3.8 Cu-0.06 B (E1) and 59.8 Ni-36.0 Al-4.3 Cu-0.06 B (E2) alloys (composition in at.%). Injection casting led to a homogeneous structure of very small, one-phase grains (2-4 microm in size). In both alloys, the phase observed at room temperature was martensite of L1(0) structure. The process of the formation of the Ni(5)Al(3) phase by atomic reordering proceeded at 285-394 degrees C in the case of E1 alloy and 450-550 degrees C in the case of E2 alloy. Further decomposition into NiAl (beta) and Ni(3)Al (gamma') phases, the microstructure and crystallography of the phases depended on the path of transformations, proceeding in the investigated case through the transformation of martensite crystallographic variants. This preserved precise crystallographic orientation between the subsequent phases, very stable plate-like morphology and very small beta + gamma' grains after annealing at 800 degrees C.

Characterization of rapidly solidified powder of high-speed steel

Czech Academy of Sciences Publication Activity Database

Miglierini, M.; Lančok, Adriana; Kusý, M.

2009-01-01

Roč. 190, 1-3 (2009), s. 51-57 ISSN 0304-3843 R&D Projects: GA ČR GP203/07/P011 Grant - others:GA(SK) VEGA1/3190/06 Institutional research plan: CEZ:AV0Z40320502 Keywords : Rapidly solidified powder * Tool steel * Mössbauer spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 0.209, year: 2007

Microstructure of rapidly solidified materials

Science.gov (United States)

Jones, H.

1984-07-01

The basic features of rapidly solidified microstructures are described and differences arising from alternative processing strategies are discussed. The possibility of achieving substantial undercooling prior to solidification in processes such as quench atomization and chill block melt spinning can give rise to striking microstructural transitions even when external heat extraction is nominally Newtonian. The increased opportunity in laser and electron beam surface melting for epitaxial growth on the parent solid at an accelerating rate, however, does not exclude the formation of nonequilibrium phases since the required undercooling can be locally attained at the solidification front which is itself advancing at a sufficiently high velocity. The effects of fluid flow indicated particularly in melt spinning and surface melting are additional to the transformational and heat flow considerations that form the present basis for interpretation of such microstructural effects.

Powder metallurgy Al-6Cr-2Fe-1Ti alloy prepared by melt atomisation and hot ultra-high pressure compaction

Energy Technology Data Exchange (ETDEWEB)

Dam, Karel, E-mail: Karel.Dam@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Vojtech, Dalibor; Prusa, Filip [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

2013-01-10

Al--6Cr--2Fe--1Ti alloy was prepared by melt atomisation into rapidly solidified powder. The powder was compacted using uniaxial hot compression at an ultra-high pressure (6 GPa). The samples were pressed at 300, 400 and 500 Degree-Sign C. The structure, mechanical properties and thermal stability were examined and compared with those of the commercially available Al--12Si--1Cu--1Mg--1Ni casting alloy, which is considered thermally stable. It was shown that the hot compression at ultra-high pressure results in a compact and pore-free material with excellent mechanical properties. The elevated pressing temperatures were found to be effective at increasing the mechanical stability after applying the ultra-high pressure. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 Degree-Sign C. In addition, the Al--6Cr--2Fe--1Ti alloy exhibited very good creep resistance. A comparison between the commercial Al--12Si--1Cu--1Mg--1Ni alloy and the powder metallurgy alloy shows that this alloy has significantly better mechanical properties and thermal stability.

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

Science.gov (United States)

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

2014-01-01

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

Effect of grain refiner on intermetallic phase formation in directional solidification of 6xxx series wrought Al alloys

Energy Technology Data Exchange (ETDEWEB)

Sha, G.; O' Reilly, K.; Cantor, B. [Oxford Univ. (United Kingdom). Centre for Adv. Mat. and Composites; Hamerton, R.; Worth, J.

2000-07-01

The effect of a grain refiner on the formation of intermetallic phases in a directionally solidified (Bridgman grown) model 6xxx series wrought Al alloy has been investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). A base alloy with and without Al-Ti-B grain refiner was directionally solidified in a Bridgman furnace at growth velocities in the range of 5-120 mm/min. In both cases, the Fe-containing intermetallic phases present were found to be mainly {alpha}-AlFeSi and {beta}-AlFeSi. However, in the alloy with grain refiner solidified at 5mm/min, Al{sub 13}Fe{sub 4} was also observed. Quantitative XRD results indicated that the addition of Al-Ti-B grain refiner has a strong influence on the relative quantities of intermetallic phases forming during solidification at different growth velocities, which was also confirmed by TEM observations. TEM observations also show that depending on where the {beta}-AlFeSi particles solidified e.g. grain boundaries or triple grain junctions, the size and morphology of the particles may change dramatically. TiB{sub 2} particles were observed to nucleate {beta}-AlFeSi at low and high growth velocities in the 6xxx series Al alloys. (orig.)

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.)

Solidified structure of Al-Pb-Cu alloys

International Nuclear Information System (INIS)

Ikeda, Tetsuyuki; Nishi, Seiki; Kumeuchi, Hiroyuki; Tatsuta, Yoshinori.

1986-01-01

Al-Pb-Cu alloys were cast into bars or plates in different two metal mold casting processes in order to suppress gravity segregation of Pb and to achieve homogeneous dispersion of Pb phase in the alloys. Solidified structures were analyzed by a video-pattern-analyzer. Plate castings 15 to 20 mm in thickness of Al-Pb-1 % Cu alloy containing Pb up to 5 % in which Pb phase particles up to 10 μm disperse are achieved through water cooled metal mold casting. The plates up to 5 mm in thickness containing Pb as much as 8 to 10 % cast in this process have dispersed Pb particles up to 5 μm in diameter in the surface layer. Al-8 % Pb-1 % Cu alloy bars 40 mm in diameter and 180 mm in height in which gravity segregation of Pb is prevented can be cast by movable and water sprayed metal mold casting at casting temperature 920 deg C and mold moving speed 1.0 mm/s. Pb phase particles 10 μm in mean size are dispersed in the bars. (author)

Effect of solidification parameters on mechanical properties of directionally solidified Al-Rich Al-Cu alloys

Science.gov (United States)

Çadırlı, Emin

2013-05-01

Al(100-x)-Cux alloys (x=3 wt%, 6 wt%, 15 wt%, 24 wt% and 33 wt%) were prepared using metals of 99.99% high purity in vacuum atmosphere. These alloys were directionally solidified under steady-state conditions by using a Bridgman-type directional solidification furnace. Solidification parameters (G, V and ), microstructure parameters (λ1, λ2 and λE) and mechanical properties (HV, σ) of the Al-Cu alloys were measured. Microstructure parameters were expressed as functions of solidification parameters by using a linear regression analysis. The dependency of HV, σ on the cooling rate, microstructure parameters and composition were determined. According to experimental results, the microhardness and ultimate tensile strength of the solidified samples was increased by increasing the cooling rate and Cu content, but decreased with increasing microstructure parameters. The microscopic fracture surfaces of the different samples were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces showed that the type of fracture significantly changed from ductile to brittle depending on the composition.

Microstructure characterization of rapidly solidified Al-Fe-Cr-Ce alloy by positron annihilation spectroscopy

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Čízek, J.; Procházka, I.; Drahokoupil, Jan; Novák, P.

2011-01-01

Roč. 509, č. 7 (2011), s. 3211-3218 ISSN 0925-8388 Institutional research plan: CEZ:AV0Z10100520 Keywords : metals and alloy s * nanostructured materials * rapid solidification * positron spectroscopies * transmission electron microscopy * x-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.289, year: 2011

Influence of cooling rate and cerium addition on rapidly solidified Al-TM alloys

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Schumacher, G.; Novák, P.; Klementová, Mariana; Šerák, J.; Mudrová, M.; Valdaufová, J.

2010-01-01

Roč. 48, č. 1 (2010), s. 1-7 ISSN 0023-432X Institutional research plan: CEZ:AV0Z40320502 Keywords : rapid solidification * Al-TM * microstructure * aluminium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.471, year: 2010

Formation of intermetallic phases in AlSi7Fe1 alloy processed under microgravity and forced fluid flow conditions and their influence on the permeability

OpenAIRE

Steinbach, Sonja; Ratke, Lorenz; Zimmermann, Gerhard; Budenkova, Olga

2016-01-01

Ternary Al-6.5wt.%Si-0.93wt.%Fe alloy samples were directionally solidified on-board of the International Space Station ISS in the ESA payload Materials Science Laboratory (MSL) equipped with Low Gradient Furnace (LGF) under both purely diffusive and stimulated convective conditions induced by a rotating magnetic field. Using different analysis techniques the shape and distribution of the intermetallic phase β-Al 5 SiFe in the dendritic microstructure was investigated, to study the influence ...

Enhanced Al and Zn removal from coal-mine drainage during rapid oxidation and precipitation of Fe oxides at near-neutral pH

Science.gov (United States)

Burrows, Jill E.; Cravotta, Charles A.; Peters, Stephen C.

2017-01-01

Net-alkaline, anoxic coal-mine drainage containing ∼20 mg/L FeII and ∼0.05 mg/L Al and Zn was subjected to parallel batch experiments: control, aeration (Aer 1 12.6 mL/s; Aer 2 16.8 mL/s; Aer 3 25.0 mL/s), and hydrogen peroxide (H2O2) to test the hypothesis that aeration increases pH, FeII oxidation, hydrous FeIII oxide (HFO) formation, and trace-metal removal through adsorption and coprecipitation with HFO. During 5.5-hr field experiments, pH increased from 6.4 to 6.7, 7.1, 7.6, and 8.1 for the control, Aer 1, Aer 2, and Aer 3, respectively, but decreased to 6.3 for the H2O2 treatment. Aeration accelerated removal of dissolved CO2, Fe, Al, and Zn. In Aer 3, dissolved Al was completely removed within 1 h, but increased to ∼20% of the initial concentration after 2.5 h when pH exceeded 7.5. H2O2 promoted rapid removal of all dissolved Fe and Al, and 13% of dissolved Zn.Kinetic modeling with PHREEQC simulated effects of aeration on pH, CO2, Fe, Zn, and Al. Aeration enhanced Zn adsorption by increasing pH and HFO formation while decreasing aqueous CO2 available to form ZnCO30 and Zn(CO3)22− at high pH. Al concentrations were inconsistent with solubility control by Al minerals or Al-containing HFO, but could be simulated by adsorption on HFO at pH oxidation with pH adjustment to ∼7.5 could be effective for treating high-Fe and moderate-Zn concentrations, whereas chemical oxidation without pH adjustment may be effective for treating high-Fe and moderate-Al concentrations.

Effect of Ce on Casting Structure of Near-rapidly Solidified Al-Zn-Mg-Cu Alloy

Directory of Open Access Journals (Sweden)

HUANG Gao-ren

2017-11-01

Full Text Available Through using XRD,DSC,SEM,EDS and other modern analysis methods, the effects of rare earth element Ce on microstructure and solidification temperature of Al-Zn-Mg-Cu under different cooling rates were studied, the principle of Ce on grain refining and melt cleaning of alloys was analyzed and discussed. The results show that MgZn2 phase and α-Al matrix are the main precipitations, Al,Cu,Mg and other elements dissolve in MgZn2 phase, a new phase Mg(Zn, Cu, Al2 is formed, solute elements in the grain boundary have higher concentration, eutectic reaction takes place between MgZn2 and α-Al, lamellar eutectic structure is generated. The addition of Ce decreases the dendritic arm spacing,reduces the layer spacing between eutectic phases and refines the eutectic structure and the grain significantly, and inhibits the appearance of the impurity phase Al7Cu2Fe in aluminum alloys. The addition of Ce also reduces the precipitation temperature of α-Al matrix and eutectic phase by 6.4℃ and 5.6℃ respectively.

Phase composition and microhardness of rapidly quenched Al-Fe alloys after high pressure torsion deformation

Energy Technology Data Exchange (ETDEWEB)

Tcherdyntsev, V.V.; Kaloshkin, S.D.; Gunderov, D.V.; Afonina, E.A.; Brodova, I.G.; Stolyarov, V.V.; Baldokhin, Yu.V.; Shelekhov, E.V.; Tomilin, I.A

2004-07-15

Aluminium-based Al-Fe alloys with Fe content of 2, 8, and 10 wt.% were prepared by rapid quenching (RQ) from the melt at a rate of 10{sup 6} K/s. Structure of the alloys was examined by X-ray diffraction (XRD) and Moessbauer spectroscopy. Phase transformations of RQ alloys by high pressure torsion (HPT) were studied. Dependences of phase composition on the intensity of HPT were investigated. Microhardness measurements of HPT alloys show a considerable structural heterogeneity of specimens, the dependence of microhardness on the radius of the pills was found out. Phase composition and microhardness during the heating were investigated. At the initial step of heating (120-150 deg. C), an increase in microhardness was observed, whereas further heating leads to a decrease in the microhardness.

RAPIDLY-SOLIDIFIED PERMANENT MAGNET MATERIALS: FACTORS AFFECTING QUENCHABILITY AND MAGNETIC PROPERTIES IN Nd2Fe14B

International Nuclear Information System (INIS)

LEWIS, L.H.; KRAMER, M.J.; MCCALLUM, R.W.; BRANAGAN, D.J.

1999-01-01

Insight into the solidification behavior of Nd 2 Fe 14 B-based materials processed by rapid solidification techniques has been obtained by a systematic experimental study of the Curie temperatures of selected phases found in these materials. Nd 2 Fe 14 B-based materials fabricated by two disparate rapid solidification techniques, inert gas atomization (IGA) and melt-spinning, has been studied. The compositions of the starting materials have been altered with additions of the refractory elements Ti and C which are known to alter the solidification behavior of these materials. Special emphasis has been placed on trying to understand the effect of alloying additions upon the nature of the quenched glass, the distribution of the elemental additions within the Nd 2 Fe 14 B lattice and the evolution of the elemental partitioning with quench rate and annealing condition. The experimental Curie temperature data obtained using thermal analysis methods from the particles produced by gas-atomization is consistent with both an ejection of quenched-in refractory species from the crystalline Nd 2 Fe 14 B lattice and with increased crystallographic order as particle size, and hence grain size, increases. Magnetic ac susceptibility measurements performed on nominally-amorphous Nd 2 Fe 14 B ribbons produced by melt-spinning indicate a decrease of the Curie temperature with increasing quench rate, a result that may be attributed either to the degree of Ti/C retention in the glass or to the degree of disorder in the glass, independent of Ti/C retention

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-02-15

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

Radioactive waste solidifying material

International Nuclear Information System (INIS)

Ono, Keiichi; Sakai, Etsuro.

1989-01-01

The solidifying material according to this invention comprises cement material, superfine powder, highly water reducing agent, Al-containing rapid curing material and coagulation controller. As the cement material, various kinds of quickly hardening, super quickly hardening and white portland cement, etc. are usually used. As the superfine powder, those having average grain size smaller by one order than that of the cement material are desirable and silica dusts, etc. by-produced upon preparing silicon, etc. are used. As the highly water reducing agent, surface active agents of high decomposing performance and comprising naphthalene sulfonate, etc. as the main ingredient are used. As the Al-containing rapidly curing material, calcium aluminate, etc. is used in an amount of less than 10 parts by weight based on 100 parts by weight of the powdery body. As the coagulation controller, boric acid etc. usually employed as a retarder is used. This can prevent dissolution or collaption of pellets and reduce the leaching of radioactive material. (T.M.)

Surface segregation of chromium in rapidly solidified Al studied by RBS and SPEM

International Nuclear Information System (INIS)

Tashlykova-Bushkevich, I.I.; Amati, M.; Aleman, B.; Gregoratti, L.; Kiskinova, M.; Ryabuhin, O.V.; Shepelevich, V.G.

2013-01-01

The present study demonstrates the advances of using scanning photoelectron microscopy and imaging accomplished by RBS and AFM to investigate the surface segregation of alloying elements in RS aluminum. Depth profiling of elemental composition indicates that RS microstructure evolution is influenced by solute-nanostructured defect interactions in Al-Cr alloys. It was found that Cr 2p and 3p core level photoemission spectra exhibits foil surface impoverishment of chromium. In agreement with dope depth profiling as carried out by RBS, the revealed phenomenon can be attributed to the fact that Cr drastically reduces the concentration of vacancies compared with RS pure Al, and affects H behaviour in RS Al-Cr alloys. Obtained results indicate that the surface microstructure of the Al alloy foils at the sub-micrometer scale, as far as the high density of quenched-in vacancies is concerned, is essential to elucidate how the microstructural morphology resulting from rapid solidification affects hydrogen trapping at lattice defects. (authors)

Morphological variants of carbides of solidification origin in the rapidly solidified powder particles of hypereutectic iron alloy

International Nuclear Information System (INIS)

Kusy, M.; Grgac, P.; Behulova, M.; Vyrostkova, A.; Miglierini, M.

2004-01-01

The paper deals with the analysis of the morphological variants of solidification microstructures and vanadium rich M 4 C 3 carbide phases in the rapidly solidified (RS) powder particles from hypereutectic Fe-C-Cr-V alloy prepared by the nitrogen gas atomisation. Five main types of solidification microstructures were identified in RS particles: microstructure with globular carbides, microstructure with globular and star-like carbides, microstructure with primary carbides in the centres of eutectic colonies, microstructure with eutectic colonies without primary carbides and microstructure with eutectic spherulites. Based on the morphological features of carbide phases and the thermal history of RS particles, the microstructures were divided into two groups - microstructures morphologically affected and non-affected during the post-recalescence period of solidification. Thermophysical reasons for the morphologically different M 4 C 3 carbide phases development in the RS powder particles are discussed

Undercooling and demixing in rapidly solidified Cu-Co alloys

DEFF Research Database (Denmark)

Battezzati, L.; Curiotto, S.; Johnson, Erik

2007-01-01

The Cu–Co system displays a metastable miscibility gap in the liquid state. A considerable amount of work has been performed to study phase separation and related microstructures showing that demixing of the liquid is followed by coagulation before dendritic solidification. Due to kinetic...... competition of transformation phenomena, the mechanisms have not been fully disclosed. This contribution reviews such findings with the help of a computer calculation of the phase diagram and extends the present knowledge by presenting new results obtained by rapidly solidifying various Cu–Co compositions...... using a wide range of cooling rates achieved by forcing the liquid into cylindric and conic moulds and by melt spinning....

Directionally solidified Al2O3/GAP eutectic ceramics by micro-pulling-down method

Science.gov (United States)

Cao, Xue; Su, Haijun; Guo, Fengwei; Tan, Xi; Cao, Lamei

2016-11-01

We reported a novel route to prepare directionally solidified (DS) Al2O3/GAP eutectic ceramics by micro-pulling-down (μ-PD) method. The eutectic crystallizations, microstructure characters and evolutions, and their mechanical properties were investigated in detail. The results showed that the Al2O3/GAP eutectic composites can be successfully fabricated through μ-PD method, possessed smooth surface, full density and large crystal size (the maximal size: φ90 mm × 20 mm). At the process of Diameter, the as-solidified Al2O3/GAP eutectic presented a combination of "Chinese script" and elongated colony microstructure with complex regular structure. Inside the colonies, the rod-type or lamellar-type eutectic microstructures with ultra-fine GAP surrounded by the Al2O3 matrix were observed. At an appropriate solidificational rate, the binary eutectic exhibited a typical DS irregular eutectic structure of "chinese script" consisting of interpenetrating network of α-Al2O3 and GAP phases without any other phases. Therefore, the interphase spacing was refined to 1-2 µm and the irregular microstructure led to an outstanding vickers hardness of 17.04 GPa and fracture toughness of 6.3 MPa × m1/2 at room temperature.

Microstructural Quantification of Rapidly Solidified Undercooled D2 Tool Steel

Science.gov (United States)

Valloton, J.; Herlach, D. M.; Henein, H.; Sediako, D.

2017-10-01

Rapid solidification of D2 tool steel is investigated experimentally using electromagnetic levitation (EML) under terrestrial and reduced gravity conditions and impulse atomization (IA), a drop tube type of apparatus. IA produces powders 300 to 1400 μm in size. This allows the investigation of a large range of cooling rates ( 100 to 10,000 K/s) with a single experiment. On the other hand, EML allows direct measurements of the thermal history, including primary and eutectic nucleation undercoolings, for samples 6 to 7 mm in diameter. The final microstructures at room temperature consist of retained supersaturated austenite surrounded by eutectic of austenite and M7C3 carbides. Rapid solidification effectively suppresses the formation of ferrite in IA, while a small amount of ferrite is detected in EML samples. High primary phase undercoolings and high cooling rates tend to refine the microstructure, which results in a better dispersion of the eutectic carbides. Evaluation of the cell spacing in EML and IA samples shows that the scale of the final microstructure is mainly governed by coarsening. Electron backscattered diffraction (EBSD) analysis of IA samples reveals that IA powders are polycrystalline, regardless of the solidification conditions. EBSD on EML samples reveals strong differences between the microstructure of droplets solidified on the ground and in microgravity conditions. While the former ones are polycrystalline with many different grains, the EML sample solidified in microgravity shows a strong texture with few much larger grains having twinning relationships. This indicates that fluid flow has a strong influence on grain refinement in this system.

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

Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength

Science.gov (United States)

Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

2011-10-01

The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

Database on Performance of Neutron Irradiated FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States); Littrell, Ken [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parish, Chad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

The present report summarizes and discusses the database on radiation tolerance for Generation I, Generation II, and commercial FeCrAl alloys. This database has been built upon mechanical testing and microstructural characterization on selected alloys irradiated within the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to doses of 13.8 dpa at temperatures ranging from 200°C to 550°C. The structure and performance of these irradiated alloys were characterized using advanced microstructural characterization techniques and mechanical testing. The primary objective of developing this database is to enhance the rapid development of a mechanistic understanding on the radiation tolerance of FeCrAl alloys, thereby enabling informed decisions on the optimization of composition and microstructure of FeCrAl alloys for application as an accident tolerant fuel (ATF) cladding. This report is structured to provide a brief summary of critical results related to the database on radiation tolerance of FeCrAl alloys.

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.

Morphological evolution of primary TiC carbide in laser clad TiC reinforced FeAl intermetallic composite coating

Institute of Scientific and Technical Information of China (English)

陈瑶; 王华明

2003-01-01

The novel rapidly solidified TiC/FeAl composite coatings were fabricated by laser cladding on the substrate of 1Cr18Ni9Ti stainless steel, particular emphasis has been placed on the growth morphologies of TiC carbide and its growth mechanism under a constant solidification conditions. Results show that the growth morphology of TiC carbide strongly depends upon the nucleation process and mass transportation process of TiC forming elements in laser melt pool. With increasing amount of titanium and carbon in melt pool, the growth morphology of TiC carbide changes from block-like to star-like and well-developed dendrite. As the amount of titanium and carbon increases further, TiC carbide particles are found to be irregular polyhedral block. Although the growth morphologies of TiC are various,their advancing fronts are all faceted, illustrating that TiC carbide grows by the mechanism of lateral ledge growth.

Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows

Science.gov (United States)

Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

2016-12-01

Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu6Sn5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu6Sn5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu6Sn5 observed, while in the melt spun alloy, Cu6Sn5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu6Sn5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. The reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu6Sn5 was maintained for both alloys.

Fabrication and tensile properties of rapidly solidified Cu-10wt. %Ni alloy. [Cu-10Ni

Energy Technology Data Exchange (ETDEWEB)

Baril, D; Angers, R; Baril, J [Dept. of Mining and Metallurgy, Laval Univ., Ste-Foy, Quebec (Canada)

1992-10-15

Cu-10wt.%Ni ribbons were produced by melt spinning and cut into small particles with a blade cutter mill. The powders were then hot consolidated to full density by hot pressing followed by hot extrusion. Tensile properties of the resulting pieces were measured. Cu-10wt.%Ni cast ingots were also hot extruded and mechanically tested to compare with the rapidly solidified alloy and to evaluate the possible benefits brought by the rapid solidification process.

The effect of boron doping on the magnetostriction of Fe-Ga and Fe-Al samples

Energy Technology Data Exchange (ETDEWEB)

Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael [TU Dresden, Institut fuer Festkoerperphysik (Germany); Teodoro dos Santos, Claudio; Bormio-Nunes, Cristina [Universidade de Sao Paulo, Escola de Engenharia de Lorena, Lorena (Brazil)

2011-07-01

Fe-Ga (Galfenol) based alloys are used in a number of magnetomechanical applications because of the high magnetostriction values of more than 100 ppm at room temperature. The addition of boron inhibits the crystallographic ordering of the alloys and stabilizes the disordered A2 structure that is responsible for the high striction values. Especially, polycrystalline and rapid cooled Fe-Ga-B and Fe-Al-B samples were investigated in our project. Magnetization and longitudinal as well as transversal magnetostriction measurements at temperatures of 5 K, 80 K and 300 K show a similar effect of the amount of B as found on single crystals. Whereas the saturation magnetization is nearly the same and mainly determined by the Fe content, a dependence of the striction values on the amount of B is visible (more than 10% in the Fe-Al system). The results illustrate the influence of the stoichiometry and the preparation conditions on the magnetomechanical properties.

Erosion resistance of FeAl-TiB2 and FeAl-WC at room and elevated temperatures

International Nuclear Information System (INIS)

Alman, D.E.; Tylczak, J.H.; Hawk, J.A.

2000-01-01

The resistance of FeAl-40%TiB 2 and FeAl-80%WC cermets to solid particle erosion at 25, 180, 500 and 700 C was evaluated and compared to the behavior of WC-6%Co (Co-90%WC) cemented carbides. Even though the WC-Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were similar in magnitude to the erosion rates of the WC-Co. However, the erosion rates of the FeAl-cermets either were constant (FeAl-TiB 2 ) or decreased (FeAl-WC) with increasing test temperature; whereas, the erosion rates of the WC-Co cemented carbides increased with increasing test temperature. This indicated that once the microstructures of the FeAl-cermets are optimized for wear resistance, these materials might make promising candidates for high-temperature wear applications

Rapidly solidified long-range-ordered alloys

International Nuclear Information System (INIS)

Lee, E.H.; Koch, C.C.; Liu, C.T.

1981-01-01

The influence of rapid solidification processing on the microstructure of long-range-ordered alloys in the (Fe, Co, Ni) 3 V system has been studied by transmission electron microscopy. The main microstructural feature of the as-quenched alloys was a fine cell structure (approx. 300 nm diameter) decorated with carbide particles. This structure was maintained aftr annealing treatments which develop the ordered crystal structure. Other features of the microstructures both before and after annealing are presented and discussed. 6 figures

Primary Dendrite Arm Spacings in Al-7Si Alloy Directionally Solidified on the International Space Station

Science.gov (United States)

Angart, Samuel; Lauer, Mark; Poirier, David; Tewari, Surendra; Rajamure, Ravi; Grugel, Richard

2015-01-01

Samples from directionally solidified Al- 7 wt. % Si have been analyzed for primary dendrite arm spacing (lambda) and radial macrosegregation. The alloy was directionally solidified (DS) aboard the ISS to determine the effect of mitigating convection on lambda and macrosegregation. Samples from terrestrial DS-experiments thermal histories are discussed for comparison. In some experiments, lambda was measured in microstructures that developed during the transition from one speed to another. To represent DS in the presence of no convection, the Hunt-Lu model was used to represent diffusion controlled growth under steady-state conditions. By sectioning cross-sections throughout the entire length of a solidified sample, lambda was measured and calculated using the model. During steady-state, there was reasonable agreement between the measured and calculated lambda's in the space-grown samples. In terrestrial samples, the differences between measured and calculated lambda's indicated that the dendritic growth was influenced by convection.

Phase composition of rapidly solidified Ag-Sn-Cu dental alloys

International Nuclear Information System (INIS)

Lecong Dzuong; Do Minh Nghiep; Nguyen van Dzan; Cao the Ha

1996-01-01

The phase composition of some rapidly solidified Ag-Sn-Cu dental alloys with different copper contents (6.22 wtpct) has been studied by XRD, EMPA and optical microscopy. The samples were prepared from melt-spun ribbons. The microstructure of the as-quenched ribbons was microcrystalline and consisted of the Ag sub 3 Sn, Ag sub 4 Sn, Cu sub 3 Sn and Cu sub 3 Sn sub 8 phases. Mixing with mercury (amalgamation) led to formation of the Ag sub 2 Hg sub 3, Sn sub 7 Hg and Cu sub 6 Sn sub 5 phases. The amount of copper atoms in the alloys played an important role in phase formation in the amalgams

Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

Science.gov (United States)

Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

2002-01-01

Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

Formation of intermetallic phases in AlSi7Fe1 alloy processed under microgravity and forced fluid flow conditions and their influence on the permeability

Science.gov (United States)

Steinbach, S.; Ratke, L.; Zimmermann, G.; Budenkova, O.

2016-03-01

Ternary Al-6.5wt.%Si-0.93wt.%Fe alloy samples were directionally solidified on-board of the International Space Station ISS in the ESA payload Materials Science Laboratory (MSL) equipped with Low Gradient Furnace (LGF) under both purely diffusive and stimulated convective conditions induced by a rotating magnetic field. Using different analysis techniques the shape and distribution of the intermetallic phase β-Al5SiFe in the dendritic microstructure was investigated, to study the influence of solidification velocity and fluid flow on the size and spatial arrangement of intermetallics. Deep etching as well as 3-dimensional computer tomography measurements characterized the size and the shape of β-Al5SiFe platelets: Diffusive growth results in a rather homogeneous distribution of intermetallic phases, whereas forced flow promotes an increase in the amount and the size of β-Al5SiFe platelets in the centre region of the samples. The β-Al5SiFe intermetallics can form not only simple platelets, but also be curved, branched, crossed, interacting with dendrites and porosity located. This leads to formation of large and complex groups of Fe-rich intermetallics, which reduce the melt flow between dendrites leading to lower permeability of the mushy zone and might significantly decrease feeding ability in castings.

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)

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...

Giant Enhancement of Magnetostrictive Response in Directionally-Solidified Fe83Ga17Erx Compounds

Directory of Open Access Journals (Sweden)

Radhika Barua

2018-06-01

Full Text Available We report, for the first time, correlations between crystal structure, microstructure and magnetofunctional response in directionally solidified [110]-textured Fe83Ga17Erx (0 < x < 1.2 alloys. The morphology of the doped samples consists of columnar grains, mainly composed of a matrix phase and precipitates of a secondary phase deposited along the grain boundary region. An enhancement of more than ~275% from ~45 to 170 ppm is observed in the saturation magnetostriction value (λs of Fe83Ga17Erx alloys with the introduction of small amounts of Er. Moreover, it was noted that the low field derivative of magnetostriction with respect to an applied magnetic field (i.e., dλs/dHapp for Happ up to 1000 Oe increases by ~230% with Er doping (dλs/dHapp,FeGa= 0.045 ppm/Oe; dλs/dHapp,FeGaEr= 0.15 ppm/Oe. The enhanced magnetostrictive response of the Fe83Ga17Erx alloys is ascribed to an amalgamation of microstructural and electronic factors, namely: (i improved grain orientation and local strain effects due to deposition of Er in the intergranular region; and (ii strong local magnetocrystalline anisotropy, due to the highly anisotropic localized nature of the 4f electronic charge distribution of the Er atom. Overall, this work provides guidelines for further improving galfenol-based materials systems for diverse applications in the power and energy sector.

Mechanical properties and electronic structures of Fe-Al intermetallic

Energy Technology Data Exchange (ETDEWEB)

Liu, YaHui; Chong, XiaoYu; Jiang, YeHua, E-mail: jiangyehua@kmust.edu.cn; Zhou, Rong; Feng, Jing, E-mail: jingfeng@kmust.edu.cn

2017-02-01

Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe{sub 3}Al, FeAl, FeAl{sub 2}, Fe{sub 2}Al{sub 5} and FeAl{sub 3}) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe{sub 2}Al{sub 5} has the lowest formation enthalpy, which shows the Fe{sub 2}Al{sub 5} is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young’s modulus and anisotropic index. Fe{sub 3}Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong’s modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

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 ...

Application of rapid solidification powder metallurgy to the fabrication of high-strength, high-ductility Mg-Al-Zn-Ca-La alloy through hot extrusion

Energy Technology Data Exchange (ETDEWEB)

Ayman, Elsayed, E-mail: ayman@jwri.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Junko, Umeda; Katsuyoshi, Kondoh [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2011-01-15

The microstructure and mechanical properties of hot extruded Mg-7Al-1Zn-1Ca powder alloys with an addition of 1.5% La or 3.3% La were investigated. Both rapidly solidified powders, produced via spinning water atomization process, and cast billets were extruded at 573, 623 and 673 K to optimize the processing conditions for obtaining better mechanical response. Powders were consolidated using both cold compaction and spark plasma sintering. The tensile properties of the extruded alloys were then evaluated and correlated to their microstructures. The results showed that the use of rapidly solidified Mg-7Al-1Zn-1Ca alloy powders with La additions could lead to effective grain refinement and super saturation of alloying elements, which in turn resulted in the improved mechanical response. The Mg-7Al-1Zn-1Ca-1.5La alloy extruded at 573 K attained ultimate tensile strength of 450 {+-} xx MPa and elongation of 17 {+-} xx%, superior to the Mg-7Al-1Zn-1Ca-3.3La alloy and other Mg alloys like Mg-Al-Mn-Ca. This may help extend the application of Mg alloys to higher load-carrying parts while maintaining the excellent advantage of light weight.

Heteroepitaxial growth of Fe{sub 2}Al{sub 5} inhibition layer in hot-dip galvanizing of an interstitial-free steel

Energy Technology Data Exchange (ETDEWEB)

Wang, Kuang-Kuo [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Chang, Liuwen, E-mail: lwchang@mail.nsysu.edu.t [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Gan, Dershin; Wang, Hung-Ping [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

2010-02-01

This work presents characterization results on inhibition layers formed on a TiNb-stabilized interstitial-free steel after short time galvanizing. The Fe-Al and steel interface was free from oxide, so that the Fe-Al intermetallic compound could directly nucleate on ferrite grains. Electron diffraction performed in a transmission electron microscope showed that only Fe{sub 2}Al{sub 5} was formed and it had a well-defined orientation relationship of [110]{sub Fe(sub/2)Al(sub/5)}// [111]{sub Fe}, (001){sub Fe(sub/2)Al(sub/5)}//(011){sub Fe} and (110){sub Fe(sub/2)Al(sub/5)}//(211){sub Fe} with Fe substrate. The structure of the interfaces between Fe{sub 2}Al{sub 5} and Fe is discussed. The epitaxially nucleated Fe{sub 2}Al{sub 5} grains on Fe substrate had very small grain size, 20 nm or less, and several variants were intimately mixed. The grains grew rapidly to hundreds of nanometers toward the Zn side.

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.

Environmental embrittlement of intermetallic compounds in Fe-Al alloys

Institute of Scientific and Technical Information of China (English)

张建民; 张瑞林; S.H.YU; 余瑞璜

1996-01-01

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

Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

Science.gov (United States)

Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

2017-12-01

Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

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.

The effect of vanadium and grain refiner additions on the nucleation of secondary phases in 1XXX Al alloys

Energy Technology Data Exchange (ETDEWEB)

Allen, C.M.; O' Reilly, K.A.Q.; Evans, P.V.; Cantor, B.

1999-11-26

High purity Al-0.3 wt% Fe-0.1 wt% Si alloys with different Si, V and grain refiner contents were melt spun to produce microstructures of submicron secondary phases entrained in a higher melting point Al matrix. On reheating, a dispersion of eutectic liquid droplets forms that represents an exaggerated version of the liquid puddles that solidify punched-off between Al dendrite arms during conventional casting. The subsequent resolidification of the droplets, analyzed using differential scanning calorimetry (DSC), allows the nucleation-controlled aspects of secondary phase selection to be studied. The droplets solidify as the metastable FeAl{sub m} phase in ribbons containing {approx{underscore}equal}500 ppm V or {approx{underscore}equal}100 ppm V plus Al-Ti-B, Al-Ti-C or Al-B grain refiner. This phase contributes to the fir-tree surface defect in commercial sheet products. this work suggests that the combination of V and Al-Ti-B promotes FeAl{sub m} in commercial ingots, and confirms that solidification rate and bulk Si content also influence phase content.

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.

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.

Radial macrosegregation and dendrite clustering in directionally solidified Al-7Si and Al-19Cu alloys

Science.gov (United States)

Ghods, M.; Johnson, L.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2016-05-01

Hypoeutectic Al-7 wt% Si and Al-19 wt% Cu alloys were directionally solidified upward in a Bridgman furnace through a range of constant growth speeds and thermal gradients. Though processing is thermo-solutally stable, flow initiated by gravity-independent advection at, slightly leading, central dendrites moves rejected solute out ahead and across the advancing interface. Here any lagging dendrites are further suppressed which promotes a curved solid-liquid interface and the eventual dendrite "clustering" seen in transverse sections (dendrite "steepling" in longitudinal orientations) as well as extensive radial macrosegregation. Both aluminum alloys showed considerable macrosegregation at the low growth speeds (10 and 30 μm s-1) but not at higher speed (72 μm s-1). Distribution of the fraction eutectic-constituent on transverse sections was determined in order to quantitatively describe radial macrosegregation. The convective mechanisms leading to dendrite-steepling were elucidated with numerical simulations, and their results compared with the experimental observations.

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

International Nuclear Information System (INIS)

Meshi, L.; Zenou, V.; Ezersky, V.; Munitz, A.; Talianker, M.

2005-01-01

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

Microstructure investigation of NiAl-Cr(Mo) interface in a directionally solidified NiAl-Cr(Mo) eutectic alloyed with refractory metal

International Nuclear Information System (INIS)

Chen, Y.X.; Cui, C.Y.; Guo, J.T.; Li, D.X.

2004-01-01

The microstructure of a directionally solidified NiAl-Cr(Mo) eutectic alloyed with refractory metal in as-processed and heat-treated states has been studied by means of scanning electron microscopy and high resolution electron microscopy (HREM). The microstructure of the NiAl-Cr(Mo) eutectic was characterized by lamellar Cr(Mo) phases embedded within NiAl matrix with common growth direction of . The interface between NiAl and lamellar Cr(Mo) did not have any transition layers. Misfit dislocations were observed at the NiAl-Cr(Mo) interface. In addition to lamellar Cr(Mo) phases, coherent Cr(Mo, Ni, Al) precipitates and NiAl precipitates were also observed in the NiAl matrix and lamellar Cr(Mo) phases, respectively. After hot isostatic pressing and heat treatment, the NiAl-Cr(Mo) interfaces became smooth and straight. Square array of misfit dislocations was directly observed at the (0 0 1) interface between NiAl and Cr(Mo, Ni, Al) precipitate. The configuration of misfit dislocation network showed a generally good agreement with prediction based on the geometric O-lattice model

Formation of coarse Al13Fe4 particles and their effects in an RS/PM Al-Fe-V-Si alloy

International Nuclear Information System (INIS)

Lee, Sunghak; Lee, D.Y.; Ahn, Sangho.

1991-01-01

The present paper analyzed the fracture behavior of an RS/PM Al-Fe-V-Si alloy after high temperature exposure, in particular the effects of coarse Al13Fe4 particles formed during the exposure at 480 C. In situ SEM observations of crack opening processes found that brittle cleavage fracture occurred at these coarse Al13Fe4 particles, leading to the reduction in strength, fracture toughness, and ductility of the Al-Fe-V-Si alloy exposed to high temperatures. The results of fracture toughness were also interpreted using a simplified ductile fracture initiation model based on a basic assumption that crack extension starts to occur at a certain critical strain over a microstructurally significant critical distance. This model correlates microstructure to fracture toughness, confirming that the presence of coarse Al13Fe4 particles is the main metallurgical factor for the embrittlement phenomenon in the Al-Fe-V-Si alloy after high temperature exposure. 12 refs

Room temperature luminescence and ferromagnetism of AlN:Fe

Energy Technology Data Exchange (ETDEWEB)

Li, H., E-mail: lihui@mail.iee.ac.cn, E-mail: wjwang@aphy.iphy.ac.cn [The Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical engineering, Chinese Academy of Sciences, Beijing 100190 (China); Cai, G. M. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Wang, W. J., E-mail: lihui@mail.iee.ac.cn, E-mail: wjwang@aphy.iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2016-06-15

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 Fe{sup 2+} 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.

Catalytic Methane Decomposition over Fe-Al2O3

KAUST Repository

Zhou, Lu; Enakonda, Linga Reddy; Saih, Youssef; Loptain, Sergei; Gary, Daniel; Del-Gallo, Pascal; Basset, Jean-Marie

2016-01-01

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% Fe

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.

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

International Nuclear Information System (INIS)

Gueneau, C.; Ansara, I.

1994-01-01

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

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.

Production of 26Al by spallation of Fe, Si, Al nuclei

International Nuclear Information System (INIS)

Paillard, P.

1977-01-01

Cross sections for 7 Be, 10 Be and 26 Al formation in Al, Si and Fe targets bombarded with 0.6 and 24GeV protons have been measured by using highly selective chemical separation and low level background counters. Results for 26 Al at 0.6GeV are in mb: 17.9 + or - 2.7 in Al, 12.5 + or - 2.5 in Si and 0.45 + or - 0.14 in Fe; at 24GeV 2.6 + or - 0.5mb in Fe. Results for 10 Be are not valid on account of experimental difficulties. It is deduced from these values of aluminium in cosmic ray propagation that 26 Al is not yet cosmic ray chronometer [fr

Developments with melt spun RE-Fe-B powder for bonded magnets

International Nuclear Information System (INIS)

Brown, D.N.; Chen, Z.; Guschl, P.; Campbell, P.

2006-01-01

Rapidly quenched isotropic rare earth iron boride (RE-Fe-B) powders have found many applications throughout the electronics, automotive and white goods industries. The magnetic performance, thermal stability, corrosion resistance and processability of a powder are important factors when selecting a RE-Fe-B powder for a particular application. For electronic devices that operate at ambient temperatures, high remanence (B r ) tends to be a priority and RE 2 Fe 14 B/α-Fe nanocomposite powder magnets are favoured. Alternatively, automotive applications tend to require greater thermal stability and corrosion resistance, which are satisfied by single-phase RE 2 Fe 14 B powder magnets with higher intrinsic coercivity (H ci ). This article reviews the performance of commercially available rapidly solidified RE-Fe-B powders and recent developments made to address the demands of applications

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.

Evolution of the microstructure and hardness of a rapidly solidified/melt-spun AZ91 alloy upon aging at different temperatures

International Nuclear Information System (INIS)

Wang Baishu; Liu Yongbing; An Jian; Li Rongguang; Su Zhenguo; Su Guihua; Lu You; Cao Zhanyi

2009-01-01

The effect of aging at different temperatures on a rapidly solidified/melt-spun AZ91 alloy has been investigated in depth. The microstructures of as-spun and aged ribbons with a thickness of approximately 60 μm were characterized using X-ray diffraction, transmission electron microscopy and laser optical microscopy; microhardness measurements were also conducted. It was found that the commercial AZ91 alloy undergoes a cellular/dendritic transition during melt-spinning at a speed of 34 m/s. A strengthening effect due to aging was observed: a maximum hardness of 110 HV/0.05 and an age-hardenability of 50% were obtained when the ribbon was aged at 200 deg. C for 20 min. The β-Mg 17 Al 12 phase exhibits net and dispersion types of distribution during precipitation. The dispersion of precipitates in dendritic grains or cells is the main source of strengthening

Influence of quench rates on the properties of rapidly solidified ...

Indian Academy of Sciences (India)

Unknown

Abstract. FeNbCuSiB based materials were produced in the form of ribbons by rapid solidification techniques. The crystallization, magnetic, mechanical and corrosion behaviour were studied for the prepared materials as a function of quenching rate from liquid to the solid state. Higher quench rates produced a more ...

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.

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.

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...

Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

Science.gov (United States)

Aghion, E; Jan, L; Meshi, L; Goldman, J

2015-11-01

Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons. © 2014 Wiley Periodicals, Inc.

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.

CALCUL DE LA VITESSE DE REFROIDISSEMENT ET MICROSTRUCTURE DE L’ALLIAGE Al-5%Cu SOLIDIFIE RAPIDEMENT

Directory of Open Access Journals (Sweden)

C SERRAR

2010-12-01

Full Text Available La technique de trempe sur roue tournante a permis d'élaborer des rubans d'épaisseur moyenne de 30 μm pour une vitesse de rotation périphérique de la roue de 42m/s. La résolution de l'équation de Fourier pour un transfert de la chaleur dans les conditions de chute brutale de l'alliage fondue sur le substrat en rotation, nous a permis de déterminer le profil de la distribution de la température du ruban suivant son épaisseur. Le temps de solidification et la vitesse de refroidissement ont été aussi recherchés et sont estimés respectivement à 2.3x10-6 s et 4x107 °C/s. La microstructure des constituants de l'alliage AL-5%Cu s'est transformée, sous l'influence de la trempe rapide, en de fins précipités de l'eutectique α-Al/Ө dispersés dans la matrice α-Al. La présence d'une nouvelle phase σ, précipitant sous forme de fines particules globulaires, a été aussi observée et confirmée par analyse structurale.

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

Microstructures and phase formation in rapidly solidified Sm-Fe alloys

International Nuclear Information System (INIS)

Shield, J.E.; Kappes, B.B.; Meacham, B.E.; Dennis, K.W.; Kramer, M.J.

2003-01-01

Sm-Fe-based alloys were produced by melt spinning with various melt spinning parameters and alloying additions. The structural and microstructural evolution varied and strongly depended on processing and alloy composition. The microstructural scale was found to vary from micron to nanometer scale depending on the solidification rate and alloying additions. Additions of Si, Ti, V, Zr and Nb with C were all found to refine the scale, and the degree of refinement was dependent on the atomic size of the alloying agent. The alloying was also found to affect the dynamical aspects of the melt spinning process, although in general the material is characterized by a poor melt stream and pool, which in part contributes to the microstructural variabilities. The alloying additions also suppressed the long-range ordering, leading to formation of the TbCu 7 -type structure. The ordering was recoverable upon heat treatment, although the presence of alloying agents suppressed the recovery process relative to the binary alloy. This was attributed to the presence of Ti (V, Nb, Zr) in solid solution, which limited the diffusion kinetics necessary for ordering. In the binary alloy, the ordering led to the development of antiphase domain structures, with the antiphase boundaries effectively pinning Bloch walls

Formation of an 18R long-period stacking ordered structure in rapidly solidified Mg88Y8Zn4 alloy

International Nuclear Information System (INIS)

Garcés, Gerardo; Requena, Guillermo; Tolnai, Domonkos; Pérez, Pablo; Medina, Judit; Stark, Andreas; Schell, Norbert; Adeva, Paloma

2016-01-01

The formation of the long-period stacking ordered structure (LPSO) in a Mg 88 Y 8 Zn 4 (at%) ribbon produced by melt spinning was studied using high energy X-ray synchrotron radiation diffraction during in-situ isochronal heating and transmission electron microscopy. The microstructure of the rapidly solidified ribbons is characterised by fine magnesium grains with yttrium and zinc in solid solution and primary 18R LPSO-phase segregated at grain boundaries. Using differential scanning calorimetry, a strong exothermal peak was observed around 300 °C which was associated with the development of the 18R-type LPSO-phase in the magnesium grains. The apparent activation energy calculated using the Kissinger model was 125 KJmol −1 and it is related to simultaneous diffusion of Y and Zn through magnesium basal plane. - Highlights: •The formation of the LPSO phase in rapidly solidified ribbons was studied. •The formation of the 18R LPSO starts at around 300 °C. •LPSO formation have to steps: Stacking faults along basal plane and then growth of 18R structure along the c direction.

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)

Influence of micro-additions of bismuth on structures, mechanical and electrical transport properties of rapidly solidified Sn-3.5% Ag Alloy from melt

International Nuclear Information System (INIS)

El Bahay, M.M.; Mady, H.A.

2005-01-01

The present study was undertaken to investigate the influence of the Bi addition in the Sn-3.5 Ag rapidly solidified binary system for use as a Pb-free solder. The resulting properties of the binary system were extended to the Sn based ternary systems Sn 9 6.5-X Ag 3 .5 Bi x (0≤ X ≤ 2.5) solder. The structure and electrical resistivity of rapidly solidified (melt spun) alloys have been investigated. With the addition of up to 2.5 mass % Bi, the melting temperature decreases from 221.1 to 214.8 degree C. Wetting contact angle of the six alloys on Cu Zn 3 0 substrate are carried out at 573 K. Microhardness evaluations were also performed on the Sn-Ag-Bi alloys. The measured values and other researcher's results were compared with the calculated data

Melting of Au and Al in nanometer Fe/Au and Fe/Al multilayers under swift heavy ions: A thermal spike study

International Nuclear Information System (INIS)

Chettah, A.; Wang, Z.G.; Kac, M.; Kucal, H.; Meftah, A.; Toulemonde, M.

2006-01-01

Knowing that Fe is sensitive to swift heavy ion irradiations whereas Au and Al are not, the behavior of nanometric metallic multilayer systems, like [Fe(3 nm)/Au(x)] y and [Fe(3 nm)/Al(x)] y with x ranging between 1 and 10 nm, were studied within the inelastic thermal spike model. In addition to the usual cylindrical geometry of energy dissipation perpendicular to the ion projectile direction, the heat transport along the ion path was implemented in the electronic and atomic sub-systems. The simulations were performed using three different values of linear energy transfer corresponding to 3 MeV/u of 208 Pb, 132 Xe and 84 Kr ions. For the Fe/Au system, evidence of appearance of a molten phase was found in the entire Au layer, provided the Au thickness is less than 7 nm and 3 nm for Pb and Xe ions, respectively. For the Fe/Al(x) system irradiated with Pb ions, the Al layers with a thickness less than 4 nm melt along the entire ion track. Surprisingly, the Fe layer does not melt if the Al thickness is larger than 2 nm, although the deposited energy surpasses the electronic stopping power threshold of track formation in Fe. For Kr ions melting does not occur in any of the multilayer systems

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.

Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

International Nuclear Information System (INIS)

Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

2008-01-01

The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

Energy Technology Data Exchange (ETDEWEB)

Plevachuk, Yu. [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Metal Physics; Egry, I.; Brillo, J.; Holland-Moritz, D. [Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. fuer Raumsimulation; Kaban, I. [Chemnitz Univ. of Technolgy (Germany). Inst. of Physics

2007-02-15

The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a noncontact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al-Fe and Al-Ni alloys. (orig.)

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.

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.

Fabrication and thermal characterization of amorphous and nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti compound

Energy Technology Data Exchange (ETDEWEB)

Tavoosi, Majid, E-mail: ma.tavoosi@gmail.com

2017-01-15

In this study, the fabrication and structural characterization of amorphous/nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti phase has been performed. In this regards, milling and annealing processes were applied on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} (at. %) powder mixture for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and differential scanning calorimetery (DSC). According to the results, supersaturated solid solution, nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti (with average crystallite size of about 7 nm) and amorphous phases indicated three different microstructures which can be formed in Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} system during milling process. The formed supersaturated solid solution and amorphous phases were unstable and transformed to Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound during annealing process. It is shown that, Al{sub 9}FeNi phase in Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound can decompose into Al{sub 3}Ni, Al{sub 13}Fe{sub 4} and liquid phases during a reversible peritectic reaction at 809 °C. - Highlights: • We study the effect of milling process on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} alloy. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} supersaturated solid solution phase. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} amorphous phase. • We study the thermal behaviour of Al{sub 9}FeNi/Al{sub 3}Ti compound.

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.

Relaxation-phenomena in LiAl/FeS-cells

Science.gov (United States)

Borger, W.; Kappus, W.; Panesar, H. S.

A theoretical model of the capacity of strongly relaxing electrochemical systems is applied to the LiAl/FeS system. Relaxation phenomena in LiAl and FeS electrodes can be described by this model. Experimental relaxation data indicate that lithium transport through the alpha-LiAl layer to the particle surface is the capacity limiting process at high discharge current density in the LiAl electrode in LiCl-KCl and LiF-LiCl-LiBr mixtures. Strong relaxation is observed in the FeS electrode with LiCl-KCl electrolyte caused by lithium concentration gradients and precipitation of KCl in the pores.

Microstructure and mechanical properties of an Al–Mg alloy solidified under high pressures

International Nuclear Information System (INIS)

Jie, J.C.; Zou, C.M.; Brosh, E.; Wang, H.W.; Wei, Z.J.; Li, T.J.

2013-01-01

Highlights: •Al–42.2Mg alloy was solidified under pressures of 1, 2, and 3 GPa and the microstructure analyzed. •A thermodynamic calculation of the Al–Mg phase diagram at high pressures was performed. •The phase content changes from predominantly γ-Al 12 Mg 17 at 1 GPa to FCC solid solution at 3 GPa. •The β-Al 3 Mg 2 is predicted to remain stable at low temperatures but is not observed. •The alloy solidified at high pressure has remarkably enhanced ultimate tensile strength. -- Abstract: Phase formation, the microstructure and its evolution, and the mechanical properties of an Al–42.2 at.% Mg alloy solidified under high pressures were investigated. After solidification at pressures of 1 GPa and 2 GPa, the main phase is the γ phase, richer in Al than in equilibrium condition. When the pressure is further increased to 3 GPa, the main phase is the supersaturated Al(Mg) solid solution with Mg solubility up to 41.6 at.%. Unlike in similar alloys solidified at ambient pressure, the β phase does not appear. Calculated high-pressure phase diagrams of the Al–Mg system show that although the stability range of the β phase is diminished with pressure, it is still thermodynamically stable at room temperature. Hence, the disappearance of the β phase is interpreted as kinetic suppression, due to the slow diffusion rate at high pressures, which inhibits solid–solid reactions. The Al–42.2 at.% Mg alloy solidified under 3 GPa has remarkably enhanced ultimate tensile strength compared to the alloy solidified under normal atmospheric pressure

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

Microstructure and Mechanical Properties of Al-5Mg-0.8Mn Alloys with Various Contents of Fe and Si Cast under Near-Rapid Cooling

Directory of Open Access Journals (Sweden)

Yulin Liu

2017-10-01

Full Text Available Al-5Mg-0.8Mn alloys (AA5083 with various iron and silicon contents were cast under near-rapid cooling and rolled into sheets. The aim was to study the feasibility of minimizing the deteriorating level of the harmful Fe-rich phases on the mechanical properties through refining the intermetallics by significantly increasing the casting rate. The results showed that the size and density of the intermetallic particles that remained in the hot bands and the cold rolled sheets increased as the contents of iron and silicon in the alloys were increased. However, the increment of the particle sizes was limited due to the significant refinement of the intermetallics formed during casting under near-rapid cooling. The mechanical properties of the alloys reduced as the contents of iron and silicon in the alloys increased. However, the decrement of tensile strengths and ductility was quite small. Therefore, higher contents of iron and silicon could be used in the Al-5Mg-0.8Mn alloy (AA5083 alloy when the material is cast under near-rapid cooling, such as in the continuous strip casting process.

Effect of rapid solidification on the microstructure and mechanical properties of hot-pressed Al-20Si-5Fe alloys

International Nuclear Information System (INIS)

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

2009-01-01

The aim of this work is to study the effect of cooling rate and subsequent hot consolidation on the microstructural features and mechanical strength of Al-20Si-5Fe-2X (X = Cu, Ni and Cr) alloys. Powder and ribbons were produced by gas atomization and melt spinning processes at two different cooling rates of 1 x 10 5 K/s and 5 x 10 7 K/s. The microstructure of the products was examined using optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The particles were consolidated by hot pressing at 400 deg. C/250 MPa/1 h under a high purity argon atmosphere and the microstructure, hardness and compressive strength of the compacts were evaluated. Results showed a profound effect of the cooling rate, consolidation stage, and transition metals on the microstructure and mechanical strength of Al-20Si-5Fe alloys. While microstructural refining was obtained at both cooling rates, the microstructure of the atomized powder exhibited the formation of fine primary silicon (∼ 1 μm), eutectic Al-Si phase with eutectic spacing of ∼ 300 nm, and δ-iron intermetallic. Supersaturated Al matrix containing 5-7 at.% silicon and nanometric Si precipitates (20-40 nm) were determined in the microstructure of the melt-spun ribbons. The hot consolidation resulted in coarsening of Si particles in the atomized particles, and precipitation of Si and Fe-containing intermetallics from the supersaturated Al matrix in the ribbons. The consolidated ribbons exhibited higher mechanical strength compared to the atomized powders, particularly at elevated temperatures. The positive influence of the transition metals on the thermal stability of the Al-20Si-5Fe alloy was noticed, particularly in the Ni-containing alloy.

Development of weldable, corrosion-resistant iron-aluminide (FeAl) alloys

Energy Technology Data Exchange (ETDEWEB)

Maziasz, P.J.; Goodwin, G.M.; Wang, X.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

1997-04-01

A boron-microalloyed FeAl alloy (Fe-36Al-0.2Mo-0.05Zr-0.13C, at.%, with 100-400 appm B) with improved weldability and mechanical properties was developed in FY 1994. A new scale-up and industry technology development phase for this work began in FY 1995, pursuing two parallel paths. One path was developing monolithic FeAl component and application technology, and the other was developing coating/cladding technology for alloy steels, stainless steels and other Fe-Cr-Ni alloys. In FY 1995, it was found that cast FeAl alloys had good strength at 700-750{degrees}C, and some (2.5%) ductility in air at room-temperature. Hot-extruded FeAl with refined grain size was found to have ductility and to also have good impact-toughness at room-temperature. Further, it was discovered that powder-metallurgy (P/M) FeAl, consolidated by direct hot-extrusion at 950-1000{degrees}C to have an ultra fine-grained microstructure, had the highest ductility, strength and impact-toughness ever seen in such intermetallic alloys.

THERMAL STABILITY OF Al-Cu-Fe QUASICRYSTALS PREPARED BY SHS METHOD

OpenAIRE

Pavel Novák; Alena Michalcová; Milena Voděrová; Ivo Marek; Dalibor Vojtěch

2013-01-01

Quasicrystal-containing materials are usually prepared by rapid solidification of the melt (e.g. by melt spinning) or mechanical alloying. In this work, the method using exothermic reactions between compressed metallic powders called SHS (Self-propagating High-temperature Synthesis) was tested. The microstructure and phase composition of the product was described in dependence on cooling regime from the reaction temperature. Thermal stability of prepared Al-Cu-Fe quasicrystals was studied by...

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

Indian Academy of Sciences (India)

FeAl-based composites; precipitation; mechanical properties; wear. 1. Introduction. Fe–Al alloys ... ground to 1500 grit and polished with alumina powder. (0.5 μm). ... Alloy-2 (figure 2) consists of cuboid-shaped ZrC (region C), an FeAl matrix ...

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

Rapid thermal annealing of FePt and FePt/Cu thin films

Energy Technology Data Exchange (ETDEWEB)

Brombacher, Christoph

2011-01-10

Chemically ordered FePt is one of the most promising materials to reach the ultimate limitations in storage density of future magnetic recording devices due to its high uniaxial magnetocrystalline anisotropy and a corrosion resistance superior to rare-earth based magnets. In this study, FePt and FePt/Cu bilayers have been sputter deposited at room temperature onto thermally oxidized silicon wafers, glass substrates and self-assembled arrays of spherical SiO{sub 2} particles with diameters down to 10 nm. Millisecond flash lamp annealing, as well as conventional rapid thermal annealing was employed to induce the phase transformation from the chemically disordered A1 phase into the chemically ordered L1{sub 0} phase. The influence of the annealing temperature, annealing time and the film thickness on the ordering transformation and (001) texture evolution of FePt films with near equiatomic composition was studied. Whereas flash lamp annealed FePt films exhibit a polycrystalline morphology with high chemical L1{sub 0} order, rapid thermal annealing can lead to the formation of chemically ordered FePt films with (001) texture on amorphous SiO{sub 2}/Si substrates. The resultant high perpendicular magnetic anisotropy and large coercivities up to 40 kOe are demonstrated. Simultaneously to the ordering transformation, rapid thermal annealing to temperatures exceeding 600 C leads to a break up of the continuous FePt film into separated islands. This dewetting behavior was utilized to create regular arrays of FePt nanostructures on SiO{sub 2} particle templates with periods down to 50 nm. The addition of Cu improves the (001) texture formation and chemical ordering for annealing temperatures T{sub a} {<=}600 C. In addition, the magnetic anisotropy and the coercivity of the ternary FePtCu alloy can be effectively tailored by adjusting the Cu content. The prospects of FePtCu based exchange spring media, as well as the magnetic properties of FePtCu nanostructures fabricated

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).

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.

Synthesis of Fe-Al-Ti Based Intermetallics with the Use of Laser Engineered Net Shaping (LENS

Directory of Open Access Journals (Sweden)

Monika Kwiatkowska

2015-04-01

Full Text Available The Laser Engineered Net Shaping (LENS technique was combined with direct synthesis to fabricate L21-ordered Fe-Al-Ti based intermetallic alloys. It was found that ternary Fe-Al-Ti alloys can be synthesized using the LENS technique from a feedstock composed of a pre-alloyed Fe-Al powder and elemental Ti powder. The obtained average compositions of the ternary alloys after the laser deposition and subsequent annealing were quite close to the nominal compositions, but the distributions of the elements in the annealed samples recorded over a large area were inhomogeneous. No traces of pure Ti were observed in the deposited alloys. Macroscopic cracking and porosity were observed in all investigated alloys. The amount of porosity in the samples was less than 1.2 vol. %. It seems that the porosity originates from the porous pre-alloyed Fe-Al powders. Single-phase (L21, two-phase (L21-C14 and multiphase (L21-A2-C14 Fe-Al-Ti intermetallic alloys were obtained from the direct laser synthesis and annealing process. The most prominent feature of the ternary Fe-Al-Ti intermetallics synthesized by the LENS method is their fine-grained structure. The grain size is in the range of 3–5 μm, indicating grain refinement effect through the highly rapid cooling of the LENS process. The Fe-Al-Ti alloys synthesized by LENS and annealed at 1000 °C in the single-phase B2 region were prone to an essential grain growth. In contrast, the alloys annealed at 1000 °C in the two-phase L21-C14 region exhibited almost constant grain size values after the high-temperature annealing.

Elution behavior of heavy metals from cement solidified products of incinerated ash waste - 59102

International Nuclear Information System (INIS)

Meguro, Yoshihiro; Kawato, Yoshimi; Nakayama, Takuya; Tomioka, Osamu; Mitsuda, Motoyuki

2012-01-01

A method, in which incinerated ash is solidified with a cement material, has been developed to dispose radioactive incinerated ash waste. In order to bury the solidified product, it is required that elution of hazardous heavy metals included in the ash from the solidified products is inhibited. In this study, the elution behavior of the heavy metals from the synthetic solidified products, which included Pb(II), Cd(II), and Cr(VI) and were prepared using ordinary portland cement (OPC), blast furnace slag cement (BFS), or a cement material that showed low alkalinity (LA-Cement), was investigated. Several chemicals and materials were added as additive agents to prevent the elution of the heavy metals. When OPC was used, Cd elution was inhibited, but Pb and Cr were not enough even using the additive agent examined. FeSO 4 and Na 2 S additive agents worked effective to inhibit elution of Cr. When BFS was used, the elution of Pb, Cd and Cr was inhibited for the all products prepared. In the case of LA-Cement, the elution of Pb and Cd was inhibited for the all products, but only the product that was added FeSO 4 showed good result of the elution of Cr. (authors)

Magnetic domain structure, crystal orientation, and magnetostriction of Tb{sub 0.27}Dy{sub 0.73}Fe{sub 1.95} solidified in various high magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Gao, Pengfei [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Liu, Tie, E-mail: liutie@epm.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Dong, Meng [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Yuan, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Wang, Qiang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China)

2016-03-01

In this paper, we studied how applying a high magnetic field during solidification of Tb{sub 0.27}Dy{sub 0.73}Fe{sub 1.95} alloys affected their magnetic domain structure, crystal orientation, and magnetostriction. We observed the morphology of the magnetic domain during solidification, finding it change with the applied field: from fiber like (0 T) to dot like and closure mixed (4.4 T) to fiber like (8.8 T) to fishbone like (11.5 T). The alloy solidified at 4.4 T showed the best contrast of light and dark in its domain image, widest magnetic domain, fastest magnetization, and highest magnetostriction; this alloy is followed in descending order by the alloys solidified at 11.5 T, 8.8 T, and 0 T. The orientation of the (Tb, Dy)Fe{sub 2} phase changed with magnetic field from random (0 T) to 〈111〉 (4.4 T) to 〈113〉 (8.8 T) to 〈110〉 (11.5 T). The improvement in magnetostriction was likely caused by modification of both the magnetization process and the alloy microstructure. - Highlights: • We present how magnetic field affects magnetic domain structure of Tb{sub 0.27}Dy{sub 0.73}Fe{sub 1.95}. • Morphology and width of magnetic domain change with increasing magnetic field. • Magnetization and magnetostriction of alloy change with increasing magnetic field. • A transformation of random–〈111〉–〈113〉–〈110〉 for (Tb, Dy)Fe{sub 2} orientation forms.

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

Science.gov (United States)

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

2016-01-01

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

Effect of Bi-content on hardness and micro-creep behavior of Sn-3.5Ag rapidly solidified alloy

Energy Technology Data Exchange (ETDEWEB)

Kamal, M. [Metal Physics Laboratory, Faculty of Science, Mansoura University (Egypt); Gouda, El Said [Metal Physics Laboratory, Department of Solid State Physics, Physics Division, National Research Center, Dokki, Giza (Egypt); Marei, L.K. [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

2009-12-15

In the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn-3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn-3.5Ag, Sn-3.5Ag-1Bi and Sn-3.5Ag-3Bi are composed of two phases; Ag{sub 3}Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn-matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn-3.5Ag-5Bi and Sn-3.5Ag-10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn-3.5Ag alloy to 202.6 C at 10 % Bi. Vickers hardness of Sn-3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro-creep behavior of Sn-3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

High pressure studies of A2Mo3O12 negative thermal expansion materials (A2=Al2, Fe2, FeAl, AlGa)

International Nuclear Information System (INIS)

Young, Lindsay; Gadient, Jennifer; Gao, Xiaodong; Lind, Cora

2016-01-01

High pressure powder X-ray diffraction studies of several A 2 Mo 3 O 12 materials (A 2 =Al 2 , Fe 2 , FeAl, and AlGa) were conducted up to 6–7 GPa. All materials adopted a monoclinic structure under ambient conditions, and displayed similar phase transition behavior upon compression. The initial isotropic compressibility first became anisotropic, followed by a small but distinct drop in cell volume. These patterns could be described by a distorted variant of the ambient pressure polymorph. At higher pressures, a distinct high pressure phase formed. Indexing results confirmed that all materials adopted the same high pressure phase. All changes were reversible on decompression, although some hysteresis was observed. The similarity of the high pressure cells to previously reported Ga 2 Mo 3 O 12 suggested that this material undergoes the same sequence of transitions as all materials investigated in this paper. It was found that the transition pressures for all phase changes increased with decreasing radius of the A-site cations. - Graphical abstract: Overlay of variable pressure X-ray diffraction data of Al 2 Mo 3 O 12 collected in a diamond anvil cell. Both subtle and discontinuous phase transitions are clearly observed. - Highlights: • The high pressure behavior of A 2 Mo 3 O 12 (A=Al, Fe, (AlGa), (AlFe)) was studied. • All compounds undergo the same sequence of pressure-induced phase transitions. • The phase transition pressures correlate with the average size of the A-site cation. • All transitions were reversible with hysteresis. • Previously studied Ga 2 Mo 3 O 12 undergoes the same sequence of transitions.

Solid-liquid phase equilibria of Fe-Cr-Al alloys and spinels

Science.gov (United States)

McMurray, J. W.; Hu, R.; Ushakov, S. V.; Shin, D.; Pint, B. A.; Terrani, K. A.; Navrotsky, A.

2017-08-01

Ferritic FeCrAl alloys are candidate accident tolerant cladding materials. There is a paucity of data concerning the melting behavior for FeCrAl and its oxides. Analysis tools have therefore had to utilize assumptions for simulations using FeCrAl cladding. The focus of this study is to examine in some detail the solid-liquid phase equilibria of FeCrAl alloys and spinels with the aim of improving the accuracy of severe accident scenario computational studies.

Core–shell structured FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite cores with tunable insulating layer thicknesses

Energy Technology Data Exchange (ETDEWEB)

Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang, E-mail: ligq-wust@mail.wust.edu.cn [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

2015-11-15

Graphical abstract: - Highlights: • FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores were prepared. • SiO{sub 2} surrounding FeSiAl were replaced by Al{sub 2}O{sub 3} during sintering process. • Fe{sub 3}Si particles were separated by Al{sub 2}O{sub 3} with tunable thickness in composite cores. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than FeSiAl core. • The insulating layer between ferromagnetic particles can reduce core loss. - Abstract: FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses have been synthesized via a modified Stöber method combined with following high temperature sintering process. Most of the conductive FeSiAl particles could be coated by insulating SiO{sub 2} using the modified Stöber method. During the sintering process, the reaction 4Al + 3SiO{sub 2} ≣ 2α-Al{sub 2}O{sub 3} + 3Si took place and the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher resistivity and lower core loss than the raw FeSiAl core. Based on this, several types of FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses were selectively prepared by simply varying TEOS contents. The thickness of Al{sub 2}O{sub 3} insulating layer and resistivity of Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores increased with increasing the TEOS contents, while the permeability and core loss changed in the opposite direction.

Aluminum Coprecipitates with Fe (hydr)oxides: Does Isomorphous Substitution of Al3plus for Fe3plus in Goethite Occur

Energy Technology Data Exchange (ETDEWEB)

E Bazilevskaya; D Archibald; M Aryanpour; J Kubicki; C Martinez

2011-12-31

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 {approx}2.25 for Fe{sup 3+} and at pH {approx}4 for Al{sup 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

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

Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); 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)

2015-09-18

FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO₂ or ZrO₂. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

The changes in the electronic structure of B2 FeAl alloy with a Fe antisite and absorbed hydrogen

International Nuclear Information System (INIS)

Gonzalez, E.A.; Jasen, P.V.; Luna, R.; Bechthold, P.; Juan, A.; Brizuela, G.

2009-01-01

The electronic structure and bonding in a B2 FeAl alloy with and without hydrogen interaction with a Fe antisite were computed using a density functional theoretical method. The hydrogen absorption turns out to be a favorable process. The hydrogen was found close to an octahedral site where one of its Al capped is replaced by a Fe antisite. The Fe-H distance is of 1.45 A same as the Al-H distance. The density of states (DOS) curves show several peaks below the d metal band which is made up mostly of hydrogen based states (>50% H 1s ) while the metal contribution in this region includes mainly s and p orbitals. An electron transfer of nearby 0.21e - comes from the metal to the H. The overlap population values reveal metal-metal bond breaking, the intermetallic bond being the most affected. The H bond mainly with the Al atom and the reported Fe-H overlap population is much lower than that corresponding to FePd alloys and BCC Fe. The changes in the overlap population show the Fe-Al bond is weakened nearly 41.5% after H absorption, while the Fe-Fe bond is only weakened 34.5%. H also develops a stronger bond with the Al atoms. The main bond is developed with Al being twice stronger than Fe-H.

Viscosity of SiO2-"FeO"-Al2O3 System in Equilibrium with Metallic Fe

Science.gov (United States)

Chen, Mao; Raghunath, Sreekanth; Zhao, Baojun

2013-08-01

The present study delivered the measurements of viscosities in SiO2-"FeO"-Al2O3 system in equilibrium with metallic Fe. The rotational spindle technique was used in the measurements at the temperature range of 1473 K to 1773 K (1200 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The Fe saturation condition was maintained by an iron plate placed at the bottom of the crucible. The equilibrium compositions of the slags were measured by EPMA after the viscosity measurements. The effect of up to 20 mol. pct Al2O3 on the viscosity of the SiO2-"FeO" slag was investigated. The "charge compensation effect" of the Al2O3 and FeO association has been discussed. The modified quasi-chemical viscosity model has been optimized in the SiO2-"FeO"-Al2O3 system in equilibrium with metallic Fe to describe the viscosity measurements of the present study.

Interface electron structure of Fe3Al/TiC composites

Institute of Scientific and Technical Information of China (English)

PANG Lai-xue; SUN Kang-ning; SUN Jia-tao; FAN Run-hua; REN Shuai

2006-01-01

Based on YU's solids and molecules emperical electron theory(EET), interface valence electron structure of TiC-Fe3Al composites was set up, and the valence electron density of different atomic states TiC and Fe3Al composites in various planes was determined. The results indicate that the electron density of (100)Fe3Al is consistent with that of (110)TiC in the first-class approximation, the absolute value of minimum electron density difference along the interface is 0.007 37 nm-2, and the relative value is 0.759%. (110)TiC//(100)Fe3Al preferred orientation is believed to benefit the formation of the cuboidal shape TiC. In the other hand, it shows that the particle growth is accompanied by the transport of electron, the deviation continuity of electron density intrinsically hinders the grain growth. The electron density of (100)TiC is not consistent with Fe3Al arbitrary crystallographic plane,thus it well explains that the increased titanium and carbon contents do not increase the size of large particles. The crystallographic orientation of (110)TiC//(100)FeAl will improve the mechanical properties. Therefore interface electron theory is an effective theoretical implement for designing excellent property of composites.

Microstructural evolution and creep of Fe-Al-Ta alloys

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-15

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

Microstructural evolution and creep of Fe-Al-Ta alloys

International Nuclear Information System (INIS)

Prokopcakova, Petra; Svec, Martin; Palm, Martin

2016-01-01

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

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.

Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

International Nuclear Information System (INIS)

Karakoese, E.; Keskin, M.

2009-01-01

The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be α-Al, fcc Si and intermetallic AlSb phases whereas only α-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

Energy Technology Data Exchange (ETDEWEB)

Karakoese, E. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Keskin, M. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Erciyes University, Physics Department, 38039 Kayseri (Turkey)], E-mail: keskin@erciyes.edu.tr

2009-06-24

The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be {alpha}-Al, fcc Si and intermetallic AlSb phases whereas only {alpha}-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

Viability of thin wall tube forming of ATF FeCrAl

Energy Technology Data Exchange (ETDEWEB)

Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Anderoglu, Osman [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-09-16

Fabrication of thin walled tubing of FeCrAl alloys is critical to its success as a candidate enhanced accident-tolerant fuel cladding material. Alloys that are being investigated are Generation I and Generation II FeCrAl alloys produced at ORNL and an ODS FeCrAl alloy, MA-956 produced by Special Metals. Gen I and Gen II FeCrAl alloys were provided by ORNL and MA-956 was provided by LANL (initially produced by Special Metals). Three tube development efforts were undertaken. ORNL led the FeCrAl Gen I and Gen II alloy development and tube processing studies through drawing tubes at Rhenium Corporation. LANL received alloys from ORNL and led tube processing studies through drawing tubes at Century Tubing. PNNL led the development of tube processing studies on MA-956 through pilger processing working with Sandvik Corporation. A summary of the recent progress on tube development is provided in the following report and a separate ORNL report: ORNL/TM-2015/478, “Development and Quality Assessments of Commercial Heat Production of ATF FeCrAl Tubes”.

Two-dimensional nano-lattice in Fe-Co-Ni-Al-Cu alloys

International Nuclear Information System (INIS)

Kalanov, M.U.; Ibragimova, E.M.; Khamraeva, R.N.; Rustamova, V.M.; Ummatov, H.D.

2007-01-01

Full text: The high coercive strength of the dispersionally solidified alloys on the base of Fe-Co-Ni-Al-Cu system appears as a result of the special thermomagnetic annealing, when particles of the strong magnetic phase are distinguished in non-magnetic matrix along an external magnetic field direction. The neutron studying allows one to reveal the correlation between magnetization and inclusion axes, and also existence of magnetic microcell and perfectness of the lattice. This work presents results of neutron diffraction study with a double-crystal spectrometer (0.145 nm). Plate like samples of size 18 12 4 mm 3 were cut from a single crystal of alloy UNDK35 T5 along (100) plane. Magnetic field of 6 kOe was applied perpendicular to the neutron beam. Zero-field spectrum had only random variation of the background. Under the applied magnetic field two maxima appeared at the angles of 12 and 24 minute. In the case of the magnetic field directed in parallel to the scattering vector, the two maxima disappeared as expected. It is evidence that nuclear scattering is less than magnetic one and the observed maxima correspond to (10) and (20) reflections from a two dimensional ferro-magnetic microcell. The cell parameter of the magnetic microcell was found 40.6 nm. The coherent scattering region size was 120-160 nm. The ferro-magnetic rod diameter estimated from the peak widths was 16 nm. The diffraction pattern for the demagnetized sample strongly differs from the initial magnetized sample, where a diffuse reflection was observed near Bragg reflection and related with residual magnetization. So, the magnetic inclusions created in the Fe-Co-Ni-Al-Cu system at the thermomagnetic annealing by means of disintegration of the solid solution are strong ferro-magnetic and one-domain. These particles form the two-dimensional magnetic microcell and interact each to other within 3-4 periods of the cell. (authors)

Light-weight alloys for aerospace applications II; Proceedings of the 2nd Symposium, New Orleans, LA, Feb. 17-21, 1991

International Nuclear Information System (INIS)

Lee, E.W.; Kim, N.J.

1991-01-01

The present symposium on applications of light-weight alloys for aerospace discusses Al-Li alloys, aluminum alloys, advanced composites, and light alloys. Attention is given to Al-Li alloy development for parts made from thick plates, the structure and properties of P/M-aluminum alloys, X-ray rocking curve analysis of aging and deformation characteristics in Al-Li alloys, and the transformation characteristics of the 2090 Al-Li alloy. Topics considered include microstructural development in a rapidly solidified Al-Fe-V-Si alloy, the structure and mechanical properties of rapidly solidified Al-Cr-Hf alloys, the deformation mechanisms in superplastic Al-Mg alloys by microtexture technique, and the design of powder metallurgy aluminum alloys. Also discussed are the mechanical properties of monolithic and particular composites of L1(2) forms of Al3Ti, in situ polymer fiber-reinforced hybrid materials, thermal cycling of Ti-1421/SiC metal matrix composites, and the fracture behavior of a Ti3-Al-Nb alloy

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

Maps of Fe-Al phases formation kinetics parameters during isothermal sintering

Energy Technology Data Exchange (ETDEWEB)

Pochec, Ewelina, E-mail: epochec@wat.edu.pl [Department of Advanced Materials and Technology, Military University of Technology (Poland); Jozwiak, Stanislaw; Karczewski, Krzysztof; Bojar, Zbigniew [Department of Advanced Materials and Technology, Military University of Technology (Poland)

2012-10-10

Highlights: Black-Right-Pointing-Pointer The sintering temperature and compaction pressure have a strong influence on the sinters structure. Black-Right-Pointing-Pointer The measurements confirmed the presence of the high-aluminium phases from Fe-Al equilibrium system in tested sinters. Black-Right-Pointing-Pointer The kinetics of Fe-Al phase formation can be described by Johnson-Mehl-Avrami modelling. - Abstract: The influence of technological parameters (compaction pressure and sintering temperature) on Fe-Al phase formation was investigated. The kinetics of phase transformation preceding and during an SHS reaction was studied in isothermal conditions by DSC using the JMA (Johnson-Mehl-Avrami) model. This model allowed us to determine basic kinetic parameters, including the Avrami exponent, which characterises the rate and manner of particular phase nucleation. The activation energy (E{sub a}) of particular phase formation was determined by the Kissinger method. XRD analysis and SEM observations of sintered material showed that not only Fe{sub 2}Al{sub 5} phase and low-aluminium solid solution in iron but also aluminium-rich FeAl{sub 2} and FeAl{sub 3} phases are formed during the sintering of an FeAl50 elementary powder mixture in isothermal conditions with an SHS reaction. The above conclusions were confirmed by iron-based solid solution lattice parameter studies and microhardness measurements.

Solidified ceramics of radioactive wastes and method of producing it

International Nuclear Information System (INIS)

Oota, Takao; Matake, Shigeru; Ooka, Kazuo.

1980-01-01

Purpose: To provide solidified ceramics which have low leaching properties to water of radioactive substance, excellent heat dissipating and resistive properties and high mechanical strength by mixing and sintering limited amounts of titanium and aluminum compounds with calcined radioactive wastes containing special compound. Method: More than 20% by weight of titanium compound (as TiO 2 ) and more than 5% by weight of aluminum compound (as Al 2 O 3 ) are mixed with the calcined radioactive wasted containing, as converted by oxide, 5 to 40% by weight of Na 2 O, 5 to 20% by weight of Fe 2 O 3 , 5 to 15% by weight of MoO 3 , 5 to 15% by weight of ZrO 2 , 2 to 10% by weight of CeO 2 , 2 to 10% by weight of Cs 2 O, 1 to 5% by weight of BaO, 1 to 5% by weight of SrO, 0.2 to 2% by weight of Rb 2 O, 0.2% by weight of Y 2 O 3 , 0.2 to 2% by weight of NiO, 5 to 20% by weight of rare earth metal oxide, and 0.2 to 2% by weight of Cr 2 O 3 . The mixture is molded, sintered, and solidified to ceramics which contains no Mo phase, Na 2 O, MoO 3 , K 2 O, MoO 3 and Cs 2 O, MoO 3 phases and the like. (Yoshino, Y.)

Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

KAUST Repository

Tao, B. S.

2014-09-08

Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

KAUST Repository

Tao, B. S.; Li, D. L.; Yuan, Z. H.; Liu, H. F.; Ali, S. S.; Feng, J. F.; Wei, H. X.; Han, X. F.; Liu, Y.; Zhao, Y. G.; Zhang, Q.; Guo, Zaibing; Zhang, Xixiang

2014-01-01

Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

Fatigue crack growth rates and fracture toughness of rapidly solidified Al-8.5 pct Fe-1.2 pct V-1.7 pct Si alloys

International Nuclear Information System (INIS)

Hariprasad, S.; Sastry, S.M.L.; Jerina, K.L.

1994-01-01

The room-temperature fatigue crack growth rates (FCGR) and fracture toughness were evaluated for different crack plane Orientations of an Al-8.5 pct Fe-1.2 pct V-1.7 pct Si alloy produced by planar flow casting (PFC) and atomized melt deposition (AMD) processes. For the alloy produced by the PFC process, properties were determined in six different orientations, including the short transverse directions S-T and S-L. Diffusion bonding and adhesive bonding methods were used to prepare specimens for determining FCGR and fracture toughness in the short transverse direction. Interparticle boundaries control fracture properties in the alloy produced by PFC. Fracture toughness of the PFC alloy varies from 13.4 MPa√ bar m to 30.8 MPa√ bar m, depending on the orientation of the crack plane relative to the interparticle boundaries. Fatigue crack growth resistance and fracture toughness are greater in the L-T, L-S, and T-S directions than in the T-L, S-T, and S-L orientations. The alloy produced by AMD does not exhibit anisotropy in fracture toughness and fatigue crack growth resistance in the as-deposited condition or in the extruded condition. The fracture toughness varies from 17.2 MPa√ bar m to 18.5 MPa√ bar m for the as-deposited condition and from 19.8 MPa√ bar m to 21.0 MPa√ bar m for the extruded condition. Fracture properties are controlled by intrinsic factors in the alloy produced by AMD. Fatigue crack growth rates of the AMD alloy are comparable to those of the PFC alloy in the L-T orientation. The crack propagation modes were studied by optical metallographic examination of crack-microstructure interactions and scanning electron microscopy of the fracture surfaces

Thermal stability of Al-Cu-Fe quasicrystals prepared by SHS method

Directory of Open Access Journals (Sweden)

Pavel Novak

2013-02-01

Full Text Available Quasicrystal-containing materials are usually prepared by rapid solidification of the melt (e.g. by melt spinning or mechanical alloying. In this work, the method using exothermic reactions between compressed metallic powders called SHS (Self-propagating High-temperature Synthesis was tested. The microstructure and phase composition of the product was described in dependence on cooling regime from the reaction temperature. Thermal stability of prepared Al-Cu-Fe quasicrystals was studied by annealing at the temperatures of 300 and 500 °C.

THERMAL STABILITY OF Al-Cu-Fe QUASICRYSTALS PREPARED BY SHS METHOD

Directory of Open Access Journals (Sweden)

Pavel Novák

2013-04-01

Full Text Available Quasicrystal-containing materials are usually prepared by rapid solidification of the melt (e.g. by melt spinning or mechanical alloying. In this work, the method using exothermic reactions between compressed metallic powders called SHS (Self-propagating High-temperature Synthesis was tested. The microstructure and phase composition of the product was described in dependence on cooling regime from the reaction temperature. Thermal stability of prepared Al-Cu-Fe quasicrystals was studied by annealing at the temperatures of 300 and 500 °C.

Mechanical Properties of Nano structured TiC-FeAl Hard Materials

International Nuclear Information System (INIS)

Shon, In-Jin; Jo, Hyoung-Gon; Kim, Byung-Su; Yoon, Jin-Kook; Hong Kyung-Tae

2015-01-01

For the formation of cemented Tic composite, Co or Ni is added as a binder. However, the high cost and low hardness of Co or Ni as binder and the low corrosion resistance of Tic-Co and Tic-Ni composite have generated interest to find alternative binder materials. It has been reported that FeAl show higher oxidation resistance and hardness as well as low cost compared to Co or Ni. Highly dense nanocrystalline Tic and Tic-FelAl with a relative density of up to 100% were obtained within 2 min by PCAS(pulsed current activated sintering) under the condition of 80MPa and up to 1300. The effect of FeAl addition of FeAl on the consolidation, the microstructure and the mechanical properties (hardness and fracture toughness) of TiC were investigated. The fracture toughness of TiC greatly increases without great decrease of the hardness by addition of FeAl. Not only fracture toughness but also hardness values of TiC-10vol.%FeAl were higher than those of TiC-10vol.%Fe, TiC-10vol.%Ni and TiC-10vol.%Co.

Hydrogen permeation in FeCrAl alloys for LWR cladding application

Science.gov (United States)

Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

2015-06-01

FeCrAl, an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In this study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. The total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

Thermodynamic analysis of (Ni, Fe)3Al formation by mechanical alloying

International Nuclear Information System (INIS)

Adabavazeh, Z.; Karimzadeh, F.; Enayati, M.H.

2012-01-01

Highlights: ► (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying. ► We use a thermodynamic analysis to predict the more stable phase. ► We calculate the Gibbs free-energy changes by using extended Miedema model. ► The results of MA compared with thermodynamic analysis and showed a good agreement with it. - Abstract: (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures of composition Ni 50 Fe 25 Al 25 . Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD). The results show that mechanical alloying resulted in a Ni (Al, Fe) solid solution. By continued milling, this structure transformed to the disordered (Ni, Fe) 3 Al intermetallic compound. A thermodynamic model developed on the basis of extended theory of Miedema is used to calculate the Gibbs free-energy changes. Final product of MA is a phase having minimal Gibbs free energy compared with other competing phases in Ni–Fe–Al system. However in Ni–Fe–Al system, the most stable phase at all compositions is intermetallic compound (not amorphous phase or solid solution). The results of MA were compared with thermodynamic analysis and revealed the leading role of thermodynamic on the formation of MA product prediction.

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.

Microstructures and microhardness evolutions of melt-spun Al-8Ni-5Nd-4Si alloy

Energy Technology Data Exchange (ETDEWEB)

Karakoese, Ercan, E-mail: ekarakose@karatekin.edu.tr [Karatekin University, Faculty of Sciences, Department of Physics, 18100 Cank Latin-Small-Letter-Dotless-I r Latin-Small-Letter-Dotless-I (Turkey); Keskin, Mustafa [Erciyes University, Faculty of Sciences, Department of Physics, 38039 Kayseri (Turkey)

2012-03-15

Al-Ni-Nd-Si alloy with nominal composition of Al-8 wt.%Ni-5 wt.%Nd-4 wt.%Si was rapidly solidified by using melt-spinning technique to examine the influence of the cooling rate/conditions on microstructure and mechanical properties. The resulting conventional cast (ingot) and melt-spun ribbons were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry, differential thermal analysis and Vickers microhardness tester. The ingot alloys consists of four phases namely {alpha}-Al, intermetallic Al{sub 3}Ni, Al{sub 11}Nd{sub 3} and fcc Si. Melt-spun ribbons are completely composed of {alpha}-Al phase. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. The change in microhardness is discussed based on the microstructural observations. - Highlights: Black-Right-Pointing-Pointer Rapid solidification allows a reduction in grain size, extended solid solution ranges. Black-Right-Pointing-Pointer We observed the matrix lattice parameter increases with increasing wheel speed. Black-Right-Pointing-Pointer Melt-spun ribbons consist of partly amorphous phases embedded in crystalline phases. Black-Right-Pointing-Pointer The solidification rate is high enough to retain most of alloying elements in the Al matrix. Black-Right-Pointing-Pointer The rapid solidification has effect on the phase constitution.

Sequestration of uranium on fabricated aluminum co-precipitated with goethite (Al-FeOOH)

Energy Technology Data Exchange (ETDEWEB)

Sun, Yubing; Yang, Shubin; Wang, Qi; Wang, Xiangke [Chinese Academy of Science, Hefei (China). Key Laboratory of Novel Thin Film Solar Cells; Alsaedi, Ahmad [King Abdulaziz Univ., Jeddah (Saudi Arabia). Nonlinear Analysis and Applied Mathematics (NAAM) Research Group

2014-11-01

Aluminum co-precipitated with goethites (Al-FeOOHs) are ubiquitous within (sub)-surface environments, which are considered one of the most important sinks for radionuclide pollution management. Accordingly, various mole ratios Al-FeOOH were synthesized and characterized by XRD, FT-IR, TEM, specific surface area and potentiometric acid-base titration. According to XRD and TEM images, the morphology of Al-FeOOH was transformed from acicular-like goethite to cotton-like gibbsite with increasing Al content. The adsorption and sequential desorption of U(VI) on Al-FeOOHs were conducted by batch techniques under N{sub 2} conditions. The batch adsorption results showed that the adsorption of U(VI) on Al-FeOOHs slightly increased at pH < 4.0, then the significant increase of U(VI) adsorption was observed at pH from 4.0 to 7.0, whereas the suppressed adsorption at pH > 8.0 was due to the electrostatic repulsion between negative charge surface and negative carbonato-complexes. The adsorption of U(VI) on Al-FeOOHs was independent of ionic strength at pH > 5.0, indicating that the inner-sphere surface complexation predominated their adsorption behaviors, whereas U(VI) adsorption on Al-FeOOH could be the outer-sphere surface/cation exchange reaction. The sequential extraction texts showed that the desorption of U(VI) from Al-FeOOHs decreased with increasing Al content. These findings highlighted the effect of Al content on the sequestration and immobilization of U(VI) onto Al-FeOOHs from (sub)-surface environments in pollution management.

Development of ODS-Fe{sub 3}Al alloys

Energy Technology Data Exchange (ETDEWEB)

Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; McKamey, C.G. [Oak Ridge National Lab., TN (United States)

1997-12-01

The overall goal of this program is to develop an oxide dispersion-strengthened (ODS) version of Fe{sub 3}Al that has sufficient creep strength and resistance to oxidation at temperatures in the range 1000 to 1200 C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The main areas being addressed are: (a) alloy processing to achieve the desired alloy grain size and shape, and (b) optimization of the oxidation behavior to provide increased service life compared to semi-commercial ODS-FeCrAl alloys intended for the same applications. The recent studies have focused on mechanically-alloyed powder from a commercial alloy vendor. These starting alloy powders were very clean in terms of oxygen content compared to ORNL-produced powders, but contained similar levels of carbon picked up during the milling process. The specific environment used in milling the powder appears to exert a considerable influence on the post-consolidation recrystallization behavior of the alloy. A milling environment which produced powder particles having a high surface carbon content resulted in a consolidated alloy which readily recrystallized, whereas powder with a low surface carbon level after milling resulted in no recrystallization even at 1380 C. A feature of these alloys was the appearance of voids or porosity after the recrystallization anneal, as had been found with ORNL-produced alloys. Adjustment of the recrystallization parameters did not reveal any range of conditions where recrystallization could be accomplished without the formation of voids. Initial creep tests of specimens of the recrystallized alloys indicated a significant increase in creep strength compared to cast or wrought Fe{sub 3}Al, but the specimens failed prematurely by a mechanism that involved brittle fracture of one of the two grains in the test cross section, followed by ductile fracture of the remaining grain. The reasons for this behavior are not yet understood. The

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.)

Microstructure and mechanical properties of Al-3Fe alloy processed by equal channel angular extrusion

International Nuclear Information System (INIS)

Fuxiao, Yu; Fang, Liu; Dazhi, Zhao; Toth, Laszlo S

2014-01-01

Al-Fe alloys are attractive for applications at temperatures beyond those normally associated with the conventional aluminum alloys. Under proper solidification condition, a full eutectic microstructure can be generated in Al-Fe alloys at Fe concentration well in excess of the eutectic composition of 1.8 wt.% Fe. The microstructure in this case is characterized by the metastable regular eutectic Al-Al 6 Fe fibers of nano-scale in diameter, instead of the equilibrium eutectic Al-Al 3 Fe phase. In this study, the microstructure and mechanical properties of the Al-3Fe alloy with metastable Al 6 Fe particles deformed by equal channel angular extrusion were investigated. Severe plastic deformation results in a microstructure consisting of submicron equiaxed Al grains with a uniform distribution of submicron Al 6 Fe particles on the grain boundaries. The room temperature tensile properties of the alloy with this microstructure will be presented

Formation of bands of ultrafine beryllium particles during rapid solidification of Al-Be alloys: Modeling and direct observations

International Nuclear Information System (INIS)

Elmer, J.W.; Tanner, L.E.; Smith, P.M.; Wall, M.A.; Aziz, M.J.

1994-01-01

Rapid solidification of dilute hyper-eutectic and monotectic alloys sometimes produces a dispersion of ultrafine randomly-oriented particles that lie in arrays parallel to the advancing solidification front. The authors characterize this effect in Al-Be where Be-rich particles with diameters on the order of 10 nm form in arrays spaced approximately 25 nm apart, and they present a model of macroscopically steady state but microscopically oscillatory motion of the solidification front to explain this unusual microstructure. The proposed mechanism involves; (i) the build-up of rejected solute in a diffusional boundary layer which slows down the growing crystal matrix, (2) the boundary layer composition entering a metastable liquid miscibility gap, (3) homogeneous nucleation of solute rich liquid droplets in the boundary layer, and crystallization of these droplets, and (4) growth of the matrix past the droplets and its reformation into a planar interface. The size of the Be-rich particles is limited by the beryllium supersaturation in the diffusional boundary layer. A numerical model was developed to investigate this solidification mechanism, and the results of the model are in good agreement with experimental observations of rapidly solidified Al-5 at.% Be

Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

Directory of Open Access Journals (Sweden)

Mohd Zobir Hussein

2014-11-01

Full Text Available Multi-walled carbon nanotubes (MWCNTs were prepared via chemical vapor deposition (CVD using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs. Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs.

Ab-initio electronic and magnetic properties of Fe-Al alloys

Directory of Open Access Journals (Sweden)

Apiñaniz, E.

2000-06-01

Full Text Available This work presents ab-initio self-consistent calculations performed with the TB-LMTO code to study the different phases of the Fe-Al phase diagram, corresponding to the ordered structures B2, DO3 and B32 and for Fe50Al50 and Fe3Al compositions. Both, unpolarized and spin-polarized calculations have been performed to deduce the energetic difference between the paramagnetic and ferromagnetic state of the corresponding structure. Calculations for the disordered structures have also been performed for the previously mentioned compositions. These results show that by disordering the alloy magnetism is enhanced and that the equilibrium lattice parameter increases.

En este trabajo se presentan cálculos autoconsistentes ab-initio realizados con el método TB-LMTO (Tight Binding Linear Muffin Tin Orbital con el fin de estudiar las diferentes estructuras que se presentan en el diagrama de fases de las aleaciones Fe-Al. Se han estudiado las estructuras ordenadas B2, DO3 y B32 para las siguientes concentraciones: Fe50Al50 y Fe3Al. Asimismo, se han realizado cálculos teniendo y sin tener en cuenta la polarización de spin con el fin de poder deducir la diferencia energética entre los estados ferromágneticos y paramágneticos de la misma estructura. Por otra parte se han realizado estos mismos cálculos para estructuras desordenadas y las mismas concentraciones. Los resultados muestran que mediante el desorden aumenta el magnetismo de estas aleaciones y crece el parámetro de red.

Thermodynamic properties of Al-Mn, Al-Cu, and Al-Fe-Cu melts and their relations to liquid and quasicrystal structure

International Nuclear Information System (INIS)

Zaitsev, A I; Zaitseva, N E; Shimko, R Yu; Arutyunyan, N A; Dunaev, S F; Kraposhin, V S; Lam, Ha Thanh

2008-01-01

Thermodynamic properties of molten Al-Mn, Al-Cu and Al-Fe-Cu alloys in a wide temperature range of 1123-1878 K and the whole range of concentrations have been studied using the integral effusion method and Knudsen mass spectrometry. Thermodynamic functions of melts were described by the associated solution model. The possibility of icosahedral quasicrystal (i-QC) precipitation from liquid Al-Mn and Al-Cu-Fe alloys was found to be a consequence of the existence in liquid associates (clusters). A geometric model is suggested for the structure of associates in liquid

Epitactical FeAl films on sapphire and their magnetic properties; Epitaktische FeAl-Filme auf Saphir und ihre magnetischen Eigenschaften

Energy Technology Data Exchange (ETDEWEB)

Trautvetter, Moritz

2011-05-05

In the presented thesis epitaxial FeAl thin films on sapphire have been prepared by pulse laser deposition (PLD). The thin films deposited at room temperature exhibits ferromagnetism and subsequent annealing is necessary to transform the thin films to paramagnetic B2-phase, where the transition temperature depends on the crystalline orientation of the sapphire substrate. Alternatively, by deposition at higher substrate temperature the B2-phase is obtained directly. However, morphology of the FeAl film is influenced by different growth modes resulting from different substrate temperatures. The paramagnetic FeAl films can then be transformed to ferromagnetic phase by successive ion irradiation. Independent of the ion species used for irradiation, the same universal relation between thin films' coercive fields and irradiation damage is identified. The ion irradiation ferromagnetism can be transformed back to paramagnetism by subsequent annealing. The mutual transition between ferromagnetic and paramagnetic phases has been performed several times and shows full reversibility. The ferromagnetic phase induced by Kr{sup +} irradiation exhibits structural relaxation, where the saturate magnetization of FeAl thin film gradually decreases in several days. Later, ion irradiation has been performed selectively on defined areas of the thin film with the help of an unconventional lithography technique. The subsequent thin film is composed of ordered hexagonal array of ferromagnetic nano-cylinders separated by a paramagnetic matrix, suggesting a promising system for magnetic data storage. (orig.)

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)

Probing Single Pt Atoms in Complex Intermetallic Al13Fe4.

Science.gov (United States)

Yamada, Tsunetomo; Kojima, Takayuki; Abe, Eiji; Kameoka, Satoshi; Murakami, Yumi; Gille, Peter; Tsai, An Pang

2018-03-21

The atomic structure of a 0.2 atom % Pt-doped complex metallic alloy, monoclinic Al 13 Fe 4 , was investigated using a single crystal prepared by the Czochralski method. High-angle annular dark-field scanning transmission electron microscopy showed that the Pt atoms were dispersed as single atoms and substituted at Fe sites in Al 13 Fe 4 . Single-crystal X-ray structural analysis revealed that the Pt atoms preferentially substitute at Fe(1). Unlike those that have been reported, Pt single atoms in the surface layers showed lower activity and selectivity than those of Al 2 Pt and bulk Pt for propyne hydrogenation, indicating that the active state of a given single-atom Pt site is strongly dominated by the bonding to surrounding Al atoms.

Liquid coated melt-spun Nd-Fe-B powders for bonded magnets

Science.gov (United States)

Li, D.; Gaiffi, S.; Kirk, D.; Young, K.; Herchenroeder, J.; Berwald, T.

1999-04-01

The liquid coating (LC) has been employed to apply epoxy and lubricant over the surface of rapidly solidified Nd-Fe-B powder particles. The LC led to an improvement of physical and magnetic properties for the powders and magnets compared to the dry blending and the encapsulation methods. The LC powders have excellent flowability and can be used for bonded magnets requiring very close tolerances; further bonded magnets made using this powder posses higher strength.

Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

Energy Technology Data Exchange (ETDEWEB)

Cai, Tanhong [Iowa State Univ., Ames, IA (United States)

2001-01-01

Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

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.)

Susceptibility of CoFeB/AlOx/Co Magnetic Tunnel Junctions to Low-Frequency Alternating Current

Directory of Open Access Journals (Sweden)

Yuan-Tsung Chen

2013-10-01

Full Text Available This investigation studies CoFeB/AlOx/Co magnetic tunneling junction (MTJ in the magnetic field of a low-frequency alternating current, for various thicknesses of the barrier layer AlOx. The low-frequency alternate-current magnetic susceptibility (χac and phase angle (θ of the CoFeB/AlOx/Co MTJ are determined using an cac analyzer. The driving frequency ranges from 10 to 25,000 Hz. These multilayered MTJs are deposited on a silicon substrate using a DC and RF magnetron sputtering system. Barrier layer thicknesses are 22, 26, and 30 Å. The X-ray diffraction patterns (XRD include a main peak at 2θ = 44.7° from hexagonal close-packed (HCP Co with a highly (0002 textured structure, with AlOx and CoFeB as amorphous phases. The full width at half maximum (FWHM of the Co(0002 peak, decreases as the AlOx thickness increases; revealing that the Co layer becomes more crystalline with increasing thickness. χac result demonstrates that the optimal resonance frequency (fres that maximizes the χac value is 500 Hz. As the frequency increases to 1000 Hz, the susceptibility decreases rapidly. However, when the frequency increases over 1000 Hz, the susceptibility sharply declines, and almost closes to zero. The experimental results reveal that the mean optimal susceptibility is 1.87 at an AlOx barrier layer thickness of 30 Å because the Co(0002 texture induces magneto-anisotropy, which improves the indirect CoFeB and Co spin exchange-coupling strength and the χac value. The results concerning magnetism indicate that the magnetic characteristics are related to the crystallinity of Co.

Moessbauer study of Fe-Al disordered alloys near the critical concentration

International Nuclear Information System (INIS)

Bohorquez, A.; Tabares, J.A.; Perez Alcazar, G.A.; Gancedo, J.R.

1994-01-01

Disordered bcc Fe 1-q Al q alloys in the composition range 0.5≤q≤0.6 were studied by Moessbauer effect measurements. The Moessbauer spectra at 300 K of all the samples consist of two paramagnetic sites, one is a singlet and the other a doublet with quadrupole splitting. The results can be interpreted by considering that the sites of this disordered system are arranged near the configurations of the Fe and Al sites of the Fe-Al ordered system. (orig.)

Neutron-scattering study of the magnetic structure of DyFe₄Al₈ and HoFe₄Al₈

DEFF Research Database (Denmark)

Paixao, J.A.; Silva, M.R.; Sørensen, S.Aa.

2000-01-01

The magnetic structures of DyFe4Al8 and HoFe4Al8, which have been reported to be unusual spin-glass systems, were studied in detail by neutron diffraction, using both unpolarized and polarized beams. In fact these compounds have long-range magnetic order in both the Fe and rare-earth sublattices....

A study on the formation of iron aluminide (FeAl) from elemental powders

Energy Technology Data Exchange (ETDEWEB)

Sina, H.; Corneliusson, J.; Turba, K.; Iyengar, S.

2015-07-05

Highlights: • Fe–40 at.% Al discs with coarse iron powder showed precombustion and combustion peaks. • Loose powder mixtures and discs with fine iron powder showed only combustion peaks. • Slower heating rate and fine aluminum particles promote precombustion. • The major product formed during both the reactions was Fe{sub 2}Al{sub 5}. • Heating the samples to 1000 °C yielded a stable FeAl phase as the final product. - Abstract: The formation of iron aluminide (FeAl) during the heating of Fe–40 at.% Al powder mixture has been studied using a differential scanning calorimeter. The effect of particle size of the reactants, compaction of the powder mixtures as well as the heating rate on combustion behavior has been investigated. On heating compacted discs containing relatively coarser iron powder, DSC data show two consecutive exothermic peaks corresponding to precombustion and combustion reactions. The product formed during both these reactions is Fe{sub 2}Al{sub 5} and there is a volume expansion in the sample. The precombustion reaction could be improved by a slower heating rate as well as a better surface coverage of iron particles using relatively finer aluminum powder. The combustion reaction was observed to be weaker after a strong precombustion stage. Heating the samples to 1000 °C resulted in the formation of a single and stable FeAl phase through the diffusional reaction between Fe{sub 2}Al{sub 5} and residual iron. DSC results for compacted discs containing relatively finer iron powder and for the non-compacted samples showed a single combustion exotherm during heating, with Fe{sub 2}Al{sub 5} as the product and traces of FeAl. X-ray diffraction and EDS data confirmed the formation of FeAl as the final product after heating these samples to 1000 °C.

Phase Constituents and Microstructure of Ti3Al/Fe3Al + TiN/TiB2 Composite Coating on Titanium Alloy

Science.gov (United States)

Li, Jianing; Chen, Chuanzhong; Zhang, Cuifang

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be used to improve the Fe3Al + B4C/TiN laser-cladded coating on the Ti-6Al-4V alloy. Furthermore, during the cladding process, C consumed the oxygen in Fe3Al + B4C /TiN + Al2O3 molten pool, which retarded the productions of the redundant metal oxides.

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

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.

Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

International Nuclear Information System (INIS)

Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

2016-01-01

Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

Energy Technology Data Exchange (ETDEWEB)

Li, Jingjing [Department of Mechanical Engineering, The University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States); Yu, Qian; Zhang, Zijiao [Department of Materials Science and Engineering, Center for Electron Microscope, Zhejiang University, Hangzhou 310027 (China); Xu, Wei; Sun, Xin, E-mail: xin.sun@pnnl.gov [Pacific Northwest National Laboratory, Richland, Washington 99354 (United States)

2016-05-16

Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

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

Chinese Script vs Plate-Like Precipitation of Beta-Al9Fe2Si2 Phase in an Al-6.5Si-1Fe Alloy

Science.gov (United States)

Ferdian, Deni; Josse, Claudie; Nguyen, Patrick; Gey, Nathalie; Ratel-Ramond, Nicolas; de Parseval, Philippe; Thebault, Yannick; Malard, Benoit; Lacaze, Jacques; Salvo, Luc

2015-07-01

The microstructure of a high-purity Al-6.5Si-1Fe (wt pct) alloy after solidification at various cooling rates was investigated. In most of the cases, the monoclinic beta-Al9Fe2Si2 phase was observed as long and thin lamellae. However, at a very slow cooling rate, Fe-bearing precipitates with Chinese script morphology appeared together with lamellae. Further analysis showed all these Chinese script precipitates correspond also to the monoclinic beta phase. This finding stresses that differentiating second phases according to their shape may be misleading.

Modified embedded-atom method interatomic potential for the Fe-Al system

International Nuclear Information System (INIS)

Lee, Eunkoo; Lee, Byeong-Joo

2010-01-01

An interatomic potential for the Fe-Al binary system has been developed based on the modified embedded-atom method (MEAM) potential formalism. The potential can describe various fundamental physical properties of Fe-Al binary alloys-structural, elastic and thermodynamic properties, defect formation behavior and interactions between defects-in reasonable agreement with experimental data or higher-level calculations. The applicability of the potential to atomistic investigations of various defect formation behaviors and their effects on the mechanical properties of high aluminum steels as well as Fe-Al binary alloys is demonstrated.

Effect of iron and cerium additions on rapidly solidified Al-TM-Ce alloys

Czech Academy of Sciences Publication Activity Database

Michalcová, A.; Vojtěch, D.; Schumacher, G.; Novák, P.; Pližingrová, Eva

2013-01-01

Roč. 47, č. 6 (2013), s. 757-761 ISSN 1580-2949 Institutional support: RVO:61388980 Keywords : rapid solidification * aluminium * quasicrystals Subject RIV: CA - Inorganic Chemistry Impact factor: 0.555, year: 2013

Oxidation Resistance of Fe3Al/TiC Composite at High Temperature%Fe3Al/TiC复合材料的高温抗氧化性能

Institute of Scientific and Technical Information of China (English)

范敏; 鲍剑斌

2003-01-01

研究了Fe3Al/TiC复合材料的高温抗氧化性能.结果表明:Fe3Al/TiC复合材料在950℃的氧化动力学特征均近似服从抛物线规律,并且随TiC含量增加,Fe3Al/TiC复合材料的高温抗氧化性能降低.

Preparation of Al/Fe-Pillared Clays: Effect of the Starting Mineral.

Science.gov (United States)

Muñoz, Helir-Joseph; Blanco, Carolina; Gil, Antonio; Vicente, Miguel-Ángel; Galeano, Luis-Alejandro

2017-11-28

Four natural clays were modified with mixed polyoxocations of Al/Fe for evaluating the effect of the physicochemical properties of the starting materials (chemical composition, abundance of expandable clay phases, cationic exchange capacity and textural properties) on final physicochemical and catalytic properties of Al/Fe-PILCs. The aluminosilicate denoted C2 exhibited the highest potential as starting material in the preparation of Al/Fe-PILC catalysts, mainly due to its starting cationic exchange capacity (192 meq/100 g) and the dioctahedral nature of the smectite phase. These characteristics favored the intercalation of the mixed (Al 13- x /Fe x ) 7+ Keggin-type polyoxocations, stabilizing a basal spacing of 17.4 Å and high increase of the BET surface (194 m²/g), mainly represented in microporous content. According to H₂-TPR analyses, catalytic performance of the incorporated Fe in the Catalytic Wet Peroxide Oxidation (CWPO) reaction strongly depends on the level of location in mixed Al/Fe pillars. Altogether, such physicochemical characteristics promoted high performance in CWPO catalytic degradation of methyl orange in aqueous medium at very mild reaction temperatures (25.0 ± 1.0 °C) and pressure (76 kPa), achieving TOC removal of 52% and 70% of azo-dye decolourization in only 75 min of reaction under very low concentration of clay catalyst (0.05 g/L).

Microstructural characterization of welded zone for Fe{sub 3}Al/Q235 fusion-bonded joint

Energy Technology Data Exchange (ETDEWEB)

Ma Haijun [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)], E-mail: hjma123@mail.sdu.edu.cn; Li Yajiang [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China); Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Puchkov, U.A. [Material Science Department, Bauman Moscow State Technical University, Moscow 105005 (Russian Federation); Wang Juan [Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, Shandong Province, Jing Shi Road 73, Shandong (China)

2008-12-20

The microstructural characterization of Fe{sub 3}Al/Q235 welded zone were analysed to investigate the welding behavior of Fe{sub 3}Al intermetallic. The results indicated that a crack-free Fe{sub 3}Al/Q235 joint was obtained when Cr25-Ni13 alloy was adopted as the filler metal. The microstructure of the welded zone presented different morphology due to the severe fluctuation of Al, Ni, Mn and Cr elements near the fusion zone. The fish-bone like structures in Q235 side fusion zone were composed of {alpha}-Fe(Cr, Al, Ni) solid solutions. Fe{sub 3}Al/Q235 joint fractured in the Fe{sub 3}Al HAZ, and shear strength of 533.33 MPa was achieved. The fracture mode of Fe{sub 3}Al side fracture surface was mainly transgranular cleavage, occured along [1 1 1] orientation on {l_brace}1 1 0{r_brace} planes. And the Q235 side fracture surface was in intergranular and quasi-cleavage mode. The phase relations of {gamma} and {alpha} in Fe{sub 3}Al side fusion zone, constituent of lower bainite in the weld and the Fe{sub 3}Al ordered transformation in HAZ were also determined.

Large tunnel magnetoresistance at room temperature with a Co2FeAl full-Heusler alloy electrode

International Nuclear Information System (INIS)

Okamura, S.; Miyazaki, A.; Sugimoto, S.; Tezuka, N.; Inomata, K.

2005-01-01

Magnetic tunnel junctions (MTJs) with a Co 2 FeAl Heusler alloy electrode are fabricated by the deposition of the film using an ultrahigh vacuum sputtering system followed by photolithography and Ar ion etching. A tunnel magnetoresistance (TMR) of 47% at room temperature (RT) are obtained in a stack of Co 2 FeAl/Al-O x /Co 75 Fe 25 magnetic tunnel junction (MTJ) fabricated on a thermally oxidized Si substrate despite the A2 type atomic site disorder for Co 2 FeAl. There is no increase of TMR in MTJs with the B2 type Co 2 FeAl, which is prepared by the deposition on a heated substrate. X-ray photoelectron spectroscopy (XPS) depth profiles in Co 2 FeAl single layer films reveal that Al atoms in Co 2 FeAl are oxidized preferentially at the surfaces. On the other hand, at the interfaces in Co 2 FeAl/Al-O x /Co 75 Fe 25 MTJs, the ferromagnetic layers are hardly oxidized during plasma oxidation for a formation of Al oxide barriers

Evolution of magnetic order in mechanically alloyed Al-1 at%Fe

International Nuclear Information System (INIS)

Sebastian, Varkey; Lakshmi, N.; Venugopalan, K.

2007-01-01

The evolution of ferromagnetic order in high-energy ball-milled Al-1 at% Fe before the onset of a considerable Fe-Al solid solution phase has been investigated using 57 Fe Moessbauer and bulk magnetization studies. The unmilled sample does not exhibit bulk magnetic properties and an onset of bulk magnetization is observed only after 30 min of milling, when the grain size becomes comparable to the ferromagnetic exchange length. The Curie temperatures of all the samples are less than that of pure iron. The reduction in grain size is accompanied by an increase in coercivity and reduced remanence and a decrease in T C . The effective magnetic moment per iron atom decreases with the development of a non-magnetic, Al-rich Fe-Al solution on longer milling. The clustering of Fe at grain boundaries is responsible for the observed bulk magnetic ordering. The systematic variation of the magnetic properties has been qualitatively correlated with the evolution of microstructure, reduction in grain size and enhanced inter-granular exchange coupling

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.

A study on crystalline phases present in the as-solidified and crystallized microstructures in Zr53Cu21Al10Ni8Ti8 alloy

International Nuclear Information System (INIS)

Neogy, S.; Tewari, R.; Srivastava, D.; Dey, G.K.

2011-01-01

In the present study the as-solidified and crystallized microstructures of Zr 53 Cu 21 Al 10 Ni 8 Ti 8 alloy have been examined in detail. Solidification was carried out by melt spinning, suction casting and copper mould casting techniques. The last technique yielded a partially crystalline microstructure, whereas, the other two techniques resulted in amorphous microstructures. (author)

Sintering of (Ni,Mg)(Al,Fe)2O4 Materials and their Corrosion Process in Na3AlF6-AlF3-K3AlF6 Electrolyte

Science.gov (United States)

Xu, Yibiao; Li, Yawei; Yang, Jianhong; Sang, Shaobai; Wang, Qinghu

2017-06-01

The application of ledge-free sidewalls in the Hall-Héroult cells can potentially reduce the energy requirement of aluminum production by about 30 pct (Nightingale et al. in J Eur Ceram, 33:2761-2765, 2013). However, this approach poses great material challenges since such sidewalls are in direct contact with corrosive electrolyte. In the present paper, (Ni,Mg)(Al,Fe)2O4 materials were prepared using fused magnesia, reactive alumina, nickel oxide, and iron oxide powders as the starting materials. The sintering behaviors of specimens as well as their corrosion resistance to molten electrolyte have been investigated by means of X-ray diffraction and scanning electron microscope. The results show that after firing at temperature ranging from 1673 K (1400 °C) up to 1873 K (1600 °C), all the specimens prepared are composed of single-phase (Ni,Mg)(Al,Fe)2O4 composite spinel, the lattice parameter of which increases with increasing Fe3+ ion concentration. Increasing the iron oxide content enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed smaller pores in the matrix. The corrosion tests show that corrosion layers consist of fluoride and Ni(Al,Fe)2O4 composite spinel grains are produced in specimens with Fe/Al mole ratio no more than 1, whereas dense Ni(Al,Fe)2O4 composite spinel layers are formed on the surface of the specimens with Fe/Al mole ratio more than 1. The dense Ni(Al,Fe)2O4 composite spinel layers formed improve the corrosion resistance of the specimens by inhibiting the infiltration of electrolyte and hindering the chemical reaction between the specimen and electrolyte.

Magnetic properties of melt-spun FeMnAlB alloys

International Nuclear Information System (INIS)

Betancourt, I.; Nava, F.

2007-01-01

Magnetic properties of melt spun Fe 89-x Mn 11 Al x (x=2,4,8,15) and Fe 87-y Mn 11 Al 2 By(y=6,8,10) alloy series were studied by vibrating sample magnetometry and complex permeability measurements. The saturation magnetization exhibited an initial high value of 210emu/g followed by a decreasing tendency with increasing Al and B additions (up to 139emu/g). On the other hand, the initial permeability showed variations within the range 1000-2000, whereas the relaxation frequency displayed a maximum of 2MHz for the 4at% Al alloy

Synthesis of laser beam rapidly solidified novel surfaces on D2 tool steel

International Nuclear Information System (INIS)

Ahmed, B.A.; Rizwan, K.F.; Minhas, J.A.; Waheed-ul-Haq, S.; Shahid, M.

2011-01-01

Surface layer of D2 tool steel was subjected to laser surface melting using continuous wave 2.5 kW CO/sub 2/ laser in point source melting mode. The processing parameters were varied to achieve a uniform depth of around 2 mm. Microstructural study revealed epitaxial growth of fine dendritic structure with secondary dendrite arm spacing in the range of 20-25 mu m. The phases in the parent annealed sample were BCC ferrite and chromium rich M7C3 carbide. The major phase after laser treatment was austenite and M7C3. The average hardness of annealed sample was 195 HV which increased to 410 HV after laser melting. Corrosion studies in 2% HCl solution exhibited a drastic improvement in corrosion resistance in laser treated samples. Improvement in properties is attributed to the refinement and uniformity of microstructure in the rapidly solidified surface. The case of a moving heat source was subjected to computer aided simulation to predict the melt depth at different processing conditions in point source melting mode. The calculated depths using the model, in ABAQUS software was found in good agreement with the experimental data. (author)

Quasicrystalline and crystalline phases in Al65Cu20(Fe, Cr)15 alloys

International Nuclear Information System (INIS)

Liu, W.; Koester, U.; Mueller, F.; Rosenberg, M.

1992-01-01

Two types of icosahedral quasicrystals are observed in Al 65 Cu 20 Fe 15-x Cr x (0 ≤ x ≤ 15) alloys, the face-centred AlCuFe-type icosahedral phase with dissoluted Cr and the primitive AlCuCr-type icosahedral phase with dissoluted Fe. In the vicinity of Al 65 Cu 20 Fe 8 Cr 7 a stable decagonal phase (a=0.45 nm and c=1.23 nm) forms competitively with the icosahedral quasicrystals. All these three quasicrystalline phases can be regarded as Hume-Rothery phases stabilized by the energy band factor. The density is measured to be 4.57, 4.44, and 4.11 g/cm 3 for the icosahedral Al 65 Cu 20 Fe 15 , the decagonal Al 65 Cu 20 Fe 8 Cr 7 , and the icosahedral Al 65 Cu 20 Cr 15 alloys, respectively. Depending on the composition in the range between Al 65 Cu 20 Fe 8 Cr 7 and Al 65 Cu 20 Cr 15 , several crystalline phases are observed during the transormation of the AlCuCr-type icosahedral phase: the 1/1-3/2-type orthorhombic (o) and the 1/0-3/2-type tetragonal (t) approximants of the decagonal phase, a hexagonal (h) phase, as well as a long-range vacancy ordered τ 3 -phase derived from a CsCl-type structure with a=0.2923 nm. The structures of all the crystalline phases are closely related to those of the icosahedral (i) and decagonal (d) quasicrystals, which leads to a definite orientation relationship as follows: i5 parallel d10 parallel o[100] parallel t[100] parallel h[001] parallel τ 3 [110]. (orig.)

Characterization of Low-Symmetry Structures from Phase Equilibrium of Fe-Al System—Microstructures and Mechanical Properties

Directory of Open Access Journals (Sweden)

Piotr Matysik

2015-03-01

Full Text Available Fe-Al intermetallic alloys with aluminum content over 60 at% are in the area of the phase equilibrium diagram that is considerably less investigated in comparison to the high-symmetry Fe3Al and FeAl phases. Ambiguous crystallographic information and incoherent data referring to the phase equilibrium diagrams placed in a high-aluminum range have caused confusions and misinformation. Nowadays unequivocal material properties description of FeAl2, Fe2Al5 and FeAl3 intermetallic alloys is still incomplete. In this paper, the influence of aluminum content and processing parameters on phase composition is presented. The occurrence of low-symmetry FeAl2, Fe2Al5 and FeAl3 structures determined by chemical composition and phase transformations was defined by scanning electron microscopy (SEM and energy-dispersive X-ray spectroscopy (EDS examinations. These results served to verify diffraction investigations (XRD and to explain the mechanical properties of cast materials such as: hardness, Young’s modulus and fracture toughness evaluated using the nano-indentation technique.

Tailoring the magnetic properties of new Fe-Ni-Co-Al-(Ta,Nb)-B superelastic rapidly quenched microwires

International Nuclear Information System (INIS)

Borza, F.; Lupu, N.; Dobrea, V.; Chiriac, H.

2015-01-01

Ferromagnetic Fe-Ni-Co-Al-(Ta,Nb)-B microwires with diameters from 170 μm to 50 μm, which possess both superelastic and good magnetic properties, have been prepared by rapid quenching from the melt using the in rotating water spinning technique followed by cold-drawing and ageing. The cold-drawing and annealing processes lead to the initialization of premartensitic phases as confirmed by the X-ray diffraction and scanning transmission electron microscopic investigations, more significantly in the 50 μm cold-drawn microwires. An increase in the coercive field and in the saturation magnetization has been obtained by annealing, more importantly in the case of Nb-containing alloy. Ageing by thermal or current annealing led to the initialization of the superelastic effect. High values of strain of up to 1.8%, very good repeatability under successive loading, and values of superelastic effect of up to 1.2% have been achieved. The structural analysis coupled with the stress-strain data suggests that these materials annealed at 800 °C have superelastic potential at reduced ageing times. The magnetic behavior was found to be easily tailored through both thermal and thermomagnetic treatments with changes in the magnetic parameters which can be contactless detected. The results are important for future applications where both mechanical and magnetic properties matter, i.e., sensing/actuating systems

In-situ investigation of the icosahedral Al-Cu-Fe phase formation in thin films

Energy Technology Data Exchange (ETDEWEB)

Haidara, F., E-mail: fanta.haidara@im2np.fr [IM2NP, UMR 6242 CNRS - Universite Aix-Marseille, Av. Escadrille Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France); Duployer, B. [Universite Paul Sabatier CIRIMAT-LCMIE 2R1, 118, Route de Narbonne, 31062 Toulouse Cedex 09 (France); Mangelinck, D.; Record, M.-C. [IM2NP, UMR 6242 CNRS - Universite Aix-Marseille, Av. Escadrille Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France)

2012-09-05

Highlights: Black-Right-Pointing-Pointer We investigated the phase formation of i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} in thin films. Black-Right-Pointing-Pointer We characterized the samples by DSC and in-situ XRD and resistance measurements. Black-Right-Pointing-Pointer The resistivity value for i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} was determined. - Abstract: This work is an investigation of the formation by reactive diffusion at high temperatures of the icosahedral phase, i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5}, in thin films. The samples were prepared by sputtering at room temperature. The elements Al, Cu and Fe were sequentially deposited onto oxidized silicon substrates. The two following stacking sequences, Al/Cu/Fe and Al/Fe/Cu, were investigated. The phase formation was studied using in situ resistivity, in situ X-ray Diffraction and Differential Scanning Calorimetry measurements. Whatever the stacking sequence, the sequences of phase formation evidenced during the heating treatment are similar. However the temperatures of formation for the first phases that are formed are different; they are higher in the case of the Al/Fe/Cu stacking sequence.

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.

Theoretical analysis of compatibility of several reinforcement materials with NiAl and FeAl matrices

Science.gov (United States)

Misra, Ajay K.

1989-01-01

Several potential reinforcement materials were assessed for their chemical, coefficient of thermal expansion (CTE), and mechanical compatibility with the intermetallic matrices based on NiAl and FeAl. Among the ceramic reinforcement materials, Al2O3, TiC, and TiB2, appear to be the optimum choices for NiAl and FeAl matrices. However, the problem of CTE mismatch with the matrix needs to be solved for these three reinforcement materials. Beryllium-rich intermetallic compounds can be considered as potential reinforcement materials provided suitable reaction barrier coatings can be developed for these. Based on preliminary thermodynamic calculations, Sc2O3 and TiC appear to be suitable as reaction barrier coatings for the beryllides. Several reaction barrier coatings are also suggested for the currently available SiC fibers.

Precipitation processes in DC-cast AlMn(Fe,Si) alloys

International Nuclear Information System (INIS)

Voeroes, G.; Kovacs, I.

1990-01-01

The precipitation processes in DC cast Al-Mn alloys were investigated by electrical resistivity measurements. It was obtained that the addition of Fe or Fe and Si influences basically the precipitation of Mn. In pure Al-Mn alloys a phase transition like behaviour was observed at about 550 degC, which can be related to the formation of two different precipitate particles below and above this temperature

Evolution of the microstructure and nanohardness of Ti-48 at.%Al alloy solidified under high pressure

International Nuclear Information System (INIS)

Wang, Hongwei; Zhu, Dongdong; Zou, Chunming; Wei, Zunjie

2012-01-01

Highlights: → The microstructure of Ti-48Al alloy changes under high pressure. → With increasing pressure, the amount of γ s phase decreases. → High pressure leads to the decreasing of lamellar spacing. → The nanohardness of lamellar structure increases with pressure. -- Abstract: In this work the microstructure and nanohardness of Ti-48 at.%Al alloy solidified under different pressures (normal pressure, 2 GPa, 4 GPa) were experimental investigated by using a tungsten-carbide six-anvil apparatus. The results indicate that high pressure does not change the phase constitution of Ti-48 at.%Al alloy. However, the microstructure changes under high pressure. With increasing pressure, the volume fraction of interdendritic γ (γ s ) phase decreases and Al concentration in lamellae increases. When the pressure is 4 GPa, there is only a little γ s embedded in lamellar structure. The volume fraction of γ s phase is approximately 17.0% for normal pressure, 8.73% for 2 GPa, 0.69% for 4 GPa. The lamellar spacings also decrease with pressure, which are 495 nm, 345 nm, 227 nm under normal pressure, 2 GPa, 4 GPa, respectively. The change in nanohardness was discussed based on the microstructural observations. It shows a certain increase of the nanohardness as the pressure increases from normal pressure to 4 GPa. When the pressure is 4 GPa, the nanohardness increases by 50.2% compared with that of normal pressure.

Method of solidifying radioactive solid wastes

International Nuclear Information System (INIS)

Fukazawa, Tetsuo; Kawamura, Fumio; Kikuchi, Makoto.

1984-01-01

Purpose: To obtain solidification products of radioactive wastes satisfactorily and safely with no destruction even under a high pressure atmosphere by preventing the stress concentration by considering the relationships of the elastic module between the solidifying material and radioactive solid wastes. Method: Solidification products of radioactive wastes with safety and securing an aimed safety ratio are produced by conditioning the modules of elasticity of the solidifying material equal to or less than that of the radioactive wastes in a case where the elastic module of radioactive solid wastes to be solidified is smaller than that of the solidifying material (the elastic module of wastes having the minimum elastic module among various wastes). The method of decreasing the elastic module of the solidifying material usable herein includes the use of such a resin having a long distance between cross-linking points of a polymer in the case of plastic solidifying materials, and addition of rubber-like binders in the case of cement or like other inorganic solidifying materials. (Yoshihara, H.)

Method of solidifying radioactive laundry wastes

International Nuclear Information System (INIS)

Yasumura, Keijiro

1984-01-01

Purpose: To enable to solidify radioactive laundry wastes containing non-ionic liquid detergents less solidifiable by plastic solidification process in liquid laundry wastes for cloths or the likes discharged from a nuclear power plant. Method: Radioactive laundry wastes are solidified by using plastic solidifying agent comprising, as a main ingredient, unsaturated polyester resins and methylmethacrylate monomers. The plastic solidifying agents usable herein include, for example, unsaturated polyester resins prepared by condensating maleic anhydride and phthalic anhydride with propylene glycol and incorporated with methylmethacrylate monomers. The mixing ratio of the methylmethacrylate monomers is preferably 30 % by weight based on the unsaturated polyester resins. (Aizawa, K.)

Environmentally-relevant concentrations of Al(III) and Fe(III) cations induce aggregation of free DNA by complexation with phosphate group.

Science.gov (United States)

Qin, Chao; Kang, Fuxing; Zhang, Wei; Shou, Weijun; Hu, Xiaojie; Gao, Yanzheng

2017-10-15

Environmental persistence of free DNA is influenced by its complexation with other chemical species and its aggregation mechanisms. However, it is not well-known how naturally-abundant metal ions, e.g., Al(III) and Fe(III), influence DNA aggregation. This study investigated aggregation behaviors of model DNA from salmon testes as influenced by metal cations, and elucidated the predominant mechanism responsible for DNA aggregation. Compared to monovalent (K + and Na + ) and divalent (Ca 2+ and Mg 2+ ) cations, Al(III) and Fe(III) species in aqueous solution caused rapid DNA aggregations. The maximal DNA aggregation occurred at 0.05 mmol/L Al(III) or 0.075 mmol/L Fe(III), respectively. A combination of atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy revealed that Al(III) and Fe(III) complexed with negatively charged phosphate groups to neutralize DNA charges, resulting in decreased electrostatic repulsion and subsequent DNA aggregation. Zeta potential measurements and molecular computation further support this mechanism. Furthermore, DNA aggregation was enhanced at higher temperature and near neutral pH. Therefore, DNA aggregation is collectively determined by many environmental factors such as ion species, temperature, and solution pH. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-02-25

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

Pressure-jump induced rapid solidification of melt: a method of preparing amorphous materials

Science.gov (United States)

Liu, Xiuru; Jia, Ru; Zhang, Doudou; Yuan, Chaosheng; Shao, Chunguang; Hong, Shiming

2018-04-01

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in rapid compression process for several kinds of materials, such as elementary sulfur, polymer polyether-ether-ketone (PEEK) and poly-ethylene-terephthalate, alloy La68Al10Cu20Co2 and Nd60Cu20Ni10Al10. Experimental results clearly show that their melts could be solidified to be amorphous states through the rapid compression process. Bulk amorphous PEEK with 24 mm in diameter and 12 mm in height was prepared, which exceeds the size obtained by melt quenching method. The bulk amorphous sulfur thus obtained exhibited extraordinarily high thermal stability, and an abnormal exothermic transition to liquid sulfur was observed at around 396 K for the first time. Furthermore, it is suggested that the glass transition pressure and critical compression rate exist to form the amorphous phase. This approach of rapid compression is very attractive not only because it is a new technique of make bulk amorphous materials, but also because novel properties are expected in the amorphous materials solidified by the pressure-jump within milliseconds or microseconds.

PHASE CONSTITUENTS AND MICROSTRUCTURE OF Ti3Al/Fe3Al + TiN/TiB2 COMPOSITE COATING ON TITANIUM ALLOY

OpenAIRE

JIANING LI; CHUANZHONG CHEN; CUIFANG ZHANG

2011-01-01

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be...

Structural and magnetic properties of Fe-Al silica composites prepared by sequential ion implantation

International Nuclear Information System (INIS)

Julian Fernandez, C. de; Tagliente, M.A.; Mattei, G.; Sada, C.; Bello, V.; Maurizio, C.; Battaglin, G.; Sangregorio, C.; Gatteschi, D.; Tapfer, L.; Mazzoldi, P.

2004-01-01

The nanostructural and magnetic properties of Fe-Al/SiO 2 granular solids prepared by ion implantation have been investigated. A strong effect of the implantation order of the Fe and Al ions has been evidenced. By implanting first the Al ions and later Fe ions, 5-40 nm core-shell nanoparticles are formed with a magnetic behavior similar to that of Fe. The lattice parameter of the nanoparticles is consistent with that of the α-Fe. By changing the implantation order, 10-15 nm core-shell nanoparticles of a bcc Fe-based phase with a lattice 2.5% smaller than that of α-Fe are formed. The temperature dependence of the magnetization indicates a superparamagnetic behavior

Structural and magnetic properties of Fe-Al silica composites prepared by sequential ion implantation

Energy Technology Data Exchange (ETDEWEB)

Julian Fernandez, C. de E-mail: dejulian@padova.infm.it; Tagliente, M.A.; Mattei, G.; Sada, C.; Bello, V.; Maurizio, C.; Battaglin, G.; Sangregorio, C.; Gatteschi, D.; Tapfer, L.; Mazzoldi, P

2004-02-01

The nanostructural and magnetic properties of Fe-Al/SiO{sub 2} granular solids prepared by ion implantation have been investigated. A strong effect of the implantation order of the Fe and Al ions has been evidenced. By implanting first the Al ions and later Fe ions, 5-40 nm core-shell nanoparticles are formed with a magnetic behavior similar to that of Fe. The lattice parameter of the nanoparticles is consistent with that of the {alpha}-Fe. By changing the implantation order, 10-15 nm core-shell nanoparticles of a bcc Fe-based phase with a lattice 2.5% smaller than that of {alpha}-Fe are formed. The temperature dependence of the magnetization indicates a superparamagnetic behavior.

Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

KAUST Repository

Balasamy, Rabindran J.; Khurshid, Alam; Al-Ali, Ali A S; Atanda, Luqman A.; Sagata, Kunimasa; Asamoto, Makiko; Yahiro, Hidenori; Nomura, Kiyoshi; Sano, Tsuneji; Takehira, Katsuomi; Al-Khattaf, Sulaiman S.

2010-01-01

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.

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.

Leaching of rapidly quenched Al65Cu20Fe15 quasicrystalline ribbons

Indian Academy of Sciences (India)

2017-12-06

Dec 6, 2017 ... stood that Al–Cu–Fe QC also presents an FCI structure similar to that .... that the precipitation rate of Fe is lower than that of Cu. Figure 2a shows the .... Renewable Energy (MNRE), India, under Mission Mode. Hydrogen ...

Band structure of the quaternary Heusler alloys ScMnFeSn and ScFeCoAl

Science.gov (United States)

Shanthi, N.; Teja, Y. N.; Shaji, Shephine M.; Hosamani, Shashikala; Divya, H. S.

2018-04-01

In our quest for materials with specific applications, a theoretical study plays an important role in predicting the properties of compounds. Heusler alloys or compounds are the most studied in this context. More recently, a lot of quaternary Heusler compounds are investigated for potential applications in fields like Spintronics. We report here our preliminary study of the alloys ScMnFeSn and ScFeCoAl, using the ab-initio linear muffin-tin orbital method within the atomic sphere approximation (LMTO-ASA). The alloy ScMnFeSn shows perfect half-metallicity, namely, one of the spins shows a metallic behaviour and the other spin shows semi-conducting behaviour. Such materials find application in devices such as the spin-transfer torque random access memory (STT-MRAM). In addition, the alloy ScMnFeSn is found to have an integral magnetic moment of 4 µB, as predicted by the Slater-Pauling rule. The alloy ScFeCoAl does not show half-metallicity.

Oxide scale formation of modified FeCrAl coatings exposed to liquid lead

Energy Technology Data Exchange (ETDEWEB)

Fetzer, Renate, E-mail: renate.fetzer@kit.edu [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Weisenburger, Alfons; Jianu, Adrian; Mueller, Georg [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Modified FeCrAl coatings show oxide scale formation when exposed to liquid lead. Black-Right-Pointing-Pointer Formation of thin Al-rich oxide scales is promoted by the presence of Y. Black-Right-Pointing-Pointer FeCrAlY with at least 8 wt.% Al forms thin Al-rich oxide scales. Black-Right-Pointing-Pointer For low Al content, thick multilayer Fe-based oxide scales are found. - Abstract: Modified FeCrAl coatings were studied with respect to their capability to form a thin protective oxide scale in liquid lead environment. They were manufactured by low pressure plasma spraying and GESA surface melting, thereby tuning the Al content. The specimens were exposed for 900 h to liquid lead containing 10{sup -6} and 10{sup -8} wt.% oxygen, respectively, at various temperatures from 400 to 550 Degree-Sign C. Threshold values for an Al content that guarantees the formation of thin protective Al-rich oxide scales are determined, dependent on the respective chromium content, on the presence of yttrium in the modified coating, and on the exposure conditions.

The bonding character and magnetic properties of Fe3Al: Comparison between disordered and ordered alloy

International Nuclear Information System (INIS)

Fan Runhua; Qi Liang; Sun Kangning; Min Guanghui; Gong Hongyu

2006-01-01

Fe 3 Al with D0 3 -ordered structure is one of the few structural intermetallics that can be disordered using non-equilibrium processing techniques. The bonding and magnetic character of the stoichiometric Fe 3 Al, with D0 3 -ordered or disordered structure, have been studied using the empirical electron theory of solid and molecular (EET). It was found that the magnetic property is basically dictated by the chemical bonding. There is a change of the character of the interatomic bonds from 3d(Fe)-3p(Al) for the D0 3 -ordered Fe 3 Al to 4sp(Fe)-3p(Al) for the disordered Fe 3 Al. For the latter, while the Fe 3d electrons participating in bonding is reduced, the mean magnetic moment is increased

Microstructure and Mechanical Properties of Al2O3/Er3Al5O12 Binary Eutectic Ceramic Prepared by Bridgman Method

Science.gov (United States)

Song, Caiyu; Wang, Shunheng; Liu, Juncheng; Zhai, Shuoyan

2018-01-01

Directionally solidified Al2O3/Er3Al5O12 (EAG) eutectic ceramic was prepared via vertical Bridgman method with high-frequency induction heating. The effects of the growth rate on the microstructure and mechanical properties of the solidified ceramic were investigated. The experimental results showed that there were no pores or amorphous phases in the directionally solidified Al2O3/EAG eutectic ceramic. Al2O3 phase was embedded in the EAG matrix phase, and the two phases were intertwined with each other to form a typical binary eutectic “hieroglyphic” structure. With the increase of growth rate, the phase size and spacing of the solidified Al2O3/EAG ceramic both decreased, and the growth rate and phase spacing satisfied the λ2v ≈ 60 formula of Jackson-Hunt theory. The cross section microstructure of the solidified ceramic always exhibited an irregular eutectic growth, while the longitudinal section microstructure presented a directional growth. The mechanical properties of the solidified ceramic gradually increased with the increase of growth rate, and the maximum hardness and fracture toughness could reach 21.57 GPa and 2.98 MPa·m1/2 respectively. It was considered that the crack deflection and branching could enhance the toughness of the solidified ceramic effectively. PMID:29601545

Solid solution inhomogeneity in DC-cast AlMn(Fe,Si) ingots

International Nuclear Information System (INIS)

Lakner, J.; Kovacs-Csetenyi, E.; Lal, K.

1990-01-01

The aim of this work was to characterize the structure in cast state of the AlMn1 alloy containing different Fe and Si concentration. The casting parameters were intended to keep constant and the effect of impurities was studied. The inhomogeneity along the diameter of cast billet was characterized by the dendrite arm spacing and by the solid solution content. To explain the results the model developed for binary AlFe and AlMn alloys was applied

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.

Incorporation of Ba in Al and Fe pollucite

Energy Technology Data Exchange (ETDEWEB)

Vance, Eric R., E-mail: erv@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gregg, Daniel J.; Griffiths, Grant J. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gaugliardo, Paul R. [Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 (Australia); Grant, Charmaine [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia)

2016-09-15

Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs{sub (1−2x)}Ba{sub x}AlSi{sub 2}O{sub 6} aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl{sub 2}Si{sub 2}O{sub 8} phases. The effect of Ba substitution in pollucite-structured CsFeSi{sub 2}O{sub 6} was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe{sup 2+} formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs{sup +} + Fe{sup 3+} ↔ Ba{sup 2+} + Ni{sup 2+} scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi{sub 2}O{sub 6} to be very leach resistant. - Highlights: • Barium can be incorporated into aluminium pollucite. • Positron annihilation lifetime spectroscopy supports a charge vacancy mechanism of incorporation. • Iron pollucite does not appear to incorporate any barium with either vacancy or charge compensation mechanisms. • Leaching data suggest iron pollucite is very leach resistant.

Synthesis, microstructure and magnetic properties of Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core

Energy Technology Data Exchange (ETDEWEB)

Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

2015-11-15

Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core have been synthesized via a modified stöber method combined with following high temperature sintering process. Most of conductive Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by insulating SiO{sub 2} using the modified stöber method. The Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles exhibited good soft magnetic properties with low coercivity and high saturation magnetization. The reaction 4Al+3SiO{sub 2}=2α-Al{sub 2}O{sub 3}+3Si took place during the sintering process. As a result the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite core displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher electrical resistivity and lower core loss than the pure Fe{sub 3}Si{sub 0.7}Al{sub 0.3} 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. - Graphical abstract: In Fe{sub 3}Si/Al{sub 2}O{sub 3} composite, Fe{sub 3}Si phases are separated by Al{sub 2}O{sub 3} layers and the eddy currents are confined in Fe{sub 3}Si phases, thus increasing resistivity and reducing core loss. - Highlights: • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores were prepared. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by nano-sized SiO{sub 2} clusters. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores showed good soft magnetic properties. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than Fe{sub 3}Si{sub 0.7}Al{sub 0.3} cores.

Effect of layer thickness in selective laser melting on microstructure of Al/5 wt.%Fe2O3 powder consolidated parts.

Science.gov (United States)

Dadbakhsh, Sasan; Hao, Liang

2014-01-01

In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM) to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75  μm layer thickness, and 50  μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance) were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe) oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

Synthesis of Cd/(Al+Fe) layered double hydroxides and characterization of the calcination products

International Nuclear Information System (INIS)

Perez, M.R.; Barriga, C.; Fernandez, J.M.; Rives, V.; Ulibarri, M.A.

2007-01-01

Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method at a constant pH value of 8. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange at pH 9. The samples have been characterized by elemental chemical analysis, powder X-ray diffraction (PXRD), and FT-IR spectroscopy. Their thermal stability has been assessed by thermogravimetric and differential thermal analyses (TG-DTA) and mass spectrometric analysis of the evolved gases. The PXRD patterns of the solids calcined at 800 deg. C show diffraction lines corresponding to Cd(Al)O and spinel-type materials, which precise nature (CdAl 2 O 4 , Cd 1-x Fe 2+x O 4 , or Cd x Fe 2.66 O 4 ) depends on location and concentration of iron in the parent material or precursor. - Graphical abstract: Layered double hydroxides (LDHs) containing Cd(II), Al(III), and Fe(III) in the brucite-like layers with different starting Fe/Al atomic ratios and with nitrate as counteranion have been prepared following the coprecipitation method. An additional Cd(II),Al(III)-LDH sample interlayered with hexacyanoferrate(III) ions has been prepared by ionic exchange. Calcination at 800 deg. C shows diffraction lines corresponding to CdO and to spinel-type materials. SEM micrograph of sample CdAlFe-N-0

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

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.

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.

Ethylbenzene dehydrogenation over Mg3Fe0.5−xCoxAl0.5 catalysts derived from hydrotalcites: Comparison with Mg3Fe0.5−yNiyAl0.5 catalysts

KAUST Repository

Atanda, Luqman A.

2011-04-01

A series of Mg3Fe0.5-xCoxAl0.5 (x = 0-0.5) catalysts were prepared from hydrotalcite precursors and their activities in the dehydrogenation of ethylbenzene were compared with those of a series of Mg3Fe0.5-yNiyAl0.5 (y = 0-0.5) catalysts also derived from hydrotalcite. The hydrotalcites prepared by co-precipitation were calcined at 550 °C to the mixed oxides with a high surface area of 150-240m2gcat-1; they were composed of Mg(Fe,Me,Al)O periclase and Mg(Me)(Fe,Al)2O4 spinel (Me = Co or Ni). Bimetallic Fe3+-Co2+ system showed a synergy, i.e., an increase in the activity, whereas Fe3+-Ni2+ bimetallic system showed no synergy. The high styrene yield was obtained on Mg 3Fe0.1Co0.4Al0.5; however, a large substitution of Fe3+ with Co2+ caused a decrease in styrene selectivity along with coking on the catalysts, due to an isolation of CoOx on the catalyst surface. The highest yield as well as the highest selectivity for styrene production was obtained at x = 0.25 at time on stream of 30 min. The coprecipitation at pH = 10.0 and the composition of Mg3Fe0.25Co0.25Al0.5 were the best for preparing the active catalyst. This is partly due to the formation of a good hydrotalcite structure. On this catalyst, the active Fe3+ species was reduced at a low temperature by the Fe3+-Co2+ bimetal formation, leading to a high activity. Simultaneously, the amount of reducible Fe3+ was the smallest, resulting in a high stability of the active Fe3+ species. It is likely that the dehydrogenation was catalyzed by the reduction-oxidation between Fe3+ and Fe2+ and that Co2+ assisted the reduction-oxidation by forming Fe 3+-Co2+ (1/1) bimetallic active species. © 2011 Elsevier B.V. All rights reserved.

Atomic-partial vibrational density of states of i-AlCuFe quasicrystals

International Nuclear Information System (INIS)

Parshin, P.P.; Zemlyanov, M.; Brand, R.A.; Dianoux, A.J.; Calvayrac, Y.

2002-01-01

We present new results on the separation of the atomic-partial vibrational density of states for the ternary quasicrystal i-Al 62 Cu 25.5 Fe 12.5 . The decomposition into three atomic-partial functions, Al-, Cu- and Fe-g(E), has been performed self-consistently with the calculation of the multi-phonon contributions. The results show the surprising result that both Cu- and Fe-g(E) are strongly peaked. The low-energy regions of Al- and Cu-g(E) show strong deviations from Debye behaviour due to the presence of non-propagating low-energy vibrational states. (orig.)

Effect of rare-earth elements and quenching wheel speed on the structure, mechanical and thermal properties of rapidly solidified AZ91 Mg melt-spun ribbons

Energy Technology Data Exchange (ETDEWEB)

Ekrami, A. [Iran University of Industries & Mines, Faculty of Engineering & High-Technology (Iran, Islamic Republic of); Shahri, F., E-mail: fshahri@irost.ir [Iranian Research Organization for Science & Technology, Department of Advanced Materials & Renewable Energy (Iran, Islamic Republic of); Mirak, A. [Iran University of Industries & Mines, Faculty of Engineering & High-Technology (Iran, Islamic Republic of)

2017-01-27

In this work, an attempt is made to study the effects of rare-earth elements as an additive (2 wt% of Ce base misch-metal) and various quenching wheel speeds (10–40 m/s) on the microstructure, thermal and mechanical properties of rapidly solidified AZ91 alloy prepared by single roller melt-spinning process. In this respect, all of the samples were studied using various techniques such as x-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and mechanical properties such as microhardness and tensile tests. The finding bore witness to proposed hypothesis in this study illustrating due to high affinity between Al and RE by adding 2 wt% rare-earth elements in the AZ91alloy, thermally stable Al{sub x}RE{sub y} intermetallic compounds are precipitated and the formation of β-Mg{sub 17}Al{sub 12} phases is reduced. DSC results revealed that by adding RE to AZ91 alloy, AlRE phases got stable up to 500 °C, while for the AZ91 sample, β-Mg{sub 17}Al{sub 12} phase was formed at temperature about 180 °C and then with increasing of temperature dissolved at 410 °C in the α-Mg matrix. Further it has been observed that the higher was the quenching wheel speed, the smaller was the grain size which in turn gives rise to a higher tensile properties (from 406 MPa for quenching wheel speed of 10 m/s to 510 MPa for 40 m/s) for the MM-added alloys. Tensile strength of 386 MPa was obtained for the AZ91 pure alloy which is prepared at wheel speed of 40 m/sec.

Effects of A1 substitution by Fe in CeAl2

International Nuclear Information System (INIS)

Takeuchi, A.Y.; Cunha, S.F. da.

1989-01-01

Magnetization and electrical resistivity measurements of the CeAl 2 with Al substitution by Fe up to 10% at Fe show that the competition between the increasing Kondo effect and the antiferromagnetism persists. Change of the electronic density is followed by a decreasing Neel temperature and an increasing residual electrical reistivity. The probable appearance of ferromagnetism of the Ce moments, at intermediate temperature range, is discussed. The small decrease of the lattice parameter with Fe concentration or the magnetic behaviour do not show evidence of valence changes in the Ceion. (author) [pt

Al-Fe interactions and growth enhancement in Melastoma malabathricum and Miscanthus sinensis dominating acid sulphate soils.

Science.gov (United States)

Watanabe, Toshihiro; Jansen, Steven; Osaki, Mitsuru

2006-12-01

Plants growing in acid sulphate soils are subject to high levels of Al availability, which may have effects on the growth and distribution of these species. Although Fe availability is also high in acid sulphate soils, little is known about the effect of Fe on the growth of native plants in these soils. Two species dominating this soil type in Asia, viz. Melastoma malabathricum and Miscanthus sinensis were grown hydroponically in a nutrient solution with different concentrations of Al and Fe. Melastoma malabathricum is found to be sensitive to Fe (40 and 100 microm). Application of 500 microm Al, however, completely ameliorates Fe toxicity and is associated with a decrease of Fe concentration in shoots and roots. The primary reason for the Al-induced growth enhancement of M. malabathricum is considered to be the Al-induced reduction of toxic Fe accumulation in roots and shoots. Therefore, Al is nearly essential for M. malabathricum when growing in acid sulphate soils. In contrast, application of both Fe and Al does not reduce the growth of M. sinensis, and Al application does not result in lower shoot concentrations of Fe, suggesting that this grass species has developed different mechanisms for adaptation to acid sulphate soils.

Short-term thermal response of rapidly solidified Type 304 stainless steel containing helium

International Nuclear Information System (INIS)

Clark, D.E.

1988-06-01

Type 304 stainless steel was heat treated for short times near its melting point in order to determine its microstructural response to thermal cycles typical of the near heat-affected zones of welding processes. The material was rapidly solidified as a powder by centrifugal atomization in a helium environment and consolidated by hot extrusion. Along with the ingot metallurgy material used for canning the powder prior to hot extrusion, it was heat treated using a Gleeble at temperatures of 1200 and 1300 degree C for times ranging from <1 to 1000 s, and the samples were examined for microstructure and the existence of porosity due to entrapped helium. At higher test temperatures and longer treatment times, the material developed extensive porosity, which was stabilized by the presence of helium and which may also have a role in anchoring grain boundaries and inhibiting grain growth. The powder material. At lower test temperatures and shorter treatment times, grain growth in the γ phase appeared to be restricted in the powder material, possible by the presence of helium. An intermediate temperatures and times, a γ-δ duplex microstructure also restricted grain growth again occurred in the δ microstructure. 9 refs., 14 figs., 3 tabs

Removal of arsenic from drinking water by the electrocoagulation using Fe and Al electrodes

International Nuclear Information System (INIS)

Kobya, M.; Gebologlu, U.; Ulu, F.; Oncel, S.; Demirbas, E.

2011-01-01

Highlights: → Removal percentages of arsenic from drinking water at optimum operating conditions in electrocoagulation process were 93.5% for Fe electrode and 95.7% for Al electrode. → Operating costs at the optimum conditions were 0.020 Euro m -3 for Fe and 0.017 Euro m -3 for Al electrodes. → Surface topography of the solid particles at Fe/Al electrodes was analyzed with scanning electron microscope. → The adsorption of arsenic followed pseudo second-order adsorption model. - Abstract: A novel technique of electrocoagulation (EC) was attempted in the present investigation to remove arsenic from drinking waters. Experiments were carried out in a batch electrochemical reactor using Al and Fe electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as pH (4-9), current density (2.5-7.5 A m -2 ), initial concentration (75-500 μg L -1 ) and operating time (0-15 min) were examined. Optimum operating conditions were determined as an operating time of 12.5 min and pH 6.5 for Fe electrode (93.5%) and 15 min and pH 7 for Al electrode (95.7%) at 2.5 A m -2 , respectively. Arsenic removal obtained was highest with Al electrodes. Operating costs at the optimum conditions were calculated as 0.020 Euro m -3 for Fe and 0.017 Euro m -3 for Al electrodes. EC was able to bring down aqueous phase arsenic concentration to less than 10 μg L -1 with Fe and Al electrodes. The adsorption of arsenic over electrochemically produced hydroxides and metal oxide complexes was found to follow pseudo second-order adsorption model. Scanning electron microscopy was also used to analyze surface topography of the solid particles at Fe/Al electrodes during the EC process.

Removal of arsenic from drinking water by the electrocoagulation using Fe and Al electrodes

Energy Technology Data Exchange (ETDEWEB)

Kobya, M., E-mail: kobya@gyte.edu.tr [Gebze Institute of Technology, Department of Environmental Engineering, 41400 Gebze (Turkey); Gebologlu, U.; Ulu, F.; Oncel, S. [Gebze Institute of Technology, Department of Environmental Engineering, 41400 Gebze (Turkey); Demirbas, E. [Gebze Institute of Technology, Department of Chemistry, 41400 Gebze (Turkey)

2011-05-30

Highlights: > Removal percentages of arsenic from drinking water at optimum operating conditions in electrocoagulation process were 93.5% for Fe electrode and 95.7% for Al electrode. > Operating costs at the optimum conditions were 0.020 Euro m{sup -3} for Fe and 0.017 Euro m{sup -3} for Al electrodes. > Surface topography of the solid particles at Fe/Al electrodes was analyzed with scanning electron microscope. > The adsorption of arsenic followed pseudo second-order adsorption model. - Abstract: A novel technique of electrocoagulation (EC) was attempted in the present investigation to remove arsenic from drinking waters. Experiments were carried out in a batch electrochemical reactor using Al and Fe electrodes with monopolar parallel electrode connection mode to assess their efficiency. The effects of several operating parameters on arsenic removal such as pH (4-9), current density (2.5-7.5 A m{sup -2}), initial concentration (75-500 {mu}g L{sup -1}) and operating time (0-15 min) were examined. Optimum operating conditions were determined as an operating time of 12.5 min and pH 6.5 for Fe electrode (93.5%) and 15 min and pH 7 for Al electrode (95.7%) at 2.5 A m{sup -2}, respectively. Arsenic removal obtained was highest with Al electrodes. Operating costs at the optimum conditions were calculated as 0.020 Euro m{sup -3} for Fe and 0.017 Euro m{sup -3} for Al electrodes. EC was able to bring down aqueous phase arsenic concentration to less than 10 {mu}g L{sup -1} with Fe and Al electrodes. The adsorption of arsenic over electrochemically produced hydroxides and metal oxide complexes was found to follow pseudo second-order adsorption model. Scanning electron microscopy was also used to analyze surface topography of the solid particles at Fe/Al electrodes during the EC process.

Formulation and catalytic performance of MOF-derived Fe@C/Al composites for high temperature Fischer–Tropsch synthesis

KAUST Repository

Oar-Arteta, Lide; Valero-Romero, Marí a José ; Wezendonk, Tim; Kapteijn, Freek; Gascon, Jorge

2017-01-01

High productivity towards C-2-C-4 olefins together with high catalyst stability are key for optimum operation in high temperature Fischer-Tropsch synthesis (HT-FTS). Here, we report the fabrication of Fe@C/Al composites that combine both the outstanding catalytic properties of the Fe-BTC MOF-derived Fe catalyst and the excellent mechanical resistance and textural properties provided by the inorganic AlOOH binder. The addition of AlOOH to Fe-BTC followed by pyrolysis in N-2 atmosphere at 500 degrees C results in composites with a large mesoporosity, a high Fe/Fe3O4 ratio, 10-35 nm average Fe crystallite size and coordinatively unsaturated Al3+ sites. In catalytic terms, the addition of AlOOH binder gives rise to enhanced C-2-C-4 selectivity and catalyst mechanical stability in HT-FTS, but at high Al contents the activity decreases. Altogether, the productivity of these Fe@C/Al composites is well above most known Fe catalysts for this process.

Formulation and catalytic performance of MOF-derived Fe@C/Al composites for high temperature Fischer–Tropsch synthesis

KAUST Repository

Oar-Arteta, Lide

2017-11-15

High productivity towards C-2-C-4 olefins together with high catalyst stability are key for optimum operation in high temperature Fischer-Tropsch synthesis (HT-FTS). Here, we report the fabrication of Fe@C/Al composites that combine both the outstanding catalytic properties of the Fe-BTC MOF-derived Fe catalyst and the excellent mechanical resistance and textural properties provided by the inorganic AlOOH binder. The addition of AlOOH to Fe-BTC followed by pyrolysis in N-2 atmosphere at 500 degrees C results in composites with a large mesoporosity, a high Fe/Fe3O4 ratio, 10-35 nm average Fe crystallite size and coordinatively unsaturated Al3+ sites. In catalytic terms, the addition of AlOOH binder gives rise to enhanced C-2-C-4 selectivity and catalyst mechanical stability in HT-FTS, but at high Al contents the activity decreases. Altogether, the productivity of these Fe@C/Al composites is well above most known Fe catalysts for this process.

Rapid solidification and dynamic compaction of Ni-base superalloy powders

Science.gov (United States)

Field, R. D.; Hales, S. J.; Powers, W. O.; Fraser, H. L.

1984-01-01

A Ni-base superalloy containing 13Al-9Mo-2Ta (in at. percent) has been characterized in both the rapidly solidified condition and after dynamic compaction. Dynamically compacted specimens were examined in the as-compacted condition and observations related to current theories of interparticle bonding. In addition, the recrystallization behavior of the compacted material at relatively low temperature (about 0.5-0.75 Tm) was investigated.

Observations of the Minor Species Al, Fe and Ca(+) in Mercury's Exosphere

Science.gov (United States)

Bida, Thomas A.; Killen, Rosemary M.

2011-01-01

We report the first detections of Al and Fe, and strict upper limits for Ca(+) in the exosphere of Mercury, using the HIRES spectrometer at the Keck I telescope. We report observed 4-sigma tangent columns of 1.5x10(exp 7) Al atoms per square centimeter at an altitude of 1220 km (1.5 Mercury radii (R(sub M)) from planet center), and that for Fe of 1.6 x 10 per square centimeter at an altitude of 950 km (1.4 R(sub M)). The observed 3-sigma Ca(+) column was 3.9x10(exp 6) ions per square centimeter at an altitude of 1630 km (1.67 R(sub M). A simple model for zenith column abundances of the neutral species were 9.5 x 10(exp 7) Al per square centimeter, and 3.0 x 10(exp 8) Fe per square centimeter. The observations appear to be consistent with production of these species by impact vaporization with a large fraction of the ejecta in molecular form. The scale height of the Al gas is consistent with a kinetic temperature of 3000 - 9000 K while that of Fe is 10500 K. The apparent high temperature of the Fe gas would suggest that it may be produced by dissociation of molecules. A large traction of both Al and Fe appear to condense in a vapor cloud at low altitudes.

Treatment of As(V) and As(III) by electrocoagulation using Al and Fe electrode.

Science.gov (United States)

Kuan, W H; Hu, C Y; Chiang, M C

2009-01-01

A batch electrocoagulation (EC) process with bipolar electrode and potentiodynamic polarization tests with monopolar systems were investigated as methods to explore the effects of electrode materials and initial solution pH on the As(V) and As(III) removal. The results displayed that the system with Al electrode has higher reaction rate during the initial period from 0 to 25 minutes than that of Fe electrode for alkaline condition. The pH increased with the EC time because the As(V) and As(III) removal by either co-precipitation or adsorption resulted in that the OH positions in Al-hydroxide or Fe-hydroxide were substituted by As(V) and As(III). The pH in Fe electrode system elevate higher than that in Al electrode because the As(V) removal substitutes more OH position in Fe-hydroxide than that in Al-hydroxide. EC system with Fe electrode can successfully remove the As(III) but system with Al electrode cannot because As(III) can strongly bind to the surface of Fe-hydroxide with forming inner-sphere species but weakly adsorb to the Al-hydroxide surface with forming outer-sphere species. The acidic solution can destroy the deposited hydroxide passive film then allow the metallic ions liberate into the solution, therefore, the acidic initial solution can enhance the As(V) and As(III) removal. The over potential calculation and potentiodynamic polarization tests reveal that the Fe electrode systems possess higher over potential and pitting potential than that of Al electrode system due to the fast hydrolysis of and the occurrence of Fe-hydroxide passive film.

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.

Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

Directory of Open Access Journals (Sweden)

Pillis Marina Fuser

2004-01-01

Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

Electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys for biomedical applications.

Science.gov (United States)

Lu, Jinwen; Zhao, Yongqing; Niu, Hongzhi; Zhang, Yusheng; Du, Yuzhou; Zhang, Wei; Huo, Wangtu

2016-05-01

The present study is to investigate the microstructural characteristics, electrochemical corrosion behavior and elasticity properties of Ti-6Al-xFe alloys with Fe addition for biomedical application, and Ti-6Al-4V alloy with two-phase (α+β) microstructure is also studied as a comparison. Microstructural characterization reveals that the phase and crystal structure are sensitive to the Fe content. Ti-6Al alloy displays feather-like hexagonal α phase, and Ti-6Al-1Fe exhibits coarse lath structure of hexagonal α phase and a small amount of β phase. Ti-6Al-2Fe and Ti-6Al-4Fe alloys are dominated by elongated, equiaxed α phase and retained β phase, but the size of α phase particle in Ti-6Al-4Fe alloy is much smaller than that in Ti-6Al-2Fe alloy. The corrosion resistance of these alloys is determined in SBF solution at 37 °C. It is found that the alloys spontaneously form a passive oxide film on their surface after immersion for 500 s, and then they are stable for polarizations up to 0 VSCE. In comparison with Ti-6Al and Ti-6Al-4V alloys, Ti-6Al-xFe alloys exhibit better corrosion resistance with lower anodic current densities, larger polarization resistances and higher open-circuit potentials. The passive layers show stable characteristics, and the wide frequency ranges displaying capacitive characteristics occur for high iron contents. Elasticity experiments are performed to evaluate the elasticity property at room temperature. Ti-6Al-4Fe alloy has the lowest Young's modulus (112 GPa) and exhibits the highest strength/modulus ratios as large as 8.6, which is similar to that of c.p. Ti (8.5). These characteristics of Ti-6Al-xFe alloys form the basis of a great potential to be used as biomedical implantation materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Convection and macrosegregation in Al-19Cu alloy directionally solidified through an abrupt contraction in cross-section: A comparison with Al-7Si

Science.gov (United States)

Ghods, M.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2017-02-01

Hypoeutectic Al-19 wt. % Cu alloys were directionally solidified in cylindrical molds that featured an abrupt cross-section decrease 9.5 to 3.2 mm in diameter). Thermo-solutal convection and cross-section-change-induced shrinkage flow effects on macrosegregation were investigated. Dendrite clustering and extensive radial macrosegregation was seen, particularly in the larger cross-section before contraction. This alloy shows positive longitudinal macrosegregation near the contraction followed by negative macrosegregation right after it; the extent of macrosegregation, however, decreases with increasing growth speed. The degree of thermo-solutal convection was compared to another study investigating directional solidification of Al-7 wt. % Si [1] in order to study the effect of solutal expansion coefficient on macrosegregation. An interesting change of the radial macrosegregation profile, attributable to the area-change-induced-shrinkage flow, was observed very close to the contraction. A two-dimensional model accounting for both shrinkage and thermo-solutal convection was used to simulate solidification, the resulting steepling as well as axial and radial macrosegregation. The experimentally observed macrosegregation associated with the contraction during directional solidification was well predicted by the numerical simulations.

Epitactical FeAl films on sapphire and their magnetic properties

International Nuclear Information System (INIS)

Trautvetter, Moritz

2011-01-01

In the presented thesis epitaxial FeAl thin films on sapphire have been prepared by pulse laser deposition (PLD). The thin films deposited at room temperature exhibits ferromagnetism and subsequent annealing is necessary to transform the thin films to paramagnetic B2-phase, where the transition temperature depends on the crystalline orientation of the sapphire substrate. Alternatively, by deposition at higher substrate temperature the B2-phase is obtained directly. However, morphology of the FeAl film is influenced by different growth modes resulting from different substrate temperatures. The paramagnetic FeAl films can then be transformed to ferromagnetic phase by successive ion irradiation. Independent of the ion species used for irradiation, the same universal relation between thin films' coercive fields and irradiation damage is identified. The ion irradiation ferromagnetism can be transformed back to paramagnetism by subsequent annealing. The mutual transition between ferromagnetic and paramagnetic phases has been performed several times and shows full reversibility. The ferromagnetic phase induced by Kr + irradiation exhibits structural relaxation, where the saturate magnetization of FeAl thin film gradually decreases in several days. Later, ion irradiation has been performed selectively on defined areas of the thin film with the help of an unconventional lithography technique. The subsequent thin film is composed of ordered hexagonal array of ferromagnetic nano-cylinders separated by a paramagnetic matrix, suggesting a promising system for magnetic data storage. (orig.)

Formation of nano quasicrystalline and crystalline phases by mechanical alloying

International Nuclear Information System (INIS)

Shamah, A.M.; Ibrahim, S.; Hanna, F.F.

2011-01-01

Research highlights: → Mechanical alloying (MA) is an important method to investigate the formation of nano sized quasicrystalline phases in Al 86 Cr 14 , Al 84 Fe 16 and Al 62.5 Cu 25 Fe 12.5 compounds. The second part of the present work is an attempt to examine the possibility of formation of the i-phase of the Al 62.5 Cu 25 Fe 12.5 , which lies in the region of the perfect i-phase in the ternary phase diagram, by rapid solidification method. To perform the obtained quasi phase mechanical alloying and heat treatment at the rapid solidified sample were done. - Abstract: In the present work, the formation of nano quasicrystalline icosahedral phase in Al 86 Cr 14 , Al 84 Fe 16 and Al 62.5 Cu 25 Fe 12.5 alloys has been investigated by mechanical alloying. Mixtures of quasicrystalline and related crystalline phases have been observed under various milling conditions. The X-ray diffraction, differential thermal analysis and electrical resistivity techniques have been used for characterization and physical property measurements. The particle size was calculated by X-ray profile using Williamson-Hall plot method and it was found to be 25-50 nm size.

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

Science.gov (United States)

Fabrizi, Alberto; Capuzzi, Stefano; Timelli, Giulio

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

Preparation of Fe-Al Intermetallic / TiC-Al2O3 Ceramic Composites from Ilmenite by SHS

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

Fe-Al intermetallic/TiC-Al2O3 ceramic composites were successfully prepared by self-propagating high-temperature synthesis (SHS) from natural ilmenite, aluminium and carbon as the raw materials. The effects of carbon sources, preheating time and heat treatment temperature on synthesis process and products were investigated in detail, and the reaction process of the FeTiO3-Al-C system was also discussed.It is shown that the temperature and velocity of the combustion wave are higher when graphite is used as the carbon source, which can reflect the effect of the carbon source structure on the combustion synthesis;Prolonging the preheating time or heat treatment temperature is beneficial to the formation of the ordered intermetallics; The temperature and velocity of the combustion wave arc improved, but the disordered alloys are difficult to eliminate with the preheating time prolonged. The compound powders mainly containing ordered Fe3Al intermetallic can be prepared through heat treatment at 750 ℃.

Numerical Research on Magnetic Field, Temperature Field and Flow Field During Melting and Directionally Solidifying TiAl Alloys by Electromagnetic Cold Crucible

Science.gov (United States)

Chen, Ruirun; Yang, Yaohua; Gong, Xue; Guo, Jingjie; Su, Yanqing; Ding, Hongsheng; Fu, Hengzhi

2017-12-01

The electromagnetic cold crucible (EMCC) technique is an effective method to melt and directionally solidify reactive and high-temperature materials without contamination. The temperature field and fluid flow induced by the electromagnetic field are very important for melting and controlling the microstructure. In this article, a 3D EMCC model for calculating the magnetic field in the charges (TiAl alloys) using the T-Ω finite element method was established and verified. Magnetic fields in the charge under different electrical parameters, positions and dimensions of the charge were calculated and analyzed. The calculated results show that the magnetic field concentrates in the skin layer, and the magnetic flux density ( B) increases with increasing of the frequency, charge diameter and current. The maximum B in the charge is affected by the position of the charge in EMCC ( h 1) and the charge height ( h 2), which emerges at the middle of coils ( h c) when the relationship of h c < h 1 + h 2 < h c + δ is satisfied. Lower frequency and smaller charge diameter can improve the uniformity of the magnetic field in the charge. Consequently, the induced uniform electromagnetic stirring weakens the turbulence and improves temperature uniformity in the vicinity of the solid/liquid (S/L) interface, which is beneficial to forming a planar S/L interface during directional solidification. Based on the above conclusions, the TiAlNb alloy was successfully melted with lower power consumption and directionally solidified by the square EMCC.

Atomic-partial vibrational density of states of i-AlCuFe quasicrystals

CERN Document Server

Parshin, P P; Brand, R A; Dianoux, A J; Calvayrac, Y

2002-01-01

We present new results on the separation of the atomic-partial vibrational density of states for the ternary quasicrystal i-Al sub 6 sub 2 Cu sub 2 sub 5 sub . sub 5 Fe sub 1 sub 2 sub . sub 5. The decomposition into three atomic-partial functions, Al-, Cu- and Fe-g(E), has been performed self-consistently with the calculation of the multi-phonon contributions. The results show the surprising result that both Cu- and Fe-g(E) are strongly peaked. The low-energy regions of Al- and Cu-g(E) show strong deviations from Debye behaviour due to the presence of non-propagating low-energy vibrational states. (orig.)

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

Observations of the Minor Species Al and Fe in Mercury's Exosphere

Science.gov (United States)

Bida, Thomas A.; Killen, Rosemary M.

2016-01-01

We report here on the first observational evidence of Al and Fe in the exosphere of Mercury, based on measurements of resolved emission lines of these metals with Keck-1/HIRES. Al emission was observed on two separate runs, in 2008 and 2013, with tangent column densities of 3.1 +/- 1.0 and 4.0 +/-1.5 x 10(exp 7) Al atoms cm(exp - 2) at altitudes of 1185 and 1870 km (1.5 and 1.75 R(sub M). The Al radiative intensity was seen to increase where the slit crossed the planetary penumbral shadow, and then decrease monotonically with altitude. Fe emission has been observed once, in 2009, indicating an extended source. We also present observed 3- Sigma Ca(+) upper limits near Mercury's equatorial anti-solar limb, from which an abundance limit of 4.0 x 10(exp 6) cm(exp -2) at 1650 km altitude is derived for the Ca ion. A simple model for zenith column abundances of the neutral species yields 1.9 -5.2 x 10(exp 7) Al cm(exp -2) , and 8.2 x 10(exp 8) Fe cm(exp -2) . The observations appear to be consistent with production of these species by impact vaporization, with a large fraction of the Al ejecta in molecular form, and that for Fe in mixed atomic and molecular forms. The scale height of the Al gas is consistent with a kinetic temperature of 6100-8000 K. The apparent high temperature and low density of the Al gas would suggest that it may be produced by dissociation of molecules.

Optimized Gen-II FeCrAl cladding production in large quantity for campaign testing

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sun, Zhiqian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-06-03

There are two major objectives in this report; (1) to optimize microstructure control of ATF FeCrAl alloys during tube drawing processes, and (2) to provide an update on the progress of ATF FeCrAl tube production via commercial manufacturers. Experimental efforts have been made to optimize the process parameters balancing the tube fabricability, especially for tube drawing processes, and microstructure control of the final tube products. Lab-scale sheet materials of Gen II FeCrAl alloys (Mo-containing and Nb-containing FeCrAl alloys) were used in the study, combined with a stepwise warm-rolling process and intermediate annealing, aiming to simulate the tube drawing process in a commercial tube manufacturer. The intermediate annealing at 650ºC for 1h was suggested for the tube-drawing process of Mo-containing FeCrAl alloys because it successfully softened the material by recovering the work hardening introduced through the rolling step, without inducing grain coarsening due to recrystallization. The final tube product is expected to have stabilized deformed microstructure providing the improved tensile properties with sufficient ductility. Optimization efforts on Nb-containing FeCrAl alloys focused on the effect of alloying additions and annealing conditions on the stability of deformed microstructure. Relationships between the second-phase precipitates (Fe₂Nb-Laves phase) and microstructure stability are discussed. FeCrAl tube production through commercial tube manufacturers is currently in progress. Three different manufacturers, Century Tubes, Inc. (CTI), Rhenium Alloys, Inc. (RAI), and Superior Tube Company, Inc. (STC), are providing capabilities for cold-drawing, warm-drawing, and HPTR cold-pilgering, respectively. The first two companies are currently working on large quantity tube production (expected 250 ft length) of Gen I model FeCrAl alloy (B136Y3, at CTI) and Gen II (C35M4, at RAI), with the process parameters obtained from the experimental

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.

Arcillas pilarizadas con Al-Fe y Al-Ce-Fe como sistema de postratamiento de las aguas residuales del beneficio húmedo del café

OpenAIRE

Peralta Ladino, Yury Marlén

2013-01-01

El efluente del sistema de tratamiento biológico de las aguas residuales del beneficio húmedo del café contiene compuestos no biodegradables, principalmente (ácidos hidroxicinámicos y clorogénicos) los cuales fueron identificados mediante análisis preliminares por LC-MS, por su toxicidad deben ser tratados antes de su descarga en las fuentes hídricas. El sistema Fenton heterogéneo empleando como soportes Al-Fe-PILC y Al-Ce-Fe-PILC (en polvo) mostró importantes conversión de compuestos fenólic...

Antifriction coating of Cu-Fe-Al-Pb system for plain bearings

Science.gov (United States)

Kotenkov, Pavel; Kontsevoi, Yurii; Mejlakh, Anna; Pastukhov, Eduard; Shubin, Alexey; Goyda, Eduard; Sipatov, Ivan

2017-09-01

Aluminium, copper and their compounds are used in common as basis for antifriction coatings of plain bearings. Antifriction testing of plain bearings (based on Al and Cu) made by leading automotive manufacturers from Germany, Japan, USA, United Kingdom and Russia were carried out to make judicious selection of basis for development of new antifriction material. Testing was carried out using friction machine. It was defined that materials based on Cu provide better durability and robustness of plain bearings in comparison with Al based ones. The new antifriction composite coatings based on copper were developed taking into account the requirements specified for plain bearings of internal-combustion engine. Pilot samples of plain bearings with antifriction coatings of Cu-Fe-Al-Pb system were produced. The antifriction composite having Cu-5Fe-5Al5Fe2-10Pb (mass %) composition has demonstrated low friction factor and high wear-resistance. Metallographic analysis of pilot samples was carried out by means of optical and scanning electron microscopy.

Corrosion Behavior of Detonation Gun Sprayed Fe-Al Type Intermetallic Coating

Science.gov (United States)

Senderowski, Cezary; Chodala, Michal; Bojar, Zbigniew

2015-01-01

The detonation gun sprayed Fe-Al type coatings as an alternative for austenitic valve steel, were investigated using two different methods of testing corrosion resistance. High temperature, 10-hour isothermal oxidation experiments at 550, 750, 950 and 1100 °C show differences in the oxidation behavior of Fe-Al type coatings under air atmosphere. The oxide layer ensures satisfying oxidation resistance, even at 950 and 1100 °C. Hematite, α-Al2O3 and metastable alumina phases were noticed on the coatings top surface, which preserves its initial thickness providing protection to the underlying substrate. In general, only negligible changes of the phase composition of the coatings were noticed with simultaneous strengthening controlled in the micro-hardness measurements, even after 10-hours of heating at 1100 °C. On the other hand, the electrochemical corrosion tests, which were carried out in 200 ppm Cl− (NaCl) and pH ~4 (H2SO4) solution to simulate the acid-rain environment, reveal higher values of the breakdown potential for D-gun sprayed Fe-Al type coatings than the ones for the bulk Fe-Al type alloy and Cr21Mn9Ni4 austenitic valve steel. This enables these materials to be used in structural and multifunctional applications in aggressive environments, including acidic ones. PMID:28787991

Effect of Fe addition on the magnetic and giant magneto-impedance behaviour of CoCrSiB rapidly solidified alloys

Energy Technology Data Exchange (ETDEWEB)

Kumari, Seema; Chattoraj, I; Panda, A K; Mitra, A; Pal, S K [National Metallurgical Laboratory, Jamshedpur 831 007 (India)

2006-05-21

Thermal electrical resistivity, magnetic hysteresis and magneto-impedance behaviour of melt spun and annealed Co{sub 71-X}Fe{sub X}Cr{sub 7}Si{sub 8}B{sub 14} (X = 0, 2, 3.2, 4, 6, 8 and 12 at.%) were investigated. The addition of Fe in the system changed crystallization as well as the magnetic properties of the materials. The alloy containing 6 at.% Fe showed an increase in resistivity during the first crystallization process. A TEM micrograph indicated the formation of nanostructure during the crystallization process. The GMI properties of the alloys are evaluated at a driving current amplitude of 5 mA and a frequency of 4 MHz. The two-peak behaviour in the GMI profile was observed for all the samples. It is found that the alloy with 4 at.% Fe has the maximum GMI ratio because of the nearly zero magnetostriction value of the sample. About 62% change in the GMI ratio was observed in the alloy with 4 at.% Fe when annealed at 673 K. The anisotropy field was also minimum for the annealed alloy. The results were explained by the formation of directional ordering and the reduction of the magnetostriction constant of the alloy due to nanocrystallization during the annealing process.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-05-15

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

Liquid wastes concentrating and solidifying device

International Nuclear Information System (INIS)

Kamiyoshi, Hideki; Ninokata, Yoshihide.

1985-01-01

Purpose: To provide a device for concentrating to solidify radioactive liquid wastes at large solidifying speed and with high decontaminating coefficient, without requirement for automatic control. Constitution: An asphalt solidifying device is disposed below a centrifugal thin film drier, and powder resulted from the drier is directly solidified with asphalt by utilizing the rotation of the drier for the mixing operation in the asphalt vessel. If abnormality should occur in the operation of the drier, resulting liquid wastes can be received and solidified in the asphalt vessel. The liquid wastes are heated to dry in a vessel main body having the heating surface at the circumferential surface. The vessel main body provided with a nozzle for supplying liquid to be treated disposed slantwise at the upper portion of the heating face, scrapers which rotate and slidingly contact the heating face and nozzles which jet out chemicals to the heating face behind the scrapers. Below the vessel main body, are disposed a funnel-like hopper for receiving falling scales, rotary vanes, and the likes by which the scales are introduced into the asphalt solidifying vessel. (Moriyama, K.)

The bonding character and magnetic properties of Fe{sub 3}Al: Comparison between disordered and ordered alloy

Energy Technology Data Exchange (ETDEWEB)

Fan Runhua [MOE Key Laboratory for Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China)]. E-mail: fan@sdu.edu.cn; Qi Liang [MOE Key Laboratory for Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Sun Kangning [MOE Key Laboratory for Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Min Guanghui [MOE Key Laboratory for Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Gong Hongyu [MOE Key Laboratory for Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China)

2006-12-25

Fe{sub 3}Al with D0{sub 3}-ordered structure is one of the few structural intermetallics that can be disordered using non-equilibrium processing techniques. The bonding and magnetic character of the stoichiometric Fe{sub 3}Al, with D0{sub 3}-ordered or disordered structure, have been studied using the empirical electron theory of solid and molecular (EET). It was found that the magnetic property is basically dictated by the chemical bonding. There is a change of the character of the interatomic bonds from 3d(Fe)-3p(Al) for the D0{sub 3}-ordered Fe{sub 3}Al to 4sp(Fe)-3p(Al) for the disordered Fe{sub 3}Al. For the latter, while the Fe 3d electrons participating in bonding is reduced, the mean magnetic moment is increased.

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

Science.gov (United States)

Fabrizi, A.; Timelli, G.

2016-03-01

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

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_._9_7Al_0_._0_3O, Zn_0_._9_5Fe_0_._0_5O and Zn_0_._9_2Al_0_._0_3Fe_0_._0_5O 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.

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.

Fe-Al2O3 nanocomposites prepared by high-energy ball milling

DEFF Research Database (Denmark)

Linderoth, Søren; Pedersen, M.S.

1994-01-01

Nanocomposites of alpha-Fe and alpha-Al2O3, prepared by high-energy ball milling, exhibit coercivities which are enhanced by about two orders of magnitude with respect to the bulk value. The degree of enhancement depends on the volume fraction (x(upsilon)) of Fe, with a maximum for x(upsilon) alm......Nanocomposites of alpha-Fe and alpha-Al2O3, prepared by high-energy ball milling, exhibit coercivities which are enhanced by about two orders of magnitude with respect to the bulk value. The degree of enhancement depends on the volume fraction (x(upsilon)) of Fe, with a maximum for x...

Nial and Nial-Based Composites Directionally Solidified by a Containerless Zone Process. Ph.D. Thesis

Science.gov (United States)

Joslin, Steven M.

1995-01-01

A containerless electromagnetically levitated zone (CELZ) process has been used to directionally solidify NiAl and NiAl-based composites. The CELZ processing results in single crystal NiAl (HP-NiAl) having higher purity than commercially pure NiAl grown by a modified Bridgman process (CP-NiAl). The mechanical properties, specifically fracture toughness and creep strength, of the HP-NiAl are superior to binary CP-NiAl and are used as a base-line for comparison with the composite materials subsequently studied. Two-phase composite materials (NiAl-based eutectic alloys) show improvement in room temperature fracture toughness and 1200 to 1400 K creep strength over that of binary HP-NiAl. Metallic phase reinforcements produce the greatest improvement in fracture toughness, while intermetallic reinforcement produces the largest improvement in high temperature strength. Three-phase eutectic alloys and composite materials were identified and directionally solidified with the intent to combine the improvements observed in the two-phase alloys into one alloy. The room temperature fracture toughness and high temperature strength (in air) serve as the basis for comparison between all of the alloys. Finally, the composite materials are discussed in terms of dominant fracture mechanism observed by fractography.

Application of plasma sprayed ceramic coatings to the base materials of the rotating disk in the centrifugal atomization process. Enshinryoku funmuho ni okeru kaiten enban eno ceramic yosha himaku no tekiyo

Energy Technology Data Exchange (ETDEWEB)

Sato, T; Okimoto, K [Government Industrial Research Inst., Kyushu, Tosu, Saga (Japan); Yasutake, R [Koeiseiko Co. Ltd., Fukuoka (Japan)

1992-07-08

Applicability of the ceramic coating on the rotating disk was studied. In regard to the synthesis of Cu-based rapidly solidified powders, centrifugal atomization with molten Cu-24.6Sn was carried out using rotating disks sprayed with four kinds of sprayed ceramic coatings. It was found that atomization of Al203-40%TiO2 sprayed coating has been the best, and the yield ratio has been about 60 %. The melt temperature in case of Fe-based rapidly solidified metal powders, has risen above 1600[degree]C, and the required conditions for rotating disk have been very difficult to meet. The reason for it is thought that there has also been limitations regarding the functions of the characteristics like heat transfer, heat capacity, etc. Fe-24Cr-5Ni-1Mo 2 phase stainless steel powder has shown the most suitable trend among the seven kinds of disk materials examined for ZrO2 ceramic sprayed coatings. 6 refs., 5 figs., 2 tabs.

Effect of Layer Thickness in Selective Laser Melting on Microstructure of Al/5 wt.%Fe2O3 Powder Consolidated Parts

Directory of Open Access Journals (Sweden)

Sasan Dadbakhsh

2014-01-01

Full Text Available In situ reaction was activated in the powder mixture of Al/5 wt.%Fe2O3 by using selective laser melting (SLM to directly fabricate aluminium metal matrix composite parts. The microstructural characteristics of these in situ consolidated parts through SLM were investigated under the influence of thick powder bed, 75 μm layer thickness, and 50 μm layer thickness in various laser powers and scanning speeds. It was found that the layer thickness has a strong influence on microstructural outcome, mainly attributed to its impact on oxygen content of the matrix. Various microstructural features (such as granular, coralline-like, and particulate appearance were observed depending on the layer thickness, laser power, and scanning speed. This was associated with various material combinations such as pure Al, Al-Fe intermetallics, and Al(-Fe oxide phases formed after in situ reaction and laser rapid solidification. Uniformly distributed very fine particles could be consolidated in net-shape Al composite parts by using lower layer thickness, higher laser power, and lower scanning speed. The findings contribute to the new development of advanced net-shape manufacture of Al composites by combining SLM and in situ reaction process.

Study the microstructure of three and four component phases in Al-Ni-Fe-La alloys

KAUST Repository

Kolobylina, Natalia

2016-12-21

Aluminium alloys play a key role in modern engineering since they are the most used non-ferrous material. They have been widely used in automotive, aerospace, and construction engineering due to their good corrosion resistance, superior mechanical properties along with good machinability, weldability, and relatively low cost. The progress in practical application has been determined by intensive research and development works on the Al alloys. A new class of Al–REM–TM aluminum alloys (REM indicates rare earth metal and TM is transition metal) was revealed in the end of the last century. These alloys differ from conventional ones by their extraordinary ability to form metal glasses and nanoscale composites in a wide range of compositions. Having low density, these alloys possess unique mechanical characteristics and corrosion resistance. Two as received alloys, namely Al85Ni9Fe2La4 and Al85Ni7Fe4La4 were obtained in the form of ingots from melts of corresponding compositions upon cooling in air were studied by scanning/transmission electron microscopy (STEM), energy dispersive X-ray (EDX) microanalysis and X-ray diffraction (XRD). The microstructural analyses were performed in a aberration corrected TITAN 80-300 TEM/STEM (FEI, USA) attached with EDX spectrometer with ultrathin window (EDAX, USA). The specimens for transmission electron microscopy (TEM) were prepared by an electrochemical or ion etching. It was found that the received alloys exhibits along with fcc Al and Al4La (Al11La3) particles, these alloys contain a ternary phase Al3Ni1 Fe isostructural to the Al3Ni phase and a quaternary phase Al8Fe2 NiLa isostructural to the Al8Fe2Eu phase and monoclinic phase Al9(Fe,Ni)2 isostructural to the Al9Co2. The study by HRSTEM together with a new atomic resolution energy dispersive X-ray microanalysis method demonstrated that Fe and Ni atoms substituted one another in the Al8Fe2–NiLa quaternary compound. Besides, several types of defects were determined: first

BISON Fuel Performance Analysis of FeCrAl cladding with updated properties

Energy Technology Data Exchange (ETDEWEB)

Sweet, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); George, Nathan M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wirth, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-30

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, suitability for normal operation must also be demonstrated. This research is focused on modeling the integral thermo-mechanical performance of FeCrAl-cladded fuel during normal reactor operation. Preliminary analysis has been performed to assess FeCrAl alloys (namely Alkrothal 720 and APMT) as a suitable fuel cladding replacement for Zr-alloys, using the MOOSE-based, finite-element fuel performance code BISON and the best available thermal-mechanical and irradiation-induced constitutive properties. These simulations identify the effects of the mechanical-stress and irradiation response of FeCrAl, and provide a comparison with Zr-alloys. In comparing these clad materials, fuel rods have been simulated for normal reactor operation and simple steady-state operation. Normal reactor operating conditions target the cladding performance over the rod lifetime (~4 cycles) for the highest-power rod in the highest-power fuel assembly under reactor power maneuvering. The power histories and axial temperature profiles input into BISON were generated from a neutronics study on full-core reactivity equivalence for FeCrAl using the 3D full core simulator NESTLE. Evolution of the FeCrAl cladding behavior over time is evaluated by using steady-state operating conditions such as a simple axial power profile, a constant cladding surface temperature, and a constant fuel power history. The fuel rod designs and

Radioactive liquid waste solidifying device

International Nuclear Information System (INIS)

Uchiyama, Yoshio.

1987-01-01

Purpose: To eliminate the requirement for discharge gas processing and avoid powder clogging in a facility suitable to the volume-reducing solidification of regenerated liquid wastes containing sodium sulfate. Constitution: Liquid wastes supplied to a liquid waste preheater are heated under a pressure higher than the atmospheric pressure at a level below the saturation temperature for that pressure. The heated liquid wastes are sprayed from a spray nozzle from the inside of an evaporator into the super-heated state and subjected to flash distillation. They are further heated to deposit and solidify the solidification components in the solidifying evaporation steams. The solidified powder is fallen downwardly and heated for removing water content. The recovered powder is vibrated so as not to be solidified and then reclaimed in a solidification storage vessel. Steams after flash distillation are separated into gas, liquid and solids by buffles. (Horiuchi, T.)

Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

Directory of Open Access Journals (Sweden)

Sung-Yun Kwak

2017-12-01

Full Text Available In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 °C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-CalcTM. Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe3O4 layer on the steel surface. The Fe3O4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al6Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al11Mn4 → FeAl3 (θ → Fe2Al5 (η phases, and the Fe3AlC (κ in several nm bands formed at the interface between the η-phase and steel.

Solidifying processing device for radioactive waste

International Nuclear Information System (INIS)

Sueto, Kumiko; Toyohara, Naomi; Tomita, Toshihide; Sato, Tatsuaki

1990-01-01

The present invention concerns a solidifying device for radioactive wastes. Solidifying materials and mixing water are mixed by a mixer and then charged as solidifying and filling materials to a wastes processing container containing wastes. Then, cleaning water is sent from a cleaning water hopper to a mixer to remove the solidifying and filling materials deposited in the mixer. The cleaning liquid wastes are sent to a separator to separate aggregate components from cleaning water components. Then, the cleaning water components are sent to the cleaning water hopper and then mixed with dispersing materials and water, to be used again as the mixing water upon next solidifying operation. On the other hand, the aggregate components are sent to a processing mechanism as radioactive wastes. With such procedures, since the discharged wastes are only composed of the aggregates components, and the amount of the wastes are reduced, facilities and labors for the processing of cleaning liquid wastes can be decreased. (I.N.)

Handbook of the Materials Properties of FeCrAl Alloys For Nuclear Power Production Applications

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snead, Mary A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

FeCrAl alloys are a class of alloys that have seen increased interest for nuclear power applications including as accident tolerant fuel cladding, structural components for fast fission reactors, and as first wall and blanket structures for fusion reactors. FeCrAl alloys are under consideration for these applications due to their inherent corrosion resistance, stress corrosion cracking resistance, radiation-induced swelling resistance, and high temperature oxidation resistance. A substantial amount of research effort has been completed to design, develop, and begin commercial scaling of FeCrAl alloys for nuclear power applications over the past half a century. These efforts have led to the development of an extensive database on material properties and process knowledge for FeCrAl alloys but not within a consolidated format. The following report is the first edition of a materials handbook to consolidate the state-of-the-art on FeCrAl alloys for nuclear power applications. This centralized database focuses solely on wrought FeCrAl alloys, oxide dispersion strengthened alloys, although discussed in brief, are not covered. Where appropriate, recommendations for applications of the data is provided and current knowledge gaps are identified.

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

International Nuclear Information System (INIS)

Fabrizi, A; Timelli, G

2016-01-01

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

Macrosegregation Due to Convection in Al-19Cu Alloy Directionally Solidified Through an Abrupt Expansion in Cross-Section: A Comparison with Al-7Si

Science.gov (United States)

Ghods, M.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

2017-10-01

Hypoeutectic Al-19 wt.% Cu alloys were directionally solidified at two different growth speeds in cylindrical molds that featured an abrupt increase in cross-section, from 3.2 to 9.5 mm in diameter. The effects of thermosolutal convection and shrinkage flow induced by the cross-section change on macrosegregation were investigated. Dendrite clustering and extensive radial macrosegregation were seen, particularly in the larger cross-section after expansion. Negative longitudinal macrosegregation right after the cross-section increase was observed; the extent of macrosegregation, however, decreases with increasing growth speed. Both thermal and flow effects due to cross-section change were seen to influence the radial macrosegregation immediately before, and after the expansion. Radial macrosegregation pattern was found to be changing as the mushy zone enters the larger cross-section region above the cross-section change where the solidification is in its unsteady state. The effect of the solutal expansion coefficient on macrosegregation was studied by comparing the degree of thermosolutal convection in Al-19 wt.% Cu with a previous study in which we investigated Al-7 wt.% Si. A two-dimensional model accounting for both shrinkage and thermosolutal convection was used to simulate the resulting steepling, as well as the axial and radial macrosegregation. The experimentally observed macrosegregation associated with the expansion during directional solidification is well predicted by the numerical simulations.

The fluctuation field and anomalous magnetic viscosity in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Collocott, S.J. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)], E-mail: stephen.collocott@csiro.au; Dunlop, J.B. [CSIRO Materials Science and Engineering, Lindfield, NSW 2070 (Australia)

2008-08-15

The fluctuation field, H{sub f}, is a useful parameter for characterising any ferromagnetic material that displays hysteresis, as it is a measure of the thermally activated rate processes that govern magnetisation reversals. Anomalous magnetic viscosity, i.e. nonmonotonic behaviour of the time dependent magnetisation, where the magnetisation is seen to increase, reach a peak, and then decrease, has been observed on both the upper and lower branches of minor loops or recoil curves in some ferromagnetic materials. Parameters relevant to the Preisach model are discussed as to their usefulness in predicting anomalous magnetic viscosity in ferromagnetic materials. This is done with reference to measurements of H{sub f} and the time dependent magnetisation in commercial NdFeB alloys, AlNiCo and the bulk amorphous ferromagnets Nd{sub 60}Fe{sub 30}Al{sub 10} and Nd{sub 60}Fe{sub 20}Co{sub 10}Al{sub 10}.

Phase separation in equiatomic AlCoCrFeNi high-entropy alloy

Energy Technology Data Exchange (ETDEWEB)

Manzoni, A., E-mail: anna.manzoni@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany); Daoud, H.; Völkl, R.; Glatzel, U. [Metals and Alloys, University Bayreuth, Ludwig-Thoma-Strasse 36b, D-95447 Bayreuth (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany)

2013-09-15

The microstructure of the as-cast AlCoCrFeNi high entropy alloy has been investigated by transmission electron microscopy and atom probe tomography. The alloy shows a very pronounced microstructure with clearly distinguishable dendrites and interdendrites. In both regions a separation into an Al–Ni rich matrix and Cr–Fe-rich precipitates can be observed. Moreover, fluctuations of single elements within the Cr–Fe rich phase have been singled out by three dimensional atom probe measurements. The results of investigations are discussed in terms of spinodal decomposition of the alloying elements inside the Cr–Fe-rich precipitates. - Highlights: ► The Alloy separates into an Al–Ni rich matrix and Cr–Fe-rich precipitates. ► Concentration depth profiles in the Cr–Fe rich regions show opposite fluctuations. ► They have been attributed to the spinodal decomposition of Fe- and Cr-rich phases. ► The Al–Ni rich region corresponds well to the Al–Ni rich phases observed in the 6 component AlCoCrCuFeNi alloy.

Manufacturing of FeCrAl/Zr Dual Layer tube for its application to LWR Fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Jun; Lim, Do Wan; Jung, Yang Il; Kim, Hyun Gil; Park, Jeong Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Many advanced materials such as MAX phases, Mo, SiC, and Fe-based alloys are being considered a possible candidate to substitute the Zr-based alloy cladding has been used in light water reactors. Among the proposed candidate materials, Fe-based alloy is one of the most promising candidates owing to its excellent formability, very good high strength, and corrosion resistance at high temperature. However, neutron cross section of FeCrAl alloy is much higher than that of existing Zr-based alloys. In this study, FeCrAl/Zr dual layer tube was manufactured by using a hot isostatic pressing (HIP) method. The thickness of outer FeCrAl layer was varied from 50 to 250 μm but all the FeCrAl/Zr dual layer tube samples maintained its total thickness of 570 μm. For a detailed microstructural characterization of FeCrAl/Zr dual layer, polarized optical microscopy and scanning electron microscopy (SEM) study carried out and its mechanical property was measured by ring compression test. FeCrAl/Zr dual layer tube sample was successfully manufactured with good adhesion between both layers. Inter layer showing gradual element variation was observed at interface. Result obtained from simulated LOCA test indicates that FeCrAl/Zr dual layer tube may maintain its integrity during LOCA and its accident tolerance had greatly improved compared to that of Zr-based alloy.

Deposition of Fe-Ni nanoparticles on Al2O3 for dechlorination of chloroform and trichloroethylene

International Nuclear Information System (INIS)

Hsieh, S.-H.; Horng, J.-J.

2006-01-01

This research proposes an efficient method for depositing Fe-Ni nanoparticles on Al 2 O 3 microparticles to decompose containments in ground water, such as chloroform and trichloroethylene. The Fe-Ni nanoparticles can be deposited onto the surface of Al 2 O 3 microparticles by electroless plating technique. The reasons why the Fe-Ni nanoparticles would be deposited on the surface of Al 2 O 3 microparticles is to avoid the agglomeration of Fe-Ni nanoparticles due to their surface effect and magnetic property. The results show that the sizes of Fe-Ni particles on Al 2 O 3 particles are between several and several hundreds of nanometers, the contents of Fe and Ni in Fe-Ni nanoparticles can be adjusted from 8 to 60 at.% for Fe and 40 to 92 at.% for Ni, the specific surface area of Fe-Ni nanoparticles can reach to 117 m 2 /g, and the reaction mechanism of dechlorination of chloroform of 2 mg/L by Fe-Ni/Al 2 O 3 particles of 5 g/L appears to be pseudo first order with a half life of 0.7 h and the half life is 0.25 h for the dechlorination of trichloroethylene of 2 mg/L

Nanophase intermetallic FeAl obtained by sintering after mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

D' Angelo, L., E-mail: luisa.dangelo@gmail.co [Departamento de Mecanica, UNEXPO, Luis Caballero Mejias, Charallave (Venezuela, Bolivarian Republic of); D' Onofrio, L. [Facultad de Ciencias, Dpto. Fisica, Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of); Gonzalez, G., E-mail: gemagonz@ivic.v [Laboratorio de Materiales, Centro Tecnologico, Instituto Venezolano de Investigaciones Cientificas, Apdo. 21827, Caracas 1020A (Venezuela, Bolivarian Republic of)

2009-08-26

The preparation of bulk nanophase materials from nanocrystalline powders has been carried out by the application of sintering at high pressure. Fe-50 at.%Al system has been prepared by mechanical alloying for different milling periods from 1 to 50 h, using vials and balls of stainless steel and a ball-to-powder weight ratio (BPR) of 8:1 in a SPEX 8000 mill. Sintering of the 5 and 50 h milled powders was performed under high uniaxial pressure at 700 deg. C. The characterization of powders from each interval of milling was performed by X-ray diffraction, Moessbauer spectroscopy, scanning and transmission electron microscopy. After 5 h of milling formation of a nanocrystalline alpha-Fe(Al) solid solution that remains stable up to 50 h occurs. The grain size decreases to 7 nm after 50 h of milling. The sintering of the milled powders resulted in a nanophase-ordered FeAl alloys with a grain size of 16 nm. Grain growth during sintering was very small due to the effect of the high pressure applied.

Metallography of a pulsed Nd:YAG laser weld in a RS/PM Al-8Fe-2Mo alloy

International Nuclear Information System (INIS)

Krishnaswamy, S.; Baeslack, W.A. III

1990-01-01

This paper reports the microstructure of a pulsed Nd:YAG laser weld in a rapid solidification/powder metallurgy (RS/PM) Al-8.0 wt.% Fe-2.3 wt.% Mo (Al-8Fe-2Mo) alloy investigated using light microcopy, canning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. This analysis revealed significant microstructure variations across the weld fusion zone (FZ). Near the fusion boundary, a light-etching FZ microstructure was observed to contain submicron dispersoids entrapped in a matrix of fine-sized dendritic alpha aluminum. At the center of the FZ, the presence of relatively coarse-sized intermetallic particles that served as growth centers for coarser dendritic alpha aluminum promoted a dark-etching microstructure. In the boundary between successive melt zones, both a heat-affected zone (HAZ) containing acicular dispersoids and a fusion boundary region (FBR) containing irregular-shaped particles in a coarse-grained dendritic alpha aluminum matrix were observed

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Method of solidifying radioactive waste

International Nuclear Information System (INIS)

Hasegawa, Akira; Mihara, Shigeru; Yamashita, Koji; Sauda, Kenzo.

1988-01-01

Purpose: To obtain satisfactory plastic solidification products rapidly and more conveniently from radioactive wastes. Method: liquid wastes contain, in addition to sodium sulfate as the main ingredient, nitrates hindering the polymerizing curing reactions and various other unknown ingredients, while spent resins contain residual cationic exchange groups hindering the polymerizing reaction. Generally, as the acid value of unsaturated liquid polyester resins is lower, the number of terminal alkyd resins is small, formation of nitrates is reduced and the polymerizing curing reaction is taken place more smoothly. In view of the above, radioactive wastes obtained by dry powderization or dehydration of radioactive liquid wastes or spent resins are polymerized with unsaturated liquid polyester resins with the acid value of less than 13 to obtain plastic solidification. Thus, if the radioactive wastes contain a great amount of polymerization hindering material such as NaNO 2 , they can be solidified rapidly and conveniently with no requirement for pre-treatment. (Kamimura, Y.)

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)

Irradiation of Wrought FeCrAl Tubes in the High Flux Isotope Reactor

Energy Technology Data Exchange (ETDEWEB)

Linton, Kory D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Petrie, Christian M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-09-01

The Advanced Fuels Campaign within the Nuclear Technology Research and Development program of the Department of Energy Office of Nuclear Energy is seeking to improve the accident tolerance of light water reactors. Alumina-forming ferritic alloys (e.g., FeCrAl) are one of the leading candidate materials for fuel cladding to replace traditional zirconium alloys because of the superior oxidation resistance of FeCrAl. However, there are still some unresolved questions regarding irradiation effects on the microstructure and mechanical properties of FeCrAl at end-of-life dose levels. In particular, there are concerns related to irradiation-induced embrittlement of FeCrAl alloys due to secondary phase formation. To address this issue, Oak Ridge National Laboratory has developed a new experimental design to irradiate shortened cladding tube specimens with representative 17×17 array pressurized water reactor diameter and thickness in the High Flux Isotope Reactor (HFIR) under relevant temperatures (300–350°C). Post-irradiation examination will include studies of dimensional change, microstructural changes, and mechanical performance. This report briefly summarizes the capsule design concept and the irradiation test matrix for six rabbit capsules. Each rabbit contains two FeCrAl alloy tube specimens. The specimens include Generation I and Generation II FeCrAl alloys with varying processing conditions, Cr concentrations, and minor alloying elements. The rabbits were successfully assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. Pictures of the rabbit assembly process and detailed dimensional inspection of select specimens are included in this report. The rabbits were inserted into HFIR starting in cycle 472 (May 2017).

Effect of a ZrO{sub 2} coating deposited by the sol–gel method on the resistance of FeCrAl alloy in high-temperature oxidation conditions

Energy Technology Data Exchange (ETDEWEB)

Chęcmanowski, Jacek Grzegorz, E-mail: jacek.checmanowski@pwr.wroc.pl [Wrocław University of Technology, Faculty of Chemistry, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland); Szczygieł, Bogdan, E-mail: bogdan.szczygiel@pwr.wroc.pl [Wrocław University of Technology, Faculty of Chemistry, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland)

2013-05-15

One-, three- and five-layer protective ZrO{sub 2} coatings were deposited on a FeCrAl alloy base by the sol–gel method. A zirconium(IV) isopropoxide isopropanol complex was used as the zirconium precursor. It has been shown that zirconium in the amount of 0.3–0.5 wt.% improves the resistance of FeCrAl alloy in high-temperature oxidation conditions (in air at T = 1060 °C for t = 2400 h). Even a very low Zr content affects the morphology, porosity and composition of the forming scale (SEM, EDS). An analysis of the chemical composition of the material after oxidation indicated to-core Zr diffusion. The presence of zirconium prevents catastrophic corrosion of the FeCrAl alloy during oxidation. In the case of the alloy without the reactive element (Zr) this type of corrosion occurred after about 1800 h. The oxidation of the FeCrAl alloy covered with ZrO{sub 2} coatings proceeds in three stages. In the first stage, lasting about 50 h, the mass of the sample grows rapidly, then for 700 h the mass changes minimally and in the third stage the oxidation proceeds according to a parabolic dependence. The presence of Zr on the surface of the FeCrAl alloy significantly contributes to the protective effect of the coatings. - Highlights: ► Multilayer ZrO{sub 2} coatings were deposited on FeCrAl alloy by sol–gel method. ► Study of alloy composition indicates to-core Zr diffusion in high temperature. ► Even very low content affects morphology and porosity of forming scale. ► Zirconium improves the resistance of FeCrAl alloy in high temperature conditions. ► Presence of ZrO{sub 2} prevents catastrophic corrosion of FeCrAl alloy during oxidation.

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.

Design and characterization of FeCrNiCoAlCu and FeCrNiCo(AlCu){sub 0,5} multicomponent alloys; Previsao e caracterizacao de ligas multicomponentes FeCrNiCoAlCu e FeCrNiCo(AlCu){sub 0,5}

Energy Technology Data Exchange (ETDEWEB)

Triveno Rios, Carlos; Artacho, Victor Falcao [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Engenharia de Materiais

2014-07-01

High entropy alloys using multi-element main quasi-equivalent atomic proportions and generally forms single-phase solid solution and has the ability to enhance levels of strain hardening combined with high levels of plastic deformation at room temperature. In this work two high-entropy alloys with almost similar composition were studied and the factors influencing the formation of solid solution phases (δ atomic radius difference, ΔH{sub mix} mixing enthalpy, ΔS{sub mix} mixing entropy) were evaluated. The microstructure as-cast and the compositions of phases in the two alloys were analyzed by SEM and XRD. The mechanical characterization was realized by measurements of microhardness and cold compression test. The results showed that FeCrNiCo(AlCu){sub 0,5} and FeCrNiCoAlCu alloys with δ equal to 5,7 and 4,9, respectively, form alloys with solid solutions of high entropy. However, the presence of FC and BCCC structures greatly influence the mechanical properties. (author)

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.

Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Thompson, Zachary T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-10-01

Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.

Correlation induced paramagnetic ground state in FeAl

Czech Academy of Sciences Publication Activity Database

Mohn, P.; Persson, C.; Blaha, P.; Schwarz, K.; Novák, Pavel; Eschrig, H.

2001-01-01

Roč. 87, č. 19 (2001), s. 196401-1-196401-4 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z1010914 Keywords : FeAl * paramagnetic ground state Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.668, year: 2001

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

Science.gov (United States)

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

2013-12-01

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

Structural evolutions of the mechanically alloyed Al70Cu20Fe10 ...

Indian Academy of Sciences (India)

The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The -phase was one of the major phases in the Al70Cu20Fe10 alloy. The w-Al7Cu2Fe1 phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled samples. The present investigation ...

Determination of Fe and Al contamination by NAA at preparation of traditional Mexican food

International Nuclear Information System (INIS)

Arriola, S.H.; Cruz, M.M.

2007-01-01

A study was carried out using NAA to measure the concentration of Al and Fe leached from kitchen ware into some popular Mexican sauces and juices. These elements were measured in red and green hot sauces cooked in Fe, Al and clay pans compared to a stainless steel pan. Similarly Al was measured in orange and grapefruit juices obtained using an Al extractor compared to a plastic one. (author)

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.

An X-ray absorption spectroscopic study of the metal site preference in Al1−xGaxFeO3

International Nuclear Information System (INIS)

Walker, James D.S.; Grosvenor, Andrew P.

2013-01-01

Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO 3 (Pna2 1 ; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al 1−x Ga x FeO 3 was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L 2,3 -, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al 1−x Ga x FeO 3 indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO 3 than in GaFeO 3 , implying more anti-site disorder is present in AlFeO 3 . - Graphical abstract: Al 1−x Ga x FeO 3 has been investigated by XANES. Through examination of Al L 2,3 -, Ga K-, and Fe K-edge XANES spectra, it was found that more anti-site disorder of the Fe atoms is present in AlFeO 3 compared to in GaFeO 3 . Highlights: ► Al 1−x Ga x FeO 3 was investigated by X-ray absorption spectroscopy. ► Ga prefers to occupy the tetrahedral site in Al 1−x Ga x FeO 3 . ► Fe prefers to occupy the octahedral sites in Al 1−x Ga x FeO 3 as x increases. ► More anti-site disorder is present in AlFeO 3 compared to in GaFeO 3.

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)

Microstructural Influence on Dynamic Properties of Age Hardenable FeMnAl Alloys

Science.gov (United States)

2011-04-01

strain amplitude on a wrought Fe-28Mn-9Al-0.86C-0.7W-0.43Mo-0.49Nb alloy and on a martensitic stainless steel of composition Fe-12Cr-1.25Ni-0.2V-1.8W...the martensite and loss of strength was used to explain the lower cyclic life of the stainless steel at elevated temperatures. Within the Fe-Mn-Al-C...through F in Table 2), 1010 carbon steel and 304 stainless steel as functions of exposure time in 1 atm flowing oxygen at 700°C (a) and 500°C (b).56

Magnetic properties of fcc (Co95Fe5)1-xAlx ribbons

International Nuclear Information System (INIS)

Makhlouf, Salah A.; Parker, F.T.; Benameur, T.

1999-01-01

Rapidly quenched (Co 95 Fe 5 ) 1-x Al x ribbons are investigated by X-ray diffraction, magnetization, and Moessbauer effect measurements. A single fcc phase is obtained for all ribbons x ≤ 10 at.%. The lattice constant increases linearly with x and is discussed in connection with magnetic moment. The influence of Al substitution on both magnetization and Fe-atom hyperfine field (H) is studied. At 296 K, the magnetization decreases linearly while H drops nonlinearly as x increases. Al substitution leads to substantial differences in iron hyperfine fields in bcc and fcc systems. Fe moment is perturbed differently by Al substitution in fcc (Co 95 Fe 5 ) 1-x Al x and bcc Fe-Al systems

Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

Indian Academy of Sciences (India)

Unknown

*Key Lab of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, ... †National Key Lab of Advanced Bonding Production Technology, Harbin Institute of .... to Fe3Al can affect the dynamic balance at the Fe3Al/.

Formation of nano quasicrystalline and crystalline phases by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Shamah, A.M.; Ibrahim, S. [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt); Hanna, F.F., E-mail: fariedhanna@yahoo.com [Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

2011-02-03

Research highlights: > Mechanical alloying (MA) is an important method to investigate the formation of nano sized quasicrystalline phases in Al{sub 86}Cr{sub 14}, Al{sub 84}Fe{sub 16} and Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} compounds. The second part of the present work is an attempt to examine the possibility of formation of the i-phase of the Al{sub 62.5}Cu{sub 25}Fe{sub 12.5}, which lies in the region of the perfect i-phase in the ternary phase diagram, by rapid solidification method. To perform the obtained quasi phase mechanical alloying and heat treatment at the rapid solidified sample were done. - Abstract: In the present work, the formation of nano quasicrystalline icosahedral phase in Al{sub 86}Cr{sub 14}, Al{sub 84}Fe{sub 16} and Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} alloys has been investigated by mechanical alloying. Mixtures of quasicrystalline and related crystalline phases have been observed under various milling conditions. The X-ray diffraction, differential thermal analysis and electrical resistivity techniques have been used for characterization and physical property measurements. The particle size was calculated by X-ray profile using Williamson-Hall plot method and it was found to be 25-50 nm size.

Ostwald Ripening Process of Coherent β′ Precipitates during Aging in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 Alloys

Directory of Open Access Journals (Sweden)

N. Cayetano-Castro

2015-01-01

Full Text Available The Ostwald ripening process was studied in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 alloys after aging at 750, 850, and 950°C for different times. The microstructural evolution shows a rounded cube morphology (Fe, NiAl β′ precipitates aligned in the ferrite matrix, which changes to elongated plates after prolonged aging. The variation of the equivalent radii of precipitates with time follows the modified Lifshitz-Slyozov-Wagner theory for diffusion-controlled coarsening. Thermo-Calc analysis shows that the chromium content is richer in the matrix than in the precipitates which causes higher hardness and coarsening resistance in the aged Fe0.74Ni0.10Al0.15Cr0.01 alloy.

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

Indian Academy of Sciences (India)

Unknown

iron lattice sites (Fair and Wood 1994). 3.2 TEM morphology at the diffusion joint of. Fe3Al/Q235. For the welding of dissimilar materials, the element diffusion and phase formed at the interface of dissimilar. Table 1. Chemical composition and thermophysical properties of Fe3Al intermetallic compound. Chemical composition ...

Fe electron transfer and atom exchange in goethite: influence of Al-substitution and anion sorption.

Science.gov (United States)

Latta, Drew E; Bachman, Jonathan E; Scherer, Michelle M

2012-10-02

The reaction of Fe(II) with Fe(III) oxides and hydroxides is complex and includes sorption of Fe(II) to the oxide, electron transfer between sorbed Fe(II) and structural Fe(III), reductive dissolution coupled to Fe atom exchange, and, in some cases mineral phase transformation. Much of the work investigating electron transfer and atom exchange between aqueous Fe(II) and Fe(III) oxides has been done under relatively simple aqueous conditions in organic buffers to control pH and background electrolytes to control ionic strength. Here, we investigate whether electron transfer is influenced by cation substitution of Al(III) in goethite and the presence of anions such as phosphate, carbonate, silicate, and natural organic matter. Results from (57)Fe Mössbauer spectroscopy indicate that both Al-substitution (up to 9%) and the presence of common anions (PO(4)(3-), CO(3)(2-), SiO(4)(4-), and humic acid) does not inhibit electron transfer between aqueous Fe(II) and Fe(III) in goethite under the conditions we studied. In contrast, sorption of a long-chain phospholipid completely shuts down electron transfer. Using an enriched isotope tracer method, we found that Al-substitution in goethite (10%), does, however, significantly decrease the extent of atom exchange between Fe(II) and goethite (from 43 to 12%) over a month's time. Phosphate, somewhat surprisingly, appears to have little effect on the rate and extent of atom exchange between aqueous Fe(II) and goethite. Our results show that electron transfer between aqueous Fe(II) and solid Fe(III) in goethite can occur under wide range of geochemical conditions, but that the extent of redox-driven Fe atom exchange may be dependent on the presence of substituting cations such as Al.

EXTRUIDOS DE AlFe-PILC EN LA OXIDACIÓN CATALÍTICA DE FENOL

Directory of Open Access Journals (Sweden)

Nancy R. Sanabria

2010-09-01

Full Text Available Extruidos de AlFe-PILC con forma de cilindro compacto se emplearon como catalizadores en la reacción de oxidación de fenol en medio acuoso. Debido a que el proceso de elaboración de los extruidos con fase activa AlFe-PILC afecta la actividad intrínseca del catalizador, en este trabajo se determinaron la resistencia mecánica y la estabilidad química del catalizador conformado, así como las limitaciones difusionales por efecto de la aglomeración. Los extruidos se elaboraron con la proporción másica 42/28/30 de arcilla intercalada con AlFe, aglomerante (mezcla 50/50 de bentonita sódica y cálcica y agua, exhibiendo elevada resistencia mecánica y estabilidad química a la inmersión en agua. Los extruidos de AlFe-PILC presentaron un factor de efectividad menor a 1; por tanto, la reacción se encuentra limitada por la difusión intrapartícula.

Parametric and experimentally informed BWR Severe Accident Analysis Utilizing FeCrAl - M3FT-17OR020205041

Energy Technology Data Exchange (ETDEWEB)

Ott, Larry J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howell, Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-01

Iron-chromium-aluminum (FeCrAl) alloys are being considered as advanced fuel cladding concepts with enhanced accident tolerance. At high temperatures, FeCrAl alloys have slower oxidation kinetics and higher strength compared with zirconium-based alloys. FeCrAl could be used for fuel cladding and spacer or mixing vane grids in light water reactors and/or as channel box material in boiling water reactors (BWRs). There is a need to assess the potential gains afforded by the FeCrAl accident-tolerant-fuel (ATF) concept over the existing zirconium-based materials employed today. To accurately assess the response of FeCrAl alloys under severe accident conditions, a number of FeCrAl properties and characteristics are required. These include thermophysical properties as well as burst characteristics, oxidation kinetics, possible eutectic interactions, and failure temperatures. These properties can vary among different FeCrAl alloys. Oak Ridge National Laboratory has pursued refined values for the oxidation kinetics of the B136Y FeCrAl alloy (Fe-13Cr-6Al wt %). This investigation included oxidation tests with varying heating rates and end-point temperatures in a steam environment. The rate constant for the low-temperature oxidation kinetics was found to be higher than that for the commercial APMT FeCrAl alloy (Fe-21Cr-5Al-3Mo wt %). Compared with APMT, a 5 times higher rate constant best predicted the entire dataset (root mean square deviation). Based on tests following heating rates comparable with those the cladding would experience during a station blackout, the transition to higher oxidation kinetics occurs at approximately 1,500°C. A parametric study varying the low-temperature FeCrAl oxidation kinetics was conducted for a BWR plant using FeCrAl fuel cladding and channel boxes using the MELCOR code. A range of station blackout severe accident scenarios were simulated for a BWR/4 reactor with Mark I containment. Increasing the FeCrAl low-temperature oxidation rate

Characteristics Of The Porous Body Sintered By Nano-Sized Fe-Cr-Al Alloy Powder

Directory of Open Access Journals (Sweden)

Lee Su-In

2015-06-01

Full Text Available Porous metal with uniform honeycomb structure was successfully produced by sintering using Fe-Cr-Al nano powder, which was prepared by the pulsed wire evaporation (PWE in ethanol. Its process consisted of the several steps; 1 coating on the surface of polyurethane sponge with the liquid droplets generated from the ethanol-based slurry where the Fe-Cr-Al nano powders were uniformly dispersed, 2 heat treatment of debinding to remove the polyurethane sponge and 3 sintering of the porous green body formed by Fe-Cr-Al nano powders. The strut thickness of porous Fe-Cr-Al was increased by the increase of spraying times in ESP step. Also, The shrinkages and the oxidation resistance of the sintered porous body was increased with increase of sintering temperature. The optimal sintering temperature was shown to 1450°C in views to maximize the oxidation resistance and sinterability.

Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

Science.gov (United States)

Stein, Frank; Philips, Noah

2018-03-01

High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

Effectively simultaneous naked-eye detection of Cu(II), Pb(II), Al(III) and Fe(III) using cyanidin extracted from red cabbage as chelating agent

Science.gov (United States)

Khaodee, Warangkhana; Aeungmaitrepirom, Wanlapa; Tuntulani, Thawatchai

Simultaneous determination of Cu(II), Pb(II), Al(III) and Fe(III) using cyanidin as a chelating agent was investigated in terms of both quantitative and qualitative detections. Cyanidin was extracted and purified from red cabbage which is a local plant in Thailand. The selectivity of this method was examined by regulating the pH of cyanidin solution operated together with masking agents. It was found that Cu(II), Pb(II), Al(III) and Fe(III) simultaneously responded with the color change at pH 7, pH 6, pH 5 and pH 4, respectively. KF, DMG and the mixture of KF and DMG were used as masking agents for the determination of Fe(III), Al(III) and Pb(II), respectively. Results from naked-eye detection were evaluated by comparing with those of inductively coupled plasma (ICP), and there was no significant difference noticed. Cyanidin using as a multianalyte reagent could be employed for simultaneous determination of Cu(II), Pb(II), Al(III) and Fe(III) at the lowest concentration at 50, 80, 50 and 200 μM, respectively, by slightly varying pHs. Moreover, the proposed method could be potentially applied for real water samples with simplicity, rapidity, low cost and environmental safety.

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

Science.gov (United States)

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

2016-04-01

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

Microstructure and magnetic behavior studies of processing-controlled and composition-modified Fe-Ni and Mn-Al alloys

Science.gov (United States)

Geng, Yunlong

L10-type (Space group P4/mmm) magnetic compounds, including FeNi and MnAl, possess promising technical magnetic properties of both high magnetization and large magnetocrystalline anisotropy energy, and thus offer potential in replacing rare earth permanent magnets in some applications. In equiatomic Fe-Ni, the disorder-order transformation from fcc structure to the L10 structure is a diffusional transformation, but is inhibited by the low ordering temperature. The transformation could be enhanced through the creation of vacancies. Thus, mechanical alloying was employed to generate more open-volume defects. A decrease in grain size and concomitant increase in grain boundary area resulted from the mechanical alloying, while an initial increase in internal strain (manifested through an increase in dislocation density) was followed by a subsequent decrease with further alloying. However, a decrease in the net defect concentration was determined by Doppler broadening positron annihilation spectroscopy, as open volume defects utilized dislocations and grain boundaries as sinks. An alloy, Fe32Ni52Zr3B13, formed an amorphous structure after rapid solidification, with a higher defect concentration than crystalline materials. Mechanical milling was utilized in an attempt to generate even more defects. However, it was observed that Fe32Ni52Zr3B13 underwent crystallization during the milling process, which appears to be related to enhanced vacancy-type defect concentrations allowing growth of pre-existing Fe(Ni) nuclei. The milling and enhanced vacancy concentration also de-stabilizes the glass, leading to decreased crystallization temperatures, and ultimately leading to complete crystallization. In Mn-Al, the L10 structure forms from the parent hcp phase. However, this phase is slightly hyperstoichiometric relative to Mn, and the excess Mn occupies Al sites and couples antiparallel to the other Mn atoms. In this study, the Zr substituted preferentially for the Mn atoms in the

The corrosion and mechanical behaviour of Al, FeCrAlY, and CoCrAlY coatings in aggressive environments

NARCIS (Netherlands)

Haanappel, V.A.C.; Haanappel, V.A.C.; Geerdink, Bert; Fransen, T.; Gellings, P.J.

1991-01-01

The mechanical and chemical behaviours of aluminide coatings applied by pack cementation, FeCrAlY coatings applied by plasma spraying and CoCrAlY coatings applied by electrodeposition were studied. The coatings were pretreated for 0.5 h in argon at 1373 K to improve the adhesion and structural

Structural Investigation of Rapidly Quenched FeCoPtB Alloys

International Nuclear Information System (INIS)

Grabias, A.; Kopcewicz, M.; Latuch, J.; Oleszak, D.

2011-01-01

Two sets of Fe 52-x Co x Pt 28 B 20 (x = 0-26 at.%) and Fe 60-x Co x Pt 25 B 15 (x = 0-40 at.%) alloys were prepared in the form of ribbons by the rapid quenching technique. Structure of the samples was characterized by Moessbauer spectroscopy and X-ray diffraction. In the as-quenched alloys the amorphous phase coexisted with the fcc-(Fe,Co)Pt disordered solid solution. Differential scanning calorimetry measurements performed in the range 50-720 ± C revealed one or two exothermal peaks. The magnetically hard ordered L1 0 (Fe,Co)Pt and magnetically soft (Fe,Co) 2 B nanocrystalline phases were formed due to thermal treatment of the alloys. The influence of Co content on the structure of the as-quenched and heated alloys was studied. (authors)

Diffusivities of an Al-Fe-Ni melt and their effects on the microstructure during solidification

International Nuclear Information System (INIS)

Zhang Lijun; Du Yong; Steinbach, Ingo; Chen Qing; Huang Baiyun

2010-01-01

A systematical investigation of the diffusivities in an Al-Fe-Ni melt was presented. Based on the experimental and theoretical data about diffusivities, the temperature- and composition-dependent atomic mobilities were evaluated for the elements in Al-Ni, Al-Fe, Fe-Ni and Al-Fe-Ni melts via an effective approach. Most of the reported diffusivities can be reproduced well by the obtained atomic mobilities. In particular, for the first time the ternary diffusivity of the liquid in a ternary system is described in conjunction with the established atomic mobilities. The effect of the atomic mobilities in a liquid on microstructure and microsegregation during solidification was demonstrated with one Al-Ni binary alloy. The simulation results indicate that accurate databases of mobilities in the liquid phase are much needed for the quantitative simulation of microstructural evolution during solidification by using various approaches, including DICTRA and the phase-field method.

Effect of nano-oxide layers on giant magnetoresistance in pseudo-spin-valves using Co2FeAl electrodes

International Nuclear Information System (INIS)

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

2011-01-01

We studied the pseudo-spin-valves (PSVs) with a structure of Ta/Co 2 FeAl/NOL 1 /Co 2 FeAl/Cu/Co 2 FeAl/NOL 2 /Ta, where NOL represents the nano-oxide layer. Compared with the normal Co 2 FeAl (CFA) PSV with a structure of Ta/Co 2 FeAl/Cu/Co 2 FeAl/Ta, which shows only a current-in-plane (CIP) giant magnetoresistance (GMR) of 0.03%, the CFA PSV with NOLs shows a large CIP-GMR of 5.84%. The enhanced GMR by the NOLs inserted in the CFA PSV is due to the large specular reflection caused by [(CoO)(Fe 2 O 3 )(Al 2 O 3 )] in NOL 1 and [(Fe 2 O 3 )(Al 2 O 3 )(Ta 2 O 5 )] in NOL 2 . Another reason is that the roughness of the interface between Ta and CFA is improved by the oxidation procedure. - Research highlights: → Nano-oxide layers are applied in the pseudo-spin-valves with the Heusler alloy. → The CIP-GMR of pseudo-spin-valves is improved from 0.03% to 5.84%. → The GMR ratio is decided by the position of nano-oxide layers.

Amorphous Al-Mn coating on NdFeB magnets: Electrodeposition from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid and its corrosion behavior

Energy Technology Data Exchange (ETDEWEB)

Chen Jing; Xu Bajin [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Ling Guoping, E-mail: linggp@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2012-06-15

Amorphous Al-Mn coating was electrodeposited on NdFeB magnets from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid with the pretreatment of anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al-Mn alloy coating to the NdFeB substrate. The amorphous Al-Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: Black-Right-Pointing-Pointer Amorphous Al-Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. Black-Right-Pointing-Pointer To remove the surface oxides of NdFeB, anodic etching pretreatment is used. Black-Right-Pointing-Pointer The deposited Al-Mn alloy coating shows high adhesion to the NdFeB substrate. Black-Right-Pointing-Pointer Corrosion tests show that amorphous Al-Mn alloy coating is anodic coating for NdFeB magnet.

Solidifying incongruently melting intermetallic phases as bulk single phases using the example of Al{sub 2}Cu and Q-phase in the Al-Mg-Cu-Si system

Energy Technology Data Exchange (ETDEWEB)

Loeffler, Andrea [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany); Groebner, Joachim; Hampl, Milan [Institute of Metallurgy, Clausthal University of Technology, Clausthal-Zellerfeld (Germany); Engelhardt, Hannes [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany); Schmid-Fetzer, Rainer [Institute of Metallurgy, Clausthal University of Technology, Clausthal-Zellerfeld (Germany); Rettenmayr, Markus, E-mail: M.Rettenmayr@uni-jena.de [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany)

2012-02-25

Highlights: Black-Right-Pointing-Pointer Samples consisting of pure Al{sub 2}Cu and 95% Q-phase respectively were prepared. Black-Right-Pointing-Pointer The Q-phase composition is Al{sub 17}Cu{sub 9}Mg{sub 44}Si{sub 30}, its solubility range is negligible. Black-Right-Pointing-Pointer The Q-phase peritectic temperature was determined by DSC measurements as 703 Degree-Sign C. Black-Right-Pointing-Pointer A new thermodynamic dataset for the Q-phase has been assessed. - Abstract: Plane front directional solidification experiments were carried out for preparing incongruently melting intermetallic phases in the quaternary alloy system Al-Cu-Mg-Si, particularly the binary Al{sub 2}Cu phase and the quaternary phase ('Q-phase'). By this method, bulk samples that consist of only a single phase are generated. Sample sections consisting of 100% single phase Al{sub 2}Cu and of 95% Q-phase, respectively, were obtained. The composition of the Q-phase was measured by Energy Dispersive X-ray Spectroscopy (EDX). The measured concentrations are close to the Al{sub 3}Cu{sub 2}Mg{sub 9}Si{sub 7} composition that has recently been predicted as most stable by ab initio calculations. A peritectic temperature of 703 Degree-Sign C for the reaction Q {yields} L + Mg{sub 2}Si + (Si) was determined by differential scanning calorimetry (DSC). An optimization of the Calphad database was performed considering the measured composition and peritectic temperature. For validating the optimized database, Scheil calculations were performed and compared with the experimentally determined sequence of solidifying phases.

Alloy composition dependence of formation of porous Ni prepared by rapid solidification and chemical dealloying

Energy Technology Data Exchange (ETDEWEB)

Qi Zhen [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Zhang Zhonghua [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)], E-mail: zh_zhang@sdu.edu.cn; Jia Haoling [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Qu Yingjie [Shandong Labor Occupational Technology College, Jingshi Road 388, Jinan 250022 (China); Liu Guodong; Bian Xiufang [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)

2009-03-20

In this paper, the effect of alloy composition on the formation of porous Ni catalysts prepared by chemical dealloying of rapidly solidified Al-Ni alloys has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and N{sub 2} adsorption experiments. The experimental results show that rapid solidification and alloy composition have a significant effect on the phase constituent and microstructure of Al-Ni alloys. The melt spun Al-20 at.% Ni alloy consists of {alpha}-Al, NiAl{sub 3} and Ni{sub 2}Al{sub 3}, while the melt spun Al-25 and 31.5 at.% Ni alloys comprise NiAl{sub 3} and Ni{sub 2}Al{sub 3}. Moreover, the formation and microstructure of the porous Ni catalysts are dependent upon the composition of the melt spun Al-Ni alloys. The morphology and size of Ni particles in the Ni catalysts inherit from those of grains in the melt spun Al-Ni alloys. Rapid solidification can extend the alloy composition of Al-Ni alloys suitable for preparation of the Ni catalysts, and obviously accelerate the dealloying process of the Al-Ni alloys.

Rapid fabrication of superhydrophobic Al/Fe{sub 2}O{sub 3} nanothermite film with excellent energy-release characteristics and long-term storage stability

Energy Technology Data Exchange (ETDEWEB)

Ke, Xiang; Zhou, Xiang, E-mail: zhouxiang@njust.edu.cn; Hao, Gaozi; Xiao, Lei; Liu, Jie; Jiang, Wei, E-mail: superfine_jw@126.com

2017-06-15

Highlights: • Superhydrophobic Al/Fe{sub 2}O{sub 3} nanothermite film is prepared by combining electrophoretic deposition and surface modification technologies. • The deposition system and kinetics of electrophoretic deposition process are investigated to optimize parameters to obtain smooth films. • Energy-release characteristics of superhydrophobic films are significantly improved for both fresh and aged samples. • Superhydrophobic films exhibit excellent long-time storage stability both in natural and accelerated aging test. • A preignition reaction is found to enhance the energy-release characteristics of superhydrophobic nanothermite film. - Abstract: One of the challenges for the application of energetic materials is their energy-retaining capabilities after long-term storage. In this study, we report a facile method to fabricate superhydrophobic Al/Fe{sub 2}O{sub 3} nanothermite film by combining electrophoretic deposition and surface modification technologies. Different concentrations of dispersion solvents and additives are investigated to optimize the deposition parameters. Meanwhile, the dependence of deposition rates on nanoparticle concentrations is also studied. The surface morphology and chemical composition are characterized by field-emission scanning electron microscopy, X-ray diffraction, X-ray energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. A static contact angles as high as 156° shows the superhydrophobicity of the nanothermite film. Natural and accelerated aging tests are performed and the thermal behavior is analyzed. Thermal analysis shows that the surface modification contributes to significantly improved energy-release characteristics for both fresh and aged samples, which is supposed to be attributed to the preignition reaction between Al{sub 2}O{sub 3} shell and FAS-17. Superhydrophobic Al/Fe{sub 2}O{sub 3} nanothermite film exhibits excellent long-time storage stability with 83.4% of energy left in

Tritium permeation characterization of Al{sub 2}O{sub 3}/FeAl coatings as tritium permeation barriers on 321 type stainless steel containers

Energy Technology Data Exchange (ETDEWEB)

Yang, Feilong; Xiang, Xin; Lu, Guangda; Zhang, Guikai, E-mail: zhangguikai@caep.cn; Tang, Tao; Shi, Yan; Wang, Xiaolin

2016-09-15

Accurate tritium transport properties of prospective tritium permeation barriers (TPBs) are essential to tritium systems in fusion reactors. By passing a temperature and rate-controlled sweeping gas over specimen surfaces to carry the permeated tritium to an ion chamber, the gas-driven permeation of tritium has been performed on 321 type stainless steel containers with Al{sub 2}O{sub 3}/FeAl barriers, to determine the T-permeation resistant performance and mechanism of the barrier. The tritium permeability of the Al{sub 2}O{sub 3}/FeAl coated container was reduced by 3 orders of magnitude at 500–700 °C by contrast with that of the bare one, which meets the requirement of the tritium permeation reduction factor (PRF) of TPBs for tritium operating components in the CN-HCCB TBM. The Al{sub 2}O{sub 3}/FeAl barrier resists the tritium permeation by the diffusion in the bulk substrate at a limited number of defect sites with an effective area and thickness, suggesting that the TPB quality is a very important factor for efficient T-permeation resistance. - Highlights: • T-permeation has been measured on bare and coated type 321 SS containers. • Al{sub 2}O{sub 3}/FeAl coating give a reduction of T-permeability of 3 orders of magnitude. • Mechanism of Al{sub 2}O{sub 3}/FeAl barrier resisting T-permeation has obtained. • Quality of TPB is a very important factor for efficient T-permeating reduction.

Disappearance of superconductivity in the solid solution between (Ca4Al2O6)(Fe2As2) and (Ca4Al2O6)(Fe2P2) superconductors.

Science.gov (United States)

Shirage, Parasharam M; Kihou, Kunihiro; Lee, Chul-Ho; Takeshita, Nao; Eisaki, Hiroshi; Iyo, Akira

2012-09-19

The effect of alloying the two perovskite-type iron-based superconductors (Ca(4)Al(2)O(6))(Fe(2)As(2)) and (Ca(4)Al(2)O(6))(Fe(2)P(2)) was examined. While the two stoichiometric compounds possess relatively high T(c)'s of 28 and 17 K, respectively, their solid solutions of the form (Ca(4)Al(2)O(6))(Fe(2)(As(1-x)P(x))(2)) do not show superconductivity over a wide range from x = 0.50 to 0.95. The resultant phase diagram is thus completely different from those of other typical iron-based superconductors such as BaFe(2)(As,P)(2) and LaFe(As,P)O, in which superconductivity shows up when P is substituted for As in the non-superconducting "parent" compounds. Notably, the solid solutions in the non-superconducting range exhibit resistivity anomalies at temperatures of 50-100 K. The behavior is reminiscent of the resistivity kink commonly observed in various non-superconducting parent compounds that signals the onset of antiferromagnetic/orthorhombic long-range order. The similarity suggests that the suppression of the superconductivity in the present case also has a magnetic and/or structural origin.

Microstructure evolution in undercooled Al–8 wt%Fe melts: Comparison between terrestrial and parabolic flight conditions

International Nuclear Information System (INIS)

Chen, J.; Lengsdorf, R.; Henein, H.; Herlach, D.M.; Dahlborg, U.; Calvo-Dahlborg, M.

2013-01-01

Highlights: ► A comparison between the solidification using electromagnetic levitation of Al–8 wt%Fe under terrestrial and reduced gravity conditions is shown. ► The microstructure evolution during solidification of Al–8 wt%Fe is formulated with the aid of a comprehensive set of complementary characterization techniques. ► Identification of Al–Fe intermetallics using TEM and Rietveld analysis. -- Abstract: Al–8 wt%Fe, a hypereutectic alloy, was studied under electromagnetic levitation (EML) solidification conditions in both terrestrial and reduced gravity conditions. The latter was carried out on the A300 aircraft using the TEMPUS facility. The solidified samples were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and neutron diffraction techniques. The results are interpreted in the light of the temperature–time measurements taken in situ during the solidification process in the EML. It is shown that both samples experienced some undercooling for the solidification of the primary Al–Fe intermetallic phase, which is likely Al m Fe. The solidification path continues with the nucleation and growth of Al 13 Fe 4 followed by primary α-Al. These last two phases do not seem to show any measureable undercooling and recalescence events. Finally, the metastable Al x Fe (where x = 5) nucleates starting with the formation of eutectic. This metastable intermetallic continues the eutectic growth as Al 13 Fe 4 . The morphology differences of the intermetallics growing under terrestrial and reduced gravity conditions are clear with acicular morphology for the former and a star like morphology for the latter. The primary α-Al has a clear strong textured structure in the reduced gravity sample, while a weak one is observed in the terrestrially processed sample. The difference in texture is attributed to the weaker fluid flow occurring in the droplet under reduced gravity conditions while the difference in

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.

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.

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

Science.gov (United States)

Zöll, Klaus; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2018-02-01

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1-5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2. In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400 °C. By increasing the temperature up to 1425 °C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450 °C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35 μm in size could be retrieved from the 1425 °C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P 1 ̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1. Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium

An X-ray absorption spectroscopic study of the metal site preference in Al1-xGaxFeO3

Science.gov (United States)

Walker, James D. S.; Grosvenor, Andrew P.

2013-01-01

Magnetoelectric materials have potential for being introduced into next generation technologies, especially memory devices. The AFeO3 (Pna21; A=Al, Ga) system has received attention to better understand the origins of magnetoelectric coupling. The magnetoelectric properties this system exhibits depend on the amount of anti-site disorder present, which is affected by the composition and the method of synthesis. In this study, Al1-xGaxFeO3 was synthesized by the ceramic method and studied by X-ray absorption spectroscopy. Al L2,3-, Ga K-, and Fe K-edge spectra were collected to examine how the average metal coordination number changes with composition. Examination of XANES spectra from Al1-xGaxFeO3 indicate that with increasing Ga content, Al increasingly occupies octahedral sites while Ga displays a preference for occupying the tetrahedral site. The Fe K-edge spectra indicate that more Fe is present in the tetrahedral site in AlFeO3 than in GaFeO3, implying more anti-site disorder is present in AlFeO3.

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

Institute of Scientific and Technical Information of China (English)

邓文; 钟夏平; 黄宇阳; 熊良钺; 王淑荷; 郭建亭; 龙期威

1999-01-01

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

Structural evolution of Fe-50 at.% Al powders during mechanical alloying and subsequent annealing processes

International Nuclear Information System (INIS)

Haghighi, Sh. Ehtemam; Janghorban, K.; Izadi, S.

2010-01-01

Iron aluminides, despite having desirable properties like excellent corrosion resistance, present low room-temperature ductility and low strength at high temperatures. Mechanical alloying as a capable process to synthesize nanocrystalline materials is under consideration to modify these drawbacks. In this study, the microstructure of iron aluminide powders synthesized by mechanical alloying and subsequent annealing was investigated. Elemental Fe and Al powders with the same atomic percent were milled in a planetary ball mill for 15 min to 100 h. The powder milled for 80 h was annealed at temperatures of 300, 500 and 700 o C for 1 h. The alloyed powders were disordered Fe(Al) solid solutions which were transformed to FeAl intermetallic after annealing. The effect of the milling time and annealing treatment on structural parameters, such as crystallite size, lattice parameter and lattice strain was evaluated by X-ray diffraction. Typically, these values were 15 nm, 2.92 A and 3.1% for the disordered Fe(Al) solid solution milled for 80 h and were 38.5 nm, 2.896 A and 1.2% for the FeAl intermetallic annealed at 700 o C, respectively.

Enhanced antiferromagnetic coupling in dual-synthetic antiferromagnet with Co2FeAl electrodes

International Nuclear Information System (INIS)

Zhang, D.L.; Xu, X.G.; Wu, Y.; Li, X.Q.; Miao, J.; Jiang, Y.

2012-01-01

We study dual-synthetic antiferromagnets (DSyAFs) using Co 2 FeAl (CFA) Heusler electrodes with a stack structure of Ta/CFA/Ru/CFA/Ru/CFA/Ta. When the thicknesses of the two Ru layers are 0.45 nm, 0.65 nm or 0.45 nm, 1.00 nm, the CFA-based DSyAF has a strong antiferromagnetic coupling between adjacent CFA layers at room temperature with a saturation magnetic field of ∼11,000 Oe, a saturation magnetization of ∼710 emu/cm 3 and a coercivity of ∼2.0 Oe. Moreover, the DSyAF has a good thermal stability up to 400 °C, at which CFA films show B2-ordered structure. Therefore, the CFA-based DSyAFs are favorable for applications in future spintronic devices. - Graphical abstract: Display Omitted Highlights: ► Co 2 FeAl can be applied in room temperature dual-synthetic antiferromagnets. ► Co 2 FeAl dual-synthetic antiferromagnets have a good thermal stability up to 400 °C. ► The Co 2 FeAl has B2-ordered structure in annealed dual-synthetic antiferromagnets.

Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

Directory of Open Access Journals (Sweden)

ZHU Xue-mei

2017-08-01

Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.