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Sample records for crystalline fe-b alloys

  1. Electronic Structures Localized at the Boron Atom in Amorphous Fe-B and Fe-B-P Alloys

    Science.gov (United States)

    Yasuda, Hidehiro; Nakayama, Hiroshi; Fujita, Hiroshi

    1989-11-01

    The electronic structures localized at the B in amorphous Fe-B and Fe-B-P alloys and their crystallized alloys were studied by Auger valence electron spectroscopy and the states of solute B are discussed based on the change in the degree of covalent bonding and the charge transfer between the Fe and B atoms. In amorphous phases, the charge transfers from Fe to B above 15at%B where B atoms occupy the substitutionallike situations, and from B to Fe below 15at%B where B atoms occupy the interstitiallike situations. Magnetic properties depend on such states of solute B. In crystalline phases, covalent bonding becomes dominant because the electron excitation occurs to the B2p state. Consequently, amorphous phases are more metallic in character than crystalline phases and amorphous structures are stabilized by a mixture of more than two different bonding states.

  2. Moessbauer study of isothermally annealed amorphous Fe-Nb-Cu-Si-B alloys

    International Nuclear Information System (INIS)

    Sitek, J.; Toth, I.; Miglierini, M.

    1993-01-01

    Amorphous ribbons of Fe 73.5 Nb 3 Cu 1 Si 13.5 B 9 have been annealed above the crystallization temperature. Annealed samples consisted of crystalline and amorphous phases in a wide temperature range. Two samples of different thicknesses of 33 μm and 27 μm were isothermally annealed at a temperature of 545 C from 0.5 to 5 h in a vacuum furnace. The amount of crystalline phase increases rapidly in the ticker sample. The crystalline part of the Moessbauer spectrum consists of four sharp sextets which can be assigned to a DO 3 -structure FeSi alloy. After 700 C annealing the amorphous phase was not observed and the crystalline phase consisted of the DO 3 -structure FeSi alloy, paramagnetic FeNbB and presumably Fe 23 B 6 and Fe 3 SiB 2 . (orig.)

  3. Moessbauer study of isothermally annealed amorphous Fe-Nb-Cu-Si-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, J. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Toth, I. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia)); Miglierini, M. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava (Slovakia))

    1993-11-01

    Amorphous ribbons of Fe[sub 73.5]Nb[sub 3]Cu[sub 1]Si[sub 13.5]B[sub 9] have been annealed above the crystallization temperature. Annealed samples consisted of crystalline and amorphous phases in a wide temperature range. Two samples of different thicknesses of 33 [mu]m and 27 [mu]m were isothermally annealed at a temperature of 545 C from 0.5 to 5 h in a vacuum furnace. The amount of crystalline phase increases rapidly in the ticker sample. The crystalline part of the Moessbauer spectrum consists of four sharp sextets which can be assigned to a DO[sub 3]-structure FeSi alloy. After 700 C annealing the amorphous phase was not observed and the crystalline phase consisted of the DO[sub 3]-structure FeSi alloy, paramagnetic FeNbB and presumably Fe[sub 23]B[sub 6] and Fe[sub 3]SiB[sub 2]. (orig.)

  4. Mechanically alloyed PrFeB nanocrystalline magnets

    International Nuclear Information System (INIS)

    Kaszuwara, W.; Leonowicz, M.

    1998-01-01

    Mechanically alloyed PrFeB nanocrystalline magnets were prepared by extensive ball milling of Pr, Fe and Fe 80 B 20 powders, followed by diffusion annealing. After milling, the material consisted of nanocrystalline α-Fe crystallites embedded in amorphous Pr-rich matrix. Thermomagnetic and calorimetric investigations of the transformations which occurred during annealing showed that the amorphous phase crystallised at 240 C, leading to the formation of crystalline Pr having lattice constants 10% greater than those shown in the ASTM data. This fact indicated that mechanical alloying and low temperature annealing led to the formation of a solid solution of either Fe or B in Pr, which does not exist in the equilibrium state. The Pr 2 Fe 14 B phase was subsequently formed within a temperature range of 420-620 C. The magnetic properties of magnets depend on the phase structure and grain size. Milling time appears to be a decisive processing parameter for the tailoring of the magnetic properties. Depending on the phase structure, the coercivities varied from 100 to 1200 kA/m and, respectively, the remanences from 0.98 T to 0.6 T. The highest maximum energy product was 80 kJ/m 3 . (orig.)

  5. Effect of hydridation on structure of amorphous and amorphous-crystalline Fe40Ni40B20 and Co70Fe5Si15B10 bands

    International Nuclear Information System (INIS)

    Il'inskij, A.G.; Brovko, A.P.; Zelinskaya, G.M.; Kosenko, N.S.; Khristenko, T.M.; Kobzenko, G.F.; Shkola, A.A.

    1988-01-01

    The structure of amorphous and amorphous-crystaliline Fe 40 Ni 40 B 20 and Co 70 Fe 5 Si-1 5 B 10 alloys, exposed to hydridation at different temperatures, is studied by X-ray diffraction technique. The presence of crystalline constituent in amorphous bands was determined on DRON-3 device and by method of small-angle scattering. The experimental data obtained verify, that hydridation does not only prevent the formation of crystalline phases at annealing, but leads, as well, to disappearance of band crystalline constituent in case of its presence

  6. Evolution of Fe environments in mechanically alloyed Fe–Nb–(B) compositions

    Energy Technology Data Exchange (ETDEWEB)

    Blázquez, J.S., E-mail: jsebas@us.es; Ipus, J.J.; Conde, C.F.; Conde, A.

    2014-12-05

    Highlights: • Nb is rapidly incorporated to the nanocrystalline FeNb(B) matrix. • B inclusions remains even after long milling times. • B is helpful to enhance the comminuting of crystallites. - Abstract: Nanocrystalline alloys of nominal composition Fe{sub 85}Nb{sub 5}B{sub 10} were produced by mechanical alloying from a mixture of elemental powders. Two commercial boron structures were used: amorphous and crystalline. In addition, a third composition Fe{sub 94.4}Nb{sub 5.6} was prepared for comparison. X-ray diffraction and Mössbauer spectroscopy were used to describe the evolution of the microstructure and Fe environments as a function of the milling time. Whereas Nb is rapidly incorporated into the nanocrystalline matrix, boron inclusions remain even after long milling times. The presence of boron is found to enhance the comminuting of crystallites.

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

    International Nuclear Information System (INIS)

    Pekala, K.; Jaskiewicz, P.; Nowinski, J.L.; Pekala, M.

    2003-01-01

    In new supercooled Fe 74 Al 4 Ga 2 P 11 B 4 Si 4 Cu 1 alloy the 10 nm size α-Fe(Si) nanocrystals are precipitated. Thermal stability is analyzed by the electron transport and magnetization measurements. Temperature variation of electrical resistivity of nanocrystals is determined and discussed for alloys with different initial crystalline fraction. Possible mechanism inhibiting the grain growth is presented

  8. Amorphous-to-crystalline phase transformation by neutron irradiation of the alloy Fe83B17

    International Nuclear Information System (INIS)

    Weis, J.; Gabris, F.; Cerven, I.; Sitek, J.

    1984-01-01

    The purpose of the present work is to investigate the structural changes of amorphous Fe 83 B 17 alloy after irradiation with fast neutrons ( > 1 MeV) and to compare with the crystallization behaviour of the amorphous Fe 83 B 17 alloy after annealing. The structural changes were studied by Moessbauer spectroscopy and X-ray diffraction with the usual Fourier analysis. (author)

  9. The corrosion behaviour and structure of amorphous and thermally treated Fe-B-Si alloys

    International Nuclear Information System (INIS)

    Raicheff, R.; Zaprianova, V.; Petrova, E.

    2003-01-01

    The corrosion behaviour of magnetic amorphous alloys Fe 78 B 13 Si 9 , Fe 81 B 13 Si 4 C 2 and Fe 67 Co 18 Bi 4 S 1 obtained by rapid quenching from the melts are investigated in a model corrosive environment of 1N H 2 SO 4 . The structure of the alloys, is, characterized by DTA, SEM, TEM, X-ray and electron diffraction techniques. The dissolution kinetics of the,alloys is studied using gravimetric and electrochemical polarization measurements. It is established that the corrosion rate of the amorphous Fe 67 Co 18 Bt 4 S 1 alloy is up to 50 times lower than that of Fe 78 Bi 3 Si 9 alloy and the addition of cobalt leads to a considerable reduction of the rates of both partial corrosion reactions, while the addition of carbon results only in a moderate decrease (2-3 times) of the corrosion rate. It is also shown that the crystallization of the amorphous Fe 78 B 13 Si 9 alloy (at 700 o C for 3 h) leads to formation of multiphase structure consisting of crystalline phases α-Fe and Fe 3 (B,Si). After crystallization an increase of the rate of both hydrogen evolution and anodic dissolution reactions is observed which results in a considerable (an order of magnitude) increase of the corrosion rate of the alloy. (Original)

  10. Sintered powder cores of high Bs and low coreloss Fe84.3Si4B8P3Cu0.7 nano-crystalline alloy

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2013-06-01

    Full Text Available Nano-crystalline Fe-rich Fe84.3Si4B8P3Cu0.7 alloy ribbon with saturation magnetic flux density (Bs close to Si-steel exhibits much lower core loss (Wt than Si-Steels. Low glass forming ability of this alloy limits fabrication of magnetic cores only to stack/wound types. Here, we report on fabrication, structural, thermal and magnetic properties of bulk Fe84.3Si4B8P3Cu0.7 cores. Partially crystallized ribbons (obtained after salt-bath annealing treatment were crushed into powdered form (by ball milling, and were compacted to high-density (∼88% bulk cores by spark plasma sintering (SPS. Nano-crystalline structure (consisting of α-Fe grain in remaining amorphous matrix similar to wound ribbon cores is preserved in the compacted cores. At 50 Hz, cores sintered at Ts = 680 K show Wt 1 kHz. A trade-off between porosity and electrical resistivity is necessary to get low Wt at higher f. In the f range of ∼1 to 100 kHz, we have shown that the cores mixed with SiO2 exhibit much lower Wt than Fe-powder cores, non-oriented Si-steel sheets and commercially available sintered cores. We believe our core material is very promising to make power electronics/electrical devices much more energy-efficient.

  11. Amorphous-to-crystalline phase transformation by neutron irradiation of the alloy Fe/sub 83/B/sub 17/

    Energy Technology Data Exchange (ETDEWEB)

    Weis, J.; Gabris, F.; Cerven, I.; Sitek, J. (Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia))

    1984-03-01

    The purpose of the present work is to investigate the structural changes of amorphous Fe/sub 83/B/sub 17/ alloy after irradiation with fast neutrons ( > 1 MeV) and to compare with the crystallization behaviour of the amorphous Fe/sub 83/B/sub 17/ alloy after annealing. The structural changes were studied by Moessbauer spectroscopy and X-ray diffraction with the usual Fourier analysis.

  12. Mechanochemical synthesis of nanocrystalline Fe and Fe–B magnetic alloys

    International Nuclear Information System (INIS)

    Mohammadi, Majid; Ghasemi, Ali; Tavoosi, Majid

    2016-01-01

    Mechanochemical synthesis and magnetic characterization of nanocrystalline Fe and Fe–B magnetic alloys was the goal of this study. In this regard, different Fe_2O_3–B_2O_3 powder mixtures with sufficient amount of CaH_2 were milled in a planetary ball mill in order to produce nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that, nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys can be successfully synthesized by the reduction reaction of Fe_2O_3 and B_2O_3 with CaH_2 during mechanical alloying. The structure of produced Fe_9_5B_5 and Fe_8_5B_1_5 alloys was a combination of Fe and Fe_2B phases with average crystallite sizes of about 15 and 10 nm, respectively. The produced nanocrystalline alloys exhibited soft magnetic properties with the coercivity and saturation of magnetization in the range of 170–240 Oe and 9–28 emu/g, respectively. Increasing the boron content has a destructive effect on soft magnetic properties of Fe–B alloys. - Highlights: • We study the mechanochemical synthesis of nanocrystalline boron, Fe and Fe–B alloys. • We study the reduction reaction of B_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–B_2O_3–CaH_2 during milling. • We study the effect of B on magnetic properties of nanocrystalline Fe–B alloys.

  13. The effect of Mn and B on the magnetic and structural properties of nanostructured Fe60Al40 alloys produced by mechanical alloying.

    Science.gov (United States)

    Rico, M M; Alcázar, G A Pérez; Zamora, L E; González, C; Greneche, J M

    2008-06-01

    The effect of Mn and B on the magnetic and structural properties of nanostructured samples of the Fe60Al40 system, prepared by mechanical alloying, was studied by 57Fe Mössbauer spectrometry, X-ray diffraction and magnetic measurements. In the case of the Fe(60-x)Mn(x)Al40 system, 24 h milling time is required to achieve the BCC ternary phase. Different magnetic structures are observed according to the temperature and the Mn content for alloys milled during 48 h: ferromagnetic, antiferromagnetic, spin-glass, reentrant spin-glass and superparamagnetic behavior. They result from the bond randomness behaviour induced by the atomic disorder introduced by the MA process and from the competitive interactions of the Fe-Fe ferromagnetic interactions and the Mn-Mn and Fe-Mn antiferromagnetic interactions and finally the presence of Al atoms acting as dilutors. When B is added in the Fe60Al40 alloy and milled for 12 and 24 hours, two crystalline phases were found: a prevailing FeAl BCC phase and a Fe2B phase type. In addition, one observes an additional contribution attributed to grain boundaries which increases when both milling time and boron composition increase. Finally Mn and B were added to samples of the Fe60Al40 system prepared by mechanical alloying during 12 and 24 hours. Mn content was fixed to 10 at.% and B content varied between 0 and 20 at.%, substituting Al. X-ray patterns show two crystalline phases, the ternary FeMnAl BCC phase, and a (Fe,Mn)2B phase type. The relative proportion of the last phase increases when the B content increases, in addition to changes of the grain size and the lattice parameter. Such behavior was observed for both milling periods. On the other hand, the magnetic hyperfine field distributions show that both phases exhibit chemical disorder, and that the contribution attributed to the grain boundaries is less important when the B content increases. Coercive field values of about 10(2) Oe slightly increase with boron content

  14. Mechanochemical synthesis of nanocrystalline Fe and Fe–B magnetic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Majid; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid

    2016-12-01

    Mechanochemical synthesis and magnetic characterization of nanocrystalline Fe and Fe–B magnetic alloys was the goal of this study. In this regard, different Fe{sub 2}O{sub 3}–B{sub 2}O{sub 3} powder mixtures with sufficient amount of CaH{sub 2} were milled in a planetary ball mill in order to produce nanocrystalline Fe, Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that, nanocrystalline Fe, Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys can be successfully synthesized by the reduction reaction of Fe{sub 2}O{sub 3} and B{sub 2}O{sub 3} with CaH{sub 2} during mechanical alloying. The structure of produced Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys was a combination of Fe and Fe{sub 2}B phases with average crystallite sizes of about 15 and 10 nm, respectively. The produced nanocrystalline alloys exhibited soft magnetic properties with the coercivity and saturation of magnetization in the range of 170–240 Oe and 9–28 emu/g, respectively. Increasing the boron content has a destructive effect on soft magnetic properties of Fe–B alloys. - Highlights: • We study the mechanochemical synthesis of nanocrystalline boron, Fe and Fe–B alloys. • We study the reduction reaction of B{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the reduction reaction of Fe{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the reduction reaction of Fe{sub 2}O{sub 3}–B{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the effect of B on magnetic properties of nanocrystalline Fe–B alloys.

  15. Effect of crystallization on corrosion behavior of Fe40Ni38B18Mo4 amorphous alloy in 3.5% sodium chloride solution

    DEFF Research Database (Denmark)

    Wu, Y.F.; Chiang, Wen-Chi; Wu, J.K.

    2008-01-01

    After the crystallization of F40Ni38B18Mo4 amorphous alloy by vacuum annealing, the corrosion resistance of its crystalline state shows inferior to its amorphous state due to the local cell action between Ni phase and (Fe, Ni, Mo)(23)B-6 phase in matrix.......After the crystallization of F40Ni38B18Mo4 amorphous alloy by vacuum annealing, the corrosion resistance of its crystalline state shows inferior to its amorphous state due to the local cell action between Ni phase and (Fe, Ni, Mo)(23)B-6 phase in matrix....

  16. Surface crystallization and magnetic properties of amorphous Fe80B20 alloy

    International Nuclear Information System (INIS)

    Vavassori, P.; Ronconi, F.; Puppin, E.

    1997-01-01

    We have studied the effects of surface crystallization on the magnetic properties of Fe 80 B 20 amorphous alloys. The surface magnetic properties have been studied with magneto-optic Kerr measurements, while those of bulk with a vibrating sample magnetometer. This study reveals that surface crystallization is similar to the bulk process but occurs at a lower temperature. At variance with previous results on other iron-based amorphous alloys the surface crystalline layer does not induce bulk magnetic hardening. Furthermore, both the remanence to saturation ratio and the bulk magnetic anisotropy do not show appreciable variations after the formation of the surface crystalline layer. The Curie temperature of the surface layer is lower with respect to the bulk of the sample. These effects can be explained by a lower boron concentration in the surface region of the as-cast amorphous alloy. Measurements of the chemical composition confirm a reduction of boron concentration in the surface region. copyright 1997 American Institute of Physics

  17. Hard magnetic properties and coercivity mechanism of melt-spun Misch Metal-Fe-B alloy

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Ningtao; Luo, Yang, E-mail: eluoyang@foxmail.com; Yan, Wenlong; Yuan, Chao; Yu, Dunbo; Sun, Liang; Lu, Shuo; Li, Hongwei; Zhang, Hongbin

    2017-09-01

    Highlights: • Melt-spun MM{sub 13}Fe{sub 81}B{sub 6} alloy shows that the distributions of the La, Ce, Pr, Nd, Fe and B elements is uniformly distributed, and the grain size is in the range of 30–40 nm, it can be seen that Pr-rich and La-rich phases concentrated on grain boundaries, which resulted in the coercivity augment with the increase of MMFe{sub 2} content, and the grain size is around 40–50 nm in MM{sub 16}Fe{sub 78}B{sub 6}. • There is a significant formation of MMFe{sub 2} with abundant Pr and La, and a small amount of Ce and Nd enriched at the interfacial region in MM{sub 16}Fe{sub 78}B{sub 6}, thus an inhomogeneous region was formed. It is considered that the inhomogeneous region is effective in increasing the coercivity. • The optimum-quenched MM{sub 13}Fe{sub 81}B{sub 6} alloy have been shown to exhibit a coercive force of 6.9 kOe and an energy product of 8.5 MGOe, which is superior to anisotropic ferrite magnets of 4.5 MGOe. - Abstract: Magnetic and structural properties of Misch Metal (MM)-Fe-B alloys, were examined in the melt-spun ribbons. Melt-spun MM-Fe-B samples were prepared at the surface velocities of 18–30 m/s. Crystalline structure and their room-temperature magnetization characteristics were analyzed, and the optimum surface velocity of 20 m/s and nominal composition of MM{sub 13}Fe{sub 81}B{sub 6} were obtained. Microstructural analyses indicate that the grain size is approximately 30–50 nm in the alloys with the optimum characteristics. In the MM{sub 16}Fe{sub 78}B{sub 6} alloys, Pr-rich and La-rich phases concentrated on grain boundaries, which resulted in the coercivity augment with the increase of MMFe{sub 2} content. Dependence of coercivity on applied magnetic field suggested that the mechanism of coercivity in moderate MM-content samples was inhomogeneous domain wall pinning type. The melt-spun ribbons in the optimum condition exhibit a coercive force of 6.9 kOe and an energy product of 8.5 MGOe, which can be used as

  18. Crystallization of Fe83B17 amorphous alloy by electric pulses produced by a capacitor discharge

    International Nuclear Information System (INIS)

    Georgarakis, Konstantinos; Dudina, Dina V.; Mali, Vyacheslav I.; Anisimov, Alexander G.; Bulina, Natalia V.; Moreira Jorge, Alberto Jr.; Yavari, Alain R.

    2015-01-01

    Heating of conductive materials by electric current is used in many technological processes. Application of electric pulses to metallic glasses induces their fast crystallization, which is an interesting and complex phenomenon. In this work, crystallization of the Fe 83 B 17 amorphous alloy induced by pulses of electric current produced has been studied using X-ray diffraction and transmission electron microscopy. Ribbons of the alloy were directly subjected to single pulses of electric current 250 μs long formed by a capacitor discharge. As the value of ∫I 2 dt was increased from 0.33 to 2.00 A 2 s, different crystallization stages could be observed. The crystallization began through the formation of the nuclei of α-Fe. At high values of ∫I 2 dt, α-Fe and tetragonal and orthorhombic Fe 3 B and Fe 23 B 6 were detected in the crystallized ribbons with crystallites of about 50 nm. Thermal annealing of the ribbons at 600 C for 2 min resulted in the formation of α-Fe and tetragonal Fe 3 B. It was concluded that pulses of electric current produced by a capacitor discharge induced transformation of the Fe 83 B 17 amorphous phase into metastable crystalline products. (orig.)

  19. 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)

  20. 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.)

  1. Structural and magnetic evolution of nanostructured Co{sub 40}Fe{sub 10}Zr{sub 10}B{sub 40} prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Raanaei, Hossein, E-mail: hraanaei@yahoo.com [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Abbasi, Sadeq [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Behaein, Saeed [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

    2015-06-15

    The structural and magnetic properties of nanocrystalline alloy powder Co{sub 40}Fe{sub 10}Zr{sub 10}B{sub 40} prepared by mechanical alloying have been characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and differential scanning calorimeter (DSC). It is shown that the crystallite size has been decreased significantly to about 15 nm after 8 h milling time. On continuing the milling time mechanical crystallization and subsequently the alloying process were noticed up to 190 h. Saturation magnetization decreased during the whole process while coercivity achieved the highest value at the crystallization stage. Post treatment of milled powder at 190 h revealed crystalline constituent elements. - Highlights: • This article focuses on mechanical alloying of Co{sub 40}Fe{sub 10}Zr{sub 10}B{sub 40} system. • Mechanical crystallization is observed. • Structural and magnetic properties were investigated. • The heat treatment revealed the crystalline phases of constituent elements.

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  3. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  4. Crystallization of an amorphous Fe72Ni9Si8B11 alloy upon laser heating and isothermal annealing

    International Nuclear Information System (INIS)

    Girzhon, V.V.; Smolyakov, A.V.; Yastrebova, T.S.

    2003-01-01

    With the use of methods of x-ray diffraction, resistometric and metallographic analyses specific features of crystallization and phase formation in amorphous alloy Fe 72 Ni 9 Si 8 B 11 are studied under various heating conditions. It is shown that laser heating results in alloy crystallization by an explosive mechanism when attaining a certain density of irradiation power. It is stated that ribbon surface laser heating with simultaneous water cooling of an opposite surface allows manufacturing two-layer amorphous-crystalline structures of the amorphous matrix + α-(Fe, Si) - amorphous matrix type [ru

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

    International Nuclear Information System (INIS)

    Lee, Kee Ahn; Kim, Yong Chan; Kim, Jung Han; Lee, Chong Soo; Namkung, Jung; Kim, Moon Chul

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-25

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

  7. Crystallization kinetics of Fe-B based amorphous alloys studied in-situ using X-rays diffraction and differential scanning calorimetry

    Directory of Open Access Journals (Sweden)

    Santos D.R. dos

    2001-01-01

    Full Text Available The crystallization processes for the amorphous metallic alloys Fe74B17Si2Ni4Mo3 and Fe86B6Zr7Cu1 (at. % were investigated using X-rays diffraction measurements performed in-situ during Joule-heating, with simultaneous monitoring of the electrical resistance. We determined the main structural transitions and crystalline phases formed during heating, and correlated these results to the observed resistance variations. As the annealing current is increased, the resistance shows an initial decrease due to stress relaxation, followed by a drop to a minimum value due to massive nucleation and growth of alpha-Fe nanocrystals. Further annealing causes the formation of small fractions of Fe-B, B2Zr or ZrO2, while the resistance increases due to temperature enhancement. In situ XRD measurements allowed the identification of metastable phases, as the gamma-Fe phase which occurs at high temperatures. The exothermal peaks observed in the differential scanning calorimetry (DSC for each alloy corroborate the results. We also have performed DSC measurements with several heating rates, which allowed the determination of the Avrami exponent and crystallization activation energy for each alloy. The obtained activation energies (362 and 301 kJ/mol for Fe-B-Zr-Cu; 323 kJ/mol for Fe-B-Si-Ni-Mo are comparable to reported values for amorphous iron alloys, while the Avrami exponent values (n = 1.0 or n = 1.2 are consistent with diffusion controlled crystallization processes with nucleation rates close to zero.

  8. Investigation of (Fe,Co)NbB-Based Nanocrystalline Soft Magnetic Alloys by Lorentz Microscopy and Off-Axis Electron Holography.

    Science.gov (United States)

    Zheng, Changlin; Kirmse, Holm; Long, Jianguo; Laughlin, David E; McHenry, Michael E; Neumann, Wolfgang

    2015-04-01

    The relationship between microstructure and magnetic properties of a (Fe,Co)NbB-based nanocrystalline soft magnetic alloy was investigated by analytical transmission electron microscopy (TEM). The microstructures of (Fe0.5Co0.5)80Nb4B13Ge2Cu1 nanocrystalline alloys annealed at different temperatures were characterized by TEM and electron diffraction. The magnetic structures were analyzed by Lorentz microscopy and off-axis electron holography, including quantitative measurement of domain wall width, induction, and in situ magnetic domain imaging. The results indicate that the magnetic domain structure and particularly the dynamical magnetization behavior of the alloys strongly depend on the microstructure of the nanocrystalline alloys. Smaller grain size and random orientation of the fine particles decrease the magneto-crystalline anisotropy and suggests better soft magnetic properties which may be explained by the anisotropy model of Herzer.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  10. Effect of heat treatment on Fe-B-Si-Nb alloy powder prepared by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Rodrigo Estevam Coelho

    2005-06-01

    Full Text Available The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA and for different milling times (1, 5, 25, 70 and 100 hours. Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm. The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.

  11. 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)

  12. Study of Nd-Fe-B alloys with nonstoichiometric Nd content in optimal magnetic state

    Directory of Open Access Journals (Sweden)

    Ćosović V.

    2009-01-01

    Full Text Available Characterization of two rapid-quenched Nd-Fe-B alloys with nonstoichiometric Nd content in the optimized magnetic state was carried out using the X-ray diffractometry (XRD, 57Fe Mössbauer spectroscopic phase analysis (MS, electron microscopy (TEM, high resolution TEM (HREM and Superconducting Quantum Interference Device (SQUID magnetometer. The experimental results demonstrate the fundamental difference in the structure and magnetic properties of the two investigated alloys in the optimized magnetic state. The Nd-Fe-B alloy with the reduced Nd content (Nd4.5Fe77B18.5 was found to have the nanocomposite structure of Fe3B/Nd2Fe14B and partly α-Fe/Nd2Fe14B, with mean grain size below 30 nm. On the other side, the overstoichiometric Nd14Fe79B7 alloy has almost a monophase structure with the dominant content of the hard magnetic phase Nd2Fe14B (up to 95 wt. % and a mean crystallite size about 60 nm, as determined by XRD and TEM analysis. The results of magnetic measurements on SQUID magnetometer also suggest the nanocomposite structure of the Nd-low alloy and nanocrystalline decoupled structure of the Nd-rich alloy after the optimal heat treatment.

  13. Structural investigation of Fe(Cu)ZrB amorphous alloy

    International Nuclear Information System (INIS)

    Duhaj, P.; Janickovic, D.

    1996-01-01

    The crystallization process in Fe 86 (Cu 1 )Zr 7 B 6 and Fe 87 Zr 7 B 6 is investigated using the methods of transmission electron microscopy, electron and X-ray diffraction and resistometry. Two crystallization reactions take place during thermal annealing of amorphous Fe 86 (Cu 1 )Zr 7 B 6 and Fe 87 Zr 7 B 6 alloys. In both alloys the first crystallization begins with the formation of nanocrystalline α-Fe at temperature to approximately 800 K. The second crystallization starts above 1000 K; the nanocrystalline phase dissolves and together with the remaining amorphous matrix form rough grains of α-Fe and dispersed Fe 23 Zr 6 phases. From Moessbauer spectroscopy it seems that there exist two neighbourhoods of Fe atoms in the amorphous structure. One of them is characterized by low Zr content and is responsible for the high-field component of the hyperfine field distribution p(H). The second one is rich in Zr and B and is responsible for the low-field component of p(H). This is in accord with the observation of two crystallization steps separated by a large interval of temperatures due to the existence of two chemically different regions or clusters. (orig.)

  14. Crystalline-to-amorphous phase transformation in mechanically alloyed Fe50W50 powders

    International Nuclear Information System (INIS)

    Sherif El-Eskandarany, M.S.; Sumiyama, K.; Suzuki, K.

    1997-01-01

    A mechanical alloying process via a ball milling technique has been applied for preparing amorphous Fe 50 W 50 alloy powders. The results have shown that during the first and second stages of milling (0 to 360 ks) W atoms emigrate to Fe lattices to form nanocrystalline b.c.c. Fe-W solid solution, with a grain size of about 7 nm in diameter. After 720 ks of the milling time, this solid solution was transformed to an amorphous Fe-W alloy coexisting with the residual fraction of the unprocessed W powders. During the last stage of milling (720 to 1,440 ks) all of this residual W powder reacts with the amorphous phase to form a homogeneous Fe 50 W 50 amorphous alloy. The crystallization temperature and the enthalpy change of crystallization of amorphous Fe 50 W 50 powders milled for 1,440 ks were measured to be 860 K and -9kJ/mol, respectively. The amorphous Fe 50 W 50 powder produced is almost paramagnetic at room temperature. The powder comprises homogeneous and smooth spheres with an average size of about 0.5 microm in diameter

  15. Chemical synthesis of magnetic Fe-B and Fe-Co-B particles and chains

    International Nuclear Information System (INIS)

    Fulmer, P.; Kim, J.; Manthiram, A.; Sanchez, J.M.

    1999-04-01

    With an objective to develop magnetic materials with high saturation magnetization for the Magnetically Assisted Chemical Separation (MACS) process the chemical synthesis of Fe-B and Fe-Co-B alloys by reducing iron and cobalt chloride solutions with potassium borohydride has been investigated systematically. The influence of the concentration of the reactants, applied magnetic field, reaction atmosphere, and method of mixing the reactants on the microstructure, particle size, composition and magnetic properties has been studied. Both M-B (M = Fe and Co) particles and elongated chains composed of nanometer size M-B particles have been obtained depending on the reaction conditions. The Fe-B samples exhibit saturation magnetization of M S of 120--190 emu/g, remanent magnetization M r of 10--22 emu/g, and coercive field H c of 400--900 Oe. A high M S value of 190 emu/g, which is close to the theoretical value of 218 emu/g for pure Fe, has been achieved particularly for samples with well-defined chain structures. Increasing the Co content in the Fe-Co-B alloys increases the boron content and thereby decreases the crystallinity and M S values although marginal increase in H c (1,250 Oe) and M r (36 emu/g) values could be made in some Fe-Co-B compositions. The chain structure with high M S may be attractive for other magnetic separation processes as well

  16. Microstructure and magnetic properties of Nd-Fe-B-(Re, Ti alloys

    Directory of Open Access Journals (Sweden)

    Hasiak Mariusz

    2015-03-01

    Full Text Available The microstructure and magnetic properties of nanocomposite hard magnetic Nd-Fe-B-(Re, Ti materials with different Nd and Fe contents are studied. The role of Re and Ti addition in phase composition and volume fraction of the Nd-Fe-B phase is determined. All samples are annealed at the same temperature of 993 K for 10 min. Mössbauer spectroscopy shows that the addition of 4 at.% of Re to the Nd8Fe78B14 alloy leads to creation of an ineligible amount of the magnetically hard Nd2Fe14B phase. Moreover, the microstructure and magnetic characteristics recorded in a wide range of temperatures for the Nd8Fe79−xB13Mx (x = 4; M = Re or Ti alloys are also analyzed.

  17. Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

    Directory of Open Access Journals (Sweden)

    W. Y. Zhang

    2016-05-01

    Full Text Available Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti3(Fe,Co5B2, FeCo-rich bcc, and NiAl-rich L21 phases; Ti3(Fe,Co5B2, is a new substitutional alloy series whose end members Ti3Co5B2 and Ti3Fe5B2 have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti11+xFe37.5-0.5xCo37.5−0.5xB14 (x = 0, 4 and alnico-like Ti11Fe26Co26Ni10Al11Cu2B14, the latter also containing an L21-type alloy. The volume fraction of the Ti3(Fe,Co5B2 phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti3(Fe,Co5B2 phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.

  18. Structural investigation of Fe(Cu)ZrB amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Duhaj, P. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Matko, I. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Svec, P. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav; Sitek, J. [Department of Nuclear Physics and Technology, Slovak Technical University, 81219 Bratislava (Slovakia); Janickovic, D. [Slovenska Akademia Vied, Bratislava (Slovakia). Fyzikalny Ustav

    1996-07-01

    The crystallization process in Fe{sub 86}(Cu{sub 1})Zr{sub 7}B{sub 6} and Fe{sub 87}Zr{sub 7}B{sub 6} is investigated using the methods of transmission electron microscopy, electron and X-ray diffraction and resistometry. Two crystallization reactions take place during thermal annealing of amorphous Fe{sub 86}(Cu{sub 1})Zr{sub 7}B{sub 6} and Fe{sub 87}Zr{sub 7}B{sub 6} alloys. In both alloys the first crystallization begins with the formation of nanocrystalline {alpha}-Fe at temperature to approximately 800 K. The second crystallization starts above 1000 K; the nanocrystalline phase dissolves and together with the remaining amorphous matrix form rough grains of {alpha}-Fe and dispersed Fe{sub 23}Zr{sub 6} phases. From Moessbauer spectroscopy it seems that there exist two neighbourhoods of Fe atoms in the amorphous structure. One of them is characterized by low Zr content and is responsible for the high-field component of the hyperfine field distribution p(H). The second one is rich in Zr and B and is responsible for the low-field component of p(H). This is in accord with the observation of two crystallization steps separated by a large interval of temperatures due to the existence of two chemically different regions or clusters. (orig.)

  19. Thermodynamic analysis of binary Fe{sub 85}B{sub 15} to quinary Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloys for primary crystallizations of α-Fe in nanocrystalline soft magnetic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, A., E-mail: takeuchi@imr.tohoku.ac.jp; Zhang, Y.; Takenaka, K.; Makino, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-05-07

    Fe-based Fe{sub 85}B{sub 15}, Fe{sub 84}B{sub 15}Cu{sub 1}, Fe{sub 82}Si{sub 2}B{sub 15}Cu{sub 1}, Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, and Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} (NANOMET{sup ®}) alloys were experimental and computational analyzed to clarify the features of NANOMET that exhibits high saturation magnetic flux density (B{sub s}) nearly 1.9 T and low core loss than conventional nanocrystalline soft magnetic alloys. The X-ray diffraction analysis for ribbon specimens produced experimentally by melt spinning from melts revealed that the samples were almost formed into an amorphous single phase. Then, the as-quenched samples were analyzed with differential scanning calorimeter (DSC) experimentally for exothermic enthalpies of the primary and secondary crystallizations (ΔH{sub x1} and ΔH{sub x2}) and their crystallization temperatures (T{sub x1} and T{sub x2}), respectively. The ratio ΔH{sub x1}/ΔH{sub x2} measured by DSC experimentally tended to be extremely high for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy, and this tendency was reproduced by the analysis with commercial software, Thermo-Calc, with database for Fe-based alloys, TCFE7 for Gibbs free energy (G) assessments. The calculations exhibit that a volume fraction (V{sub f}) of α-Fe tends to increase from 0.56 for the Fe{sub 85}B{sub 15} to 0.75 for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy. The computational analysis of the alloys for G of α-Fe and amorphous phases (G{sub α-Fe} and G{sub amor}) shows that a relationship G{sub α-Fe} ∼ G{sub amor} holds for the Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, whereas G{sub α-Fe} < G{sub amor} for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy at T{sub x1} and that an extremely high V{sub f} = 0.75 was achieved for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy by including 2.8 at. % Si and 4.5 at. % P into α-Fe. These computational results indicate that the Fe{sub 85}Si{sub 2}B

  20. Comparison of high temperature, high frequency core loss and dynamic B-H loops of two 50 Ni-Fe crystalline alloys and an iron-based amorphous alloy

    International Nuclear Information System (INIS)

    Wieserman, W.R.; Schwarze, G.E.; Niedra, J.M.

    1994-01-01

    The availability of experimental data that characterizes the performance of soft magnetic materials for the combined conditions of high temperature and high frequency is almost non-existent. An experimental investigation was conducted over the temperature range of 23 to 300 C and frequency range of 1 to 50 kHz to determine the effects of temperature and frequency on the core loss and dynamic B-H loops of three different soft magnetic materials; an oriented-grain 50Ni-50Fe alloy, a nonoriented-grain 50Ni-50Fe alloy, and an iron-based amorphous material (Metglas 2605SC). A comparison of these materials show that the nonoriented-grain 50Ni-50Fe alloy tends to have either the lowest or next lowest core loss for all temperatures and frequencies investigated

  1. Effect of heating rates of crystallization behaviour of amorphous Fe/sub 83/01/B/sub 17/ alloy

    International Nuclear Information System (INIS)

    Ashfaq, A.; Shamim, A.

    1993-01-01

    The electric resistivity of amorphous Fe/sub 83/01/B/sub 17/ alloy has been measured to study its crystallization behaviour from room temperature to about 900 K at the constant heating rates of 40, 60 and 80 K/hr. The crystallization temperature was observed to increase with the increase of heating g rate. However amorphous to crystalline path of RT-curve between the maximum and the minimum decreases with heating rate. The Resistivity Temperature (RT) curves exhibit different steps which are shown to correspond to the phase change stages of the alloy. The slope of the rt-curve after the previous step increases with the rise in heating rate and finally passes through a board peak and then rises again. From the peak shift dta of first crystallization stage activation energy was calculated by applying various peak shift equations. The values so obtained were in good agreement with those obtained with DSC measurement for (FeM)/sub 83/01/B/sub 17/ amorphous alloys where M=Mo, Ni, Cr, and V. (author)

  2. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Directory of Open Access Journals (Sweden)

    Grujić Aleksandar

    2005-01-01

    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

  3. Methods of characterization of multiphase Nd-Fe-B melt-spun alloys

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2007-01-01

    Full Text Available Nanocomposite permanent magnetic materials based on Nd-Fe-B alloys with a low Nd content are a new type of permanent magnetic material. The microstructure of these nanocomposite permanent magnets is composed of a mixture of magnetically soft and hard phases providing the so called exchange coupling effect. Beside the optimization process parameters, methods of characterization have a very important role in the design of an optimal magnetic matrix of multiphase melt-spun Nd-Fe-B alloys. Different methods and techniques of characterization were used for observation and study of the microstructure evolution during crystallization. A summary results of measurements using different methods of characterization are presented to enable a better insight into relations between the microstructure and magnetic properties of the investigated melt-spun Nd-Fe-B alloys. .

  4. Crystallization of the amorphous Fe80Zr12B8 alloy under controlled heating

    International Nuclear Information System (INIS)

    Huang, H.; Shao, G.; Tsakiropoulos, P.

    2008-01-01

    The devitrification process of amorphous Fe 80 Zr 12 B 8 alloy ribbons were studied under controlled thermal conditions. The major crystallization event during continuous heating with differential scanning calorimetory (DSC) is dictated by diffusion controlled growth and the associated atom mobility of the slow diffusing species Zr. The existence of prior nano-crystals formed by pre-annealing below the crystallization temperature had little effect on the major crystallization temperature. The crystallization sequence during heating was: amorphous → amorphous + α-Fe + Fe 3 Zr(B) → amorphous + α-Fe + Fe 3 Zr(B) + Fe 2 Zr. Different from previous findings in alloys of lower Zr and B contents, the peak for the crystallization of the α-Fe phase alone is missing in the DSC traces of this alloy

  5. Microstructure Formation in Strip-Cast RE-Fe-B Alloys for Magnets

    Science.gov (United States)

    Yamamoto, Kazuhiko; Matsuura, Masashi; Sugimoto, Satoshi

    2017-07-01

    During the manufacturing of sintered NdFeB magnets, it is well known that the microstructure of the starting alloy has a strong influence on the processing and the magnetic properties of the product. In this study, we clarify the microstructure formation in strip-cast rare earth (R)-Fe-B alloys used to produce magnets. The microstructure of the alloy surface in contact with the cooling roll and its cross-section were observed using laser microscopy, field emission electron microprobe analysis, and transmission electron microscopy. The orientations of crystal grains were determined by X-ray diffraction and electron backscatter diffraction analyses. Petal-shaped structures were found to cover the alloy surface in contact with the cooling roll, each consisting of a central nucleation region and radially grown Nd2Fe14B dendritic structures. The nucleation region, consisting of a "disc" and "predendrites", occurs in the super-cooled region of the contact area between the cooling roll and melt. In the disc region, spherical Nd2Fe14B particles in the thickness direction increase in volume. These discs and predendrites observed in the super-cooled area negatively influence the magnetic orientation and sinterability in the produced magnets. Therefore, it is important to avoid excessive super-cooling to obtain optimum magnetic properties.

  6. Hydriding properties of amorphous Ni-B alloy studied by DSC and thermogravimetry

    International Nuclear Information System (INIS)

    Spassov, T.; Rangelova, V.

    1999-01-01

    The hydrogenation behaviour of melt-spun Ni 81.5 B 18.5 amorphous alloy was studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) and compared with the hydriding properties of a Fe-B-Si glass. It was found that the amorphous Ni-B alloy absorbs larger amounts of hydrogen than the Fe-B-Si glass, as the initial kinetics of hydrogen absorption and desorption of both the alloys are comparable. Hydrogen absorption and desorption reactions in Ni-B were observed to proceed with similar rates at ca. 300 K. The hydrogen desorption is revealed in DSC as an endothermic peak in the 350-450 K range, preceding the crystallization peak of the amorphous alloy. The enthalpy of hydrogen desorption (ΔH des =22 kJ/mol H 2 ) for Ni-B was found to be smaller than that for the Fe-B-Si glass, which finding is in contrast to the results on hydrogen diffusion in crystalline αFe and Fe-based alloys and Ni and Ni-based alloys. The hydrogen desorption temperature and enthalpy for Ni 81.5 B 18.5 were found to be independent of the amount of hydrogen absorbed. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Ferromagnetic alloy material CoFeC with high thermal tolerance in MgO/CoFeC/Pt structure and comparable intrinsic damping factor with CoFeB

    Science.gov (United States)

    Chen, Shaohai; Zhou, Jing; Lin, Weinan; Yu, Jihang; Guo, Rui; Poh, Francis; Shum, Danny; Chen, Jingsheng

    2018-02-01

    The thermal tolerance and perpendicular magnetic anisotropy (PMA) of ferromagnetic alloy Co40Fe40C20 in the structure MgO/CoFeC/Pt (or Ta) were investigated and compared with the commonly used CoFeB alloy. It is found that the PMA of CoFeC with {{K}i,CoFeC}=2.21 erg c{{m}-2} , which is 59% higher than that of CoFeB, can be obtained after proper post-annealing treatment. Furthermore, CoFeC alloy provides better thermal tolerance to temperature of 400 °C than CoFeB. The studies on ferromagnetic resonance show that the intrinsic damping constant α in of Co40Fe40C20 alloy is 0.0047, which is similar to the reported value of 0.004 for Co40Fe40B20 alloy. The comprehensive comparisons indicate that CoFeC alloy is a promising candidate for the application of the integration of spin torque transfer magnetic random access memory with complementary metal-oxide semiconductor processes.

  8. Structure and Properties of Nd-Fe-B Alloy Subjected to HDDR Process

    Directory of Open Access Journals (Sweden)

    Szymański M.

    2016-03-01

    Full Text Available In this paper the Hydrogenation, Disproportionation, Desorption and Recombination (HDDR route was tested, for the Nd-Fe-B master alloy, as a prospective procedure for recycling of sintered scrap neodymium magnets. The HDDR method is based on the hydrogen induced reversal phase transformation of Nd-Fe-B alloy: Nd2Fe14B + (2±x H2 = 2NdH2±x + Fe2B + 12Fe. Microstructural observations (SEM, phase constitution studies (XRD and measurement of magnetic properties (VSM were done to investigate the HDDR transformation progress. It was observed that disproportionation reaction starts at the grain boundaries, where the Nd-rich phase is located. Average grain size was reduced and coercive material was produced as a result of the HDDR process. Obtained results are similar to literature data.

  9. Aluminium base amorphous and crystalline alloys with Fe impurity

    International Nuclear Information System (INIS)

    Sitek, J.; Degmova, J.

    2006-01-01

    Aluminium base alloys show remarkable mechanical properties, however their low thermal stability still limits the technological applications. Further improvement of mechanical properties can be reached by partial crystallization of amorphous alloys, which gives rise to nanostructured composites. Our work was focused on aluminium based alloys with Fe, Nb and V additions. Samples of nominal composition Al 90 Fe 7 Nb 3 and Al 94 Fe 2 V 4 were studied in amorphous state and after annealing up to 873 K. From Moessbauer spectra taken on the samples in amorphous state the value of f-factor was determined as well as corresponding Debye temperatures were calculated. Annealing at higher temperatures induced nano and microcrystalline crystallization. Moessbauer spectra of samples annealed up to 573 K are fitted only by distribution of quadrupole doublets corresponding to the amorphous state. An increase of annealing temperature leads to the structural transformation, which consists in growth of nanometer sized aluminium nuclei. This is partly reflected in Moessbauer parameters. After annealing at 673 K intermetallic phase Al 3 Fe and other Al-Fe phases are created. In this case Moessbauer spectra are fitted by quadrupole doublets. During annealing up to 873 K large grains of Fe-Al phases are created. (authors)

  10. Microstructure of Fe-Cr-C hardfacing alloys with additions of Nb, Ti and, B

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.

    1987-01-01

    The abrasive wear of machine parts and tools used in the mining, earth moving, and transporting of mineral materials can be lowered by filler wire welding of hardfacing alloys. In this paper, the microstructures of Fe-Cr-C and Fe-Cr-C-Nb/Ti hardfacing alloys and deposits and those of newly developed Fe-Cr-C-B and Fe-Ti-Cr-C-B ones are described. They show up to 85 vol.% of primarily solidified coarse hard phases; i.e., Carbides of MC-, M/sub 7/C/sub 3/-, M/sub 3/C-type and Borides of MB/sub 2/-, M/sub 3/B/sub 2/-, M/sub 2/B-, M/sub 3/B-, M/sub 23/B/sub 6/-type, which are embedded in a hard eutectic. This itself consists of eutectic hard phases and a martensitic or austenitic metal matrix. The newly developed Fe-Cr-C-B alloys reach hardness values of up to 1200 HV and are harder than all purchased ones. The primary solidification of the MB/sub 2/-type phase of titanium requires such high amounts of titanium and boron that these alloys are not practical for manufacture as commercial filler wires

  11. Modification of dielectric function and electronic structure of the alloys at the phase transformation amorphous-crystalline state

    International Nuclear Information System (INIS)

    Belij, M.U.; Poperenko, L.V.; Shajkevich, I.A.; Karpusha, V.D.; Kravets, V.G.

    1989-01-01

    The relation between the features of the optical spectrum and the electronic structure parameters for non-crystalline nickel- and iron-based alloys is not yet precisely found. Therefore the main purpose of the study consists in investigation of the basic metal band structure modification at metalloid alloying. The density of electron states N(E) and structural parameters of amorphous alloys nickel-M, iron-M, Fe-TM-M (M - metalloid B,Si,C; TM - transition metal 3d (Ti,V,Cr,Mn,Co,Ni), 4d (Nb,Mo), 5d (Hf,Ta,W) and their transformation changes from amorphous (AS) to crystalline state (CS) have been determined. The methods of ellipsometry, Auger-spectroscopy and X-ray absorption spectroscopy are used. The function N(E) of the Ni- and Fe-based alloys has shown 4 density-of-states peaks, one of them located above the Fermi level E F and the others - below it. The observed features of the absorbed spectra of Ni-M (M = B,P) are related both to the interband transition from the levels falling into the occupied peaks of N(E) to the levels at E F , and to the 1-peak-states. When B increases the distance between 1-peak and E F decreases. With introduction of the TM atoms into Fe-B the impurities states related to them are formed above E F . From the X-ray data the cluster with nonhomogeneous electronic density for FeBSi (7.0 nm) and FeNbBSi (7.0 and 4.2 nm along and transverse to foil respectively) are estimated. The frequencies of relaxation and plasma oscillations are also calculated. (author)

  12. Observation of Pseudopartial Grain Boundary Wetting in the NdFeB-Based Alloy

    Science.gov (United States)

    Straumal, B. B.; Mazilkin, A. A.; Protasova, S. G.; Schütz, G.; Straumal, A. B.; Baretzky, B.

    2016-08-01

    The NdFeB-based alloys were invented in 1980s and remain the best-known hard magnetic alloys. In order to reach the optimum magnetic properties, the grains of hard magnetic Nd2Fe14B phase have to be isolated from one another by the (possibly thin) layers of a non-ferromagnetic Nd-rich phase. In this work, we observe that the few-nanometer-thin layers of the Nd-rich phase appear between Nd2Fe14B grains due to the pseudopartial grain boundary (GB) wetting. Namely, some Nd2Fe14B/Nd2Fe14B GBs are not completely wetted by the Nd-rich melt and have the high contact angle with the liquid phase and, nevertheless, contain the 2-4-nm-thin uniform Nd-rich layer.

  13. Magnetic regimes in amorphous Ni--Fe--P--B alloys

    International Nuclear Information System (INIS)

    Durand, J.

    1976-10-01

    A complete substitution of iron for nickel was obtained by splat-cooling in amorphous alloys of composition (Ni/sub 100-y/Fe/sub y/) 79 P 13 B 8 . Results of high-field magnetization (up to 70 kOe), ac and dc low-field susceptibility, Curie temperature, and resistivity measurements over a temperature range of 1.7 to 300 0 K are reported. The Ni 79 P 13 B 8 alloy is not ferromagnetic, but the magnetization behavior as a function of field and temperature is typically that of alloys in the critical concentration range for ferromagnetism. The Fe 79 P 13 B 8 alloy is ferromagnetic with a Curie temperature T/sub c/ of 616 0 K. For y = 1 at. percent, the Fe atoms are magnetic. The variation of the moment per Fe atom as a function of y is discussed. When y is increased, the Ni atoms are likely to be polarized progressively and the moment per Ni atom would be roughly constant for y equal to or greater than 30 at. percent. Various magnetic behaviors were defined as a function of the Fe content. The value of T/sub c/ reaches a maximum for y similarly ordered 90 at. percent and extrapolates to zero for y similarly ordered 7 at. percent. Alloys within the range 1 equal to or less than y equal to or less than 10 at. percent did not exhibit well-defined Curie transition, but sharp maxima in low-field susceptibility measurements were observed at T/sub M/. The value of T/sub M/ is proportional to y for 1 equal to or less than y equal to or less than 4 at. percent, as in classical spin-glass regimes. For 4 less than y equal to or less than 10 at. percent, the variation of T/sub M/ as a function of y implies a more complicated type of magnetic ordering (micromagnetism or superparamagnetism). Homogeneous ferromagnetic ordering emerges only for y greater than 10 at. percent. Results of resistivity measurements are discussed in relation to the magnetic properties of different regimes in the magnetic phase diagram. 6 figures, 2 tables

  14. Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

    International Nuclear Information System (INIS)

    Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

    1983-01-01

    Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

  15. Cold compaction behavior of nano-structured Nd-Fe-B alloy powders prepared by different processes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoya [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Hu, Lianxi, E-mail: hulx@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Erde [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2013-02-25

    Graphical abstract: Relative density enhancement and nanocrystallization of Nd{sub 2}Fe{sub 14}B phase are two major effective means to improve magnetic properties. Since the matrix Nd{sub 2}Fe{sub 14}B phase in the starting Nd-Fe-B alloy can be disproportionated into a nano-structured mixture of NdH{sub 2.7}, Fe{sub 2}B, and {alpha}-Fe phases during mechanical milling in hydrogen. It is thus important to study the densification behavior of nanocrystalline powders to evaluate and predict the cold compactibility of powders. By comparison with the as milled as well as melt-spun Nd{sub 16}Fe{sub 76}B{sub 8} alloy powders, we find that the as-disproportionated Nd{sub 16}Fe{sub 76}B{sub 8} alloy powder exhibits the best cold compactibility. As evident from the illustration presented below, compaction parameters (representing the powder compactibility) have been determined by fitting density-pressure data with double logarithm compaction equation. Densification mechanisms involved during cold compaction process are clarified in our work by referring to microstructure observation of samples prepared by various methods. As a result, highly densified green magnet compact can be obtained by cold pressing of as-disproportionated NdFeB alloy powders. Highlights: Black-Right-Pointing-Pointer Nano-structured disproportionated Nd-Fe-B alloy powders by mechanical milling in hydrogen. Black-Right-Pointing-Pointer Highly densified green magnet compact by cold pressing of as-disproportionated Nd-Fe-B alloy powders. Black-Right-Pointing-Pointer Density-pressure data fitted well by an empirical powder compaction model. Black-Right-Pointing-Pointer As-disproportionated powder showed better compactibility than as milled and melt-spun counterparts. Black-Right-Pointing-Pointer The effects of physical properties on powder compactibility and densification mechanisms are clarified. - Abstract: The compaction behavior of nano-structured Nd{sub 16}Fe{sub 76}B{sub 8} (atomic ratio) alloy

  16. Influence of cobalt content on the structure and hard magnetic properties of nanocomposite (Fe,Co)-Pt-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grabias, A., E-mail: agnieszka.grabias@itme.edu.pl [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Kopcewicz, M. [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Latuch, J.; Oleszak, D. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Pękała, M. [Department of Chemistry, University of Warsaw, Al. Żwirki i Wigury 101, 02-089 Warsaw (Poland); Kowalczyk, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland)

    2017-07-15

    Highlights: • Nanocomposite alloys were formed by annealing of the rapidly quenched alloys. • Magnetically hard L1{sub 0} (Fe,Co)Pt and soft (Fe,Co){sub 2}B or (Fe,Co)B were formed. • Mössbauer spectra revealed Co substitution for Fe in L1{sub 0} FePt, FeB and Fe{sub 2}B phases. • Annealed alloys exhibit hard magnetic properties which depend on phase compositions. • Co addition was found to decrease the magnetization and the energy product. - Abstract: The influence of Co content on the structural and hard magnetic properties of two sets of nanocrystalline Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} (x = 0–26) and Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} (y = 0–40) alloys was studied. The alloys were prepared as ribbons by the rapid quenching technique. The nanocomposite structure in the alloys was obtained by annealing at 840–880 K for 30 min. Structural characterization of the samples was performed using the Mössbauer spectroscopy and X-ray diffraction. Magnetic properties of the samples were studied by the measurements of the hysteresis loops and of the magnetization at increasing temperatures. An amorphous phase prevailed in the as-quenched Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} alloys while a disordered solid solution of fcc-(Fe,Co)Pt was a dominating phase in the Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} ribbons. Differential scanning calorimetry measurements revealed one or two exothermic peaks at temperatures up to 993 K, depending on the composition of the alloys. Thermal treatment of the samples led to the formation of the magnetically hard ordered L1{sub 0} tetragonal (Fe,Co)Pt nanocrystallites and magnetically softer phases of (Fe,Co)B (for Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20}) or (Fe,Co){sub 2}B (for Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15}). Detailed Mössbauer spectroscopy studies revealed that cobalt substituted for iron in both the L1{sub 0} phase and in iron borides. The nanocomposite Fe{sub 60−y}Co{sub y

  17. Study of the mechanical and magnetic properties of Fe{sub 61}Co{sub 10}Zr{sub 5-x}Hf{sub x}W{sub 2}Y{sub 2}B{sub 20} (x = 0 or 3) bulk amorphous and crystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nabialek, Marcin G. [Institute of Physics, Czestochowa University of Technology, 19 Armii Krajowej Av., 42-200 Czestochowa (Poland); Szota, Michal [Institute of Materials Engineering, Czestochowa University of Technology, 19 Armii Krajowej Av., 42-200 Czestochowa (Poland); Dospial, Marcin J.

    2010-05-15

    The microstructure, thermal stability, mechanical and magnetic properties of Fe{sub 61}Co{sub 10}Zr{sub 5-x}Hf{sub x}W{sub 2}Y{sub 2}B{sub 20} (where x = 0 or 3) bulk metallic glasses (BMG) and their crystalline equivalents were investigated. The crystalline materials were smelted on a copper mould using an electric arc; their amorphous equivalents were prepared using the induction suction casting method (ISC). All samples investigated were in the form of plates with dimensions of 10x10x0.5mm. From X-ray diffraction and Moessbauer spectroscopy, it was found that both investigated alloys prepared using this method have an amorphous structure. From magnetic measurements obtained by a vibrating sample magnetometer (VSM), it was shown that all measured samples displayed soft magnetic properties with relatively high saturation of the magnetization. The thermal stability and glass-forming ability (GFA) for investigated alloys were derived from differential scanning calorimetry (DSC) curves. The measurements of mechanical properties for amorphous alloys were found to be better than those for crystalline alloys with the same atomic composition. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Electron microscopy investigations of rapidly solidified Fe-Zr-B-Cu alloys

    International Nuclear Information System (INIS)

    Majumdar, B.; Arvindha Babu, D.; Akhtar, D.

    2010-01-01

    Rapidly solidified Fe-based nanocrystalline soft magnetic materials possess a unique combination of properties i,e high permeability, saturation and Curie temperature and very low coercivity which are otherwise not attainable in conventional soft magnetic materials. The alloys are processed by producing amorphous phase through melt spinning route followed by a partial devitrification for incorporation of nanocrystalline phase in the amorphous matrix. In this paper, detailed electron microscopic investigations of melt spun Fe-Zr-B-Cu alloys are presented. Melt spun ribbons of Fe 99-x-y Zr x BCu 1 alloys with x+y = 11 and x+y = 13 were prepared under different wheel speed conditions and then vacuum annealed for 1 h at different temperatures. The microstructure changes from completely amorphous to a cellular/dendritic bcc solid solution coexisting with the amorphous phase at intercellular/dendritic regions when Zr/B ratio or the process parameters are varied. Annealing leads to the precipitation of nanocrystalline bcc-Fe phase from both amorphous phase and already existing bcc solid solution. (author)

  19. Diffusion in ordered Fe-Si alloys

    International Nuclear Information System (INIS)

    Sepiol, B.; Vogl, G.

    1995-01-01

    The measurement of the diffusional Moessbauer line broadening in single crystalline samples at high temperatures provides microscopic information about atomic jumps. We can separate jumps of iron atoms between the various sublattices of Fe-Si intermetallic alloys (D0 3 structure) and measure their frequencies. The diffusion of iron in Fe-Si samples with Fe concentrations between 75 and 82 at% shows a drastic composition dependence: the jump frequency and the proportion between jumps on Fe sublattices and into antistructure (Si) sublattice positions change greatly. Close to Fe 3 Si stoichiometry iron diffusion is extremely fast and jumps are performed exclusively between the three Fe sublattices. The change in the diffusion process when changing the alloy composition from stoichiometric Fe 3 Si to the iron-rich side is discussed. (orig.)

  20. Effect of solute atoms on glass-forming ability for Fe–Y–B alloy: An ab initio molecular dynamics study

    International Nuclear Information System (INIS)

    Han, J.J.; Wang, W.Y.; Liu, X.J.; Wang, C.P.; Hui, X.D.; Liu, Z.K.

    2014-01-01

    The glass-forming abilities of Fe 78 B 22 , Fe 70 Y 6 B 24 , Fe 72 Y 6 B 22 and Fe 72.5 Y 3.5 B 24 alloys were characterized comprehensively using ab initio molecular dynamics simulations. The calculated results were correlated with the properties and atomic structures. It was found that the Fe 72 Y 6 B 22 alloy consists of both the most stable and the least deformed body centered cubic atomic packing structures in the supercooled liquid and glassy states. It was observed that the local compositions in the Fe 72 Y 6 B 22 alloy significantly deviate from the compositions of stable crystalline phases, indicating that the Fe 72 Y 6 B 22 alloy has the best glass-forming ability among the alloys studied. However, Fe 72 Y 6 B 22 alloy has two flaws in terms of glass-forming ability, i.e. relatively large atomic diffusivity and insufficiently close atomic packing. The best performance in these two aspects is observed in the Fe 72.5 Y 3.5 B 24 alloy. Thus, the theoretical study predicts that the best glass former for the Fe–Y–B system is within the compositional range of 22–24 at.% B and 3.5–6 at.% Y

  1. Mechanical behaviour of Nd-Fe-B alloys in the semi-solid state

    International Nuclear Information System (INIS)

    Oliveira, I.L.; Sinka, V.; Ferrante, M.

    1996-01-01

    Two alloys with composition Nd 17.6 Fe 75.3 B1.2 Cu 5.9 and Nd 15.9 Fe 77.7 B 5 Cu 1.4 were vacuum induction melted and cast into cylindrical ingots. Samples with 12.3 and 13 mm diameter were deformed with different rates and deformation ratios. One alloy was deformed at 800 deg C between two parallel disks under constant load. Results show that these alloys behave as no-Newtonian fluids. This fact gives a better understanding of both magnetic and crystallographic texture development. Also, changes were detected in the behaviour of semisolid in the course of deformation. (author)

  2. The effect of additional elements on the magnetic properties of hot-rolled Nd-Fe-B alloys

    International Nuclear Information System (INIS)

    Chang, W.C.; Nakamura, H.; Paik, C.R.; Sugimoto, S.; Okada, M.; Homma, M.

    1992-01-01

    The magnetic properties of hot-rolled Nd 16 Fe bal. B 6 M 1.5 (M = Cu, Ga and Al) and Nd 16 Fe 76 B 5.5 Ga 1.5 Al 1 alloys were investigated, in order to study the role of additive elements in improving the magnetic properties in the Nd-Fe-B system. It is found that the original grain size of Cu, Ga or Ga-Al added alloys is much finer than that of the ternary and Al added alloys. But the grain size is almost identical for all the alloys after hot-rolling at 1000degC with 90% reduction in thickness. The coercivity of hot-rolled alloys with Cu, Ga or Ga-Al addition is not improved as was expected, because Nd-rich liquid phase in these alloys is very easily squeezed out during high-reduction-ratio rolling. Less quantity and nonuniform distribution of Nd-rich phase between distributed grains are believed to be the main reasons to depress the effect on the grain boundary smoothing. This effect is not the same as those observed in the Pr-Fe-B system. The highest magnetic properties achieved in this study are B r = 10 kG, i H c = 8.2 kOe, (BH) max = 18.5 MGOe for the Nd 16 Fe 76.5 B 6 Al 1.5 alloy. (orig.)

  3. Moessbauer study of the amorphous Pd70Fe10Si20 alloy upon transition to the crystalline state

    International Nuclear Information System (INIS)

    Sitek, J.; Prejsa, M.; Cirak, J.; Hucl, M.; Lipka, J.

    1978-01-01

    Foils of the amorphous alloy Pd 70 Fe 10 Si 20 were investigated after isothermal heating at the temperature range 350-450 0 C with a heating period from 15 min to 4 h. At 350 0 C no changes were observed in the shape of the Moessbauer spectra. At 400 0 C and at 450 0 C up to 30 min only the parameters of Moessbauer spectra consisting of two quadrupole doublets corresponding to palladium and silicon vicinities of iron atoms were changed. After further heating at 450 0 C crystalline phases of Pd 3 Fe and Fe 3 Si appeared on the Moessbauer spectra. (Auth.)

  4. Mechanical alloying of Hf and Fe powders

    International Nuclear Information System (INIS)

    Mendoza Zelis, L.; Crespo, E.; Creus, M.; Damonte, L.C.; Sanchez, F.H.; Punte, G.

    1994-01-01

    Pure crystalline Hf and Fe powders were mixed and milled under an argon atmosphere. The evolution of the system with milling time was followed with Moessbauer effect spectroscopy and X-ray diffraction. The results indicate that in the first stages an amorphous Fe-rich alloy was gradually formed together with a solid solution of Hf in Fe beyond the solubility limit. (orig.)

  5. Crystallization of the amorphous Fe{sub 80}Zr{sub 12}B{sub 8} alloy under controlled heating

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H. [School of Engineering (H6), University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Shao, G. [Centre for Materials Research and Innovation, University of Bolton, Bolton BL3 5AB (United Kingdom)], E-mail: G.Shao@bolton.ac.uk; Tsakiropoulos, P. [Department of Engineering Materials, Sir Robert Hadfirld Building, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2008-07-14

    The devitrification process of amorphous Fe{sub 80}Zr{sub 12}B{sub 8} alloy ribbons were studied under controlled thermal conditions. The major crystallization event during continuous heating with differential scanning calorimetory (DSC) is dictated by diffusion controlled growth and the associated atom mobility of the slow diffusing species Zr. The existence of prior nano-crystals formed by pre-annealing below the crystallization temperature had little effect on the major crystallization temperature. The crystallization sequence during heating was: amorphous {yields} amorphous + {alpha}-Fe + Fe{sub 3}Zr(B) {yields} amorphous + {alpha}-Fe + Fe{sub 3}Zr(B) + Fe{sub 2}Zr. Different from previous findings in alloys of lower Zr and B contents, the peak for the crystallization of the {alpha}-Fe phase alone is missing in the DSC traces of this alloy.

  6. NMR and Moessbauer studies of the amorphous system Fe79P/sub 21-x/B/sub x/

    International Nuclear Information System (INIS)

    Amamou, A.; Durand, J.

    1977-05-01

    Combined NMR, spin-echo and Moessbauer experiments have been performed to obtain hyperfine field distributions of the transition metal and metalloid elements in splat-cooled amorphous Fe 79 P 21 /sub -x/B/sub x/ alloys. These distributions are related to the local environments of the elements. The NMR signals are observed in the low frequency range 20-60 MHz and all the nuclei, i.e. Fe, P and B, may contribute to the spectral distribution. The resolution of the spectra into that due to Fe and (P + B) nuclei was made possible by using samples prepared with an Fe 56 isotope. The Fe distribution thus obtaned shows general agreement with the Moessbauer field distribution. From a careful analysis of the NMR data, the hyperfine field at the B nuclei in these amorphous alloys is found to range from 24 to 26 KG increasing with B content. An upper limit of 8 KG for the half-width is attributed to this distribution. The Moessbauer spectra of the Fe 57 nuclei resemble those for the crystalline Fe 75 P 25 /sub -x/B/sub x/ alloys. A fit of the spectra shows a field distribution which suggests the presence of structure. Such a structure may correspond to various Fe sites, also seen in the crystalline alloys. The distributions generally lie between about 160 and 330 KG, with a maximum at about 260 KG. These spectra do not show the presence of Fe nuclei with essentially zero hyperfine field as was obtained for amorphous Fe-Pd-P by Sharon et al. and for amorphous Fe-P by Logan et al. With increasing B content the center of gravity of the Fe distribution shifts to higher values. From a systematic study of the NMR lines and other considerations it is concluded that the P field distribution is broad and its hyperfine field is between 20 and 35 KG for the higher P concentration alloys

  7. Roles of Co element in Fe-based bulk metallic glasses utilizing industrial FeB alloy as raw material

    Directory of Open Access Journals (Sweden)

    Shouyuan Wang

    2017-08-01

    Full Text Available A series of Fe-based bulk metallic glasses were fabricated by a conventional copper mold casting method using a kind of Fe-B industrial raw alloy. It is found that Fe-B-Y-Nb bulk metallic glass with 3 at% of Co addition possesses the best glass forming ability, thermal stability, hardness, magnetic property and anti-corrosion property. The hardness test result indicates a synchronically trend with glass-forming ability parameters. The excellent glass-forming ability and a combination of good mechanical and functional properties suggest that the alloys in this work might be good candidates for commercial use.

  8. 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

  9. Effect of annealing on the structural and magnetic properties of (Fe{sub 1−x}Co{sub x}){sub 83}B{sub 17} metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, Neeru, E-mail: neerubhagat@hotmail.com [Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Mulshi, Pune 412115 (India); Gupta, Ajay [Center for Spintronic Materials, Amity University, Sector 125, Noida (India); Reddy, V.R. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore (India); Pandey, Brajesh, E-mail: bpandey@gmail.com [Department of Applied Science, Symbiosis Institute of Technology, SIU, Lavale, Mulshi, Pune 412115 (India)

    2015-05-01

    Amorphous alloys of (Fe{sub 1−x}Co{sub x}){sub 83}B{sub 17} (x=22, 25.3, 28.4) in the vicinity of 25 at% of Co were prepared by melt spun technique. The samples were annealed at different temperatures and the changes in structural and magnetic properties have been studied. Phase stabilization and magnetic properties of amorphous alloys were studies using X-ray diffraction and Mössbauer spectroscopy. The result shows anomalies in structure and in magnetic properties in the studied samples. Annealing at 475 °C brings about the formation of complete and stable crystalline structure. At this stage multiple crystalline phases have been observed. Mössbauer spectroscopy also revealed that two phases of Fe{sub 3}B were formed along with stable Fe{sub 3}Co phase. - Highlights: • Using melt spun technique alloys of (Fe{sub 1−x}Co{sub x}){sub 83}B{sub 17} (x=22, 25.3, 28.4) in amorphous phase were prepared. • Crystalline phase increases with increasing the Co concentration. • Appearance of one crystalline phase is observed when samples annealing at 345 °C. • Annealing at higher temperature leads to emergence of multiple crystalline phases. • Different phases of Fe–Co, and Fe–Co–B were identified.

  10. First-order-reversal-curve analysis of exchange-coupled SmCo/NdFeB nanocomposite alloys

    International Nuclear Information System (INIS)

    Pan, Mingxiang; Zhang, Pengyue; Ge, Hongliang; Yu, Nengjun; Wu, Qiong

    2014-01-01

    Exchange-coupled SmCo 5 /Nd 2 Fe 14 B nanocomposite magnets have been fabricated by ball milling of the micrometer sized SmCo 5 and Nd 2 Fe 14 B powders. The influence of Nd 2 Fe 14 B content on the microstructure and magnetic properties of these hybrid alloys was investigated. The alloys that show strong intergrain exchange-coupling behavior with (BH) max =2.95 MGOe was obtained when the two hard phases are well coupled. A first-order-reversal-curve (FORC) analysis was performed for both SmCo 5 single-phase magnet and SmCo 5 /Nd 2 Fe 14 B hybrid magnet; the FORC diagrams results show two major peaks for the hybrid magnets. In both cases, the magnetization reversal behaviors for these alloys were discussed in detail and are consistent with the results of δM plots. - Highlights: • Exchange-coupled SmCo 5 /Nd 2 Fe 14 B nanocomposite magnets were studied. • Magnetization reversal behaviors of the hybrid magnet were discussed. • The FORCs analysis is taken to identify the optimal conditions for hybrid magnet

  11. Magnetic properties of melt-spun Nd-rich NdFeB alloys with Dy and Ga substitutions

    International Nuclear Information System (INIS)

    Harland, C.L.; Davies, H.A.

    1998-01-01

    The results of a systematic investigation of the effects of Dy and Ga additions on the magnetic properties of a Nd-rich NdFeB alloy are presented and discussed. Particular attention is given to the effect of increasing Dy substitutions on the coercivity of the Nd 18 Fe 76 B 6 alloy. Substitution of 30% of the Nd by Dy resulted in a coercivity increase from 1590 to 3290 kA m -1 . However, contrary to previous suggestions, substitution of 1% of the Fe by Ga was found to have only a small influence on the magnetic properties of all the alloys in the compositional series (Nd 100-x Dy x ) 18 Fe 76 B 6 (x=0-30). (orig.)

  12. First-order-reversal-curve analysis of exchange-coupled SmCo/NdFeB nanocomposite alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Mingxiang; Zhang, Pengyue, E-mail: Zhang_pengyue@cjlu.edu.cn; Ge, Hongliang; Yu, Nengjun; Wu, Qiong

    2014-06-01

    Exchange-coupled SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B nanocomposite magnets have been fabricated by ball milling of the micrometer sized SmCo{sub 5} and Nd{sub 2}Fe{sub 14}B powders. The influence of Nd{sub 2}Fe{sub 14}B content on the microstructure and magnetic properties of these hybrid alloys was investigated. The alloys that show strong intergrain exchange-coupling behavior with (BH){sub max}=2.95 MGOe was obtained when the two hard phases are well coupled. A first-order-reversal-curve (FORC) analysis was performed for both SmCo{sub 5} single-phase magnet and SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B hybrid magnet; the FORC diagrams results show two major peaks for the hybrid magnets. In both cases, the magnetization reversal behaviors for these alloys were discussed in detail and are consistent with the results of δM plots. - Highlights: • Exchange-coupled SmCo{sub 5}/Nd{sub 2}Fe{sub 14}B nanocomposite magnets were studied. • Magnetization reversal behaviors of the hybrid magnet were discussed. • The FORCs analysis is taken to identify the optimal conditions for hybrid magnet.

  13. Effect of boron addition to the hard magnetic bulk Nd60Fe30Al10 amorphous alloy

    International Nuclear Information System (INIS)

    Kong, H.Z.; Li, Y.; Ding, J.

    2000-01-01

    A detailed study of the effect of boron addition to crystallinity, magnetic properties and thermal properties was carried out for alloys Nd 60-x Fe 30 Al 10 B x with x=0, 1, 3 and 5 produced by copper mold chill casting and melt-spinning. The cast rods of alloys Nd 60-x Fe 30 Al 10 B x were largely amorphous. Remanence up to 0.154 T and coercivity up to 355 kA/m were observed, which were higher than those of the bulk amorphous Nd 60 Fe 30 Al 10 rod of the same diameter. A step in hysteresis loop was observed for the hard magnetic cast rod and ribbon melt-spun at a low speed of 5 m/s of the alloys with boron addition. Consistent increase in the amplitude of the step and magnetic field (H) at which the step was observed as the boron content increased. A single magnetic phase with low coercivity was observed for fully amorphous ribbon melt-spun at high speed of 30 m/s. Full crystallization due to heat treatment resulted in transition of hard magnetic amorphous phase of Nd 55 Fe 30 Al 10 B 5 cast rod to paramagnetic crystalline phases. TEM results of the as-cast rods illustrated the existence of numerous minute Nd-crystallites in amorphous matrix

  14. Amorphous and nanocrystalline fraction calculus for the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Muraca, D. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Moya, J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina); Cremaschi, V.J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina) and Carrera del Investigador, CONICET (Argentina)]. E-mail: vcremas@fi.uba.ar; Sirkin, H.R.M. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina)

    2007-09-01

    We studied the relationship between the saturation magnetization (M {sub S}) of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy and its nanocrystalline structure. Amorphous ribbons obtained by the melt spinning technique were heat-treated for 1 h at different temperatures. The optimal treatment to obtain a homogeneous structure of Fe{sub 3}(Si,Ge) nanocrystals with a grain size of around 10 nm embedded in an amorphous matrix involved heating at 540 C for 1 h. We calculated the magnetic contribution of the nanocrystals to the heat treated alloy using a linear model and measured the M {sub S} of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} nanocrystalline and of an amorphous alloy of the same composition of the amorphous matrix: Fe{sub 58}Si{sub 0.5}Ge{sub 3.5}Cu{sub 3}Nb{sub 9}B{sub 26}. Using experimental data and theoretical calculations, we obtained the amorphous and crystalline fraction of the heat-treated ribbons.

  15. Corrosion resistance of Fe-based amorphous alloys

    International Nuclear Information System (INIS)

    Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

    2014-01-01

    Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

  16. Stability of (Fe-Tm-B) amorphous alloys: relaxation and crystallization phenomena

    International Nuclear Information System (INIS)

    Zemcik, T.

    1994-01-01

    Fe-Tm-B base (TM = transition metal) amorphous alloys (metallic glasses) are thermodynamically metastable. This limits their use as otherwise favourable materials, e.g. magnetically soft, corrosion resistant and mechanically firm. By analogy of the mechanical strain-stress dependence, at a certain degree of thermal activation the amorphous structure reaches its limiting state where it changes its character and physical properties. Relaxation and early crystallization processes in amorphous alloys, starting already around 100 C, are reviewed involving subsequently stress relief, free volume shrinking, topological and chemical ordering, pre-crystallization phenomena up to partial (primary) crystallization. Two diametrically different examples are demonstrated from among the soft magnetic materials: relaxation and early crystallization processes in the Fe-Co-B metallic glasses and controlled crystallization of amorphous ribbons yielding rather modern nanocrystalline ''Finemet'' alloys where late relaxation and pre-crystallization phenomena overlap when forming extremely dispersive and fine-grained nanocrystals-in-amorphous-sauce structure. Moessbauer spectroscopy seems to be unique for magnetic and phase analysis of such complicated systems. (orig.)

  17. Phase transformation in rapidly quenched Fe-Cr-Co-Mo-Ti-Si-B alloys

    Science.gov (United States)

    Zhukov, D. G.; Shubakov, V. S.; Zhukova, E. Kh; Gorshenkov, M. V.

    2018-03-01

    The research results of phase transformations in Fe-24Cr-16Co-3Mo-0.2Ti-1Si-B alloys (with a boron content of 1 to 3% by mass) obtained by rapid quenching are presented. The structure formation regularities during the melt spinning and during the subsequent crystallization annealing in rapidly quenched bands of the Fe-Cr-Co-Mo-Ti-Si-B system alloys were studied. The changes in the phase composition of the rapidly quenched Fe-Cr-Co-Mo-Ti- Si-B system alloys after quenching at various quench rates and at different boron concentrations in the alloys are studied. It is shown that during crystallization from an amorphous state, at temperatures above 570 °C, in addition to the α-phase, the σ-phase appears first, followed by the γ-phase. Heat treatment of rapidly quenched bands to high-coercive state was carried out. A qualitative assessment of magnetic properties in a high-coercivity state was carried out. An evaluation of the level of magnetic properties in a high-coercivity state allows us to conclude that the application of a magnetic field during crystallization from an amorphous state leads to anisotropy of the magnetic properties, that is, an anisotropic effect of thermo-magnetic treatment is detected.

  18. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  19. Magnetic properties of centrifugally prepared melt-spun Nd-Fe-B alloys and their powders

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Kozlov, A.I.; Markin, P.E.; Pushkarskiy, V.I.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching on to the internal surface of an iron spinning wheel at the tangential speeds in the range 5-20 m/sec are reported. The alloy composition was Nd-36% wt. B-1.2% wt. and Fe-reminder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in the applied range (1430 kA/m at 5 m/sec and 1750 kA/m at 20 m/sec), whereas the grain size of the basic phase (2-14-1) steadily decreases when the speed rises, starting from 2-3 μm for 5 m sec alloy down to the 200-300 nm for 20 m/sec alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for traditionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbons subjected to hydrogen and annealing treatments causes the coercivity drop. However, this operations increase the powder alignment ability and, as a result, the energy product for fully dense magnet from such powder rises to 160-180 kJ/m 3 . (orig.)

  20. 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.

  1. STUDY OF COATINGS OBTAINED FROM ALLOY Fe-Mn-C-B-Si-Ni-Cr

    Directory of Open Access Journals (Sweden)

    Mychajło Paszeczko

    2016-09-01

    Full Text Available Tribological behaviour of coatings obtained from eutectic alloy Fe-Mn-C-B-Si-Ni-Cr was studied. The coatings were obtained by the method of gas metal arc welding (GMA with use of powder wire. GMA welding method is widely used for the regeneration of machine parts. Eutectic Fe-Mn-C-B-Si-Ni-Cr alloys can be used to obtain high quality coatings resistant to wear and corrosion. Pin-on-disk dry sliding wear tests at sliding speeds 0.4 m/s and under load 10 MPa were conducted for pin specimens. During friction a typical tribological behavior was observed. The mechanism of wear was mechanical-chemical.

  2. Microstructure, soft magnetic properties and applications of amorphous Fe-Co-Si-B-Mo-P alloy

    Science.gov (United States)

    Hasiak, Mariusz; Miglierini, Marcel; Łukiewski, Mirosław; Łaszcz, Amadeusz; Bujdoš, Marek

    2018-05-01

    DC thermomagnetic properties of Fe51Co12Si16B8Mo5P8 amorphous alloy in the as-quenched and after annealing below crystallization temperature are investigated. They are related to deviations in the microstructure as revealed by Mössbauer spectrometry. Study of AC magnetic properties, i.e. hysteresis loops, relative permeability and core losses versus maximum induction was aimed at obtaining optimal initial parameters for simulation process of a resonant transformer for a rail power supply converter. The results obtained from numerical analyses including core losses, winding losses, core mass, and dimensions were compared with the same parameters calculated for Fe-Si alloy and ferrite. Moreover, Steinmetz coefficients were also calculated for the as-quenched Fe51Co12Si16B8Mo5P8 amorphous alloy.

  3. Single step preparation of NdFeB alloy by magnesiothermic reduction-diffusion process

    International Nuclear Information System (INIS)

    Singha, Vinay Kant; Surendranathana, A.O.; John Berchmans, L.

    2014-01-01

    Magnesiothermic reduction is a new approach to produce the NdFeB alloy on a commercial scale. Similar studies were conducted for the preparation of LaNi 5 and SmCo 5 using magnesium as the reductant. In the present investigation NdFeB Hard magnetic bulk materials were synthesized by metallothermic 'Reduction – Diffusion (R-D) Process' using Magnesium as a reductant. For this process oxide precursors of Nd, Fe and B were blended with flux (LiCl/CaCl 2 ) and Mg chips were sandwiched in alternate layers. Thermal analysis (TGA/DTA) was carried out to find the dissociation and decomposition temperature of the reactants. The phase analysis, structure, and elemental composition were assessed by X-ray diffraction (XRD) and electron dispersive spectrometry (EDS). The infrared (IR) spectra were recorded by Fourier transform infrared spectrometer (FTIR). The morphological features and particle size was assessed by scanning electron microscope (SEM). The magnetic behaviour of the alloy was assessed using electron paramagnetic resonance (EPR) and vibratory sample magnetometer (VSM). From these studies it has been concluded that the NdFeB magnetic particles can be prepared using magnesium as the reductant. The process is faster and consumes very less amount of energy for the completion as compared to conventional calciothermic reduction process. Traces of MgO were detected in the alloy which increases the perpendicular anisotropy, thus increasing the coercivity of the material

  4. Magnetic hysteresis properties of melt-spun Nd-Fe-B alloys prepared by centrifugal method

    International Nuclear Information System (INIS)

    Andreev, S.V.; Kudrevatykh, N.V.; Pushkarsky, V.I.; Markin, P.E.; Zaikov, N.K.; Tarasov, E.N.

    1998-01-01

    Magnetic hysteresis properties and microstructure peculiarities of melt spun Nd-Fe-B alloys (ribbons) prepared by melt quenching onto the internal surface of an iron spinning wheel at tangential speeds in the range 5-20 m/s are reported. The alloy composition was Nd-36% wt, B-1.2% wt. and Fe-remainder. It was found that the coercivity of ribbons does not practically depend on the wheel speed in applied range (18 kOe at 5 m/s and 22 kOe at 20 m/s), whereas the grain size of the basic phase (2-14-1) ste[ily decreases when the speed rises, starting from 2-3 μm for 5 m/s alloy down to the 200-300 nm for 20 m/s alloy. All ribbons have normal convex demagnetization curves, even those prepared at low wheel speeds (without peculiar step near H∝0, which usually exists on such curves for tr[itionally prepared underquenched melt-spun Nd-Fe-B alloys). Grinding the ribbon in a vibration mill causes the coercivity drop to 7 kOe after 120 min of treatment. However, this operation increases the powder alignment ability and, as a result, the energy product for a fully dense magnet from anisotropic powder prepared from some ribbons rises to 20-23 MGOe. (orig.)

  5. Hyperfine interaction and some thermomagnetic properties of amorphous and partially crystallized Fe70−xMxMo5Cr4Nb6B15 (M = Co or Ni, x = 0 or 10 alloys

    Directory of Open Access Journals (Sweden)

    Rzącki Jakub

    2015-03-01

    Full Text Available As revealed by Mössbauer spectroscopy, replacement of 10 at.% of iron in the amorphous Fe70Mo5Cr4Nb6B15 alloy by cobalt or nickel has no effect on the magnetic structure in the vicinity of room temperature, although the Curie point moves from 190 K towards ambient one. In the early stages of crystallization, the paramagnetic crystalline Cr12Fe36Mo10 phase appears before α-Fe or α-FeCo are formed, as is confirmed by X-ray diffractometry and transmission electron microscopy. Creation of the crystalline Cr12Fe36Mo10 phase is accompanied by the amorphous ferromagnetic phase formation at the expense of amorphous paramagnetic one.

  6. Effect of Si on the glass-forming ability, thermal stability and magnetic properties of Fe-Co-Zr-Mo-W-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.-M. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany); Key Lab of Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Gebert, A. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)], E-mail: a.gebert@ifw-dresden.de; Roth, S.; Kuehn, U.; Schultz, L. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)

    2008-07-14

    This paper presents investigations on the effect of Si on the glass-forming ability, thermal stability and magnetic properties of the Fe-Co-Zr-Mo-W-B samples (group I: Fe{sub 60}Co{sub 8}Zr{sub 10}Mo{sub 5}W{sub 2}B{sub 15-x}Si{sub x}, 1 {<=} x {<=} 4; group II: Fe{sub 60}Co{sub 8}Zr{sub 10-x}Mo{sub 5}W{sub 2}B{sub 15}Si{sub x}, 0 {<=} x {<=} 4; group III: Fe{sub 60}Co{sub 8}Zr{sub 8}Mo{sub 5}W{sub 2}B{sub 17-x}Si{sub x}, 0 {<=} x {<=} 2) prepared by melt spinning, injection casting, and centrifugal casting methods. It is found that the glass-forming ability (GFA) of the alloys in group I is more deteriorated than that in group II, and that the alloys in group III can be cast into the rods of 1-3 mm diameter without crystalline reflections in their XRD patterns. For the amorphous ribbons and rods, a non-monotonic change of the nearest neighbour distance r{sub 1} with increasing Si content c{sub Si} was detected, which is parallel to that of the glass transition and crystallization temperatures T{sub g} and T{sub x}, but opposite to that of the magnetization at room temperature M{sub RT} and the Curie temperature T{sub c}. This correlation can be interpreted by a structure model presuming that iron atoms appear simultaneously in two types of local structures in the amorphous samples.

  7. Surface Properties of a Nanocrystalline Fe-Ni-Nb-B Alloy After Neutron Irradiation

    Science.gov (United States)

    Pavùk, Milan; Sitek, Jozef; Sedlačková, Katarína

    2014-09-01

    The effect of neutron radiation on the surface properties of the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy was studied. Firstly, amorphous (Fe0.25Ni0.75)81Nb7B12 ribbon was brought by controlled annealing to the nanocrystalline state. After annealing, the samples of the nanocrystalline ribbon were irradiated in a nuclear reactor with neutron fluences of 1×1016cm-2 and 1 × 1017cm-2 . By utilizing the magnetic force microscopy (MFM), topography and a magnetic domain structure were recorded at the surface of the ribbon-shaped samples before and after irradiation with neutrons. The results indicate that in terms of surface the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy is radiation-resistant up to a neutron fluence of 1 × 1017cm-2 . The changes in topography observed for both irradiated samples are discussed

  8. Soft Magnetic Properties of Nanocrystalline Fe-M-(B and/or O)(M=Group IV A, V A Elements) Alloy Films

    OpenAIRE

    Hayakawa, Y.; Makino, A.; Inoue, A.; Masumoto, T.

    1996-01-01

    In Fe-M-(B and/or O)(M=group IV A, V A elements) alloy films, nanocrystalline bcc phase are formed by annealing the amorphous single phase for Fe-M-B films, whereas the bcc nanocrystals are already formed in an as-deposited state for Fe-M-O or Fe-M-B-O) films. Among Fe-M-B films with various M elements, Fe-(Zr, Hf, Nb, Ta)-B alloy films exhibit high saturation magnetization (Is) above 1.4 T and high relative permeability (|μ|) above 1000 at 1MHz. The highest |μ| of 3460 at 1MHz is obtained fo...

  9. Microstructure, soft magnetic properties and applications of amorphous Fe-Co-Si-B-Mo-P alloy

    Directory of Open Access Journals (Sweden)

    Mariusz Hasiak

    2018-05-01

    Full Text Available DC thermomagnetic properties of Fe51Co12Si16B8Mo5P8 amorphous alloy in the as-quenched and after annealing below crystallization temperature are investigated. They are related to deviations in the microstructure as revealed by Mössbauer spectrometry. Study of AC magnetic properties, i.e. hysteresis loops, relative permeability and core losses versus maximum induction was aimed at obtaining optimal initial parameters for simulation process of a resonant transformer for a rail power supply converter. The results obtained from numerical analyses including core losses, winding losses, core mass, and dimensions were compared with the same parameters calculated for Fe-Si alloy and ferrite. Moreover, Steinmetz coefficients were also calculated for the as-quenched Fe51Co12Si16B8Mo5P8 amorphous alloy.

  10. Effects of Tungsten Addition on the Microstructure and Corrosion Resistance of Fe-3.5B Alloy in Liquid Zinc

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-04-01

    Full Text Available The effects of tungsten addition on the microstructure and corrosion resistance of Fe-3.5B alloys in a liquid zinc bath at 520 °C were investigated by means of scanning electron microscopy, X-ray diffraction and electron probe micro-analysis. The microstructure evolution in different alloys is analyzed and discussed using an extrapolated Fe-B-W ternary phase diagram. Experimental results show that there are three kinds of borides, the reticular (Fe, W2B, the rod-like (Fe, W3B and flower-like FeWB. The addition of tungsten can refine the microstructure and improve the stability of the reticular borides. Besides, it is beneficial to the formation of the metastable (Fe, W3B phase. The resultant Fe-3.5B-11W (wt % alloy possesses excellent corrosion resistance to liquid zinc. When tungsten content exceeds 11 wt %, the formed flower-like FeWB phase destroys the integrity of the reticular borides and results in the deterioration of the corrosion resistance. Also, the corrosion failure resulting from the spalling of borides due to the initiation of micro-cracks in the grain boundary of borides is discussed in this paper.

  11. Thermoelectric power measurements in liquid quenched amorphous alloys for FeZr and (FeCo)B

    International Nuclear Information System (INIS)

    Raza, S.M.; Naqvi, S.M.M.R.; Rizvi, S.; Hussain, A.; Rahman, F.

    1999-01-01

    Thermoelectric power (TEP) measurements have been carried out on six samples of LQA alloys from two different series, namely FeZr and Fe(Co)B, at relatively low temperatures. Thermoelectric power shows an overall Gaussian trend. The scattering centers are the major contributors to the residual TEP. Ziman theoretical model was used to estimate TEP. It was found that Ziman theory fails to account for quantitative TEP measurements at relatively low temperatures (77K< T<300K). (author)

  12. 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

  13. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.D., E-mail: fanxd@seu.edu.cn; Shen, B.L., E-mail: blshen@seu.edu.cn

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe{sub 86}B{sub 7}C{sub 7} alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe{sub 3}C and α-Fe phase impedes the devitrification. • Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity.

  14. Magnetic and structural characterization of Mo-Hitperm alloys with different Fe/Co ratio

    Energy Technology Data Exchange (ETDEWEB)

    Conde, C.F., E-mail: conde@us.es [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Borrego, J.M.; Blazquez, J.S.; Conde, A. [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain); Svec, P.; Janickovic, D. [Department of Metal Physics, Institute of Physics, Slovak Academy of Sciences, Dubravska Cesta 9, 845 11 Bratislava (Slovakia)

    2011-02-03

    Research highlights: > Nanocrystallization kinetics results based on isothermal (TMG) and non-isothermal (DSC) experiments agree describing a strongly inhibited grain growth process. > The crystalline volume fraction at the end of the nanocrystallization process is practically not affected with the increase of Co in the alloy, although it is lower than in the corresponding Co free alloy. The lattice parameter and the crystal size of the {alpha}-FeCo(Mo) phase nanocrystals decreases as the Co content in the alloy increases. > Moessbauer spectra were analyzed in the frame of three different contributions: pure crystalline, interface and amorphous contribution. Comparison between TEM, XRD and Moessbauer data indicates that some Mo could be present inside the nanocrystals. > Changing the Fe/Co ratio allows to increase the Curie temperature of the amorphous alloys for these compositions between room temperature and {approx}800 K, and therefore, allows tuning the temperature at which the maximum magnetocaloric effect takes place opening a possibility for these alloys as potential low cost magnetic refrigerants. - Abstract: The influence of the Co content on the microstructure and magnetic behaviour of a series of amorphous and nanocrystalline (FeCo){sub 79}Mo{sub 8}Cu{sub 1}B{sub 12} alloys is reported. Changes in the magnetic properties provoked by the microstructural evolution upon different thermal treatments of as-cast samples are analyzed as well. Kinetics of nanocrystallization process can be described by an isokinetic approach. As the Co content in the alloy increases, the Curie temperature of the amorphous as-cast samples increases while the crystallization onset temperature decreases. The crystalline volume fraction as well as the mean grain size of the nanocrystals at the end of the nanocrystallization process are slightly higher for the lowest Co content alloy but smaller than in similar Hitperm Mo-free alloys. The average magnetic field and the average isomer

  15. 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.

  16. NdFeB alloy as a magnetic electrode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang, J.; Shui, J.L.; Zhang, S.L.; Wei, X.; Xiang, Y.J.; Xie, S.; Zhu, C.F.; Chen, C.H.

    2005-01-01

    The search for a reliable indicator of state of charge and even the remaining energy of a lithium-ion cell is of great importance for various applications. This study was an exploratory effort to use magnetic susceptibility as the indicator. In this work, for the first time the change of ac susceptibility of cells was in situ monitored during charge-discharge process. A strong permanent magnetic material, NdFeB alloy, was investigated as an anode material for rechargeable lithium batteries. Both original and partially oxidized NdFeB powders were made into electrodes. Structural characterization was performed on the NdFeB electrodes by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. An alloy (core)-oxide (shell) structure was found for those partially oxidized samples. The electrochemical cycling of cells made of the NdFeB electrodes against lithium was measured. The first lithium intercalation capacity of a treated NdFeB can be up to about 831 mAh/g, while a rather reversible capacity of up to 352 mAh/g can be obtained. With a specially designed cell, we were able to monitor in situ the change of relative ac susceptibility during charge and/or discharge steps. A clearly monotonous relationship is found between the ac susceptibility of a cell and its depth-of-discharge (DOD). A mechanism based on skin effect and eddy current change is proposed to explain this susceptibility versus DOD relationship

  17. NdFeB alloy as a magnetic electrode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Shui, J.L. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Zhang, S.L. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Wei, X. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Xiang, Y.J. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Xie, S. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Zhu, C.F. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China); Chen, C.H. [Department of Materials Science and Engineering, University of Science and Technology of China, Anhui Hefei 230026 (China)]. E-mail: cchchen@ustc.edu.cn

    2005-04-05

    The search for a reliable indicator of state of charge and even the remaining energy of a lithium-ion cell is of great importance for various applications. This study was an exploratory effort to use magnetic susceptibility as the indicator. In this work, for the first time the change of ac susceptibility of cells was in situ monitored during charge-discharge process. A strong permanent magnetic material, NdFeB alloy, was investigated as an anode material for rechargeable lithium batteries. Both original and partially oxidized NdFeB powders were made into electrodes. Structural characterization was performed on the NdFeB electrodes by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. An alloy (core)-oxide (shell) structure was found for those partially oxidized samples. The electrochemical cycling of cells made of the NdFeB electrodes against lithium was measured. The first lithium intercalation capacity of a treated NdFeB can be up to about 831 mAh/g, while a rather reversible capacity of up to 352 mAh/g can be obtained. With a specially designed cell, we were able to monitor in situ the change of relative ac susceptibility during charge and/or discharge steps. A clearly monotonous relationship is found between the ac susceptibility of a cell and its depth-of-discharge (DOD). A mechanism based on skin effect and eddy current change is proposed to explain this susceptibility versus DOD relationship.

  18. A comparative thermomagnetic study of melt-spun Nd-Fe-B alloys with different Nd content

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2009-01-01

    Full Text Available Changes in the phase composition and magnetic properties of three types of commercial Nd-Fe-B alloys with different Nd content - low (10-12 wt%, near stoichiometric (21-25 wt% and rich (26-29 wt% caused by thermomagnetic analysis (TM were observed in regard to optimal magnetic state. Phase compositions of investigated alloys before and after TM measurement up to 800°C were compared using 57Fe Mössbauer spectroscopy and X-Ray analysis. The TM measurements decompose all three materials and the main products of decomposition process α-Fe and Fe2B phase. Observed changes in structure and phase composition had direct influence on magnetic properties. Loss of magnetic properties induced by thermal decomposition is clearly illustrated on corresponding SQUID hysteresis loops.

  19. Lattice dynamics, elasticity and magnetic abnormality in ordered crystalline alloys Fe3Pt at high pressures

    Science.gov (United States)

    Cheng, Tai-min; Yu, Guo-Liang; Su, Yong; Ge, Chong-Yuan; Zhang, Xin-Xin; Zhu, Lin; Li, Lin

    2018-05-01

    The ordered crystalline Invar alloy Fe3Pt is in a special magnetic critical state, under which the lattice dynamic stability of the system is extremely sensitive to external pressures. We studied the pressure dependence of enthalpy and magnetism of Fe3Pt in different crystalline alloys by using the first-principles projector augmented-wave method based on the density functional theory. Results show that the P4/mbm structure is the ground state structure and is more stable relative to other structures at pressures below 18.54 GPa. The total magnetic moments of L12, I4/mmm and DO22 structures decrease rapidly with pressure and oscillate near the ferromagnetic collapse critical pressure. At the pressure of 43 GPa, the ferrimagnetic property in DO22 structure becomes apparently strengthened and its volume increases rapidly. The lattice dynamics calculation for L12 structures at high pressures shows that the spontaneous magnetization of the system in ferromagnetic states induces the softening of the transverse acoustic phonon TA1 (M), and there exists a strong spontaneous volume magnetostriction at pressures below 26.95 GPa. Especially, the lattice dynamics stability is sensitive to pressure, in the pressure range between the ferromagnetic collapse critical pressure (41.9 GPa) and the magnetism completely disappearing pressure (57.25 GPa), and near the pressure of phase transition from L12 to P4/mbm structure (27.27 GPa). Moreover, the instability of magnetic structure leads to a prominent elastic modulus oscillation, and the spin polarizability of electrons near the Fermi level is very sensitive to pressures in that the pressure range. The pressure induces the stability of the phonon spectra of the system at pressures above 57.25 GPa.

  20. Ultra-soft magnetic Co-Fe-B-Si-Nb amorphous alloys for high frequency power applications

    Science.gov (United States)

    Ackland, Karl; Masood, Ansar; Kulkarni, Santosh; Stamenov, Plamen

    2018-05-01

    With the continuous shrinkage of the footprint of inductors and transformers in modern power supplies, higher flux, while still low-loss metallic replacements of traditional ferrite materials are becoming an intriguing alternative. One candidate replacement strategy is based on amorphous CoFeBSi soft-magnetic alloys, in their metallic glass form. Here the structural and magnetic properties of two different families of CoFeBSi-based soft magnetic alloys, prepared by arc-melting and subsequent melt spinning (rapid quenching) are presented, targeting potential applications at effective frequencies of 100 kHz and beyond. The nominal alloy compositions are Co67Fe4B11Si16Mo2 representing commercial Vitrovac and Co72-xFexB28-y (where B includes non-magnetic elements such as Boron, Silicon etc. x varies between 4 and 5 % and y is varied from 0 to 2 %) denoted Alloy #1 and prepared as a possible higher performance alternative, i.e. lower power loss and lower coercivity, to commercial Vitrovac. Room temperature magnetization measurements of the arc-melted alloys reveal that compared to Vitrovac, Alloy #1 already presents a ten-fold decrease in coercivity, with Hc ˜ 1.4 Am-1 and highest figure of merit of (Ms/Hc > 96). Upon melt-spinning the alloys into thin (< 30 μm) ribbons, the alloys are essentially amorphous when analyzed by XRD. Magnetization measurements of the melt-spun ribbons demonstrate that Alloy #1 possesses a coercivity of just 2 Am-1, which represents a significant improvement compared to melt-spun ribbons of Vitrovac (17 Am-1). A set of prototype transformers of approximately 10 turns of Alloy #1 ribbon exhibits systematically Hc < 10 Am-1 at 100 kHz, without a noticeable decrease in coupled flux and saturation.

  1. Grain Refinement of Al-Si-Fe-Cu-Zn-Mn Based Alloy by Al-Ti-B Alloy and Its Effect on Mechanical Properties.

    Science.gov (United States)

    Yoo, Hyo-Sang; Kim, Yong-Ho; Jung, Chang-Gi; Lee, Sang-Chan; Lee, Seong-Hee; Son, Hyeon-Taek

    2018-03-01

    We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

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

    International Nuclear Information System (INIS)

    Xiao, M.; Kong, Q.P.

    1997-01-01

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

  3. Westendorf effect in the magnet alloy Nd-Dy-Fe-Co-B

    International Nuclear Information System (INIS)

    Piskorskij, V.P.; Valeev, R.A.; Sychev, I.V.

    2006-01-01

    Sintered magnets of the composition as follows, at. %: (Nd 0.6 Dy 0.4 ) 15 (Fe 1-x Co x ) rest Al 1 B 8 , are under study. It is revealed that the course of coercive force dependence on the temperature of heat treatment varies with a cobalt content increase (within a range of 0.19 - 0.26). The dependence of coercive force on heat treatment temperature for the alloys studied has a pronounced minimum at 700 deg C which is known as a Westendorf effect. This effect is taken to be due to the presence of R(Fe, Co) 4 B phase where R is the sum of REM [ru

  4. Low temperature thermal conductivity of amorphous (Fe, Ni, Co) (P, B, Si) alloys and their change by heat treatment

    International Nuclear Information System (INIS)

    Pompe, G.; Gaafar, M.; Buettner, P.; Francke, T.

    1983-01-01

    The thermal conductivity of amorphous metallic alloys (Fe, Ni, Co)/sub 1-x/ (B, P, Si)/sub x/ is measured in the temperature range 2 to 100 K in the as-produced and heat-treated states. By taking into account the results of Matey and Anderson the influence of the nature of the metalloid and the number of metallic components can be discussed. The change of the thermal conductivity due to a structural relaxation caused by a heat treatment is very different. In the whole range of temperature a rise of the phonon thermal conductivity of the Fe-Co-B alloy is obtained, whereas no change is observed for the Fe-B alloy. At low temperature ( 80 B 20 is investigated. (author)

  5. Properties of amorphous FeCoB alloy particles (abstract)

    DEFF Research Database (Denmark)

    Charles, S. W.; Wells, S.; Meagher, A.

    1988-01-01

    -ray diffraction. Magnetic measurements of the saturation magnetization, coercivity, and remanence of the particles have been measured. The transition from the amorphous-to-crystalline state has been studied using differential scanning calorimetry (DSC) and thermomagnetometry up to a temperature of 450 °C (see Fig......Amorphous and crystalline alloy particles (0.05–0.5 nm) of FexCoyBz in which the ratio x:y ranges from 0 to 1 have been prepared by the borohydride reduction of iron and cobalt salts in aqueous solution. The structure of the particles has been studied using Mössbauer spectroscopy and x....... 1). It has been shown that the fraction of boron in the alloys (10–35 at. %) is dependent upon the rate of addition of salts to borohydride and the concentration of cobalt present; this in turn influences the crystallinity and magnetic properties . Journal of Applied Physics is copyrighted...

  6. Fluxing purification and its effect on magnetic properties of high-B{sub s} FeBPSiC amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Jing [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang, Liaoning 110870 (China); Wang, Anding, E-mail: anding@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Yue, Shiqiang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Kong, Fengyu [School of Materials and Chemical Engineering, Ningbo University of Technology, Ningbo 315016 (China); Qiu, Keqiang, E-mail: kqqiu@163.com [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang, Liaoning 110870 (China); Chang, Chuntao; Wang, Xinmin [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Liu, Chain-Tsuan, E-mail: chainliu@cityu.edu.hk [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2017-07-01

    Highlights: • Surface crystallization in Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbon was inhibited by flux purification. • Amorphous Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbon was made with industrial process and materials. • The ribbons exhibit high B{sub s} of 1.65 T, low H{sub c} of 2 A/m, and high μ{sub e} of 9.7 × 10{sup 3}. • High melting point inclusions trigger the surface crystallization as nuclei. - Abstract: A high-B{sub s} amorphous alloy with the base composition Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} was used to study the effects of fluxing purification on amorphous forming ability and magnetic properties of the alloy prepared with raw materials in industrialization. By using fluxing purification, the surface crystallization was suppressed and fully amorphous Fe{sub 83}B{sub 11}P{sub 3}Si{sub 2}C{sub 1} ribbons with a maximum thickness of 48 μm were successfully achieved by using an industrial process and materials. The amorphous ribbons made with industrial-purified alloys exhibit excellent magnetic properties, containing high-B{sub s} of 1.65 T, low H{sub c} of 2.0 A/m, and high μ{sub e} of 9.7 × 10{sup 3} at 1 kHz. Impurities in the melting alloys exist in three forms and have different effluences on magnetic properties. The surface crystallization was triggered by the impurities which exist as high melting point inclusions serving as nuclei. Thus, fluxing purification is a feasible way for industrialization of high-B{sub s} FeBPSiC amorphous alloys.

  7. Alloy with metallic glass and quasi-crystalline properties

    Science.gov (United States)

    Xing, Li-Qian; Hufnagel, Todd C.; Ramesh, Kaliat T.

    2004-02-17

    An alloy is described that is capable of forming a metallic glass at moderate cooling rates and exhibits large plastic flow at ambient temperature. Preferably, the alloy has a composition of (Zr, Hf).sub.a Ta.sub.b Ti.sub.c Cu.sub.d Ni.sub.e Al.sub.f, where the composition ranges (in atomic percent) are 45.ltoreq.a.ltoreq.70, 3.ltoreq.b.ltoreq.7.5, 0.ltoreq.c.ltoreq.4, 3.ltoreq.b+c.ltoreq.10, 10.ltoreq.d.ltoreq.30, 0.ltoreq.e.ltoreq.20, 10.ltoreq.d+e.ltoreq.35, and 5.ltoreq.f.ltoreq.15. The alloy may be cast into a bulk solid with disordered atomic-scale structure, i.e., a metallic glass, by a variety of techniques including copper mold die casting and planar flow casting. The as-cast amorphous solid has good ductility while retaining all of the characteristic features of known metallic glasses, including a distinct glass transition, a supercooled liquid region, and an absence of long-range atomic order. The alloy may be used to form a composite structure including quasi-crystals embedded in an amorphous matrix. Such a composite quasi-crystalline structure has much higher mechanical strength than a crystalline structure.

  8. Neutron transmission through crystalline Fe

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; Kilany, M.; El-Mesiry, M.S.

    2004-01-01

    The neutron transmission through crystalline Fe has been calculated for neutron energies in the range 10 4 < E<10 eV using an additive formula. The formula permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-section as a function of temperature and crystalline form. The obtained agreement between the calculated values and available experimental ones justifies the applicability of the used formula. A feasibility study on using poly-crystalline Fe as a cold neutron filter and a large Fe single crystal as a thermal one is given

  9. Otimização do banho eletrolítico da liga Fe-W-B resistente à corrosão Optimization of the electrolytic bath for electrodeposition of corrosion resistant Fe-W-B alloys

    Directory of Open Access Journals (Sweden)

    Renato Alexandre Costa de Santana

    2007-04-01

    Full Text Available A study on optimization of bath parameters for electrodeposition of Fe-W-B alloys from plating baths containing ammonia and citrate is reported. A 2³ full factorial design was successfully employed for experimental design analysis of the results. The corrosion resistance and amorphous character were evaluated. The bath conditions obtained for depositing the alloy with good corrosion resistance were: 0.01 M iron sulfate, 0.10 M sodium tungstate and 0.60 M ammonium citrate. The alloy was deposited at 12% current efficiency. The alloy obtained had Ecorr -0.841 V and Rp 1.463 x 10(4 Ohm cm². The deposit obtained under these conditions had an amorphous character and no microcracks were observed on its surface. Besides this, the bath conditions obtained for depositing the alloy with the highest deposition efficiency were: 0.09 M iron sulfate, 0.30 M sodium tungstate and 0.50 M ammonium citrate. The alloy was deposited at 50% current efficiency, with an average composition of 34 wt% W, 66 wt% Fe and traces of boron. The alloy obtained had Ecorr -0.800 V and Rp 1.895 x 10³ Ohm cm². Electrochemical corrosion tests verified that the Fe-W-B alloy deposited under both conditions had better corrosion resistance than Fe-Mo-B.

  10. Magnetoresistance in amorphous NdFeB/FeB compositionally modulated multilayers

    International Nuclear Information System (INIS)

    Peral, G.; Briones, F.; Vicent, J.L.

    1991-01-01

    Resistance measurements have been done in amorphous Nd 12 Fe 80 B 8 sputtered films and in amorphous sputtered Nd 26 Fe 68 B 6 /Fe 92 B 8 multilayers between 6 and 150 K with applied magnetic field parallel (LMR) and perpendicular (TMR) up to 7 T. The samples were grown by dc triode sputtering, with nominal unequal (2:1) layer thicknesses. The layered character of the samples have been tested by x-ray diffraction. Longitudinal magnetoresistance (LMR) is positive and transverse magnetoresistance (TMR) is negative. The magnetoresistance values are higher than in amorphous ferromagnets, and multilayering of these alloys produces much larger magnetoresistance values than either alloy alone and there is a strong dependence on the multilayer wavelength. The MR shows a weak temperature dependence in the temperature interval that was investigated

  11. Development of Fe-B Based Bulk Metallic Glasses: Morphology of Residual Phases in Fe50Ni16Mo6B18Zr10 Glass

    Directory of Open Access Journals (Sweden)

    Tiburce A. Aboki

    2013-04-01

    Full Text Available Iron-boron based bulk metallic glasses (BMG development has been initiated using Fe40Ni38Mo4B18 as precursor. Addition of zirconium up to 10 atomic % along with the reduction of Ni proportion improves the glass forming ability (GFA, which is optimum when Ni is suppressed in the alloy. However melting instability occurred during the materials fabrication resulting in the formation of residual crystalline phases closely related to the amorphous phase. Microstructure study shows an evolution from amorphous structure to peculiar acicular structure, particularly for Fe50Ni16Mo6B18Zr10, suggesting the amorphous structure as interconnected atomic sheets like “atomic mille feuilles” whose growth affects the alloys’ GFA.

  12. Mean field analysis of exchange coupling in amorphous DyFe2-B alloy ribbons

    International Nuclear Information System (INIS)

    Lee, J.M.; Jung, J.K.; Lim, S.H.

    2001-01-01

    Experimental magnetization-temperature curves for melt-spun ribbons of amorphous alloys (Dy 0.33 Fe 0.67 ) 1-x B x with x=0, 0.05, 0.1 and 0.15 (in atomic fraction) are fitted with theoretical equations based on the mean field theory in order to investigate exchange couplings between constituent elements as a function of the B content. The sign of the exchange coupling between Dy and Fe is negative, indicating that the magnetization direction of Dy is antiparallel to that of Fe. The sign of the other two couplings are positive. The exchange coupling between Fe ions are greatest, while that between Dy ions is negligible. The exchange couplings between Fe ions, and between Dy and Fe increase with increasing B content, the increase of the latter being much greater than the former. Resulting, the exchange coupling between Dy and Fe becomes about one half of that between Fe ions at the highest B content. The increase of the exchange coupling between Fe ions may be explained by the increase of the Fe-Fe separation with the increase of the B content. The total magnetization is dominated by the Dy sublattice magnetization. As the B content increases, the magnetization decreases over the whole temperature range, and the Curie temperature also decreases

  13. Composition-dependent magnetic properties of melt-spun La or/and Ce substituted nanocomposite NdFeB alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, M.; Zhao, L.Z.; Zhang, C.; Jiao, D.L.; Zhong, X.C.; Liu, Z.W.

    2016-02-15

    Aiming at high-performance low-cost NdFeB magnets, the magnetic properties and microstructure for melt spun nanocrystalline (Nd{sub 1−x}M{sub x}){sub 10}Fe{sub 84}B{sub 6} (M=La, Ce, or La{sub 0.5}Ce{sub 0.5}; x=0–0.7) alloys were investigated. Relatively, LaCe-substituted alloys show high values of the remanent magnetization M{sub r}, the maximum energy product (BH){sub max} and the coercivity H{sub c}, up to 114 emu/g (1.07 T), 147 kJ/m{sup 3} and 471 kA/m, respectively, at x=0.1. The unusual increase in coercivity for the alloys with 10% La or 10% La{sub 0.5}Ce{sub 0.5} substitution is possibly attributed to the phase segregation in alloys with certain La or LaCe contents. The reduced Curie temperature and spin-reorientation temperature were obtained for La, Ce or LaCe substituted alloys. Transmission electron microscope analysis has revealed that a fine and uniform distributed grain structure leads to remanence enhancement for La{sub 0.5}Ce{sub 0.5} substituted alloys. The present results indicate that partially substituting Nd by La or/and Ce cannot only effectively reduce the cost of nanocrystalline NdFeB based magnetic powders but also can maintain a relatively good combination of magnetic properties.

  14. Impact of the B2 ordering behavior on the mechanical properties of a FeCoMo alloy

    Energy Technology Data Exchange (ETDEWEB)

    Turk, C., E-mail: chris.turk@unileoben.ac.at [Montanuniversität Leoben, Department of Physical Metallurgy and Materials Testing, Franz-Josef Straße 18, 8700 Leoben (Austria); Leitner, H.; Kellezi, G. [Böhler Edelstahl GmbH & Co KG, Mariazellerstraße 25, 8605 Kapfenberg (Austria); Clemens, H. [Montanuniversität Leoben, Department of Physical Metallurgy and Materials Testing, Franz-Josef Straße 18, 8700 Leoben (Austria); Gan, W.M.; Staron, P. [German Engineering Materials Science Centre, Helmholtz-Zentrum Geesthacht, D-21502 Geesthacht (Germany); Primig, S. [Montanuniversität Leoben, Department of Physical Metallurgy and Materials Testing, Franz-Josef Straße 18, 8700 Leoben (Austria)

    2016-04-26

    A Fe - 25 at% Co - 9 at% Mo alloy can be hardened by nm-sized (Fe, Co){sub 7}Mo{sub 6} µ-phase precipitates which is accomplished by solution annealing in the austenite region followed by rapid quenching to room temperature and subsequent aging below the austenite transition temperature. In overaged condition the Mo-content in the remaining matrix drops towards zero and, therefore, the matrix consist of 71 at% Fe and 29 at% Co. The binary Fe-Co system shows a disorder-order, A2↔B2 transition at a critical ordering temperature between 25 at% and 72 at% Co. It is expected that the remaining matrix of an overaged Fe - 25 at% Co - 9 at% Mo alloy also exhibits such an ordering reaction. It will be demonstrated that the formation of a B2 ordered FeCo phase can be delayed or completely prevented by rapid quenching from temperatures above the critical ordering temperature. This has a strong impact on the mechanical properties of this alloy which have been studied by means of tensile, impact toughness and hardness testing. The evidence for a disorder-order transition in this alloy has been given by neutron diffraction as well as high resolution transmission electron microscopy.

  15. Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

    International Nuclear Information System (INIS)

    Xu Jiang; Liu Wenjin; Kan Yide; Zhong Minlin

    2006-01-01

    In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB 2 and Ti 3 B 4 peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO 2 laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB 2 , Ti 3 B 4 , Al 3 Ti, Al 3 Fe and α-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB 2 and Ti 3 B 4 peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB 2 and Ti 3 B 4 peritectic improve wear resistance when compared with the as-received Al substrate

  16. Influence of Microstructure on Microhardness of Fe81Si4B13C2 Amorphous Alloy after Thermal Treatment

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica, M.; Blagojević, V.; Minić, Dušan M.; Gavrilović, A.; Rafailović, L.; Žák, Tomáš

    42A, č. 13 (2011), s. 4106-4112 ISSN 1073-5623 R&D Projects: GA MŠk(CZ) 1M0512 Institutional research plan: CEZ:AV0Z2041904 Keywords : bulk metallic-glass * mechanical properties * Fe81B13SI4C2 alloy * B alloys * alpha-Fe * crystallization * phase * nanocrystallization * behavior Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.545, year: 2011

  17. 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.

  18. Ce-didymium-Fe-B sintered permanent magnets

    International Nuclear Information System (INIS)

    Homma, M.; Okada, M.; Sugimoto, S.

    1985-01-01

    Present works report the development of the low cost R-Fe-B permanent magnets. The best magnetic properties obtained in this studies are Br=13.5 kG, iHc=10.2 kOe and (BH)max=40 MGOe with an Fe-33.5wt%(5Ce-Didymium)-1wt% B alloy. Topics considered in this paper include cerium alloys, boron alloys, fabrication, capitalized cost, iron alloys, permanent magnets, and magnetic properties

  19. Crystallization of some amorphous metallic alloys studied by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sitek, J.; Miglierini, M.; Lipka, J.; Valko, P.; Toth, I.

    1990-01-01

    The present work provides an analysis of crystallization processes in amorphous metallic alloys Fe 80 Si 4 Cr 1.8 B 14 and Fe 67 Co 18 B 14 Si 1 . Crystallization of the first sample started at the temperature of 648 K. The fully crystalline state was observed after annealing at 748 K. We identified four sextets. One corresponds to crystalline Fe 2 B and the three others to FeSi solid solution with 10 at.% of Si. Crystallization of Fe 67 Co 18 B 14 Si 1 started at the temperature of 623 K. We identified two crystalline phases. The first may have its origin as (Fe 1-x Co x ) 3 B, the second one may correspond to a Fe-Co solid solution with a different Co content. (orig.)

  20. Structure and soft magnetic properties of Fe-Si-B-P-Cu nanocrystalline alloys with minor Mn addition

    Directory of Open Access Journals (Sweden)

    Xingjie Jia

    2018-05-01

    Full Text Available Addition of minor Mn effectively improves the amorphous-forming ability and thermal stability of the Fe85Si2B8P4Cu1 alloy. With increasing the Mn content from 0 to 3 at.%, the critical thickness for amorphous formation and onset temperature of the primary crystallization increase from 14 μm and 659 K to 27 μm and 668 K, respectively. The fine nanocrystalline structure with α-Fe grains in size (D of < 20 nm was obtained for the annealed amorphous alloys, which show excellent soft magnetic properties. The alloying of Mn reduces the coercivity (Hc by decreasing the D value and widens the optimum annealing temperature range for obtaining low Hc, although the saturation magnetic flux density (Bs is decreased slightly. The Fe83Mn2Si2B8P4Cu1 nanocrystalline alloy possesses fine structure with a D of ∼17.5 nm, and exhibits a high Bs of ∼1.75 T and a low Hc of ∼5.9 A/m. The mechanism related to the alloying effects on the structure and magnetic properties was discussed in term of the crystallization activation energy.

  1. Structure and soft magnetic properties of Fe-Si-B-P-Cu nanocrystalline alloys with minor Mn addition

    Science.gov (United States)

    Jia, Xingjie; Li, Yanhui; Wu, Licheng; Zhang, Wei

    2018-05-01

    Addition of minor Mn effectively improves the amorphous-forming ability and thermal stability of the Fe85Si2B8P4Cu1 alloy. With increasing the Mn content from 0 to 3 at.%, the critical thickness for amorphous formation and onset temperature of the primary crystallization increase from 14 μm and 659 K to 27 μm and 668 K, respectively. The fine nanocrystalline structure with α-Fe grains in size (D) of < 20 nm was obtained for the annealed amorphous alloys, which show excellent soft magnetic properties. The alloying of Mn reduces the coercivity (Hc) by decreasing the D value and widens the optimum annealing temperature range for obtaining low Hc, although the saturation magnetic flux density (Bs) is decreased slightly. The Fe83Mn2Si2B8P4Cu1 nanocrystalline alloy possesses fine structure with a D of ˜17.5 nm, and exhibits a high Bs of ˜1.75 T and a low Hc of ˜5.9 A/m. The mechanism related to the alloying effects on the structure and magnetic properties was discussed in term of the crystallization activation energy.

  2. Formation and Applications of Bulk Glassy Alloys in Late Transition Metal Base System

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Shen Baolong

    2006-01-01

    This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM base BGAs are promising as new metallic engineering materials

  3. Microstructure and tensile properties of Fe-40 at. pct Al alloys with C, Zr, Hf, and B additions

    Science.gov (United States)

    Gaydosh, D. J.; Draper, S. L.; Nathal, M. V.

    1989-01-01

    The influence of small additions of C, Zr, and Hf, alone or in combination with B, on the microstructure and tensile behavior of substoichiometric FeAl was investigated. Tensile properties were determined from 300 to 1100 K on powder which was consolidated by hot extrusion. All materials possessed some ductility at room temperature, although ternary additions generally reduced ductility compared to the binary alloy. Adding B to the C- and Zr-containing alloys changed the fracture mode from intergranular to transgranular and restored the ductility to approximately 5 percent elongation. Additions of Zr and Hf increased strength up to about 900 K. Fe6Al6Zr and Fe6Al6Hf precipitates, both with identical body-centered tetragonal structures, were identified as the principal second phase in these alloys. Strength decreased steadily as temperature increased above 700 K, as diffusion-assisted mechanisms became operative. Although all alloys had similar strengths at 1100 K, Hf additions significantly improved high-temperature ductility by suppressing cavitation.

  4. Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xu Jiang [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)]. E-mail: xujiang73@sina.com.cn; Liu Wenjin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Kan Yide [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Zhong Minlin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)

    2006-07-01

    In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO{sub 2} laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB{sub 2}, Ti{sub 3}B{sub 4}, Al{sub 3}Ti, Al{sub 3}Fe and {alpha}-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic improve wear resistance when compared with the as-received Al substrate.

  5. 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.

  6. Minor-Cu doped soft magnetic Fe-based FeCoBCSiCu amorphous alloys with high saturation magnetization

    Science.gov (United States)

    Li, Yanhui; Wang, Zhenmin; Zhang, Wei

    2018-05-01

    The effects of Cu alloying on the amorphous-forming ability (AFA) and magnetic properties of the P-free Fe81Co5B11C2Si1 amorphous alloy were investigated. Addition of ≤ 1.0 at.% Cu enhances the AFA of the base alloy without significant deterioration of the soft magnetic properties. The Fe80.5Co5B11C2Si1Cu0.5 alloy with the largest critical thickness for amorphous formation of ˜35 μm possesses a high saturation magnetization (Bs) of ˜1.78 T, low coercivity of ˜14.6 A/m, and good bending ductility upon annealing in a wide temperature range of 513-553 K with maintaining the amorphous state. The fabrication of the new high-Fe-content Fe-Co-B-C-Si-Cu amorphous alloys by minor doping of Cu gives a guideline to developing high Bs amorphous alloys with excellent AFA.

  7. Interface interaction in the B4C/(Fe-B-C) system

    International Nuclear Information System (INIS)

    Aizenshtein, M.; Mizrahi, I.; Froumin, N.; Hayun, S.; Dariel, M.P.; Frage, N.

    2008-01-01

    The wetting behavior in the B 4 C/(Fe-C-B) system was investigated in order to clarify the role of Fe additions on the sinterability of B 4 C. Iron and its alloys with C and B react with the boron carbide substrate and form a reaction zone consisting of a fine mixture of FeB and graphite. The apparent contact angles are relatively low for the alloys with a moderate concentration of the boron and carbon and allow liquid phase sintering to occur in the B 4 C-Fe mixtures. A dilatometric study of the sintering kinetics confirms that liquid phase sintering actually takes place and leads to improved mass transfer. A thermodynamic analysis of the ternary Fe-B-C system allows accounting for the experimental observations

  8. 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.

  9. Coercivity enhancement of NdFeB sintered magnets by low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy modification

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Zhang, Pei; Jin, Jiaying; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2014-04-15

    To improve coercivity without sacrificing other magnetic performance of NdFeB sintered magnets, a low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced as an intergranular additive. Magnetic properties and microstructure of the magnets with different Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} contents were studied. At the optimum addition of 3 wt%, coercivity H{sub cj} was enhanced from 12.7 to 15.2 kOe, the maximum magnetic energy product (BH){sub max} was simultaneously increased from 46.6 to 47.8 MG Oe, accompanied by a slight reduction in remanence B{sub r}. Further investigation on microstructure and grain boundary composition indicated that the enhanced H{sub cj} and (BH){sub max} could be attributed to the refined and uniform 2:14:1 phase grains, continuous grain boundaries and a (Nd,Dy){sub 2}Fe{sub 14}B hardening shell surrounding the 2:14:1 phase grains. - Highlights: • Low melting-point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced to NdFeB magnets. • The doped magnet exhibits enhanced coercivity and maximum energy product. • (Nd,Dy){sub 2}Fe{sub 14}B shell was expected to form in the surface of Nd{sub 2}Fe{sub 14}B grains. • The continuous grain boundary layer formed between neighboring Nd{sub 2}Fe{sub 14}B grains.

  10. In vitro corrosion properties and cytocompatibility of Fe-Ga alloys as potential biodegradable metallic materials.

    Science.gov (United States)

    Wang, Henan; Zheng, Yang; Liu, Jinghua; Jiang, Chengbao; Li, Yan

    2017-02-01

    The in vitro biodegradable properties and cytocompatibility of Fe-Ga alloys including Fe 81 Ga 19 , (Fe 81 Ga 19 ) 98 B 2 and (Fe 81 Ga 19 ) 99.5 (TaC) 0.5 , and pure Fe were investigated for biomedical applications. The microstructure of the alloys was characterized using X-ray diffraction spectroscopy and optical microscopy. The results showed that A2 and D0 3 phases were detected for the three types of Fe-Ga alloys, and additional Fe 2 B and TaC phases were found in the (Fe 81 Ga 19 ) 98 B 2 and (Fe 81 Ga 19 ) 99.5 (TaC) 0.5 alloys, respectively. The corrosion rates of the Fe-Ga alloys were higher than that of pure Fe, as demonstrated by both potentiodynamic polarization measurements and immersion tests in simulated body fluid. The alloying element Ga lowered the corrosion potential of the Fe matrix and made it more susceptible to corrosion. Severe pitting corrosion developed on the surface of the Fe 81 Ga 19 alloy after the addition of ternary B or TaC due to the multi-phase microstructures. The MC3T3-E1 cells exhibited good adhesion and proliferation behavior on the surfaces of the Fe-Ga alloys after culture for 4h and 24h. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Low temperature irradiation effects on iron-boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, Alain.

    1983-01-01

    Three iron-boron amorphous alloys and the crystalline Fe 3 B alloy have been irradiated at liquid hydrogen temperature. 2,4 MeV electron irradiation induces the creation of point defects in the amorphous alloys as well as in the crystalline Fe 3 B alloy. These point defects can be assimilated to iron ''Frenkel pairs''. They have been characterized by determining their intrinsic electrical resistivity and their formation volume. The displacement threshold energy of iron atoms has also been determined. 10 B fission fragments induce, in these amorphous alloys, displacement cascades which lead to stable vacancy rich zones. This irradiation also leads to a structural disorder in relation with the presence of defects. 235 U fission fragments irradiation modifies drastically the structure of the amorphous alloys. The results have been interpreted on the basis of the coexistence of two opposite processes which induce local disorder and crystallisation respectively [fr

  12. Effects of surface crystallization and oxidation in nanocrystalline FeNbCuSiB(P) ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Butvinová, B., E-mail: beata.butvinova@savba.sk [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Butvin, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Brzózka, K. [Department of Physics, University of Technology and Humanities in Radom, Krasickiego 54, 26-600 Radom (Poland); Kuzminski, M. [Institute of Physics PAS, Al. Lotnikow 36/42, 02-668 Warsaw (Poland); Maťko, I.; Švec Sr, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Chromčíková, M. [Institute of Inorg. Chem. SAS, Centrum VILA, Študentská 2, 911 50 Trenčín (Slovakia)

    2017-02-15

    Si-poor Fe{sub 74}Nb{sub 3}Cu{sub 1}Si{sub 8}B{sub 14−x}P{sub x}, (x=0, 3) nanocrystalline ribbon-form alloys often form surfaces, which exert in-plane force on underlying ribbon interior when nanocrystallized in even modest presence of oxygen. Mostly unwanted hard-ribbon-axis magnetic anisotropy is standard result. Essential sources of the surface-caused stress have been sought and influence of P instead of B substitution on this effect was studied too. Preferred surface crystallization (PSC) was found to be the major reason. However P substitution suppresses PSC and promotes Fe-oxide formation, which eases the stress, softens the surfaces and provides different annealing evolution of surface properties. - Highlights: • Ar anneal of low-Si FeNbCuBSi ribbons produce surfaces that stress ribbon interior. • The stress comes mainly from preferred crystallization of surfaces. • Partial substitution of B by P changes annealing evolution of surface properties. • Without P, more crystalline surfaces significantly reduce ribbon's elasticity. • P suppresses surface crystallinity, promotes oxides and reduces mutual stress.

  13. Surface properties of a nanocrystalline Fe-Ni-Nb-B alloy after neutron irradiation

    International Nuclear Information System (INIS)

    Pavuk, M.; Sitek, J.; Sedlackova, K.

    2014-01-01

    In this work, we studied the impact of a neutron radiation on the surface properties of the nanocrystalline (Fe_0_._2_5Ni_0_._7_5)_8_1Nb_7B_1_2 alloy. Changes in topography and domain structure were observed by means of magnetic force microscopy (MFM). (authors)

  14. Study on magnetic properties of (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) alloys

    Science.gov (United States)

    Tan, G. S.; Xu, H.; Yu, L. Y.; Tan, X. H.; Zhang, Q.; Gu, Y.; Hou, X. L.

    2017-09-01

    In the present work, (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) permanent alloys are prepared by melt-spinning method. The hard magnetic properties of (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) alloys annealed at optimum temperatures have been investigated systematically. Depending on the Nd, Ce concentration, the maximum energy product ((BH)max) and remanence (Br) increase gradually with x in the range of 0 ≤ x ≤ 0.4, whereas decrease gradually in the alloys with 0.4 plays a certain role in the magnetization reversal behavior and can improve the microstructure of (Nd0.8Ce0.2)1.6Fe12Co2B alloy.

  15. Interface interaction in the B{sub 4}C/(Fe-B-C) system

    Energy Technology Data Exchange (ETDEWEB)

    Aizenshtein, M. [Department of Material Engineering, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel); NRC-Negev, P.O. Box 9001, Beer-Sheva 84190 (Israel); Mizrahi, I.; Froumin, N.; Hayun, S.; Dariel, M.P. [Department of Material Engineering, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel); Frage, N. [Department of Material Engineering, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel)], E-mail: nfrage@bgu.ac.il

    2008-11-15

    The wetting behavior in the B{sub 4}C/(Fe-C-B) system was investigated in order to clarify the role of Fe additions on the sinterability of B{sub 4}C. Iron and its alloys with C and B react with the boron carbide substrate and form a reaction zone consisting of a fine mixture of FeB and graphite. The apparent contact angles are relatively low for the alloys with a moderate concentration of the boron and carbon and allow liquid phase sintering to occur in the B{sub 4}C-Fe mixtures. A dilatometric study of the sintering kinetics confirms that liquid phase sintering actually takes place and leads to improved mass transfer. A thermodynamic analysis of the ternary Fe-B-C system allows accounting for the experimental observations.

  16. In vitro corrosion properties and cytocompatibility of Fe-Ga alloys as potential biodegradable metallic materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Henan; Zheng, Yang; Liu, Jinghua; Jiang, Chengbao; Li, Yan, E-mail: liyan@buaa.edu.cn

    2017-02-01

    The in vitro biodegradable properties and cytocompatibility of Fe-Ga alloys including Fe{sub 81}Ga{sub 19}, (Fe{sub 81}Ga{sub 19}){sub 98}B{sub 2} and (Fe{sub 81}Ga{sub 19}){sub 99.5}(TaC){sub 0.5}, and pure Fe were investigated for biomedical applications. The microstructure of the alloys was characterized using X-ray diffraction spectroscopy and optical microscopy. The results showed that A2 and D0{sub 3} phases were detected for the three types of Fe-Ga alloys, and additional Fe{sub 2}B and TaC phases were found in the (Fe{sub 81}Ga{sub 19}){sub 98}B{sub 2} and (Fe{sub 81}Ga{sub 19}){sub 99.5}(TaC){sub 0.5} alloys, respectively. The corrosion rates of the Fe-Ga alloys were higher than that of pure Fe, as demonstrated by both potentiodynamic polarization measurements and immersion tests in simulated body fluid. The alloying element Ga lowered the corrosion potential of the Fe matrix and made it more susceptible to corrosion. Severe pitting corrosion developed on the surface of the Fe{sub 81}Ga{sub 19} alloy after the addition of ternary B or TaC due to the multi-phase microstructures. The MC3T3-E1 cells exhibited good adhesion and proliferation behavior on the surfaces of the Fe-Ga alloys after culture for 4 h and 24 h. - Highlights: • Fe-Ga alloys showed a higher degradation rate than pure Fe. • Fe-Ga alloys exhibited good cytocompatibility for the MC3T3-E1 cells. • The MC3T3-E1 cells were tolerable to the corrosion products of Fe-Ga alloys.

  17. Short range order in FeCo-X alloys

    International Nuclear Information System (INIS)

    Fultz, B.

    1988-01-01

    Moessbauer spectrometry was used to study the kinetics of chemical ordering in FeCo and in FeCo alloyed with ternary solutes. With respect to the binary FeCo alloy, the kinetics of B2 ordering were slowed when 2% of 4d- or 5d-series ternary solute atoms were present, but 3p- and 3d-series ternary solutes had little effect on ordering kinetics. The relaxation of order around the ternary solute atoms could be discerned in Moessbauer spectra, and it seems that the development of B2 short range order is influenced by structural relaxations around the ternary solute atoms. Different thermal treatments were shown to cause different relaxations of and correlations, suggesting that Moessbauer spectrometry can be used to identify different kinetic paths of ordering in ternary alloys. (orig.)

  18. Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

    2011-06-15

    Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

  19. Magnetic and Moessbauer studies of amorphous Fe72-xYxHo8B20 alloys

    International Nuclear Information System (INIS)

    Krishnan, R.; Dumond, Y.; Ajan, A.; Shringi, S.N.; Prasad, S.

    1996-01-01

    We have carried out magnetic and Moessbauer studies of amorphous Fe 72-x Y x Ho 8 B 20 alloys. The Fe moment decreases with the addition of Y and a magnetic compensation occurs at 4 K for x=16. The temperature and field dependences of the magnetization have been interpreted using the mean field theory and Chudnovsky's model, respectively. These analyses yield some interesting parameters such as the random anisotropy, the exchange interactions J Fe-Fe , J Fe-Ho , etc. The Moessbauer studies show that the average hyperfine field decreases linearly with the addition of Y, in accordance with the decrease in the Fe moment. (orig.)

  20. Magnetic structure at the surface of a FeZrB alloy

    International Nuclear Information System (INIS)

    Pavuk, M.; Miglierini, M.; Sitek, J.

    2013-01-01

    The aim of this work was to examine two structural states of the "5"7Fe_9_0Zr_7B_3 alloy from the point of view of their domain structure. As the method for obtaining the image of a domain structure we used the magnetic force microscopy (MFM). Its advantage is that besides the image of a domain structure, it also records the image of topography. Another advantage is the high spatial resolution. From both of these advantages, one can benefit in the study of nanocrystalline alloys. Nevertheless, the use of MFM in the study of nanocrystalline materials is so far only rare. Additional structural characterization was obtained by the help of Conversion Electron Moessbauer Spectrometry (CEMS). (authors)

  1. 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...

  2. Magnetic properties and microstructure of as-spun Fe3B/Nd2Fe14B nanocomposite permanent magnets produced by low-speed melt spinning technique

    International Nuclear Information System (INIS)

    Hirosawa, S.; Kanekiyo, H.; Ping, D.H.; Hono, K.

    1998-01-01

    Thick permanent magnet flakes of Fe 3 B/Nd 2 Fe 14 B nanocomposites have been produced directly from molten alloys by means of the low surface-velocity melt spinning technique. The thickness of the flakes varies from 70 to 300 μm depending on the surface velocity (V s ) of a quenching copper roll. Melt-spun flakes of Nd 4 Fe 77.5 B 18.5 alloy exhibit the intrinsic coercivity of 276 kA/m at V s of 5 m/s. X-ray diffraction and transmission electron microscopy results have revealed that this material is composed of nanocrystalline Fe 3 B and Nd 2 Fe 14 B grains ranging from 10 to 50 nm in diameter. The melt-spun alloy produced at V s = 3 m/s contains large grains of Nd 2 Fe 14 B, small grains of Fe 3 B, and large dendritic α-Fe of a few μm in length. In contrast, at V s = 7 m/s, a large portion of the quenched alloy is amorphous. These melt-spun alloys do not possess a hard magnetic property. We have also found that small additions of additives affect the optimum range of V s that give rise to hard magnetic properties in the as-melt-spun condition. Cr has a large effect in shifting the optimum V s values down to a 2-3 m/s range. Simultaneous addition of Co and Ga is effective in extending the optimum values of V s . A platelet permanent magnet with a thickness of 240 μm and magnetic properties of (BH) max = 131 kJ/m 3 , H cJ = 400 kA/m, and B r = 1.15 T has been produced from a Nd 3.5 Dy 1 Fe 73 Co 3 Ga 1 B 18.5 alloy. (orig.)

  3. High saturation magnetization FeB(C) nanocapsules

    International Nuclear Information System (INIS)

    Ma, S.; Si, P.Z.; Zhang, Y.; Wu, B.; Li, Y.B.; Liu, J.J.; Feng, W.J.; Ma, X.L.; Zhang, Z.D.

    2007-01-01

    FeB(C) nanocapsules were prepared by arc-discharging Fe 80 B 20 alloy in Ar and CH 4 . X-ray diffraction and transmission electron microscopy analyses showed that the FeB(C) nanocapsules had a core-shell structure with α-Fe and Fe 3 B as cores and graphite as shells. The formation mechanism of the FeB(C) nanocapsules is discussed. The graphite shells display a strong anti-acid effect. The saturation magnetization at room temperature of the FeB(C) nanocapsules is much higher than that of Fe(B) nanocapsules. The blocking temperature of FeB(C) nanocapsules is above 300 K

  4. Mass transport in non crystalline metallic alloys

    International Nuclear Information System (INIS)

    Limoge, Y.

    1986-08-01

    In order to improve our understanding of mass transport in non crystalline metallic alloys we have developed indirect studies of diffusion based on electron irradiation and hydrostatic pressure effects upon crystallization. In a first part we present the models of crystallization which are used, then we give the experimental results. The main point is the first experimental measurement of the activation volume for diffusion in a metallic glass: the value of which is roughly one atomic volume. We show also recent quantitative results concerning radiation enhanced diffusion in metallic glasses (FeNi) 8 (PB) 2 and Ni 6 Nb 4 . In a last part we discuss the atomic model needed to explain our results

  5. Short-range order of amorphous FeNiB alloy after neutron irradiation

    International Nuclear Information System (INIS)

    Miglierini, M.; Sitek, J.; Baluch, S.; Cirak, J.; Lipka, J.

    1990-01-01

    Transmission Moessbauer spectroscopy was used to study irradiation-induced changes in the short-range order of an amorphous Fe 80-x Ni x B 20 alloy. Neutron irradiation led to an increase of the width of a hyperfine field distribution implying atomic rearrangement towards disordering. Changes in a mean value of a HFD and Moessbauer line areas can be associated with a reorientation of spins due to radiation damage. (orig.)

  6. Crystallization characteristics of amorphous alloys of FeZr

    International Nuclear Information System (INIS)

    Rozhan, M. Idrus; Grundy, P.J.

    1993-01-01

    The crystallization characteristics of sputter-deposited amorphous alloys of Fe 100-x Zr x prepared at zirconium concentrations between 9 and 89 at.% was investigated. The transformation of the alloys from the amorphous to the crystalline state has been examined by thermal analysis, electrical resistance and X-ray diffraction. The crystallization temperatures were determined by differential scanning calorimetry (DSC) and electrical resistance as a function of temperature. The final phases were determined by X-ray diffraction. The activation energies were calculated from the Kissinger plots and the heats of crystallization were calculated and correlations between the thermal analysis and the resistance results are presented

  7. Crystallization processes in an amorphous Co-Fe-Cr-Si-B alloy under isothermal annealing

    Science.gov (United States)

    Fedorets, A. N.; Pustovalov, E. V.; Plotnikov, V. S.; Modin, E. B.; Kraynova, G. S.; Frolov, A. M.; Tkachev, V. V.; Tsesarskaya, A. K.

    2017-09-01

    Research present the crystallization processes investigation of the amorphous Co67Fe3Cr3Si15B12 alloy. In-situ experiments on heating in a transmission electron microscope (TEM) column were carried out. Critical temperatures influencing material structure are determined. The onset temperature of material crystallization was determined.

  8. Synthesis and structural characterization of amorphous alloys of the Fe-Ni-B type

    International Nuclear Information System (INIS)

    Cabral P, A.; Jimenez B, J.; Garcia S, I.

    2004-01-01

    It was prepared the alloy FeNiB for chemical reduction, using four p H values (5, 6, 7 and 7.5). To p H=6 partially oxidized particles were obtained, between 16 and 20%. In the synthesis to other p H values, the obtained particles were highly oxidized (65-90%) according to the X-ray diffraction results, in all the preparations the particles were partially crystallized, with crystal size that varied between 4 and 10 nm. The structure of these particles can be consider that they are formed by a nucleus due to the alloy and an oxide armor recovering it. (Author)

  9. Polarization and resistivity measurements of post-crystallization changes in amorphous Fe-B-Si alloys

    International Nuclear Information System (INIS)

    Chattoraj, I.; Bhattamishra, A.K.; Mitra, A.

    1993-01-01

    The effects of grain growth and compositional changes on the electrochemical behavior and the resistivity of amorphous iron-boron-silicon (Fe 77.5 B 15 Si 7.5 ) alloys after crystallization were studied. Deterioration of the protective passive film was observed, along with increased annealing. Potentiodynamic polarization provided excellent information about microstructural and chemical changes. It was concluded that electrochemical measurements could be used in conjunction with resistivity measurements in direct studies of grain growth and chemical changes occurring in different phases of the devitrified alloy

  10. Processing and characterization of AlCoFeNiXTi0,5 (X = Mn, V) high entropy alloys

    International Nuclear Information System (INIS)

    Triveno Rios, C.; Kiminami, C.S.

    2014-01-01

    The microstructure of high entropy alloys consists of solid solution phases with FC and BCC simple structures, contrary to classical metallurgy where they form complex structures of intermetallic compounds. Because of this they have several attractive properties for engineering applications. In this work the AlCoFeNiMnTi 0,5 and AlCoFeNiVTi 0,5 alloys were processed by melting arc. Since the main objective was the microstructural and mechanical characterization of ingots as-cast. The alloys were characterized by scanning electron microscopy, X-ray diffraction, microhardness and cold compression test. The results showed that the microstructure consists mainly of dendrites and interdendritic regions consisting of metastable crystalline phases. It was also observed that the AlCoFeNiVTi 0,5 alloy showed better mechanical properties than the AlCoFeNiMnTi 0,5 alloy. This may be associated with differences in the parameters of formation of simple solid solution phases between the two alloys. (author)

  11. Magnetic exchange coupling in amorphous Fe80-xDy xB20 alloys

    International Nuclear Information System (INIS)

    Annouar, F.; Lassri, H.; Ayadi, M.; Omri, M.; Lassri, M.; Krishnan, R.

    2005-01-01

    Amorphous Fe 80-x Dy x B 20 alloys have been prepared by melt spinning and their magnetic properties have been studied. The mean field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Dy-Co atom pairs have been evaluated. High-field magnetization studies on samples with stoichiometry close to that of a compensated ferrimagnet show a magnetic behavior that is characteristic of a non-collinear magnetic structure of the Dy and Fe sublattices. The region of the canted moments can be described by a phase diagram in the H-T plane

  12. Intrinsic evolution of novel (Nd, MM)2Fe14B-system magnetic flakes

    Science.gov (United States)

    Yu, Xiaoqiang; Zhu, Minggang; Liu, Weiqiang; Li, Yanfeng; Zhang, Jiuxing; Yue, Ming; Li, Wei

    2018-01-01

    The Nd-substituted (Nd x MM1- x )-Fe-B strip-casting flakes were prepared by induction melting in the vacuum furnace and then subsequently by strip-casting technology. The microstructure and magnetic properties of (Nd x MM1- x )-Fe-B alloys are related to the Nd substitution. 2:14:1 main phases and minor impure phases coexist in the MM-Fe-B flake. For example, La2O3 and CeFe2 impure phases are obviously detected in the x = 0 specimen. As an increase of the Ce concentration is inversely accompanied with the decrease of the Nd content ( x) in (Nd x MM1- x )2Fe14B main phases (0 ≤ x ≤ 1), XRD analysis shows that the overall diffraction peaks of the main phases shift to right domestically because of smaller radius Ce4+. The melting point, spin reorientation phase transition temperature, Curie temperature, magneto-crystalline anisotropy field (at 300 K), and the magnetization ( M 9T) for MM-Fe-B/(Nd0.4MM0.6)-Fe-B/(Nd0.7MM0.3)-Fe-B/Nd-Fe-B strip-casting alloys are 1376.15/1414.15/1439.15/1458.15 K, 74/113/124/135 K, 493.2/538.4/559.7/582.3 K, 48/55.2/64.4/70.1 kOe and 136.5/143.7/151.5/153.7 emu/g, respectively. Due to the varied composition of hard magnetic main phases, M 9T increases gradually with the increase of Nd content ( x). SEM observation and EDX results demonstrate that more Nd and Pr elements aggregate into the 2:14:1 ferromagnetic phase, while less La and Ce elements are prone to the RE-rich region compared with the nominal ratio. As a result, the growth of M 9T becomes extraordinary under maximum external field 9 T, indicating that the (Nd0.7MM0.3)-Fe-B flake may display relatively good magnetic properties and those with higher Nd content have evident effect on magnetization, compositions, and microstructures of hard magnetic main phases. Therefore, practical application of (Nd x MM1- x )-Fe-B-sintered magnets will be very prospective.

  13. 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.

  14. 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.

  15. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Science.gov (United States)

    Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 1689±85 HV0.01, and 181±7 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  16. The effect of phase constitution on the magnetic structure of nanophase NdFeB alloys observed by magnetic force microscopy

    Science.gov (United States)

    Al-Khafaji, M. A.; Rainforth, W. M.; Gibbs, M. R. J.; Davies, H. A.; Bishop, J. E. L.

    1998-09-01

    Magnetic force microscopy (MFM) has been employed to image the magnetic structure in nanocrystalline melt spun ribbon samples of NdFeB alloys of three markedly different and contrasting compositions: Low-Nd (Nd 9.5Fe 84.5B 6) containing Nd 2Fe 14B and α-Fe phases, stoichiometric (Nd 11.8Fe 82.3B 5.9), and high-Nd (Nd 18Fe 76B 6) containing Nd 2Fe 14B and Nd-rich phases. It was found that the magnetic domain length scale is significantly larger than the mean Nd 2Fe 14B grain size (˜35 nm) in each case, although small changes in force gradient occurred down to ˜20 nm. However, both the domain length scale and the tip-sample interaction `strength' were found to decrease with increasing Nd-content. An interpretation of these results in terms of the microstructure is given.

  17. 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.

  18. 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.

  19. Anti-Invar properties and magnetic order in fcc Fe-Ni-C alloy

    International Nuclear Information System (INIS)

    Nadutov, V.M.; Kosintsev, S.G.; Svystunov, Ye.O.; Garamus, V.M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

    2011-01-01

    Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy, which demonstrates high values of thermal expansion coefficient (TEC) (15-21)x10 -6 K -1 accompanied by almost temperature-insensitive behavior in temperature range of 122-525 K. Alloying with carbon considerably expanded the low temperature range of anti-Invar behavior in fcc Fe-Ni-based alloy. The Curie temperature of the alloy T C =195 K was determined on measurements of temperature dependences of magnetic susceptibility and saturation magnetization. The Moessbauer and small-angle neutron scattering (SANS) experiments on the fcc Fe-25.3%Ni-(0.73-0.78)%C alloys with the varying temperatures below and above the Curie point and in external magnetic field of 1.5-5 T were conducted. Low value of the Debye temperature Θ D =180 K was estimated using the temperature dependence of the integral intensity of Moessbauer spectra for specified temperature range. The inequality B eff =(0.7-0.9)B ext was obtained in external field Moessbauer measurement that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B ext . Nano length scale magnetic inhomogeneities nearby and far above T C were revealed, which assumed that it is caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond. - Highlights: → Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy. → Carbon expanded the temperature range of anti-Invar behavior in Fe-Ni-based alloy. → Moessbauer data point to mixed interspin interaction and low the Dedye temperature. → The SANS experiments reveal nano length scale magnetic inhomogeneities ≤6 nm. → Anti-Invar behavior of Fe-Ni-C alloy explained by thermally varied magnetic order.

  20. An investigation of domains and walls in two NdFeB alloys by transmission electron microscopy

    International Nuclear Information System (INIS)

    Young, S.; Chapman, J.N.

    1993-01-01

    Transmission Electron Microscopy (TEM) has been used to investigate the domain structure in NdFeB alloy ampersand The variation of domain period in thinned sections has been studied for two different alloys and an energy minimization model has been used to calculate the specific domain wall energy (σ) for each alloy. For the basic alloy (A) a value for σ of 20.4mJ/m 2 Was found, whilst the alloy with additions of Dy (B) had a value which was ∼10% lower. This apparently surprising result is attributed to a decrease in the RE-TM exchange energy which more than offsets the increase in anisotropy resulting from the addition of Dy. The behavior of domains as they approach a grain boundary has also been investigated. It has been observed that the relative orientation of the c-axes of two adjacent grains is extremely important in determining the behavior of the domain structure at the grain boundary

  1. Effect of borohydride addition rate on chemically prepared amorphous Fe-B particles

    International Nuclear Information System (INIS)

    Koch, C.B.; Morup, S.; Linderoth, S.

    1991-01-01

    Amorphous Fe-B alloys can be prepared by reacting aqueous solutions of Fe salts and NaBH 4 . In this paper the effect of the addition rate of the NaBH 4 solution to the FeSO 4 solution on the precipitate is investigated. The chemical composition of the amorphous alloys formed varies between Fe 79 B 21 and Fe 68 B 32 . The hyperfine parameters of the alloys, derived from Mossbauer spectra, show a decrease from 29 to 25 T of the magnetic hyperfine field and an increase from 0.19 to 0.28 mms -1 of the isomer shift with increasing NaBH 4 addition rate. The results suggest that alloys with different structures but identical composition may be produced by chemical reduction

  2. Fusion welding of Fe-added lap joints between AZ31B magnesium alloy and 6061 aluminum alloy by hybrid laser-tungsten inert gas welding technique

    International Nuclear Information System (INIS)

    Qi, Xiao-dong; Liu, Li-ming

    2012-01-01

    Highlights: → Hybrid Laser-TIG fusion welding technique was used for joining Mg to Al alloys. → Laser defocusing amount determined penetration depth inside Al alloy of joints. → The addition of Fe interlayer suppressed Mg-Al intermetallics greatly in joints. → A maximum joint strength with optimum thickness of Fe interlayer was obtained. → Excessive addition of Fe interlayer was adverse for the strength improvement. -- Abstract: AZ31B magnesium alloy and 6061-T6 aluminum alloy were lap joined together with the addition of Fe interlayer by fusion welding of hybrid laser-tungsten inert gas (TIG) technique. The influence of location of laser focal spot (LFS) on joint penetration depth and that of the depth on joint strength were investigated. The results showed that when the LFS was just on the surface of Al plate, the deepest penetration could be obtained, which contributed to the improvement of shear strength of Fe-added joints, but not to the elevation of the strength of Mg/Al direct joints. The addition of Fe interlayer suppressed massive production of Mg-Al intermetallics but produced Fe-Al intermetallics in the fusion zone of the joints, whose micro-hardness was extremely high and was also adverse for the enhancement of joint shear strength. The effect of Fe-interlayer thickness on the joint shear strength was also examined, and the maximum shear strength of Fe-added joint could achieve 100 MPa with 0.13 mm thick Fe interlayer. The fracture modes of 0.07 and 0.13 mm Fe-interlayer-added joints were both quasi-cleavage, while those of direct and 0.22 mm interlayer-added joints were completely cleavage. The theoretical shear strength of the Fe-added joints was also discussed.

  3. Synthesis and structural characterization of amorphous alloys of the Fe-Ni-B type; Sintesis y caracterizacion estructural de aleaciones amorfas del tipo Fe-Ni-B

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Jimenez B, J.; Garcia S, I. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    It was prepared the alloy FeNiB for chemical reduction, using four p H values (5, 6, 7 and 7.5). To p H=6 partially oxidized particles were obtained, between 16 and 20%. In the synthesis to other p H values, the obtained particles were highly oxidized (65-90%) according to the X-ray diffraction results, in all the preparations the particles were partially crystallized, with crystal size that varied between 4 and 10 nm. The structure of these particles can be consider that they are formed by a nucleus due to the alloy and an oxide armor recovering it. (Author)

  4. The Magnetization Reversal Processes Of Bulk (Nd, Y-(Fe, Co-B Alloy In The As-Quenched State

    Directory of Open Access Journals (Sweden)

    Dośpiał M.

    2015-09-01

    Full Text Available The magnetization reversal processes of bulk Fe64Co5Nd6Y6B19 alloy in the as-quenched state have been investigated. From the analysis of the initial magnetization curve and differential susceptibility versus an internal magnetic field it was deduced, that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain’s boundaries of the Nd2Fe14B phase. Basing on the dependence of the reversible magnetization component as a function of magnetic field it was found that reversible rotation of a magnetic moment vector and motion of domain walls in multi-domain grains result in high initial values of the reversible component. The presence of at least two maxima on differential susceptibility of irreversible magnetization component in function of magnetic field imply existence of few pinning sites of domain walls in Fe64Co5Nd6Y6B19 alloy. The dominant interactions between particles have been determined on the basis of the Wohlfarth dependence. Such a behavior of Wohlfarth’s plot implies that the dominant interaction between grains becomes short range exchange interactions.

  5. Coercivity of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering method

    Directory of Open Access Journals (Sweden)

    Tetsuji Saito

    2017-05-01

    Full Text Available The effects of Nd-Cu alloy powder addition on the microstructures and magnetic properties of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering (SPS method were investigated. The addition of a small amount of Nd-Cu alloy powder, up to 2%, significantly increased the coercivity of the Nd-Fe-B hot-deformed magnets without deteriorating the crystallographic alignment of the Nd2Fe14B phase. The Nd-Fe-B hot-deformed magnet with 2% Nd-Cu alloy powder had the same remanence value as the Nd-Fe-B hot-deformed magnet without Nd-Cu alloy powder addition, but the magnet with 2% Nd-Cu alloy powder exhibited higher coercivity and a higher maximum energy product than the magnet without Nd-Cu alloy powder addition.

  6. Improvements of room temperature tensile properties in cast TiAl-Fe-V-B alloy by microstructural control; Fe, V, B tenka TiAl gokin no soshiki seigyo ni yoru joon hippari tokusei no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Nishikiori, S.; Matsuda, K. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1998-05-01

    Conditions of homogenization to follow the HIP (hot isostatic press) treatment of the TiAl alloy are tested and discussed for the optimization of the relationship between mechanical properties and the structure resulting from heat treatment. Fe, V, and B are added for improved castability to a TiAl alloy newly developed in this report, and this allows {beta} precipitation to take place which does not occur in the two-element alloy. Attention is paid to this {beta} phase, and the effect of homogenizing conditions and the amount of oxygen is investigated from the metallographic point of view. Some findings obtained are mentioned below. The {beta} phase size 30-50{mu}m emerges in the vicinity of {gamma} grains, containing more Fe and V in the solid solution state than the other structural phases. The {beta} phase rich in Fe and V concentration is high in Vickers hardness, and is supposedly brittle at room temperature. The added oxygen reduces the amount of {beta} phase precipitation for the stabilization of the {alpha} phase. The TiAl alloy containing Fe, V, and B exhibits a duplex structure after HIP treatment and the homogenization process to follow. It has a tensile strength of 550MPa, proof stress of 390MPa, and elongation of 1.80%, on the average at room temperature. 14 refs., 10 figs., 1 tab.

  7. Study of Fe-Ni-Si-B alloy and films on its base by X-ray photospectroscopy method

    International Nuclear Information System (INIS)

    Kozlenko, V.G.; Parfenenok, M.A.; Pukhov, I.K.; Shaposhnikov, A.N.; Shirkov, A.V.

    1983-01-01

    By the method of X ray photoelectron spectroscopy the chemical composition of Fe-Ni-Si-B alloy and films on its base prepared by ion-plasma sputtering is investigated. The identity of chemical bonds in film samples and initial target is revealed, realized are in them mostly Fe-B, Ni-C, Si-Si interatomic bonds. It is shown that lono. films contact with atmosphere is the cause of difference of film composition in the near-surface region (up to 100 nm) from its main volume composition

  8. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Energy Technology Data Exchange (ETDEWEB)

    Kilinc, B., E-mail: bkilinc@sakarya.edu.tr; Durmaz, M.; Abakay, E. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, SakaryaUniversity, Esentepe Campus, 54187Sakarya (Turkey); Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  9. Corrosion behaviour of Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Mummert, K.; El-Aziz, A.M.; Barkleit, G.; Schultz, L.; Rodewald, W.

    2000-01-01

    The corrosion behaviour of Nd-Fe-B permanent magnetic alloys as well as of single phases of these alloys have been investigated in sulphuric acid at room temperature and humid air at 150 C using mass loss and electrochemical techniques. Scanning electron microscopy and scanning probe microscopy were used to study the surface topography. The electrostatic surface potential was examined by scanning probe microscopy using tapping mode. A correlation between the electrostatic surface potential and the corrosion rate of these alloys was found. The higher the value of the electrostatic surface potential of the intergranular phases the higher is the corrosion sensitivity. The strength of the corrosion attack on the phases of sintered permanent magnetic alloys is as follows: Ferromagnetic phase < B-rich phase < Nd-rich phase. The differences in the chemical composition as well as in the preparation of these magnetic alloys have distinct influence on the corrosion resistance of the magnetic Nd-Fe-B alloys. (orig.)

  10. Analysis of grain growth process in melt spun Fe-B alloys under the initial saturated grain boundary segregation condition

    International Nuclear Information System (INIS)

    Chen, Z.; Liu, F.; Yang, X.Q.; Fan, Y.; Shen, C.J.

    2012-01-01

    Highlights: → We compared pure kinetic, pure thermodynamic and extended thermo-kinetic models. → An initial saturated GB segregation condition of nanoscale Fe-B alloys was determined. → The controlled-mechanism was proposed using two characteristic times (t 1 and t 2 ). - Abstract: A grain growth process in the melt spun low-solid-solubility Fe-B alloys was analyzed under the initial saturated grain boundary (GB) segregation condition. Applying melt spinning technique, single-phase supersaturated nanograins were prepared. Grain growth behavior of the single-phase supersaturated nanograins was investigated by performing isothermal annealing at 700 deg. C. Combined with the effect of GB segregation on the initial GB excess amount, the thermo-kinetic model [Chen et al., Acta Mater. 57 (2009) 1466] was extended to describe the initial GB segregation condition of nanoscale Fe-B alloys. In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, an initial saturated GB segregation condition was determined. The controlled-mechanism of grain growth under initial saturated GB segregation condition was proposed using two characteristic annealing times (t 1 and t 2 ), which included a mainly kinetic-controlled process (t ≤ t 1 ), a transition from kinetic-mechanism to thermodynamic-mechanism (t 1 2 ) and pure thermodynamic-controlled process (t ≥ t 2 ).

  11. Study of point defects in non crystalline alloys by high temperature mass transport experiments

    International Nuclear Information System (INIS)

    Limoge, Y.

    1986-09-01

    We present in this communication the results of new experiments designed to study the mass transport mechanism in non-crystalline metallic alloys. They are based on the isothermal measurement of the crystallization kinetics, either without constraint or under electron irradiation or hydrostatic pressure. These experiments show that in the alloys studied, (FeNi) 8 (Pb) 2 and Ni 6 Nb 4 ), irradiation enhances the diffusion on the one hand, and on the other that there exist an activation volume for diffusion, of the order of one atomic volume. We discuss then the atomic model of diffusion needed to explain our results

  12. Crystalline structure and XMCD studies of Co40Fe40B20 grown on Bi2Te3, BiTeI and Bi2Se3

    OpenAIRE

    Kaveev, A. K.; Sokolov, N. S.; Suturin, S. M.; Zhiltsov, N. S.; Golyashov, V. A.; Tereshchenko, O. E.; Prosvirin, I. P.; Kokh, K. A.; Sawada, M.

    2018-01-01

    Epitaxial films of Co40Fe40B20 (further - CoFeB) were grown on Bi2Te3(001) and Bi2Se3(001) substrates by laser molecular beam epitaxy (LMBE) technique at 200-400C. Bcc-type crystalline structure of CoFeB with (111) plane parallel to (001) plane of Bi2Te3 was observed, in contrast to polycrystalline CoFeB film formed on Bi2Se3(001) at RT using high-temperature seeding layer. Therefore, structurally ordered ferromagnetic thin films were obtained on the topological insulator surface for the firs...

  13. The Effect of Substitution of Fe By Co on Rapidly Quenched (FeCoMoCuB Amorphous Alloys

    Directory of Open Access Journals (Sweden)

    Marek Paluga

    2005-01-01

    Full Text Available (Fe1-xCox79Mo8Cu1B15 amorphous alloys ware prepared in the form of ribbons by rapid quenching for x=0. 0.25 and 0.5. The effect of variation of Co/Fe ratio is analyzed with respect to the formation of amorphous state and to transformation of the structure into nancrystalline phases formed after subsequent thermal treatment. Selected properties and atomic structure in as-quenched state are studied by TEM, AFM, XRD any by measurement of magnetoresistance characteristics. The influence of heat treatment on transport and magnetic properties is shown on temperature dependencies of electrical resistivity and magnetization. It was founf that while the increase of Co content leads to the increase of Curie temperature of as-quenched structure, transition to nanocrystalline state is not affected in a significant manner. The as-quenched state for alloy without Co was found to contain thin crystal-containing layer which, however, was observed, contary to general behavior, at the side of the ribbon exposed to higher quenching rates.

  14. XMCD study of the local magnetic and structural properties of microcrystalline NdFeB-based alloys

    Science.gov (United States)

    Menushenkov, A. P.; Ivanov, V. G.; Shchetinin, I. V.; Zhukov, D. G.; Menushenkov, V. P.; Rudnev, I. A.; Ivanov, A. A.; Wilhelm, F.; Rogalev, A.; Savchenko, A. G.

    2017-01-01

    X-ray Magnetic Circular Dichroism (XMCD) technique was used to investigate local magnetic properties of microcrystalline Nd10.4Zr4.0Fe79.2B6.4 samples, oriented along either easy or hard magnetization direction. The Nd L 2,3 and Fe K edge XMCD spectra were measured at room temperature under a magnetic field of T. A very strong dependence of XMCD spectra on the sample orientation has been observed at the Nd L 2,3-edges, whereas the Fe K-edge XMCD spectra are found to be practically isotropic. This result indicates that magnetic anisotropy of NdFeB-based alloys originates from the Nd sublattice. In addition, element selective magnetization curves have been recorded by measuring the intensity of XMCD signals as a function of an applied magnetic field up to T. To find a correlation between local and macroscopic magnetic properties of studied samples we compared these data with magnetization curves, measured by vibrating sample magnetometer up to T. Results are important for understanding the origin of high-coercivity state in NdFeB-based intermetallic compounds.

  15. 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

  16. Structural and magnetic properties of nanocrystalline Fe–Co–Ni alloy processed by mechanical alloying

    International Nuclear Information System (INIS)

    Raanaei, Hossein; Eskandari, Hossein; Mohammad-Hosseini, Vahid

    2016-01-01

    In this present work, a nanostructured iron–cobalt–nickel alloy with Fe_5_0Co_3_0Ni_2_0 composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe_3O_4 crystalline phase. - Highlights: • This article focuses on mechanical alloying of Fe_5_0Co_3_0Ni_2_0 composition. • Structural and magnetic properties were investigated. • Saturation magnetization was increased sharply after 16 h of milling time. • The heat treatment revealed the signature of Fe_3O_4 as well as FeNi_3 and Co crystalline phases.

  17. Structural and magnetic properties of nanocrystalline Fe–Co–Ni alloy processed by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Raanaei, Hossein, E-mail: hraanaei@yahoo.com [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Eskandari, Hossein [Department of Mechanical Engineering, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of); Mohammad-Hosseini, Vahid [Department of Physics, Persian Gulf University, Bushehr 75169 (Iran, Islamic Republic of)

    2016-01-15

    In this present work, a nanostructured iron–cobalt–nickel alloy with Fe{sub 50}Co{sub 30}Ni{sub 20} composition has been processed by mechanical alloying. The structural and magnetic properties have been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometer. It is shown that the crystallize size reaches to about 18.7 nm after 32 h milling time. A remarkable decrease in coercivity after 16 h milling time and also a continuous increase in remanent magnetization during the mechanical alloying process are observed. Heat treatment of the samples milled at 32 and 48 h demonstrates the crystalline constituent elements and also Fe{sub 3}O{sub 4} crystalline phase. - Highlights: • This article focuses on mechanical alloying of Fe{sub 50}Co{sub 30}Ni{sub 20} composition. • Structural and magnetic properties were investigated. • Saturation magnetization was increased sharply after 16 h of milling time. • The heat treatment revealed the signature of Fe{sub 3}O{sub 4} as well as FeNi{sub 3} and Co crystalline phases.

  18. Fe-Cr-Ni system alloys

    International Nuclear Information System (INIS)

    Levin, F.L.

    1986-01-01

    Phase diagram of Fe-Cr-Ni system, which is the basic one for production of corrosion resistant alloys, is considered. Data on corrosion resistance of such alloys are correlated depending on a number of factors: quality and composition of modifying elements, corrosion medium, temperature, alloy structure, mechanical and thermal treatment. Grades of Fe-Ni-Cr alloys are presented, and fields of their application are pointed out

  19. 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

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

    Science.gov (United States)

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

    2018-09-01

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

  1. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  2. Development of shear bands in amorphous-crystalline metallic alloys

    International Nuclear Information System (INIS)

    Pozdnyakov, V.A.

    2004-01-01

    A theoretical study is made into conditions of shear band evolution in amorphous-crystalline alloys with various morphological types of structural constituents. The condition of shear band evolution in thin amorphous alloys in the interior of the crystalline matrix is obtained. It is shown that a scale effect exists which manifests itself in suppression of the process of localized plastic flow with amorphous alloy thickness decreasing down to the limit. The analysis of the condition for shear band evolution in an amorphous alloy with nanocrystalline inclusions is accomplished. The relationship of a critical stress of shear band evolution to a volume fraction of disperse crystal inclusions is obtained. A consideration is also given to the evolution of shear bands in the material containing amorphous and crystalline areas of micro meter size. For the alloy with the structure of this type conditions for propagation of localized flows by a relay race type mechanism are determined [ru

  3. Dynamic Analysis of Recalescence Process and Interface Growth of Eutectic Fe82B17Si1 Alloy

    Science.gov (United States)

    Fan, Y.; Liu, A. M.; Chen, Z.; Li, P. Z.; Zhang, C. H.

    2018-03-01

    By employing the glass fluxing technique in combination with cyclical superheating, the microstructural evolution of the undercooled Fe82B17Si1 alloy in the obtained undercooling range was studied. With increase in undercooling, a transition of cooling curves was detected from one recalescence to two recalescences, followed by one recalescence. The two types of cooling curves were fitted by the break equation and the Johnson-Mehl-Avrami-Kolmogorov model. Based on the cooling curves at different undercoolings, the recalescence rate was calculated by the multi-logistic growth model and the Boettinger-Coriel-Trivedi model. Both the recalescence features and the interface growth kinetics of the eutectic Fe82B17Si1 alloy were explored. The fitting results that were obtained using TEM (SAED), SEM and XRD were consistent with the changing rule of microstructures. Finally, the relationship between the microstructure and hardness was also investigated.

  4. Corrosion study of the passive film of amorphous Fe-Cr-Ni-(Si, P, B alloys

    Directory of Open Access Journals (Sweden)

    López, M. F.

    1996-12-01

    Full Text Available Amorphous Fe62Cr10Ni8X20 (X = P, B, Si alloys in 0.01M HCl solution have been investigated by means of standard electrochemical measurements in order to evaluate their corrosion resistance. The study reveals that the best corrosion behaviour is given by the Si containing amorphous alloy. X-ray photoelectron spectroscopy (XPS and Auger electron spectroscopy (AJES have been employed to study the composition of the passive layers, formed on the surface of the different amorphous alloys. The results on Fe62Cr10Ni8X20 show that a protective passive film, mainly consisting of oxidized chromium, greatly enhances its corrosion resistance.

    La resistencia a la corrosión de las aleaciones amorfas Fe62Cr10Ni8X20 (X = P, B, Si inmersas en HCl 0,01M se evaluó usando técnicas electroquímicas. Las técnicas de espectroscopia de fotoemisión de rayos X y espectroscopia Auger se emplearon para estudiar la composición de las capas pasivas, formadas en aire sobre la superficie de las aleaciones amorfas. Del estudio realizado se concluye que el mejor comportamiento frente a la corrosión viene dado por la aleación amorfa que contiene como metaloide Si. Esto es debido a que la capa pasiva de dicha aleación está formada principalmente de óxido de cromo, lo cual confiere una alta resistencia a la corrosión.

  5. Hyperfine Interactions and Some Magnetic Properties of Nanocrystalline Co40Fe50Ni10 and Co50Fe45Ni5 Alloys Prepared by Mechanical Synthesis and Subsequently Heat Treated

    International Nuclear Information System (INIS)

    Pikula, T.; Oleszak, D.; Pekala, M.

    2011-01-01

    Co 40 Fe 50 Ni 10 and Co 50 Fe 45 Ni 5 ternary alloys were prepared by mechanical alloying method. To check the stability of their structure thermal treatment was applied subsequently. As X-ray diffraction studies proved the final products of milling were the solid solutions with bcc lattice and the average grain sizes ranged of tens of nanometers. After heating of the Co 50 Fe 45 Ni 5 alloy up to 993 K the mixture of two solid solutions with bcc and fcc lattices was formed. In other cases thermal treatment did not change the type of the crystalline lattice. Moessbauer spectroscopy revealed hyperfine magnetic field distributions which reflected the different possible atomic surroundings of 57 Fe isotopes. Results of the macroscopic magnetic measurements proved that both investigated alloys had relatively good soft magnetic properties. (authors)

  6. Phase composition, structure and magnetic behaviour of low neodymium rapid-quenched Nd-Fe-B alloys

    Czech Academy of Sciences Publication Activity Database

    Ćosović, V.; Žák, Tomáš; Talijan, N.; Grujić, A.; Stajić-Trošić, J.

    2008-01-01

    Roč. 456, 1-2 (2008), s. 251-256 ISSN 0925-8388 R&D Projects: GA MŠk 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : multiphase Nd(Pr)-Fe-B alloys * rapid solidification * magnetic measurements * Mossbauer spectroscopy * X-ray diffraction * Nanocrystalline composite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.510, year: 2008

  7. Effect of B addition to hypereutectic Ti-based alloys

    International Nuclear Information System (INIS)

    Louzguina-Luzgina, Larissa V.; Louzguine-Luzgin, Dmitri V.; Inoue, Akihisa

    2009-01-01

    The structure and mechanical properties of Ti-Fe-B and Ti-Fe-Co-B alloys produced in the shape of the arc-melted ingots of about 25 mm diameter and 10 mm height are studied. The hypereutectic alloys showed excellent compressive mechanical properties. The structures of the high-strength and ductile hypereutectic alloys studied by X-ray diffractometry and scanning electron microscopy were found to consist of the primary cubic cP2 intermetallic compound (TiFe-phase or a solid solution on its base) and a dispersed eutectic consisting of this cP2 intermetallic compound + BCC cI2 β-Ti supersaturated solid solution phase. The addition of B increased mechanical strength. Si causes embrittlement owing to the formation of alternative intermetallic compounds. The structure and deformation behaviour were studied

  8. Defects and related phenomena in electron irradiated ordered or disordered Fe-Co and Fe-Co-V alloys

    International Nuclear Information System (INIS)

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

    1983-01-01

    Two B 2 type alloys Fe 50 at.%-Co 50 at.% and Fe 49 at.%-Co 49 at.%-V 2 at.% either in the ordered or the disordered state have been irradiated with 2.5 MeV electrons at liquid hydrogen temperature. The recovery of the resistivity damage was studied during subsequent isochronal annealing up to 700 K. The resistivity damage rates for both initially disordered Fe-Co and Fe-Co-V alloys are interpreted in terms of point defect production. The intrinsic resistivities rhosub(F) of Frenkel pairs and the effective recombination volumes V 0 are determined. In the Fe-Co ordered alloy point defect production superimposed with a disordering process can account for the resistivity damage. The effective displacement rate causing disordering is determined, indicating that replacement collisions are the dominant disordering mechanism. A calculation of the average number of replacements along directions per Frenkel pair is proposed. During the recovery of the radiation induced resistivity three main stages are observed in both ordered and disordered alloys. The particular resistivity behavior of the Fe-Co-V alloy complicates the interpretation of production and recovery data. (author)

  9. Magnetic and frequency properties for nanocrystalline Fe-Ni alloys prepared by high-energy milling method

    International Nuclear Information System (INIS)

    Liu Yongsheng; Zhang Jincang; Yu, Liming; Jia Guangqiang; Jing Chao; Cao Shixun

    2005-01-01

    Fe-based nano-crystalline soft magnetic alloy with Ni-doping was fabricated successfully by high-energy milling. It was proved that a Fe-Ni solid solution is formed and the evaluated average grain size is about 20 nm. The effect of doping Ni on the frequency properties was systematically investigated. From the magnetic measurement results, it can be concluded that, the nickel doped decreases the resonance frequency of Fe-Ni alloy, but Ni doping enhances the frequency stability. The corresponding value of initial permeability as a function of Ni doping concentration was given at 10 kHz and the result indicates that the peak value of initial permeability shifts to the region of low Ni concentration for the samples milled for 72 h

  10. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    Science.gov (United States)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E. M.

    1991-10-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$-- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y2).

  11. Correlated spin glass generated by structural disorder in the amorphous Dy6Fe74B20 alloy

    International Nuclear Information System (INIS)

    Tejada, J.; Martinez, B.; Labarta, A.; Chudnovsky, E.M.

    1991-01-01

    Magnetic properties of the amorphous Dy-Fe-B alloy are studied in terms of the correlated-spin-glass approach of Chudnovsky et al.$---- Features predicted by the theory are clearly observed in the experiment. It is shown that the magnetization law may be presented in the form where it is determined by the dimensionless correlation function of structural disorder, C(y), only. The analysis of the magnetization curve allows one to distinguish between different models of disorder in amorphous solids. Experimental data on Dy-Fe-B are in favor of C=exp(-1/2y 2 )

  12. Microstructure evolution and coercivity enhancement in Nd-Fe-B thin films diffusion-processed by R-Al alloys (R=Nd, Pr)

    Science.gov (United States)

    Xie, Yigao; Yang, Yang; Zhang, Tongbo; Fu, Yanqing; Jiang, Qingzheng; Ma, Shengcan; Zhong, Zhenchen; Cui, Weibin; Wang, Qiang

    2018-05-01

    Diffusion process by Nd-Al and Pr-Al alloys was compared and investigated in Nd-Fe-B thin films. Enhanced coercivity 2.06T and good squareness was obtained by using Pr85Al15 and Nd85Al15 alloys as diffusion sources. But the coercivity of diffusion-processed thin films by Pr70Al30 and Pr55Al45 alloys decreased to 2.04T and 1.82T. High ambient coercivity of 2.26T was achieved in diffusion-processed thin film by Nd70Al30 leading to an improved coercivity thermal stability because Nd2Fe14B grains were enveloped by Nd-rich phase as seen by transmission electron microscopy Nd-loss image. Meanwhile, microstructure-dependent parameters α and Neff were improved. However, high content of Al in diffusion-processed thin film by Nd55Al45 lead to degraded texture and coercivity.

  13. Magnetic and Mössbauer studies of amorphous Fe 72- xY xHo 8B 20 alloys

    Science.gov (United States)

    Krishnan, R.; Driouch, L.; Lassri, H.; Dumond, Y.; Ajan, Antony; Shringi, S. N.; Prasad, Shiva

    1996-11-01

    We have carried out magnetic and Mössbauer studies of amorphous Fe 72- xY xHo 8B 20 alloys. The Fe moment decreases with the addition of Y and a magnetic compensation occurs at 4 K for x = 16. The temperature and field dependences of the magnetization have been interpreted using the mean field theory and Chudnovsky's model, respectively. These analyses yield some interesting parameters such as the random anisotropy, the exchange interactions JFe-Fe, JFe-Ho, etc. The Mössbauer studies show that the average hyperfine field decreases linearly with the addition of Y, in accordance with the decrease in the Fe moment.

  14. Moessbauer spectroscopy studies of spin reorientations in amorphous and crystalline (Co0.2Fe0.8)72.5Si12.5B15 glass coated micro-wires

    International Nuclear Information System (INIS)

    Nowik, I.; Felner, I.; Garcia-Miquel, H.

    2007-01-01

    Thermo-gravimetric, differential scanning calorimetry and comprehensive 57 Fe Moessbauer spectroscopy studies of amorphous and crystalline ferromagnetic glass coated (Co 0.2 Fe 0.8 ) 72.5 Si 12.5 B 15 micro-wires have been recorded. The Curie temperature of the amorphous phase is T C (amorp) ∼730 K. The analysis of the Moessbauer spectra reveals that below 623 K the easy axis of the magnetization is axial-along the wires, and that a tangential or/and radial orientation occurs at higher temperatures. At 770 K, in the first 4 hours the Moessbauer spectrum exhibits a pure paramagnetic doublet. Crystallization and decomposition to predominantly α-Fe(Si) and Fe 2 B occurs either by raising the temperature above 835 K or isothermally in time at lower temperatures. Annealing for a day at 770 K, leads to crystallization. In the crystalline material the magnetic moments have a complete random orientation. After cooling back to ambient temperature, both α-Fe(Si) and Fe 2 B in the glass coated wire show pure axial magnetic orientation like in the original amorphous state. The observed spin reorientations are associated with changes in the stress induced by the glass coating

  15. EXAFS study of short range order in Fe-Zr amorphous alloys

    International Nuclear Information System (INIS)

    Fernandez-Gubieda, M.L.; Gorria, P.; Barandiaran, J.M.; Barquin, L.F.

    1995-01-01

    Room temperature X-ray absorption spectra on Fe K-edge have been performed in Fe 100-x-y Zr x B y and Fe 86 Zr 7 Cu 1 B 6 alloys (x=7, 7.7, 9; y=0, 2, 4, 6). Fe-Fe coordination number and interatomic distances do not change in any sample. However, small changes in the Fe-Zr short range order, which could explain the evolution of the magnetic properties, have been observed. (orig.)

  16. Effect of calcium chloride on the preparation of NdFeB alloy powder by calciothermic reduction process

    International Nuclear Information System (INIS)

    Sidhu, R.K.; Verma, A.; Raina, K.K.

    1999-01-01

    The calciothermic reduction process has been identified to be one of the cost effective processes for producing NdFeB from Nd 2 O 3 . Use of CaCl 2 as slag former in calciothermic reduction is well established. This paper describes the effect of CaCl 2 on the various properties of NdFeB alloy powder prepared by calciothermic reduction. The effect of CaCl 2 on ease of disintegration of the reacted product during calcium leaching, particle size distribution, grain size, lattice parameters and residual calcium has been studied and compared with the alloy powder prepared without using calcium chloride. Addition of CaCl 2 has been found to result in easier disintegration, reduction in grain size and more uniform particle size distribution. Substantial decrease in the residual calcium in case of charge consisting of CaCl 2 was observed. The effect of lattice parameters was not found to be very significant. (author)

  17. Magnetic studies of melt spun NdFeAl-C alloys

    International Nuclear Information System (INIS)

    Rodriguez Torres, C.E.; Cabrera, A.F.; Sanchez, F.H.; Billoni, O.V.; Urreta, S.E.; Fabietti, L.M.

    2004-01-01

    Alloys with compositions Nd 60-x C x Fe 30 Al 10 (x=0, 1, 5 and 10) were processed by melt spinning at a tangential speed of 5 m/s. The as-cast ribbons were characterized by X-ray diffraction, Moessbauer Effect spectroscopy and their room temperature hysteresis loops. The substitution of Nd by C is found to affect the phase selection, from mainly DHCP-Nd for x=0 to DHCP-Nd /FCC-Nd for the other ones. Moessbauer spectra of all the as-cast samples indicate that Fe is present in crystalline magnetic phases as well as in a paramagnetic one. The major crystalline phase was identified as a μ-type (or A1) metastable phase, which is reported to have a large anisotropy field and a relatively high saturation polarization. Interstitial C stabilizes the μ-type phase and improves its average hyperfine field. The magnetic measurements display an increase of coercivity and remanence with the C concentration

  18. Strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy

    International Nuclear Information System (INIS)

    Shi, Guodong; Chen, Xiaohua; Jiang, Han; Wang, Zidong; Tang, Hao; Fan, Yongquan

    2015-01-01

    A single crystal Cu–Fe alloy with finely dispersed precipitate Fe nanoparticles was fabricated in this study. The interface relationship of iron nanoparticle and copper matrix was analyzed with a high-resolution transmission electron microscope (HRTEM), and the effect of Fe nanoparticles on mechanical properties of single crystal Cu–Fe alloy was discussed. Results show that, the finely dispersed Fe nanoparticles can be obtained under the directional solidification condition, with the size of 5–50 nm and the coherent interface between the iron nanoparticle and the copper matrix. Single crystal Cu–Fe alloy possesses improved tensile strength of 194.64 MPa, and total elongation of 44.72%, respectively, at room temperature, in contrast to pure Cu sample. Nanoparticles which have coherent interface with matrix can improve the dislocation motion state. Some dislocations can slip through the nanoparticle along the coherent interface and some dislocations can enter into the nanoparticles. Thus to improve the tensile strength of single crystal Cu–Fe alloy without sacrificing the ductility simultaneously. Based on the above analyses, strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy was described

  19. Mössbauer spectroscopic studies in U-Fe and U-Fe-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Alaka; Singh, L. Herojit; Rajagopalan, S.; Govindaraj, R., E-mail: govind@igcar.gov.in; Ramachandran, Renjith; Kalavathi, S.; Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2016-05-23

    {sup 57}Fe Mössbauer studies have been carried out in an alloy of U and Fe with atomic percentage in the ratio of 68%:32% in order to understand the local structure and valence of Fe atoms associated with different phases that may get formed. The effect of changes in the hyperfine parameters such as isomer shift and quadrupole splitting at Fe sites due to additional alloying of Zr has been studied in an alloy of U, Fe and Zr in the ratio of 44%:33%:23% respectively with respect to that of the U-Fe alloy chosen in the present study. Possible effect of solute clustering in these systems has been addressed in an analogous alloy of uranium and zirconium using positron lifetime spectroscopy.

  20. Design of multi materials combining crystalline and amorphous metallic alloys

    International Nuclear Information System (INIS)

    Volland, A.; Ragani, J.; Liu, Y.; Gravier, S.; Suéry, M.; Blandin, J.J.

    2012-01-01

    Highlights: ► Elaboration of multi materials associating metallic glasses and conventional crystalline alloys by co-deformation performed at temperatures close to the glass transition temperature of the metallic glasses. ► Elaboration of filamentary metal matrix composites with a core in metallic glass by co extrusion. ► Sandwich structures produced by co-pressing. ► Detection of atomic diffusion from the glass to the crystalline alloys during the processes. ► Good interfaces between the metallic glasses and the crystalline alloys, as confirmed by mechanical characterisation. - Abstract: Multi materials, associating zirconium based bulk metallic glasses and crystalline metallic alloys like magnesium alloys or copper are elaborated by co-deformation processing performed in the supercooled liquid regions (SLR) of the bulk metallic glasses. Two processes are investigated: co-extrusion and co-pressing. In the first case, filamentary composites with various designs can be produced whereas in the second case sandwich structures are obtained. The experimental window (temperature, time) in which processing can be carried out is directly related to the crystallisation resistance of the glass which requires getting information about the crystallisation conditions in the selected metallic glasses. Thermoforming windows are identified for the studied BMGs by thermal analysis and compression tests in their SLR. The mechanical properties of the produced multi materials are investigated thanks to specifically developed mechanical devices and the interfaces between the amorphous and the crystalline alloys are characterised.

  1. Studies on the Production of NdFeB Alloy by Calciothermic Reduction of Neodymium Oxide

    International Nuclear Information System (INIS)

    Charoensri, Apisara

    2003-06-01

    Neodymium-Iron-Boron (NdFeB) is a class of permanent magnets having the highest energy product (BH max ). It has been used in various electronic devices of small size and light weight. This research is to study the preparation of Neodymium-Iron-Boron alloy by calciothermic reduction of neodymium oxide mixed with iron and iron-boron. The reduction process essentially involves the compaction of the charge mixture with calcium metal and then heating at 900-1200οC in argon atmosphere. The results show that charge blend compaction, temperature and time of reaction are important parameters of the process. It is found that at proper conditions, magnetic phase structure of Neodymium-Iron-Boron alloy can be prepared satisfactory although the alloy produced from the reduction contains higher impurities of oxygen and calcium than the alloy produced from the conventional method using Nd metal

  2. Martensitic transformation, fcc and hcp relative phase stability, and thermal cycling effects in Fe-Mn and Fe-Mn-X Alloys (X = Si, Co)

    International Nuclear Information System (INIS)

    Baruj, Alberto

    1999-01-01

    In this Thesis we present a study of the fcc and hcp relative phase stability in the Fe-Mn and Fe-Mn-Co systems. In particular, we have investigated the effect of two main factors affecting the relative phase stability: changes in the chemical composition of the alloys and changes in the density of crystalline defects in the microstructure.In order to analyse the effect of chemical composition, we have performed an experimental study of the fcc/hcp martensitic transformation temperatures in Fe-Mn-Co alloys in the composition range lying between 15% and 34% Mn, and between 1% and 16% Co.We have measured the martensitic transformation temperatures by means of dilatometry and electrical resistivity.We have combined this information with measurements of the fcc/hcp martensitic transformation temperatures in Co-rich alloys to perform a modelling of the Gibbs energy function for the hcp phase in the Fe-Mn-Co and Fe-Co systems.We found that, for alloys in the Mn range between 17% and 25%, Co additions tend to stabilise slightly the fcc phase.In the alloys with Mn contents below that range, increasing the amount of Co stabilise the bcc phase. In alloys with Mn contents above 25% the Neel temperature is depressed by the addition of Co, which stabilise the hcp phase.In order to investigate the effect of changes in the density of crystalline defects, we have performed thermal cycling experiments through the fcc/hcp martensitic transformation in Fe-Mn, Fe-Mn-Co and Fe-Mn-Si alloys.We have applied the thermodynamic description obtained before in order to analyse these experiments.We found in the thermal cycling experiments a first stage where the martensitic transformation is promoted.This stage occurs in all the studied alloys during the first cycle or the two first cycles.Increasing the number of thermal cycles, the promotion stage is replaced by an inhibition of the transformation stage.We propose a possible microstructural interpretation of these phenomena where the plastic

  3. The practical limits for enhancing magnetic property combinations for bulk nanocrystalline NdFeB alloys through Pr, Co and Dy substitutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.W. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (Singapore)]. E-mail: phylz@nus.edu.sg; Davies, H.A. [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (Singapore)

    2007-06-15

    Pr, Co and Dy additions have been employed to improve the combinations of magnetic properties for nanocrystalline Nd {sub x} Fe{sub 94-} {sub x} B{sub 6} melt spun alloys. The dependences of the magnetic properties on the solute element concentrations have been extensively investigated and the relationships between the measured remanence, maximum energy product (BH){sub max} and intrinsic coercivity for several compositional series are discussed. The composition ranges for these elemental substitutions which can be used to achieve the highest values of (BH){sub max} are identified. It is found that, when we employ individual or combined substitutions of Pr and Dy for Nd and Co for Fe in NdFeB alloys with various RE:Fe ratios, the practical limit of (BH){sub max} lies in the range {approx}160-180 kJ/m{sup 3}, combined with a coercivity in the range {approx}400-800 kA/m.

  4. Transport and magnetic properties of HITPERM alloys

    Science.gov (United States)

    Pekala, K.; Latuch, J.; Pekala, M.; Skorvanek, I.; Jaskiewicz, P.

    2003-02-01

    Nanocrystalline HITPERM alloys Fe44.6Co43.3X7.4B3.7Cu1 (X = Nb, Zr, Hf) prepared by crystallization of amorphous precursors are studied by magnetization and electrical resistivity measurements for the first time. Structural and magnetic components of the electrical resistivity are separated. The electrical resistivity of the nanocrystalline α' (FeCo) phase calculated using the Maxwell Garnett relation proves strong electron scattering on the grain boundaries. The temperature variation of the crystalline fraction during the first crystallization stage is calculated for the Hf based alloy.

  5. Effect of processing on the microstructural development in a rapidly solidified Al-Fe-V-Si alloy

    International Nuclear Information System (INIS)

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

    1993-01-01

    An Al 80 Fe 10 Si 6 alloy has been rapidly solidified using melt spinning, gas atomization and spray forming processes. The effect of processing techniques on the microstructural characteristics of the alloy has ben evaluated. The melt spun alloy has shown an icosahedral quasicrystalline phase surrounded by a rational approximant structure of the icosahedral phase. The rational approximant structure has been identified as a crystalline cubic silicide phase. The atomized powders have exhibited cellular and dendritic morphology depending on the size of particles. In addition, the second phase particles of the silicide phase are observed to decorate the cell boundaries and interdendritic regions. In contrast, the alloy processed by spray deposition has revealed an equiaxed solidification morphology with a uniform dispersion of find silicon phase inside the grain. The origin of the microstructure in the alloy processed by these techniques is discussed. The results are compared wherever possible with the commercially available Al-Fe-V-Si alloys

  6. Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

    Science.gov (United States)

    Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

    2016-04-01

    This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

  7. Effect of Co addition on the magnetic properties and microstructure of FeNbBCu nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Lin [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Yang, Weiming [School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Men, He [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Wang, Anding, E-mail: anding@nimte.ac.cn [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Chang, Chuntao [Ningbo Institute of Industrial Technology, Chinese Academy of Sciences, Ningbo 315201 (China); Shen, Baolong, E-mail: blshen@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-12-01

    Through gradient substitution of Co for Fe, the magnetic properties and microstructures of (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} (x=0.1, 0.2, 0.3, 0.4, 0.5) nanocrystalline alloys were investigated. Because of the strong ferromagnetic exchange coupling between Co and Fe, substantial improvement in saturation magnetization was achieved with proper levels of Co addition. Meanwhile, the Curie temperature increased noticeably with increasing Co addition. After heat treatment, the (Fe{sub 0.9}Co{sub 0.1}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloy showed a refined microstructure with an average grain size of 10–20 nm, exhibiting a comparatively high saturation magnetization of 1.82 T and a lower coercivity of 12 A/m compared to other Hitperm-type alloys with higher Co contents. Additionally, the Curie temperature reached 1150 K upon introduction of Co. As the soft magnetic properties are strengthened by adding a small amount of Co, the combination of fine, soft magnetic properties and low cost make this nanocrystalline alloy a potential magnetic material. - Highlights: • New (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloys are successfully synthesized. • Minor Co addition improves the Curie temperature of (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} alloy system. • (Fe{sub 1−x}Co{sub x}){sub 83}Nb{sub 2}B{sub 14}Cu{sub 1} nanocrystalline alloys exhibit high saturation magnetization above 1.82 T.

  8. Microstructural and magnetic characterization of iron precipitation in Ni-Fe-Al alloys

    International Nuclear Information System (INIS)

    Duman, Nagehan; Mekhrabov, Amdulla O.; Akdeniz, M. Vedat

    2011-01-01

    The influence of annealing on the microstructural evolution and magnetic properties of Ni 50 Fe x Al 50-x alloys for x = 20, 25, and 30 has been investigated. Solidification microstructures of as-cast alloys reveal coarse grains of a single B2 type β-phase and typical off eutectic microstructure consisting of proeutectic B2 type β dendrites and interdendritic eutectic for x = 20 and x > 20 at.% Fe respectively. However, annealing at 1073 K results in the formation of FCC γ-phase particles along the grain boundaries as well as grain interior in x = 20 at.% Fe alloy. The volume fraction of interdentritic eutectic regions tend to decrease and their morphologies start to degenerate by forming FCC γ-phase for x > 20 at.% Fe alloys with increasing annealing temperatures. Increasing Fe content of alloys induce an enhancement in magnetization and a rise in the Curie transition temperature (T C ). Temperature scan magnetic measurements and transmission electron microscopy reveal that a transient rise in the magnetization at temperatures well above the T C of the alloys would be attributed to the precipitation of a nano-scale ferromagnetic BCC α-Fe phase. Retained magnetization above the Curie transition temperature of alloy matrix, together with enhanced room temperature saturation magnetization of alloys annealed at favorable temperatures support the presence of ferromagnetic precipitates. These nano-scale precipitates are shown to induce significant precipitation hardening of the β-phase in conjunction with enhanced room temperature saturation magnetization in particular when an annealing temperature of 673 K is used. - Research Highlights: → Evolution of microstructure and magnetic properties with varying Fe content. → Transient rise in magnetization via the formation of ferromagnetic phase. → Enhancements in saturation magnetization owing to precipitated ferromagnetic phase. → Nanoscale precipitation of ferromagnetic BCC α-Fe confirmed by TEM.

  9. Structural and magnetic properties of Fe{sub x}Ni{sub 100−x} alloys synthesized using Al as a reducing metal

    Energy Technology Data Exchange (ETDEWEB)

    Srakaew, N. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Jantaratana, P., E-mail: fscipsj@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Nipakul, P. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Sirisathitkul, C. [Molecular Technology Research Unit, School of Science, Walailak University, Nakhon Si Thammarat 80161 (Thailand)

    2017-08-01

    Highlights: • Reduction by aluminum is a simple and safe route to synthesize iron-nickel alloys. • Alloy compositions with up to 90 at.% Fe can be obtained with minimal oxidation. • Morphology and magnetic properties are varied with the alloy composition. - Abstract: Iron-nickel (Fe-Ni) alloys comprising nine different compositions were rapidly synthesized from the redox reaction using aluminum foils as the reducing metal. Compared with conventional chemical syntheses, this simple approach is relatively safe and allows control over the alloy morphology and magnetic behavior as a function of the alloy composition with minimal oxidation. For alloys having low (10%–30%) Fe content the single face-centered cubic (FCC) FeNi{sub 3} phase was formed with nanorods aligned in the (1 1 1) crystalline direction on the cluster surface. This highly anisotropic morphology gradually disappeared as the Fe content was raised to 40%–70% with the alloy structure possessing a mixture of FCC FeNi{sub 3} and body-centered cubic (BCC) Fe{sub 7}Ni{sub 3}. The FCC phase was entirely replaced by the BCC structure upon further increase the Fe content to 80%–90%. The substitution of Ni by Fe in the crystals and the dominance of the BCC phase over the FCC structure gave rise to enhanced magnetization. By contrast, the coercive field decreased as a function of increasing Fe because of the reduction in shape anisotropy and the rise of saturation magnetization.

  10. Formation and stability of Fe-rich precipitates in dilute Zr(Fe) single-crystal alloys

    International Nuclear Information System (INIS)

    Zou, H.; Hood, G.M.; Roy, J.A.; Schultz, R.J.

    1993-02-01

    The formation and stability of Fe-rich precipitates in two α-Zr(Fe) single-crystal alloys with nominal compositions (I, 50 ppma Fe, and II, 650 ppma Fe) have been investigated (the maximum solid solubility of Fe in α-Zr is 180 ppma - 800 C). Optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to examine the characteristics of Fe-rich precipitates. SEM and TEM micrographs show that in as-grown alloy II, Zr 2 Fe precipitates are located at 'stringers'. Precipitates were not observed in as-grown alloy I. During annealing, below the solvus, Fe diffuses to the surfaces to form Zr 3 Fe precipitates in both alloys. The precipitates on the surfaces of alloy I tend to be star-like (0001) or pyramidal (1010), and their distribution is heterogeneous. Dissolution of Zr 3 Fe surface precipitates of alloy I (annealing above the solvus) leaves precipitate-like features on the surfaces. Zr 2 Fe precipitates in as-grown alloy II can be dissolved only by β-phase annealing. (Author) 8 figs., 18 refs

  11. Fabrication, magnetostriction properties and applications of Tb-Dy-Fe alloys: a review

    Directory of Open Access Journals (Sweden)

    Nai-juan Wang

    2016-03-01

    Full Text Available As an excellent giant-magnetostrictive material, Tb-Dy-Fe alloys (based on Tb0.27-0.30Dy0.73-0.70Fe1.9-2 Laves compound can be applied in many engineering fields, such as sonar transducer systems, sensors, and micro-actuators. However, the cost of the rare earth elements Tb and Dy is too high to be widely applied for the materials. Nowadays, there are two different ways to substitute for these alloying elements. One is to partially replace Tb or Dy by cheaper rare earth elements, such as Pr, Nd, Sm and Ho; and the other is to use non-rare earth elements, such as Co, Al, Mn, Si, Ce, B, Be and C, to substitute Fe to form single MgCu2-type Laves phase and a certain amount of Re-rich phase, which can reduce the brittleness and improve the corrosion resistance of the alloy. This paper systemically introduces the development, the fabrication methods and the corresponding preferred growth directions of Tb-Dy-Fe alloys. In addition, the effects of alloying elements and heat treatment on magnetostrictive and mechanical properties of Tb-Dy-Fe alloys are also reviewed, respectively. Finally, some possible applications of Tb-Dy-Fe alloys are presented.

  12. Amorphization of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Pană, O. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

    2016-11-01

    Amorphization of Fe{sub 75}Si{sub 20}B{sub 5} (at.%) alloy has been attempted both by wet and dry mechanical alloying starting from a mixture of elemental powders. Powder amorphization was not achieved even after 140 hours of dry mechanical alloying. Using the same milling parameters, when wet mechanical alloying was used, the powder amorphization was achieved after 40 h of milling. Our assumption regarding the powder amorphization capability enhancement by contamination with carbon was proved by X-ray Photoelectron Spectroscopy (XPS) measurements which revealed the presence of carbon in the chemical composition of the wet mechanically alloyed sample. Using shorter milling times and several process control agents (PCA) (ethanol, oleic acid and benzene) with different carbon content it was proved that the milling duration required for powder amorphization is linked to the carbon content of the PCA. Differential Scanning Calorimetry (DSC), thermomagnetic (TG) and X-ray Diffraction (XRD) measurements performed to the heated samples revealed the fact that, the crystallisation occurs at 488 °C, thus leading to the formation of Fe{sub 3}Si and Fe{sub 2}B. Thermogravimetry measurements performed under H{sub 2} atmosphere, showed the same amount of contamination with C, which is about 2.3 wt%, for the amorphous samples regardless of the type of PCA. Saturation magnetisation of the wet milled samples decreases upon increasing milling time. In the case of the amorphous samples wet milled with benzene up to 20 h and with oleic acid up to 30 h, the saturation magnetisation has roughly the same value, indicating the same degree of contamination. The XRD performed on the samples milled using the same parameters, revealed that powder amorphization can be achieved even via dry milling, just by adding the equivalent amount of elemental C calculated from the TG plots. This proves that in this system by considering the atomic species which can contaminate the powder, they can be

  13. Internal friction of Fe-B alloys neutron irradiated at low temperature

    International Nuclear Information System (INIS)

    Kitajima, Kazunori; Futagami, Koji; Abe, Hironobu; Yoshida, Hiroyuki.

    1975-01-01

    Measurements were made on the internal friction of Fe-B alloys irradiated by neutron at 16 0 K to the dose of 3x10 16 nvt (>1 MeV) and 6x10 17 nvt (thermal). Boron was used to enhance the production of defects by the nuclear transformation B 10 (n,α)Li 7 . Relaxation peaks were found in specimens containing dispersed fine precipitates of NbB 2 in range of B 500--7200 wt ppm and Nb 2000--30000 wt ppm. The most prominent peak is the one with the peak temperature of 169 0 K at the frequency of 264 c/sec. Activation energy determined from the peak shift is 0.28+-0.01 eV, which is nearly equal to that of migration of self-interstitial reported on pure iron. However activation energy of the decay of peaks by annealing is about 0.7 eV. Interpretation was presented that the peak may be attributed to re-orientation of self-interstitials loosely bound to a boron atom. (auth.)

  14. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  15. 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.

  16. Nanocrystal Growth in Thermally Treated Fe75Ni2Si8B13C2 Amorphous Alloy

    Czech Academy of Sciences Publication Activity Database

    Minić, Dragica M.; Blagojević, V.; Minić, Dušan M.; David, Bohumil; Pizúrová, Naděžda; Žák, Tomáš

    43A, č. 9 (2012), s. 3062-3069 ISSN 1073-5623 R&D Projects: GA MŠk 1M0512 Institutional support: RVO:68081723 Keywords : Nanocrystal growth * Fe75Ni2Si8B13C2 * Amorphous alloy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.627, year: 2012

  17. Studies of alloy structures and properties. Annual summary report, December 1, 1976--December 1, 1977

    International Nuclear Information System (INIS)

    Duwez, P.

    1977-01-01

    Brief summaries of research activities in the following areas are given: superconductivity to ferromagnetism in amorphous Gd--La--Au alloys; magnetic regimes in amorphous Ni--Fe--P--B alloys; electronic and magnetic properties of amorphous Fe--P--B alloys; critical phenomena and magnetic properties of amorphous gadolinium based ferromagnets; Kondo effect, spin correlations, and superconductivity in amorphous alloys doped with magnetic impurities; flux pinning by crystalline phase precipitates embedded in an amorphous superconducting matrix; kinetics of crystallization of amorphous alloys; properties of the flux lattice in amorphous superconductors; low temperature calorimeter; low temperature heat capacity of metastable superconductors; thermal relaxation effects and crystallization of amorphous alloys; fundamental studies of amorphous superconductors using superconductive tunneling; low temperature calorimetry of bulk amorphous metals; and mictomagnetism in amorphous alloys

  18. Compression of Fe-Si-H alloys

    Science.gov (United States)

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

    2014-12-01

    The light elements in the Earth's core have not been fully identified yet, but hydrogen is now collecting more attention in part because recent planet formation theory suggests that large amount of water should have been brought to the Earth during its formation (giant-impact stage). Nevertheless, the effect of hydrogen on the property of iron alloys is little known so far. The earlier experimental study by Hirao et al. [2004 GRL] examined the compression behavior of dhcp FeHx (x ≈ 1) and found that it becomes much stiffer than pure iron above 50 GPa, where magnetization disappears. Here we examined the solubility of hydrogen into iron-rich Fe-Si alloys and the compression behavior of dhcp Fe-Si-H alloy at room temperature. Fe+6.5wt.%Si or Fe+9wt.%Si foil was loaded into a diamond-anvil cell (DAC), and then liquid hydrogen was introduced at temperatures below 20 K. X-ray diffraction measurements at SPring-8 revealed the formation of a dhcp phase with or without thermal annealing by laser above 8.4 GPa. The concentration of hydrogen in such dhcp lattice was calculated following the formula reported by Fukai [1992]; y = 0.5 and 0.2 for Fe-6.5wt.%Si-H or Fe-9wt.%Si-H alloys, respectively when y is defined as Fe(1-x)SixHy. Unlike Fe-H alloy, hydrogen didn't fully occupy the octahedral sites even under hydrogen-saturated conditions in the case of Fe-Si-H system. Anomaly was observed in obtained pressure-volume curve around 44 Å3 of unit-cell volume for both Fe-6.5wt.%Si-H and Fe-9wt.%Si-H alloys, which may be related to the spin transition in the dhcp phase. They became slightly stiffer at higher pressures, but their compressibility was still similar to that of pure iron.

  19. Atomic level structural modulation during the structural relaxation and its effect on magnetic properties of Fe81Si4B10P4Cu1 nanocrystalline alloy

    Science.gov (United States)

    Cao, C. C.; Zhu, L.; Meng, Y.; Zhai, X. B.; Wang, Y. G.

    2018-06-01

    The evolution of local structure and defects in the Fe81Si4B10P4Cu1 amorphous alloy during the structural relaxation has been investigated by Mössbauer spectroscopy, positron annihilation lifetime spectroscopy and transmission electron microscopy to explore their effects on magnetic properties of the nanocrystalline. The atomic rearrangements at the early stage of the structural relaxation cause the density increase of the amorphous matrix, but the subsequent atomic rearrangements contribute to the transformation of Fe3B-like atomic arrangements to FeB-like ones with the temperature increasing. As the structural relaxation processes, the released Fe atoms both from Fe3B- and Fe3P-like atomic arrangements result in the formation of new Fe clusters and the increase of Fe-Fe coordination number in the existing Fe clusters and the nucleation sites for α-Fe gradually increase, both of which promote the crystallization. However, the homogeneity of amorphous matrix will be finally destroyed under excessive relaxation temperature, which coarsens nanograins during the crystallization instead. Therefore, soft magnetic properties of the Fe81Si4B10P4Cu1 nanocrystalline alloy can be improved by pre-annealing the amorphous precursor at an appropriate temperature due to the atomic level structural optimization.

  20. Temperature compensation of NdFeB permanent magnets

    International Nuclear Information System (INIS)

    Kim, S.H.; Doose, C.

    1997-01-01

    Permanent magnet blocks of NdFeB have a relatively high maximum energy product. Because of its relatively low Curie temperature, however, NdFeB has a large temperature coefficient for its residual induction. The temperature coefficients of the relative magnetic fields (ΔB/B)/ΔT in the air gap of NdFeB dipole magnets were reduced from -1.1 x 10 -3 /c to less than 2 x 10 -5 /degree C under operating temperatures of ± 6 C. This was achieved passively by using 1.25-mm-thick strips of 30%-Ni-Fe alloy as flux shunts for the NdFeB blocks. The magnets with soft-steel poles and flux-return yokes were assembled and measured in a temperature-controlled environment

  1. Fe(Co)SiBPCCu nanocrystalline alloys with high Bs above 1.83 T

    Science.gov (United States)

    Liu, Tao; Kong, Fengyu; Xie, Lei; Wang, Anding; Chang, Chuntao; Wang, Xinmin; Liu, Chain-Tsuan

    2017-11-01

    Fe84.75-xCoxSi2B9P3C0.5Cu0.75 (x = 0, 2.5 and 10) nanocrystalline alloys with excellent magnetic properties were successfully developed. The fully amorphous alloy ribbons exhibit wide temperature interval of 145-156 °C between the two crystallization events. It is found that the excessive substitution of Co for Fe greatly deteriorates the magnetic properties due to the non-uniform microstructure with coarse grains. The alloys with x = 0 and 2.5 exhibit high saturation magnetization (above 1.83 T), low core loss and relatively low coercivity (below 5.4 A/m) after annealing. In addition, the Fe84.75Si2B9P3C0.5Cu0.75 nanocrystalline alloy also exhibits good frequency properties and temperature stability. The excellent magnetic properties were explained by the uniform microstructure with small grain size and the wide magnetic domains of the alloy. Low raw material cost, good manufacturability and excellent magnetic properties will make these nanocrystalline alloys prospective candidates for transformer and motor cores.

  2. Parallel between steels alloyed with chrome-nickel and Fe-Mn-Al-C steels, in their response to fracture and wear (Review)

    International Nuclear Information System (INIS)

    Ramos, J; Perez, G.A

    2008-01-01

    The big worldwide demand for chrome-nickel alloy steels ('conventional steel') leads to the need for advanced materials for applications in different engineering systems that operate at high temperatures and in aggressive environmental conditions, favoring research and development in alternate alloys. In this technological race in search of these new materials, the FeMnAlC alloys ('new steels') have attracted attention for their excellent mechanical and tribological properties as well as for their good performance in corrosive-oxide environments, which make them similar to conventional steel. There are two important similarities between these two steels. First, an agent that causes the passive film to become stainless appears in both steels: chrome in the conventional steel, and aluminum in the FeMnAl alloy. The second similarity is that a stabilizing agent of the austenitic phase (FCC) appears in both, so that excellent mechanical properties can be obtained: nickel in the conventional steel, and manganese in the FeMnAl alloy. In certain sectors, such as aeronautics, conventional steel is rarely used because it is a very heavy material. This conventional steel is almost three times heavier that aluminum (7.85/2.7). Two advantages that the new FeMnAIC steels have compared to the conventional steels are that they are about 13% lighter in weight and they are less expensive. The FeMnAl also have excellent mechanical properties and good corrosion-oxidation resistance, which generates big expectations for their application in a broad scientific spectrum. This work reports the state of the information currently available about FeMnAlC alloys, comparing the mechanical and tribological behaviors of conventional alloy steels with chrome and nickel alloys, specifying the scopes of their application. A condition that favors the steels' fragility is the high speed of deformation and impact, where the FCC crystalline structure materials do not have a fragile ductile transition

  3. Thermal treatment of the Fe78 Si9 B13 alloy and the analysis of it magnetic properties through Moessbauer spectroscopy and Positronium annihilation

    International Nuclear Information System (INIS)

    Lopez M, A.

    2005-01-01

    The present work is divided in five chapters. In the first one a general vision of the amorphous alloys is given from antecedents, structure, obtaining methods, properties and problems that at the moment, focusing us in a certain moment to the iron base alloys and the anomalous problem of hardness that it presents the alloy Fe 78 Si 9 B 13 like previously mention us. The second chapter tries on the basic theory of the techniques of Moessbauer spectroscopy and Positron Annihilation spectroscopy, used for the characterization of our alloy as well as the complementary technique of X-ray diffraction (XRD) to observe that the amorphous phase was even studying. The third chapter describes the experimental conditions that were used to study the alloy Fe 78 Si 9 B 13 in each one of their thermal treatments. In the fourth chapter the obtained results and their discussion are presented. In the fifth chapter the conclusions to which were arrived after analyzing the results are presented. (Author)

  4. Effect of Mo-Fe substitution on glass forming ability, thermal stability, and hardness of Fe-C-B-Mo-Cr-W bulk amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, Hesham E.; Cheney, Justin L. [University of California, San Diego Materials Science and Engineering Program, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States); Vecchio, Kenneth S. [University of California, San Diego Department of NanoEngineering, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: kvecchio@ucsd.edu

    2008-08-25

    Amorphous Fe{sub 67-x}C{sub 10}B{sub 9}Mo{sub 7+x}Cr{sub 4}W{sub 3} (x = 1-7 at.%) plates with 640 {mu}m thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry (DSC), differential thermal analysis, and X-ray diffractometry (XRD). The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe{sub 62}C{sub 10}B{sub 9}Mo{sub 12}Cr{sub 4}W{sub 3} is the best glass former in this study, demonstrating a supercooled liquid region, {delta}T{sub x} = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three-phase evolution during crystallization. A second set of heat treatments was performed to identify each phase. Hardness data was collected at each of the heat treatment conditions, and a bulk metallic glasses (BMG)-derived composite containing a Mo-rich phase exhibited Vickers Hardness in excess of 2000. The fully amorphous alloys had an average hardness approaching 1500.

  5. Mossbauer studies of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    1996-01-01

    This paper reports a Mossbauer study of amorphous Fe73.5Cu1Nb3Si13.5B9 alloy between 10 and 673 K. The Curie temperature Tc is found to be 620-+ 1 K. The temperature dependence of the reduced average hyperfine field can be explained on the basis of Handrich's model of amorphous ferromagnetism...

  6. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    Science.gov (United States)

    La Roca, P.; Baruj, A.; Sade, M.

    2017-03-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  7. Sulfidation behavior of Fe20Cr alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    2001-01-01

    Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

  8. Ti2FeZ (Z=Al, Ga, Ge) alloys: Structural, electronic, and magnetic properties

    International Nuclear Information System (INIS)

    Liping, Mao; Yongfan, Shi; Yu, Han

    2014-01-01

    Using the first-principle projector augmented wave potential within the generalized gradient approximation taking into account the on-site Coulomb repulsive, we investigate the structural, electronic and magnetic properties of Ti 2 FeZ (Z=Al, Ga, Ge) alloys with Hg 2 CuTi-type structure. These alloys are found to be half-metallic ferrimagnets. The total magnetic moments of the Heusler alloys Ti 2 FeZ follow the µ t =Z t −18 rule and agree with the Slater–Pauling curve quite well. The band gaps are mainly determined by the bonding and antibonding states created from the hybridizations of the d states between the Ti(A)–Ti(B) coupling and Fe atom. - Highlights: • Ti 2 FeZ (Z=Al, Ga, Ge) are found to be half-metallic ferrimagnets. • The band gaps are mainly determined by the hybridizations of the d states between the Ti(A)–Ti(B) coupling and Fe atom. • The s–p elements play an important role in the half-metallicity of these Heusler alloys

  9. Atomic scale study of grain boundary segregation before carbide nucleation in Ni–Cr–Fe Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui, E-mail: huili@shu.edu.cn [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Institute of Materials, Shanghai University, Shanghai 200072 (China); Xia, Shuang [Institute of Materials, Shanghai University, Shanghai 200072 (China); Liu, Wenqing [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Liu, Tingguang; Zhou, Bangxin [Institute of Materials, Shanghai University, Shanghai 200072 (China)

    2013-08-15

    Highlights: • Impurities segregated at grain boundaries were observed by atom probe tomography. • The comparison of segregation features in two Ni–Cr–Fe alloys was studied by APT. • C and Cr atoms co-segregated at grain boundaries before carbide precipitation. -- Abstract: Three dimensional chemical information concerning grain boundary segregation before carbide nucleation was characterized by atom probe tomography in two Ni–Cr–Fe alloys which were aged at 500 °C for 0.5 h after homogenizing treatment. B, C and Si atoms segregation at grain boundary in Alloy 690 was observed. B, C, N and P atoms segregation at grain boundary in 304 austenitic stainless steel was observed. C atoms co-segregation with Cr atoms at the grain boundaries both in Alloy 690 and 304 austenitic stainless steel was found, and its effect on the carbide nucleation was discussed. The amount of each segregated element at grain boundaries in the two Ni–Cr–Fe alloys were analyzed quantitatively. Comparison of the grain boundary segregation features of the two Ni–Cr–Fe alloys were carried out based on the experimental results.

  10. Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys

    Directory of Open Access Journals (Sweden)

    Bae K.C.

    2017-06-01

    Full Text Available To investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the number of nucleation sites and the volume fraction of the α phase decreased. We observed a significant difference in the shape and size of the α phase in the matrix before and after Fe addition. In addition, these morphological deformations were accompanied by a change in the shape of the α phase, which became increasingly discontinuous, and changed into globular-type α phase in the matrix. These phenomena affected the microstructure and mechanical properties of Ti alloys. Specimen #2 exhibited a high ultimate tensile strength (1071 MPa, which decreased with further addition of Fe.

  11. Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1986-06-01

    Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

  12. Coercivity of the Nd–Fe–B hot-deformed magnets diffusion-processed with low melting temperature glass forming alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Akiya, T.; Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Sakuma, N.; Yano, M.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan)

    2016-08-15

    Nd- and Pr-based alloys with bulk glass forming ability and low melting temperatures, Nd{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20} and Pr{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20}, were used for grain boundary diffusion process to enhance the coercivity of hot-deformed magnets. The coercivity increment was proportional to the weight gain after the diffusion process. For the sample with 64% weight gain, the coercivity increased up to 2.8 T, which is the highest value for bulk Nd–Fe–B magnets that do not contain heavy rare-earth elements, Dy or Tb. Approximately half of the intergranular regions were amorphous and the remaining regions were crystalline. Magnetic isolation of the Nd{sub 2}Fe{sub 14}B grains by the Nd-rich amorphous/crystalline intergranular phases is attributed to the large coercivity enhancement. The coercivity does not change after the crystallization of the intergranular phase, indicating that the coercivity is not influenced by the strain at the interface with the crystalline intergranular phase. - Highlights: • Bulk-glass forming alloys were infiltrated into hot-deformed Nd–Fe–B magnets. • Very high coercivity of 2.8 T was attained without heavy rare-earth elements. • Approximately half of the inter-granular regions were amorphous. • Crystallization of amorphous intergranular phase does not change coercivity.

  13. On the structural and magnetic properties of amorphous Fe84-xWxB16 alloys in dependence of W content

    International Nuclear Information System (INIS)

    Novakova, A.A.; Sidorova, G.V.; Katsnelson, A.A.; Szasz, A.; Kojnok, J.

    1990-01-01

    A series of rapidly solidificated amorphous Fe 84-x W x B 16 (x=0-5) alloys have been studied. A strictly linear decrease of H eff versus concentration of W has been observed by Moessbauer spectroscopy. (orig.)

  14. The nonaqueous inhibition of Fe-Co-B-Si amorphous electrodes: An a.c. impedance study in HCl solutions

    International Nuclear Information System (INIS)

    Habib, K.; Abdullah, A.

    1995-01-01

    An electrochemical study on Fe-Co-B-Si amorphous electrodes has been conducted. The study was focused on determining the electrochemical impedance spectroscopy (EIS) of four different alloys of Fe-Co-B-Si in various HCl acid solutions. The A.C. impedance and the capacitance of Fe-Co-B-Si, Co-Fe-Ni-B-Si, Co-Fe-Mn-B-Si, and Co-Fe-Ni-Mo-B-Si alloys were obtained in 25, 50, 75 and 100% of HCl acid at room temperature. Electrochemical parameters, i.e., impedance, were found to vary depending on additions of the Ni, Mn, Ni-Mo to Fe-Co-B-Si alloy, the acid concentration, and the nanoscopic surface roughness of the electrodes. Consequently, a correlation between the obtained data is established

  15. Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Hsu, T.Y.

    2000-01-01

    Characteristics of martensitic transformation fcc(γ)→hcp(ε) in Fe-Mn-Si based alloys are briefly reviewed. By analyzing the influences of constituents and treatments on shape memory effect (SME) in Fe-Mn-Si, the main factors controlling SME are summarized as austenite strengthening, stacking fault energy (probability) and antiferromagnetic temperature. Contribution of thermomechanical training to SME is introduced. The Fe-Mn-Si-RE (rare earth elements) and Fe-Mn-Si-Cr-N alloys are recommended as two novel shape memory alloys with superior SME. (orig.)

  16. Anomalous grain growth in nanocrystalline Fe73.5Cu1Nb3Su13.5B9 alloys

    DEFF Research Database (Denmark)

    Jiang, Jianzhong

    1997-01-01

    The grain growth of the FeSi phase during the crystallization process of the amorphous Fe73.5Cu1Nb3Si13.5B9 alloy was studied using transmission electron microscopy and x-ray diffractometry. An anomalous grain growth behaviour of the FeSi phase in the samples annealed in temperature range from 743...... to 823 K for one hour was observed, i.e. the grain size of the FeSi phase slightly decreases when the annealing temperature increases from 743 K ot 823 K. The mechanism of the anomalous grain growth may be due to the different nucleation and volume diffusion rates in the samples anneales at low and high...

  17. Effect of boron addition on the magnetic properties of the Fe-Nd-Al alloys prepared by suction casting

    International Nuclear Information System (INIS)

    Bai, Q.; Xu, H.; Tan, X.H.; Zhang, S.Y.

    2007-01-01

    The microstructure and magnetic properties of the Fe-Nd-Al alloys prepared by suction casting with boron addition have been investigated. The increasing boron content in the Fe-Nd-Al alloys significantly increases the intrinsic coercivity ( i H c ) and decreases the proportion of the amorphous phase. The magnetization at the maximum applied field (σ ' s ) of the Fe-Nd-Al-B alloys decreases, while the coercivity increases markedly after annealing. The high intrinsic coercivity is due to the presence of the Nd 2 Fe 14 B phase

  18. Structural Relaxation in Fe78Nb2B20 Amorphous Alloy Studied by Moessbauer Spectroscopy

    International Nuclear Information System (INIS)

    Kansy, J.; Hanc, A.; Rasek, J.; Haneczok, G.; Pajak, L.; Stoklosa, Z.; Kwapulinski, P.

    2011-01-01

    It was shown that soft magnetic properties of Fe 78 Nb 2 B 20 amorphous alloy can be significantly improved by applying 1-h annealing at temperature 623 K (permeability increases even about 8 times). The Moessbauer Spectroscopy technique indicated that the optimized microstructure (corresponding to the maximum magnetic permeability) is free of iron nanograins and should be attributed to annealing out of free volume and a reduction of internal stresses i.e. to the relaxed amorphous phase. (authors)

  19. Bulk synthesis by spray forming of Al–Cu–Fe and Al–Cu–Fe–Sn alloys containing a quasicrystalline phase

    International Nuclear Information System (INIS)

    Srivastava, V.C.; Huttunen-Saarivirta, E.; Cui, C.; Uhlenwinkel, V.; Schulz, A.; Mukhopadhyay, N.K.

    2014-01-01

    Highlights: • 40 kg Bulk material spray formed based on Al–Cu–Fe and Al–Cu–Fe + Sn. • Deposited Al–Cu–Fe alloy showed single phase bulk quasicrystals(QC). • DSC, XRD and microscopic analyses were done to ascertain the QC nature. • Sn does not help in single phase quasicrystal formation in the deposit. • The possible structural evolution mechanisms have been discussed in detail. - Abstract: In this study, Al–Cu–Fe alloys without and with the addition of Sn and containing a quasicrystalline phase were spray deposited. The spray-deposited bulk materials were characterized in terms of microstructure and hardness. The results showed that the Al 62.5 Cu 25 Fe 12.5 alloy contains the icosahedral quasicrystalline phase (i-phase) along with the minor λ-Al 13 Fe 4 phase, whereas the Al 62.5 Cu 25 Fe 12.5 + Sn alloy contains five phases: the major i-phase and the crystalline phases of Sn, θ-Al 2 Cu, λ-Al 13 Fe 4 and β-AlFe(Cu) phases. These results have been corroborated by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM) and differential scanning calorimetry (DSC). The hardness value of the Al–Cu–Fe alloy reached 10.5 GPa at 50 g load and then decreased steadily with increase in the applied load, while that for Al–Cu–Fe–Sn alloy it was originally somewhat lower, then decreased dramatically with slight increase in the applied load but stayed constant with further load increase. The hardness indentations in Al–Cu–Fe alloy introduced cracking in the material, whereas in the case of Al–Cu–Fe–Sn alloy the Sn-rich areas inhibited the crack growth. The present study provides an insight into the mechanism of phase and microstructural evolutions during spray forming of the studied alloys. Furthermore, the role of Sn in terms of microstructure and properties is highlighted

  20. Site preference and elastic properties of ternary alloying additions in B2 YAg alloys by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yurong, E-mail: winwyr@126.com [College of Electromechanical Engineering, Hunan University of Science and Technology, Xiantang 411201 (China); Hu Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China); Xu Longshan [Department of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024 (China)

    2012-09-15

    First-principles calculations were preformed to study the site preference behavior and elastic properties of 3d (Ti-Cu) transition-metal elements in B2 ductility YAg alloy. In YAg, Ti is found to occupy the Y sublattice whereas V, Cr, Co, Fe, Ni and Cu tend to substitute for Ag sublattice. Due to the addition of 3d transition metals, the lattice parameters of YAg is decreased in the order: VFeFe, Co and Cu can improve the ductility of YAg alloy, and Fe is the most effective element to improve the ductility of YAg, while Ti, Ni and V alloying elements can reduce the ductility of YAg alloy, especially, V transforms ductile into brittle for YAg alloy. In addition, both V and Ni alloying elements can increase the hardness of YAg alloy, and Y{sub 8}Ag{sub 7}V is harder than Y{sub 8}Ag{sub 7}Ni.

  1. Novel Amorphous Fe-Zr-Si(Cu) Boron-free Alloys

    Science.gov (United States)

    Kopcewicz, M.; Grabias, A.; Latuch, J.; Kowalczyk, M.

    2010-07-01

    Novel amorphous Fe80(ZrxSi20-x-y)Cuy boron-free alloys, in which boron was completely replaced by silicon as a glass forming element, have been prepared in the form of ribbons by a melt quenching technique. The X-ray diffraction and Mössbauer spectroscopy measurements revealed that the as-quenched ribbons with the composition of x = 6-10 at. % and y = 0, 1 at. % are predominantly amorphous. DSC measurements allowed the estimation of the crystallization temperatures of the amorphous alloys. The soft magnetic properties have been studied by the specialized rf-Mössbauer technique in which the spectra were recorded during an exposure of the samples to the rf field of 0 to 20 Oe at 61.8 MHz. Since the rf-collapse effect observed is very sensitive to the local anisotropy fields it was possible to evaluate the soft magnetic properties of amorphous alloys studied. The rf-Mössbauer studies were accompanied by the conventional measurements of the quasi-static hysteresis loops from which the magnetization and coercive fields were estimated. It was found that amorphous Fe-Zr-Si(Cu) alloys are magnetically very soft, comparable with those of the conventional amorphous B-containing Fe-based alloys.

  2. Pr2Fe14B/α-Fe nanocomposites for thermal applications

    International Nuclear Information System (INIS)

    Silva, Suelanny Carvalho da

    2012-01-01

    In this work, Pr x Fe 94 - x B 6 (x = 6, 8, 10 and 12) nanostructured powders were prepared by a combination of hydrogenation, disproportionation, desorption and recombination (HDDR) process with high energy milling applied to the mixture of an as-cast alloy (Pr 14 Fe 80 B 6 ) and α-Fe. The produced nanoparticles showed magnetic properties comparable to those reported in hyperthermia studies. The optimal time to obtain the magnetic nanoparticles is 5 hours (at 900 rpm). It was verified that longer milling times cause an increase in carbon percentage on the particles. The carbon is derived from oleic acid added as a surfactant in the milling step. The nanocomposites exhibit coercive force ranging from 80 Oe (6.5 kAm -1 ) to 170 Oe (13.5 kAm -1 ) and magnetic moments in the range of 81 129 Am2kg -1 . From the X-ray diffraction analyses, only two phases were found in all samples: α-Fe and the magnetic phase Pr 2 Fe 14 B. Individual nanoparticles with diameter of about 20 nm were verified. The samples studied presented heating when exposed to an alternating magnetic field (f = 222 kHz e H max ∼3.7 kAm -1 ) comparable to reported in literature. Temperature variations (ΔT) of the powders were: 51 K for Pr 6 Fe 88 B 6 , 41 K for Pr 8 Fe 86 B 6 , 38 K for Pr 10 Fe 8 4 B 6 and T = 34 K for Pr 12 Fe 82 B 6 . The specific absorption rates (SARs) of the powders were 201 Wkg -1 for Pr 6 Fe 88 B 6 composition, 158 Wkg -1 on the composition Pr 8 Fe 86 B 6 , and 114 Wkg -1 for Pr 10 Fe 84 B 6 and Pr 12 Fe 82 B 6 compositions. (author)

  3. Identification of Optimum Magnetic Behavior of NanoCrystalline CmFeAl Type Heusler Alloy Powders Using Response Surface Methodology

    Science.gov (United States)

    Srivastava, Y.; Srivastava, S.; Boriwal, L.

    2016-09-01

    Mechanical alloying is a novelistic solid state process that has received considerable attention due to many advantages over other conventional processes. In the present work, Co2FeAl healer alloy powder, prepared successfully from premix basic powders of Cobalt (Co), Iron (Fe) and Aluminum (Al) in stoichiometric of 60Co-26Fe-14Al (weight %) by novelistic mechano-chemical route. Magnetic properties of mechanically alloyed powders were characterized by vibrating sample magnetometer (VSM). 2 factor 5 level design matrix was applied to experiment process. Experimental results were used for response surface methodology. Interaction between the input process parameters and the response has been established with the help of regression analysis. Further analysis of variance technique was applied to check the adequacy of developed model and significance of process parameters. Test case study was performed with those parameters, which was not selected for main experimentation but range was same. Response surface methodology, the process parameters must be optimized to obtain improved magnetic properties. Further optimum process parameters were identified using numerical and graphical optimization techniques.

  4. Ion-beam mixing and tribology of Fe/B multilayers

    International Nuclear Information System (INIS)

    Hu, R.; Rehn, L.E.; Baldo, P.M.; Fenske, G.R.

    1990-01-01

    This paper reports the interdiffusion of Fe and B trilayer specimens during 1-MeV Kr + bombardment studied using Rutherford backscattering and electron microscopy. The square of the interdiffusion distance during mixing at 300 degrees C was found to depend linearly on the irradiation dose. Arrhenius behavior with an apparent activation enthalpy of 0.7 eV was observed for the mixing between 200 and 500 degrees C. Electron microscopy of ion-beam mixed multilayer specimens revealed that two crystalline compounds, Fe 2 B and Fe 3 B, formed during bombardment at 450 degrees C, while two different amorphous Fe/B phases formed at 300 degrees C. Substantially improved adhesion and reduced friction were observed for Fe/B multilayers ion-beam mixed onto M50 steel substrates at 450 degrees C

  5. Resistivity changes of some amorphous alloys undergoing nanocrystallization

    Science.gov (United States)

    Barandiarán, J. M.; Fernández Barquín, L.; Sal, J. C. Gómez; Gorría, P.; Hernando, A.

    1993-10-01

    The electrical resistivity of amorphous alloys with compositions: Fe 73.5Nb 3Cu 1Si 13.5B 9, Fe 86Zr 7Cu 1B 6 and Co 80Nb 8B 12 has been studied in the temperature range from 300 to 1100 K, where crystallization occurs. The products of crystallization and the grain size have been studied by X-ray diffraction. In a first step, all the alloys crystallize with small grains of a few nanometers in diameter (nanocrystalline state), and the resistivity behavior at this process accounts for the difference between the amorphous and nanocrystalline phases. The nanocrystalline phases are: α-Fe-Si, α-Fe and fcc Co for the three compounds studied respectively. A second process, at which grain growth and precipitation of intermetallic compounds and borides takes place, has been found for all the alloys. The resistivity is sensitive, not only to the total transformed sample amount, but to the topological distribution of the crystalline phases, and therefore shows a more complex behavior than other well established techniques, as differential scanning calorimetry. This supplementary information given by the resistivity is also discussed.

  6. Corrosion behavior of electrodeposited Co-Fe alloys in aerated solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chansena, A. [Research Unit on Corrosion, College of Data Storage Innovation, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Sutthiruangwong, S., E-mail: sutha.su@kmitl.ac.th [Department of Chemistry, Faculty of Science, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand); Research Unit on Corrosion, College of Data Storage Innovation, King Mongkut' s Institute of Technology Ladkrabang, Bangkok 10520 (Thailand)

    2017-05-01

    Co-Fe alloy is an important component for reader-writer in hard disk drive. The surface of the alloy is exposed to the environment both in gas phase and in liquid phase during manufacturing process. The study of corrosion behavior of Co-Fe alloys can provide useful fundamental data for reader-writer production planning especially when corrosion becomes a major problem. The corrosion study of electrodeposited Co-Fe alloys from cyclic galvanodynamic polarization was performed using potentiodynamic polarization technique. The composition of electrodeposited Co-Fe alloys was determined by X-ray fluorescence spectrometry. The patterns from X-ray diffractometer showed that the crystal structure of electrodeposited Co-Fe alloys was body-centered cubic. A vibrating sample magnetometer was used for magnetic measurements. The saturation magnetization (M{sub s}) was increased and the intrinsic coercivity (H{sub ci}) was decreased with increasing Fe content. The corrosion rate study was performed in aerated deionized water and aerated acidic solutions at pH 3, 4 and 5. The corrosion rate diagram for Co-Fe alloys was constructed. It was found that the corrosion rate of Co-Fe alloys was increased with increasing Fe content in both aerated deionized water and aerated acidic solutions. In aerated pH 3 solution, the Co-Fe alloy containing 78.8% Fe showed the highest corrosion rate of 7.7 mm yr{sup −1} with the highest M{sub s} of 32.0 A m{sup 2} kg{sup −1}. The corrosion rate of the alloy with 23.8% Fe was at 1.1 mm yr{sup −1} with M{sub s} of 1.2 A m{sup 2} kg{sup −1}. In aerated deionized water, the alloy with the highest Fe content of 78.5% still showed the highest corrosion rate of 0.0059 mm yr{sup −1} while the alloy with the lowest Fe content of 20.4% gave the lowest corrosion rate of 0.0045 mm yr{sup −1}. - Highlights: • The aeration during corrosion measurement simulates reader-writer head production environment. • The corrosion rate diagram for Co-Fe alloys

  7. Effect of Fe-Mn addition on microstructure and magnetic properties of NdFeB magnetic powders

    Science.gov (United States)

    Kurniawan, C.; Purba, A. S.; Setiadi, E. A.; Simbolon, S.; Warman, A.; Sebayang, P.

    2018-03-01

    In this paper, the effect of Fe-Mn alloy addition on microstructures and magnetic properties of NdFeB magnetic powders was investigated. Varied Fe-Mn compositions of 1, 5, and 10 wt% were mixed with commercial NdFeB type MQA powders for 15 minutes using shaker mill. The characterizations were performed by powder density, PSA, XRD, SEM, and VSM. The Fe-Mn addition increased the powder density of NdFeB/Fe-Mn powders. On the other side, particle size distribution slightly decreased as the Fe-Mn composition increases. Magnetic properties of NdFeB/Fe-Mn powders changed with the increasing of Fe-Mn content. SEM analysis showed the particle size of NdFeB/Fe-Mn powder was smaller as the Fe-Mn composition increases. It showed that NdFeB/Fe-Mn particles have different size and shape for NdFeB and Fe-Mn particles separately. The optimum magnetic properties of NdFeB/Fe-Mn powder was achieved on the 5 wt% Fe-Mn composition with remanence M r = 49.45 emu/g, coercivity H c = 2.201 kOe, and energy product, BH max = 2.15 MGOe.

  8. 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

  9. Compositional optimization for nanocrystalline hard magnetic MRE–Fe–B–Zr alloys via modifying RE and B contents

    Energy Technology Data Exchange (ETDEWEB)

    Qian, D.Y.; Hussain, M.; Zheng, Z.G.; Zhong, X.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, X.X. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Z.W., E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-06-15

    To reduce the rare earth content and maintain good magnetic properties for NdFeB based alloys, the effects of RE and B contents on the micro-structure and magnetic properties of nanocrystalline MRE{sub 11−y}Fe{sub 79.5}B{sub 8+y}Zr{sub 1.5} (MRE=Nd{sub 0.8}(Dy{sub 0.5}Y{sub 0.5}){sub 0.2}, y=0–3) alloys have been investigated. Increasing B concentration leads to the appearance and increase of soft magnetic Fe{sub 3}B phase and reduced grain size. With decreasing MRE and increasing B concentrations, the coercivity decreased from 1159.8 kA/m for y=0 to 619.0 kA/m for y=3. The saturation magnetization and remanence increased with B content until y=2 then decreases. The B content also has effects on the exchange coupling, microstructure and thermal stability. While comparing MRE{sub 10}Fe{sub 82.5}B{sub 6}Zr{sub 1.5} alloy with MRE{sub 11−y}Fe{sub 79.5}B{sub 8+y}Zr{sub 1.5} (y=1 and 2) alloys, the alloy with 9 at% MRE can achieve similar magnetic properties as that with 10 at% MRE. The magnetic properties with coercivity of 792.2 kA/m, (BH){sub max} of 128 kJ/m{sup 3} and good thermal stability have been obtained for MRE{sub 9}Fe{sub 79.5}B{sub 10}Zr{sub 1.5} alloy. - Highlights: • Nanocomposite NdFeB composition is optimized to reduce RE from 10 to 9 at.%. • Increasing B content benefits microstructure, exchange coupling, thermal stability. • Alloy with 9% RE has H{sub c}=792kA/m, (BH){sub max}=128kJ/m{sup 3} and low temperature coefficients.

  10. Pressure-induced preferential growth of nanocrystals in amorphous Nd9Fe85B6

    International Nuclear Information System (INIS)

    Wu Wei; Li Wei; Sun Hongyu; Li Hui; Zhang Xiangyi; Li Xiaohong; Liu Baoting

    2008-01-01

    Control over the growth and crystallographic orientation of nanocrystals in amorphous alloys is of particular importance for the development of advanced nanocrystalline materials. In the present study, Nd 2 Fe 14 B nanocrystals with a strong crystallographic texture along the [410] direction have been produced in Nd-lean amorphous Nd 9 Fe 85 B 6 under a high pressure of 6 GPa at 923 K. This is attributed to the high pressure inducing the preferential growth of Nd 2 Fe 14 B nanocrystals in the alloy. The present study demonstrates the potential application of high-pressure technology in controlling nanocrystalline orientation in amorphous alloys

  11. First-principles investigation of Cr-doped Fe2B: Structural, mechanical, electronic and magnetic properties

    Science.gov (United States)

    Wei, Xiang; Chen, Zhiguo; Zhong, Jue; Wang, Li; Wang, Yipeng; Shu, Zhongliang

    2018-06-01

    The structural, mechanical, electronic and magnetic properties of Fe8-xCrxB4 (x = 0, 0.25, 0.5, 1, 2, 3, 4, 5, 6, 7 and 8) have been investigated by first-principles calculation. It was found that the calculated structural parameters are well consistent with available experimental data. Moreover, all studied compounds are thermodynamically stable phases. On the whole, the moduli of the compounds firstly increase and then decrease with the increase of Cr concentration, whereas the variation of hardness exhibits more fluctuations. All Cr-doped Fe2B have better ductility than Fe2B except Fe2Cr6B4 and Fe5Cr3B4. Interestingly, Fe4Cr4B4 is of not only the slightly larger hardness, but also much better ductility than Fe2B. As the Cr concentration is lower than 20 wt%, the hardness of Cr-doped Fe2B slightly decreases with increasing Cr, whereas the sharply increased hardness of (Fe, Cr)2B in Fe-B alloys or boriding layer should be attributed to the multiple alloying effects resulting from Cr and the other alloying elements. The electronic structures revealed that the Fe-B and/or Cr-B bonds are mainly responsible for their mechanical properties, and the M-N (M = Fe or Cr, N = Fe or Cr) bonds in 〈2 2 0〉 and 〈1 1 3〉 orientations show covalent character. Additionally, the magnetic moments (Ms) of the compounds do not monotonically decrease with increasing Cr.

  12. Development and structural characterization of exchange-spring-like nanomagnets in (Fe,Co)-Pt bulk nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Crisan, O.; Crisan, A.D.; Mercioniu, I. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Magurele, Bucharest (Romania); Nicula, R. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Advanced Materials Processing, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland); Vasiliu, F., E-mail: fvasiliu@infim.ro [National Institute for Materials Physics, P.O. Box MG-7, 077125 Magurele, Bucharest (Romania)

    2016-03-01

    FePt-based alloys are currently under scrutiny for their possible use as materials for perpendicular magnetic recording. Another possible application is in the field of permanent magnets without rare-earths, magnets that may operate at higher temperatures than the classic Nd–Fe–B magnets. Within this study, FeCoPt alloys prepared by rapid solidification from the melt are structurally and magnetically characterized. In the as-cast FeCoPt ribbons, a three-phase structure comprising well-ordered CoFePt and CoPt L1{sub 0} phases embedded in a disordered fcc FePt matrix was evidenced by XRD, HREM and SAED. Extended transmission electron microscopy analysis demonstrates the incipient formation of ordered L1{sub 0} phases. X-ray diffraction was used to characterize the phase structure and to obtain the structural parameters of interest for L1{sub 0} ordering. In the as-cast state, the co-existence of hard magnetic CoFePt and CoPt L1{sub 0} tetragonal phases with the soft fcc FePt phase is obtained within a refined microstructure made of alternatively disposed grains (grain sizes from 1 to 7 nm). Following a thermal treatment of 1 h at 670 °C, the soft magnetic fcc matrix phase transforms to tetragonal L1{sub 0} phases (disorder–order transition). The resulting CoPt and CoFePt L1{sub 0} phases have grains of around 5–20 nm in size. In the as-cast state, magnetic measurements show a quite large remanence (0.75 T), close to the value of the parent L1{sub 0} FePt phase. Coercive fields of about 200 kA/m at 5 K were obtained, comparable with those reported for some FePt-based bulk alloys. Upon annealing both remanence and coercivity are increased and values of up to 254 kA/m at 300 K are obtained. The polycrystalline structure of the annealed FeCoPt samples, as well as the formation of multiple c-axis domains in different CoPt and CoFePt regions (which leads to a reduction of the magneto-crystalline anisotropy) may account for the observed coercive fields that are

  13. Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel - A macroscopic assessment

    Science.gov (United States)

    Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.; Camino, F.; Şavklıyıldız, İ.; Akdoğan, E. K.

    2017-06-01

    The study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ∼2 × 1018 n/cm2. At the higher neutron dose of ∼2 × 1019, macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe2B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

  14. NdFeB magnets with zero temperature coefficient of induction

    International Nuclear Information System (INIS)

    Ma, B.M.; Narasimhan, K.S.V.L.; Hurt, J.C.

    1986-01-01

    Temperature compensation for the induction of NdFeB type magnets has been investigated. A computer assisted alloy selection method was adopted to identify composition of zero temperature coefficient of induction over -50 to 200 0 C. Selected alloys were processed into magnet by the conventional powder metallurgy method. The experimental temperature coefficient on the sintered magnet correlated with the prediction satisfactory. Holmium is an essential ingredient required for temperature compensation of NdFeB magnets. A magnet, (Nd/sub 0.23/Ho/sub 0.64/Dy/sub 0.13/)/sub 15/Fe/sub 79/B/sub 6/ with B/sub r/ of 7,700 Gauss, H/sub c/ of 7,700 Oe, H/sub ci/ of 20,600 Oe, Bh/sub max/ of 14.8 MGOe and temperature coefficient of -0.029% per 0 C over -50 to +150 was obtained

  15. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness

    International Nuclear Information System (INIS)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J.

    2007-01-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  16. {gamma}-Fe phase plasma-induced on the surface of thin S3A alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Garcia-Sosa, I., E-mail: irma.garcia@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Nava, N., E-mail: tnava@imp.mx [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas (Mexico); Camps, E., E-mail: enrique.camps@inin.gob.mx; Escobar, Luis, E-mail: luis.escobar@inin.gov.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Lopez-Castanarez, R., E-mail: rlc@anuies.mx; Olea-Cardoso, O., E-mail: olc@anuies.mx [Universidad Autonoma del Edo. de Mexico, Facultad de Quimica (Mexico)

    2011-11-15

    Amorphous alloy ribbons of Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} were exposed to cold plasmas of N{sub 2} and Ar-N{sub 2} at temperatures lower than T{sub x} = 808 K. The conversion X-ray Moessbauer spectra of the plasma-exposed ribbons consist of a singlet and a broadened magnetic sextet. The singlet with isomer shift {delta} = -0.11 mm/s can be assigned to {gamma}-Fe austenite phase. Minor bulk magnetic changes in the alloy were measured as a consequence of these treatments; e.g. the relative intensities A23 of the transmission Moessbauer spectra of the untreated and treated samples, were 3.22 and 3.56, respectively, the B{sub hf} values changed from 22.9 T (untreated sample) to 22.4 T (plasma treated samples). Unexpectedly, the {gamma}-Fe phase can also be produced by simply heating the alloy ribbons under N{sub 2} flux at temperatures as low as 423 K. Moessbauer data of the crystallized samples are also reported, and a qualitative assessment on the mechanical properties of the Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} alloy associated with the plasma and/or temperature surface induced {gamma}-Fe phase is given.

  17. Structural transformations in quenched Fe-Ga alloys

    International Nuclear Information System (INIS)

    Lograsso, T.A.; Ross, A.R.; Schlagel, D.L.; Clark, A.E.; Wun-Fogle, M.

    2003-01-01

    It has been speculated that the large increase in magnetostriction in Fe-Ga alloys results from local short-range ordering of the Ga atoms along specific crystallographic directions in the disordered Fe structure. The structural transitions associated with different cooling rates from the high temperature disordered state were investigated with X-ray diffraction of oriented single crystals of Fe-19 at% Ga. Results are presented for long-range ordering during slow cooling and indirect evidence of local short-range ordering of Ga atoms in the disordered state when the alloys are quenched is also presented. In the latter case, the short-range ordering of Ga atoms leads to a tetragonal distortion of the lattice. The dependence of the magnetostrictive response of Fe-Ga alloys on thermal history has been found to be directly related to these structural transformations in Fe-19 at% Ga alloys and experimental support for the proposed magnetostriction model based on Ga-Ga pairing along [100] crystallographic directions is presented

  18. Effect of P addition on glass forming ability and soft magnetic properties of melt-spun FeSiBCuC alloy ribbons

    International Nuclear Information System (INIS)

    Xu, J.; Yang, Y.Z.; Li, W.; Chen, X.C.; Xie, Z.W.

    2016-01-01

    The dependency of phosphorous content on the glass forming ability, thermal stability and soft magnetic properties of Fe 83.4 Si 2 B 14−x P x Cu 0.5 C 0.1 (x=0,1,2,3,4) alloys was investigated. The experimental results showed that the substitution of B by P increased the glass forming ability in this alloy system. The Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 alloy shows a fully amorphous character. Thermal stability of melt-spun ribbons increases and temperature interval between the first and second crystallization peaks enlarges with the increase of P content. And the saturation magnetic flux density (Bs) shows a slight increase with the increase of P content. The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high Bs about 200.6 emu/g. The Bs of fully amorphous alloy Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 drops dramatically to 172.1 emu/g, which is lower than that of other nanocrystallines. Low material cost and excellent soft magnetic properties make the FeSiBPCuC alloys promise soft magnetic materials for industrial applications. - Highlights: • Partial substituting B by P helps to improve the glass forming ability of the alloy. • The addition of P content reduces the thermal stability and improves heat treatment temperature region for these alloys. • The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high saturation magnetic density of 200.6 emu/g.

  19. Cold compaction behavior of nano-structured Nd–Fe–B alloy powders prepared by different processes

    International Nuclear Information System (INIS)

    Liu, Xiaoya; Hu, Lianxi; Wang, Erde

    2013-01-01

    Graphical abstract: Relative density enhancement and nanocrystallization of Nd 2 Fe 14 B phase are two major effective means to improve magnetic properties. Since the matrix Nd 2 Fe 14 B phase in the starting Nd–Fe–B alloy can be disproportionated into a nano-structured mixture of NdH 2.7 , Fe 2 B, and α-Fe phases during mechanical milling in hydrogen. It is thus important to study the densification behavior of nanocrystalline powders to evaluate and predict the cold compactibility of powders. By comparison with the as milled as well as melt-spun Nd 16 Fe 76 B 8 alloy powders, we find that the as-disproportionated Nd 16 Fe 76 B 8 alloy powder exhibits the best cold compactibility. As evident from the illustration presented below, compaction parameters (representing the powder compactibility) have been determined by fitting density–pressure data with double logarithm compaction equation. Densification mechanisms involved during cold compaction process are clarified in our work by referring to microstructure observation of samples prepared by various methods. As a result, highly densified green magnet compact can be obtained by cold pressing of as-disproportionated NdFeB alloy powders. Highlights: ► Nano-structured disproportionated Nd–Fe–B alloy powders by mechanical milling in hydrogen. ► Highly densified green magnet compact by cold pressing of as-disproportionated Nd–Fe–B alloy powders. ► Density–pressure data fitted well by an empirical powder compaction model. ► As-disproportionated powder showed better compactibility than as milled and melt-spun counterparts. ► The effects of physical properties on powder compactibility and densification mechanisms are clarified. - Abstract: The compaction behavior of nano-structured Nd 16 Fe 76 B 8 (atomic ratio) alloy powders, which were prepared by three different processing routes including melt spinning, mechanical milling in argon, and mechanically activated disproportionation by milling in

  20. Micromagnetic finite element study for magnetic properties of nanocomposite exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems

    Energy Technology Data Exchange (ETDEWEB)

    Ryo, Hyok-Su [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Hu, Lian-Xi [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Kim, Jin-Guk [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Faculty of Physics, Kim Il Sung University, Pyongyang 999093, Democratic People’s Republic of Korea (Korea, Republic of); Yang, Yu-Lin [School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-03-15

    In this study, magnetic properties of exchange coupled nanocomposite multilayer thin films constructed alternately with magnetic hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers have been studied by micromagnetic finite element method (FEM). According to the results, effects of the thicknesses of layers and the magneto-crystalline anisotropy on the magnetic properties of the Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems have been estimated. On the other hand, the results have been analyzed by means of efficiency of interphase exchange coupling, which can be estimated by volume ratios of exchange coupled areas between magnetically hard Nd{sub 2}Fe{sub 14}B and soft α-Fe phase layers. The results show that the magnetic properties of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayer systems can be enhanced by efficient interphase exchange coupling between magnetically hard Nd{sub 2}Fe{sub 14}B layers and soft α-Fe layers. - Highlights: • Phase layer thicknesses dependence of magnetic properties of Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Analyzation of the effectiveness of exchange coupling between the Nd{sub 2}Fe{sub 14}B and α-Fe layers. • Dependence of the magnetic properties on direction of external field of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers. • Dependence of the magnetic properties on magneto-crystalline anisotropy of exchange coupled Nd{sub 2}Fe{sub 14}B/α-Fe multilayers.

  1. Fe-based bulk amorphous alloys with iron contents as high as 82 at%

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jin-Feng; Liu, Xue; Zhao, Shao-Fan; Ding, Hong-Yu [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yao, Ke-Fu, E-mail: kfyao@tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-07-15

    Fe-based bulk amorphous alloys (BAAs) with high Fe contents are advantageous due to their high saturation magnetization and low cost. However, preparing Fe-based BAAs with Fe contents higher than 80 at% is difficult due to their poor glass forming abilities (GFA). In this study, an Fe{sub 81}P{sub 8.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA with a diameter of 1 mm and a saturation magnetization of 1.56 T was successfully prepared using the fluxing and copper mold casting methods. In addition, by introducing a small amount of elemental Mo to the alloy, an Fe{sub 82}Mo{sub 1}P{sub 6.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA rod with a diameter of 1 mm, a high saturation magnetization of 1.59 T, a high yield stress of 3265 MPa, and a clear plasticity of 1.3% was prepared in the same way. The cost effectiveness and good magnetic properties of these newly-developed Fe-based BAAs with Fe contents as high as 82 at% would be advantageous and promising for industrial applications. - Highlights: • Novel Fe-based BAA with no other metallic element except 81 at% Fe was prepared. • Fe-based bulk amorphous alloy (BAA) with the highest Fe content (82%) was prepared. • Very high saturation magnetization of 1.59 T has been achieved. • A new thought for designing Fe-based BAA with high Fe content was provided.

  2. Effect of wheel speed on the crystallization behavior of as-quenched Nd-Fe-B alloys

    Directory of Open Access Journals (Sweden)

    Kuo Men

    2016-02-01

    Full Text Available A series of alloys composed of Nd9Fe85Nb0.5B5.5 were prepared through rapid quenching by different wheel speeds. Nanocomposite was usually obtained by subjecting the as-quenched alloys to a crystallization annealing. The crystallization behavior was investigated by differential scanning calorimetry (DSC as the primary method. The results showed that the DSC curve of sample prepared at 15 m/s had only one exothermic peak at about 690 °C. When the wheel speed increased to 18-27 m/s, one more peak at 590 °C appeared. Moreover, the intensity of this new peak enhances while the original one at 690 °C declined as the speed increases within this range. When the speed further grew up to 30, 35, or 40 m/s , only the peak at 590 °C remained while the other disappeared. This could be ascribed to the different initial phase structures of the alloys, which were found to vary with the wheel speeds. As can be seen, with increasing the wheel speed, the contents of amorphous and metastable phase increased while Nd2Fe14B phase decreased. This change resulted in a huge effect on the crystallization behavior. We could deduce the relative content of each phase from the integral areas of peaks in DSC curves in different samples and figure out the phase transition in the crystallization. The results showed that the crystallization of samples prepared by relatively high speeds, which are almost amorphous initially, manifest as only one step, while those prepared by relatively low speeds showed two. Subsequently, we analyzed the crystallization process and interpreted it from the theory of energy barrier.

  3. Effect Of DyMn Alloy-Powder Addition On Microstructure And Magnetic Properties Of NdFeB Sintered Magnets

    Directory of Open Access Journals (Sweden)

    Lee M.-W.

    2015-06-01

    Full Text Available Micostructural change and corresponding effect on coercivity of a NdFeB sintered magnet mixed with small amount of DyMn powder was investigated. In the sintered magnet mixed with the DyMn alloy-powder Dy-rich shell was formed at outer layer of the main grains, while Mn was mostly concentrated at Nd-rich triple junction phase (TJP, lowering melting temperature of the Nd-rich phase that eventually improved the microstructural characteristics of the gain boundary phase. The coercivity of a magnet increased more than 3.5 kOe by the mixing of the DyMn alloy-powder.

  4. Defects spectroscopy by means of the simple trapping model of the Fe78Si9B13 alloy

    International Nuclear Information System (INIS)

    Lopez M, A.; Cabral P, A.; Garcia S, S.F.

    2007-01-01

    In this work it is analyzed quantitatively the results of the positron annihilation in the Fe 78 Si 9 B 13 alloy by means of the simple trapping model. From this analysis its are derived: a reason of positron trapping in the defects (K), the defects concentration (C d ) and the electronic density associated to the defect (n d ); both first parameters, (K, C d ) its increase and n d diminishes when increasing the alloy temperature. From this analysis it is also inferred that the defect consists of a multi vacancy of between 15 and 20 mono vacancies. (Author)

  5. Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

    International Nuclear Information System (INIS)

    Xiaoya, Liu; Yuping, Li; Lianxi, Hu

    2013-01-01

    The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd 16 Fe 76 B 8 (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd 2 Fe 14 B phase decomposed into an intimate mixture of nano-structured NdH 2.7 , Fe 2 B and α-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd 2 Fe 14 B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 °C×30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m 3 , respectively. - Highlights: ► Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. ► Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. ► Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. ► Magnetic properties significantly improved by relative density enhancement and nanocrystallization of Nd 2 Fe 14 B phase. ► The effects of sintering parameters on magnetic properties and the underlying

  6. Synthesis of FeSiBPNbCu nanocrystalline soft-magnetic alloys with high saturation magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zongzhen [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Wang, Anding; Chang, Chuntao [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai District, Ningbo, Zhejiang 315201 (China); Wang, Yanguo [Institute of Physics, Chinese Academy of Sciences, PO Box 603, Beijing 100080 (China); Dong, Bangshao [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Zhou, Shaoxiong, E-mail: sxzhou@atmcn.com [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

    2014-10-25

    Highlights: • Thermal stability of the FeSiBPNbCu alloys is strongly dependent on the Fe content. • The FeSiBPNbCu alloys with high Fe content exhibit good soft magnetic properties. • The coexistence of Cu, P and Nb leads to the excellent soft magnetic properties. - Abstract: A series of [Fe{sub 0.76+x}(Si{sub 0.4}B{sub 0.4}P{sub 0.2}){sub 0.24−x}]{sub 98.25}Nb{sub 1}Cu{sub 0.75} (x = 0–0.08) nanocrystalline soft-magnetic alloys with high saturation magnetization were synthesized by adjusting Fe content and improving the crystallization behavior, soft-magnetic properties and microstructure. It is found that the temperature interval between the two crystallization peaks is significantly enlarged from 50 to 180 °C when the Fe content of the alloys increases from x = 0 to x = 0.08, which greatly expands the optimum annealing temperature range. The alloys with higher Fe content are prone to form more uniform nanocomposite microstructure with better thermal stability and soft magnetic properties. The Fe-rich FeSiBPNbCu nanocrystalline alloys with x = 0.08 exhibit excellent soft-magnetic properties, including the high saturation magnetic flux density of up to 1.74 T, low coercivity of about 3.3 A/m and high effective permeability of more than 2.2 × 10{sup 4} at 1 kHz under a field of 1 A/m. The combination of excellent soft-magnetic properties, low cost and good productivity makes the FeSiBPNbCu alloys to be a kind of promising soft-magnetic materials for electrical and electronic industry applications.

  7. Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel – A macroscopic assessment

    International Nuclear Information System (INIS)

    Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.

    2017-01-01

    Here, this study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ~2 x 10 18 n/cm 2 . At the higher neutron dose of ~2 x 10 19 , macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe 2 B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

  8. Monocrystalline Heusler Co2FeSi alloy glass-coated microwires: Fabrication and magneto-structural characterization

    Science.gov (United States)

    Galdun, L.; Ryba, T.; Prida, V. M.; Zhukova, V.; Zhukov, A.; Diko, P.; Kavečanský, V.; Vargova, Z.; Varga, R.

    2018-05-01

    Large scale production of single crystalline phase of Heusler Co2FeSi alloy microwire is reported. The long microwire (∼1 km) with the metallic nucleus diameter of about 2 μm is characterized by well oriented monocrystalline structure (B2 phase, with the lattice parameter a = 5.615 Å). Moreover, the crystallographic direction [1 0 1] is parallel to the wire's axis along the entire length. Additionally, the wire is characterized by exhibiting a high Curie temperature (Tc > 800 K) and well-defined magnetic anisotropy mainly governed by shape. Electrical resistivity measurement reveals the exponential suppression of the electron-magnon scattering which provides strong evidence on the half-metallic behaviour of this material in the low temperature range.

  9. Plastic anomaly of the B2 ordered Fe-40Al alloy

    International Nuclear Information System (INIS)

    Calonne, O.

    2002-05-01

    The plastic behaviour of Fe-40Al (B2-ordered) alloys was studied. This material has the particularly of exhibiting a yield stress that increases in a given temperature range ('yield stress anomaly'). This anomaly is usually associated with a zero strain rate sensitivity in the very same temperature range. These two peculiarities can be explained as a whole by a thermally activated exhaustion of the mobile dislocations. In this work, the macroscopic mechanical behaviour of the FeAl alloys was first characterised. Then, slip geometry was studied in a large temperature range using oriented single crystals. Finally, the elementary deformation processes were studied through an analysis of dislocation structures in deformed materials using TEM post-mortem and in-situ techniques. Our results show that the yield stress anomaly stems from superdislocations exhaustion through the formation of antiphase boundary tubes, due to vacancy absorption. The number of antiphase boundary tubes produced during dislocation motion depends on vacancy concentration, that in turn increases with temperature. This is believed to be the main reason for thermally activated exhaustion. In addition, the anomaly peak and the related stress fall-off at higher temperatures can be ascribed to superdislocation decomposition, which provides the material with ordinary dislocations that cannot generate antiphase boundary tubes. Superdislocations exhaustion seems to be the catalyzing factor for decomposition. We have proposed a basis for an exhaustion/multiplication model. Considering a classical Frank-Read type multiplication mechanism, we express the yield stress as a function of temperature and we show that this results in an anomaly. Moreover, supposing that boron modifies vacancy migration energy, we suggest that the influence of boron on the stress anomaly stems from an increase of vacancy capture radius by mobile superdislocations. (authors)

  10. The influence of ingot annealing on the corrosion resistance of a PrFeCoBNbP alloy

    International Nuclear Information System (INIS)

    Oliveira, M.C.L.; Takiishi, H.; Faria, R.N.; Costa, I.

    2008-01-01

    The influence of the annealing time on the corrosion resistance of a Pr-Fe-Co-B-Nb alloy with the addition of 0.1 wt% P was investigated here using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The cast ingot alloys were annealed at 1100 deg. C for 10, 15 and 20 h. The specimens were immersed for 30 days in naturally aerated 0.02 M Na 2 HPO 4 solution at room temperature, during which period the evolution of the electrochemical behavior was assessed using EIS. The results indicated that the corrosion resistance of the Pr 14 Fe bal Co 16 B 6 Nb 0.1 P 0.25 alloy was related to the annealing time and, hence, to its microstructure. Annealing at 1100 deg. C for 10 h was insufficient to eliminate the Fe-α phase from the alloy microstructure, whereas annealing for 15 and 20 h removed an increasing amount of Fe-α phase, thereby increasing the alloy's corrosion resistance

  11. External influence on magnetic properties of Fe-based nanocrystalline alloys

    International Nuclear Information System (INIS)

    Sitek, Jozef; Degmova, Jarmila; Sedlackova, Katarina; Butvin, Pavol

    2006-01-01

    Amorphous and nanocrystalline ribbons of NANOPERM, FINEMET and HITPERM were studied by Moessbauer spectroscopy (MS) after the influence of external factors: different annealing atmospheres, tensile stress and several kinds of corrosion. MS is a suitable tool for such studies because the spectral parameters are very sensitive to changes in the vicinity of the probe - 57 Fe nuclei. The most sensitive parameters were hyperfine magnetic field in crystalline component, average hyperfine field in amorphous component and direction of net magnetic moments. Influence of external factors modified also the structure of the alloys, i.e. new or modified phases were identified by MS phase analysis

  12. Investigation of finely dispersed grind of magnetically hard SmCo5 and Nd2Fe14B alloys

    International Nuclear Information System (INIS)

    Balalaev, Yu.N.; Kosobudskij, I.D.

    2000-01-01

    Possibility of preparation of finely dispersed powders of SmCo 5 and Nd 2 Fe 14 B allays investigated and comparison of different types of grinding processes is conducted. Results of comparison of the processes in vibrational mills and disintegrators permit to conclude that density and structure of grindable materials effect on the rate and quality of grinding of magnetically hard alloys [ru

  13. Lattice dynamic properties of Rh2XAl (X=Fe and Y) alloys

    Science.gov (United States)

    Al, Selgin; Arikan, Nihat; Demir, Süleyman; Iyigör, Ahmet

    2018-02-01

    The electronic band structure, elastic and vibrational spectra of Rh2FeAl and Rh2YAl alloys were computed in detail by employing an ab-initio pseudopotential method and a linear-response technique based on the density-functional theory (DFT) scheme within a generalized gradient approximation (GGA). Computed lattice constants, bulk modulus and elastic constants were compared. Rh2YAl exhibited higher ability to resist volume change than Rh2FeAl. The elastic constants, shear modulus, Young modulus, Poisson's ratio, B/G ratio electronic band structure, total and partial density of states, and total magnetic moment of alloys were also presented. Rh2FeAl showed spin up and spin down states whereas Rh2YAl showed none due to being non-magnetic. The calculated total densities of states for both materials suggest that both alloys are metallic in nature. Full phonon spectra of Rh2FeAl and Rh2YA1 alloys in the L21 phase were collected using the ab-initio linear response method. The obtained phonon frequencies were in the positive region indicating that both alloys are dynamically stable.

  14. Processing and characterization of AlCoFeNiXTi{sub 0,5} (X = Mn, V) high entropy alloys; Processamento e caracterizacao de ligas de alta entropia AlCoFeNixTi{sub 0,5} (X = Mn, V)

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, C., E-mail: carlos.triveno@ufabc.edu.br [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Engenharia de Materiais; Lopes, E.S.N.; Caram, R. [Universidade Estadual de Campinas (FEM/DEMA/UNICAMP), Campinas, SP (Brazil); Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    The microstructure of high entropy alloys consists of solid solution phases with FC and BCC simple structures, contrary to classical metallurgy where they form complex structures of intermetallic compounds. Because of this they have several attractive properties for engineering applications. In this work the AlCoFeNiMnTi{sub 0,5} and AlCoFeNiVTi{sub 0,5} alloys were processed by melting arc. Since the main objective was the microstructural and mechanical characterization of ingots as-cast. The alloys were characterized by scanning electron microscopy, X-ray diffraction, microhardness and cold compression test. The results showed that the microstructure consists mainly of dendrites and interdendritic regions consisting of metastable crystalline phases. It was also observed that the AlCoFeNiVTi{sub 0,5} alloy showed better mechanical properties than the AlCoFeNiMnTi{sub 0,5} alloy. This may be associated with differences in the parameters of formation of simple solid solution phases between the two alloys. (author)

  15. Microstructure and composition in rapidly quenched NdFeB-based hard magnet alloys

    International Nuclear Information System (INIS)

    Nguyen, T.D.; Krishnan, K.M.; Lewis, L.H.; Zhu, Y.; Welch, D.O.

    1996-01-01

    A detailed study of the microstructure and composition in hot-pressed (MQ-2) and die-upset (MQ-3) magnet alloys based on the Nd 2 Fe 14 B composition, utilizing high resolution and analytical transmission electron microscopy, is reported. The initial magnetic properties of the two samples show different behaviors, which are attributed to the difference in the anisotropy of the grain structure and the grain boundaries. The hot-pressed sample shows faceted grains of the 2-14-1 phase, while die-upset sample shows plate-like grains, together with larger equiaxed grains that contain a speckling of precipitates in the grain interior. The grain structure and composition remain rather similar in the two samples. The grain boundary phase averages ∼1 endash approx-gt 10 nm in width. The thicker grain boundaries are Nd-rich, while the thinner grain boundaries in the hot-pressed sample exhibit an Fe-rich composition near that of the NdFe 3 phase. Nd-rich phases are found at the grain boundary junctions of both samples, with the Nd:Fe ratio near 7:3 in the die-upset sample, and up to 3:2 in the hot-pressed sample. The significance of the microstructure and the grain boundary phases on the magnetic behavior in the two samples is discussed. copyright 1996 American Institute of Physics

  16. Resonant Ni and Fe KLL Auger spectra photoexcited from NiFe alloys

    International Nuclear Information System (INIS)

    Koever, L.; Cserny, I.; Berenyi, Z.; Egri, S.; Novak, M.

    2005-01-01

    Complete text of publication follows. KLL Auger spectra of 3d transition metal atoms in solid environment, measured using high energy resolution, give an insight into the details of the local electronic structure surrounding the particular atoms emitting the signal Auger electrons. Fine tuning the energy of the exciting monochromatic photons across the K-absorption edge, features characteristic to resonant phenomena can be identified in the spectra. The shapes of the resonantly photoexcited KLL Auger spectra induced from 3d transition metals and alloys are well interpreted by the single step model of the Auger process, based on the resonant scattering theory. The peak shapes are strongly influenced by the 4p partial density of unoccupied electronic states around the excited atom. High energy resolution studies of KLL Auger spectra of 3d transition metals using laboratory X-ray sources, however, request very demanding experiments and yield spectra of limited statistical quality making the evaluation of the fine details in the spectra difficult. The Tunable High Energy XPS (THE- XPS) instrument at BW2 offers optimum photon x and energy resolution for spectroscopy of deep core Auger transitions. For the present measurements high purity polycrystalline Ni and Fe sheets as well as NiFe alloy samples of different compositions (Ni 80 Fe 20 , Ni 50 Fe 50 , Ni 20 Fe 80 ) were used. The surfaces of the samples were cleaned by in-situ argon ion sputtering. The measurements of the Ni and Fe KL 23 L 23 Auger spectra of the metal and alloy samples were performed with the THE-XPS instrument using high electron energy resolution (0.2 eV). In Fig.1, the measured Fe KL 23 L 23 spectrum, photoexcited at the Fe K absorption edge from Fe metal, is compared with the respective spectrum excited from a Ni 50 Fe 50 alloy. A significant broadening of the 1 D 2 peak and an enhancement of the spectral intensity at the low energy loss part of this peak observed in the alloy sample, while the

  17. Sulfide phase in the Fe-Ti-S and Fe-C-Ti-S alloys

    International Nuclear Information System (INIS)

    Malinochka, Ya.N.; Balakina, N.A.; Shmelev, Yu.S.

    1976-01-01

    The nature of the sulfide phases in Fe-Ti-S and Fe-C-Ti-S alloys was studied. The carbide and the sulfide phase were identified the aid of X-ray spectral microanalysis. It was established that for a small content of titanium and sulfur in ternary Fe-Ti-S alloys the solidification of the γ-solution on the boundaries of dendritic branches is accompanied, along with the precipitation of a sulfide rich in iron of the (Fe, Ti) S type where a small quantity of titanium is dissolved, by the formation of a titanium-bearing sulfide eutectic γ + TiS. The amount of the sulfide eutectic increases with the contents of titanium and sulfur until a purely eutectic alloy is formed. Both carbides and sulfides may be formed in the solidification of quaternary alloys Fe-C-Ti-S

  18. High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2002-01-16

    An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

  19. High coercivity in Fe-Nb-B-Dy bulk nanocrystalline magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ziolkowski, Grzegorz; Chrobak, Artur; Klimontko, Joanna [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007, Katowice (Poland); Chrobak, Dariusz; Rak, Jan [Institute of Materials Science, University of Silesia, 75 Pulku Piechoty 1, 41-500, Chorzow (Poland); Zivotsky, Ondrej; Hendrych, Ales [Department of Physics, VSB-TU Ostrava, Ostrava (Czech Republic)

    2016-11-15

    The paper refers to structural and magnetic properties of the (Fe{sub 80}Nb{sub 6}B{sub 14}){sub 1-x}Dy{sub x} (x = 0.08, 0.10, 0.12, 0.16) bulk nanocrystalline alloys prepared by making use of the vacuum suction casting technique. The samples are in a form of rods with different diameters d = 1.5, 1, and 0.5 mm. The phase structure was investigated by XRD technique and reveals an occurrence of magnetically hard Dy{sub 2}Fe{sub 14}B as well as other relatively soft Dy-Fe, Fe-B, and Fe phases dependently on the Dy content. The alloys show hard magnetic properties with high coercive field up to 5.5 T (for x = 0.12 and d = 0.5 mm). The observed magnetic hardening effect with the increase of cooling rate (decrease of sample diameter d) can be attributed to a formation of ultra-hard magnetic objects as well as increasing role of low dimensional microstructure. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Tuning Ce distribution for high performanced Nd-Ce-Fe-B sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xiaodong [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); Guo, Shuai; Chen, Kan; Chen, Renjie; Lee, Don [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China); You, Caiyin, E-mail: caiyinyou@xaut.edu.cn [School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048 (China); Yan, Aru, E-mail: aruyan@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo 315201 (China)

    2016-12-01

    A dual-alloy method was applied to tune the distribution of Ce for enhancing the performance of Nd-Ce-Fe-B sintered magnets with a nominal composition of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B. In comparison to the single alloy of (Nd{sub 0.75}Ce{sub 0.25}){sub 30.5}Fe{sub bal}Al{sub 0.1}Cu{sub 0.1}B, the coercivity was enhanced from 10.3 kOe to 12.1 kOe and the remanence was increased from 13.1 kG to 13.3 kG for the magnets with a dual-alloy method. In addition, the remanence temperature coefficient α and coercivity temperature coefficient β were also slightly improved for the magnet with the dual alloys. The results of microstructure characterizations show the uniform distribution of Ce for the magnet with a single alloy, and the coexistence of the Ce-rich and Ce-lean regions for the magnet with the dual alloys. In combinations with the nucleation of reversal domains and magnetic recoil curves, the property enhancement of magnets with a dual-alloy method was well explained. - Highlights: • Improved magnetic properties were obtained in dual-alloy magnet. • This is due to the tuning of Ce distribution and the change in microstructure. • The magnetic hardening effect can be observed in dual-alloy magnet.

  1. FeNbB bulk metallic glass with high boron content

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, M.; Das, Jayanta; Eckert, Juergen [IFW Dresden, Institute for Complex Materials, P.O. Box 270016, D-01171 Dresden (Germany); Hajlaoui, Khalil; Yavari, Alain Reza [LTPCM-CNRS, I.N.P. Grenoble, 1130 Rue de la Piscine, BP 75, F-38402 University Campus (France)

    2007-07-01

    Fe-based alloys able to form magnetic bulk metallic glasses (BMGs) are of the type transition metal - metalloid and often contain 5 or more elements. Usually, the metalloid content is around 20 atomic %. Very recently, the Fe{sub 66}Nb{sub 4}B{sub 30} alloy was found to be able to form BMG by copper mold casting technique, despite its high metalloid content. Several composition with boron contents around 30 at. % or even higher were calculated since 1993 as possible compositions of the remaining amorphous matrix after the first stage of nanocrystallization of Finemet-type Fe{sub 77}Si{sub 14}B{sub 9} glassy ribbons with 0.5 to 1 atomic % Cu and a few percent Nb addition. Melt-spun ribbons of all calculated compositions were found to be glassy. The composition of the ternary Fe-based BMG investigated in the present study resulted as an optimization of all possibilities. The alloy is ferromagnetic with glass transition temperature T{sub g}=845 K, crystallisation temperature T{sub x}=876 K, liquidus temperature T{sub liq}=1451 K and mechanical strength of 4 GPa. The coercivity of as-cast samples is very low, around 1.5 A/m. The present contribution aims at discussing the thermal stability, mechanical and magnetic properties of the Fe{sub 66}Nb{sub 4}B{sub 30} BMG.

  2. Crystallization of amorphous Fe78Si9B13 alloy

    International Nuclear Information System (INIS)

    Jakubczyk, E; Krajczyk, A; Jakubczyk, M

    2007-01-01

    The crystallization process of Fe 78 Si 9 B 13 metallic glass was investigated by DSC, X-ray diffraction, electrical resistivity, Hall effect and TEM methods. The investigations proved two-stages crystallization. By means of non-isothermal DSC experiments the activation energy and the Avrami exponent were determined for both stages. The created phases: α-Fe(Si) and (Fe,Si) 2 B were identified on the basis of X-ray and TEM investigations. However, TEM observations showed also a little amount of the FeB 49 phase as well as some rest of the amorphous phase. The electrical and Hall resistivities decrease abruptly after the creation of the phases out of the amorphous matrix

  3. Study of the oxidation of Fe-Cr alloys at high temperatures

    International Nuclear Information System (INIS)

    Carneiro, J.F.; Sabioni, A.C.S.

    2010-01-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1μg. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10 -9 g 2 .cm -4 .s -1 , for the alloy Fe-1.5% Cr, to 1.18 x 10-14g 2 .cm -4 .s -1 for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  4. Magnetoresistance in ferromagnetic shape memory alloy NiMnFeGa

    International Nuclear Information System (INIS)

    Liu, Z.H.; Ma, X.Q.; Zhu, Z.Y.; Luo, H.Z.; Liu, G.D.; Chen, J.L.; Wu, G.H.; Zhang Xiaokai; Xiao, John Q.

    2011-01-01

    The magnetoresistance (MR){=[R(H)-R(0)]/R(0)} properties in ferromagnetic shape memory alloy of NiMnFeGa ribbons and single crystals, and NiFeGa ribbons have been investigated. It is found that the NiMnFeGa melt-spun ribbon exhibited GMR effect, arising from the spin-dependent scattering from magnetic inhomogeneities consisting of antiferromagnetically coupled Mn atoms in B2 structure. In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8T C , regardless of sample structures. This may be explained by the s-d model. At low temperatures, conventional AMR behaviors due to the spin-orbital coupling are observed. This is most likely due to the diminished MR from s-d model because of much less spin fluctuation, and is not associated with martensite phase. MR anomaly at intermediate field (ρ perpendicular >ρ || ) is also observed in single crystal samples, which may be related to unique features of Heusler alloys. - Highlights: → NiMnFeGa melt-spun ribbon exhibited GMR effect with a large negative MR up to -13%. → GMR behavior is arising from the spin-dependent scattering from magnetic inhomogeneities. → In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8T C . → Conventional AMR behaviors due to the spin-orbital coupling are observed in NiMnFeGa single crystal and Ni 2 FeGa ribbon samples at low temperatures.

  5. Oxide Morphology of a FeCrAl Alloy, Kanthal APMT, following Extended Aging at 300-600C

    Energy Technology Data Exchange (ETDEWEB)

    Li, Nan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Stephen Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wood, Elizabeth Sooby [Univ. of Texas, San Antonio, TX (United States)

    2017-09-19

    Iron-chromium-aluminum (FeCrAl) alloys are of interest to the nuclear materials community due to their resistance to high temperature steam oxidation under accident conditions. The present work investigates oxide formation at temperatures relevant to light water reactor cladding operation following extended aging to assess growth kinetics, chemical composition, and microstructure of oxide formation on a commercial FeCrAl alloy, Fe-21wt.%Cr-5wt.%Al-3wt.%Mo (Kanthal APMT). Aging treatments were performed for 100-1000 hours in stagnant air at 300, 400, 500, and 600 °C, respectively. Oxide growth behavior under the investigated conditions follows a logarithmic time dependence. When the oxidization temperature is 400 °C or below, the oxide is amorphous. At 500 °C, isolated crystalline regions start to appear during short period aging time and expand with extended exposures. Crystalline α-Al2O3 oxide film develops at 600 °C and the correlated logarithmic rate constant decreases significantly, indicating enhanced oxidation resistance of the formed oxide film. In addition, Mo segregation at grain boundaries has been observed when the aging temperature exceeds 500 °C. The results of this study can be viewed as an upper bounding result for potential oxide coarsening during reactor operation.

  6. Hydrogen storage in Ti-Mn-(FeV) BCC alloys

    International Nuclear Information System (INIS)

    Santos, S.F.; Huot, J.

    2009-01-01

    Recently, the replacement of vanadium by the less expensive (FeV) commercial alloy has been investigated in Ti-Cr-V BCC solid solutions and promising results were reported. In the present work, this approach of using (FeV) alloys is adopted to synthesize alloys of the Ti-Mn-V system. Compared to the V-containing alloys, the alloys containing (FeV) have a smaller hydrogen storage capacity but a larger reversible hydrogen storage capacity, which is caused by the increase of the plateau pressure of desorption. Correlations between the structure and the hydrogen storage properties of the alloys are also discussed.

  7. First principle investigations on Boron doped Fe2VAl Heusler alloy

    International Nuclear Information System (INIS)

    Venkatesh, Ch.; Srivastava, S.K.; Rao, V.V.

    2014-01-01

    The role of atomic size of sp-element is investigated through theoretical calculations and basic experiments to understand the physical properties of Boron doped Fe 2 VAl alloy. The results of ab-initio calculations on ordered L2 1 structure of Fe 2 VAl 1-x B x (x=0, 0.5, 1) alloys have been compared to understand the role of sp-element size on the hybridization among their respective valance states. Interestingly, semi-metallic and paramagnetic like ground states were found in the Boron doped alloys in similar to Fe 2 VAl, eliminating the role of size of the doppent sp-atom. These calculations result in hybridization where the covalent distribution of valance states among the atoms is responsible to produce a finite pseudo-gap at the Fermi level. The observed features could be explained on the basis of covalent theory of magnetism in which an amount of spectral weight transfer occurs in the DOS spectrum among the same spin orbitals, leading to symmetric distribution of bonding and anti-bonding states. However, the obtained experimental findings on Boron doped alloys are in contrast with these calculations, indicating that experimentally the alloy formation into an ideal L2 1 lattice does not happen while doping with Boron. Further, the micro structural analysis shows Boron segregation across the grain boundaries that may form magnetic inhomogeneities in the lattice of Boron doped Fe 2 VAl alloys which preferably cause these experimental anomalies

  8. Thermomagnetic behaviour and microstructure of a rapidly quenched Nd4.5Fe77B18.5 alloy

    Czech Academy of Sciences Publication Activity Database

    Talijan, N.; Ćosović, V.; Grujić, A.; Stajić-Trošić, J.; Žák, Tomáš

    2008-01-01

    Roč. 113, č. 1 (2008), s. 525-528 ISSN 0587-4246. [Czech and Slovak Conference on Magnetism /13./ (CSMAG'07). Košice, 09.08.2007-12.08.2007] R&D Projects: GA MŠk(CZ) 1M0512 Institutional research plan: CEZ:AV0Z20410507 Keywords : Thermomagnetic behaviour * NdFeB alloy * Mossbauer effect * X-ray Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.321, year: 2008

  9. Electrical and Magnetic Properties of Binary Amorphous Transition Metal Alloys.

    Science.gov (United States)

    Liou, Sy-Hwang

    The electrical, superconductive and magnetic properties of several binary transition metal amorphous and metastable crystalline alloys, Fe(,x)Ti(,100-x) (30 (LESSTHEQ) x (LESSTHEQ) 100), Fe(,x)Zr(,100-x) (20 (LESSTHEQ) x (LESSTHEQ) 93), Fe(,x)Hf(,100-x) (20 (LESSTHEQ) x (LESSTHEQ) 100), Fe(,x)Nb(,100 -x) (22 (LESSTHEQ) x (LESSTHEQ) 85), Ni(,x)Nb(,100-x) (20 (LESSTHEQ) x (LESSTHEQ) 80), Cu(,x)Nb(,100-x) (10 (LESSTHEQ) x (LESSTHEQ) 90) were studied over a wide composition range. Films were made using a magnetron sputtering system, and the structure of the films was investigated by energy dispersive x-ray diffraction. The composition region of each amorphous alloys system was determined and found in good agreement with a model proposed by Egami and Waseda. The magnetic properties and hyperfine interactions in the films were investigated using a conventional Mossbauer spectrometer and a ('57)Co in Rh matrix source. In all Fe-early transition metal binary alloys systems, Fe does not retain its moment in the low iron concentration region and the result is that the critical concentration for magnetic order (x(,c)) is much larger than anticipated from percolation considerations. A direct comparison between crystalline alloys and their amorphous counterparts of the same composition illustrate no clear correlation between crystalline and amorphous states. Pronounced discontinuities in the magnetic properties with variation in Fe content of all Fe-early transition metal alloys at phase boundaries separating amorphous and crystalline states have been observed. This is caused by the differences in the atomic arrangement and the electronic structure between crystalline and amorphous solids. The temperature dependence of resistivity, (rho)(T), of several binary amorphous alloys of Fe-TM (where TM = Ti, Zr, Hf, Nb etc.) has been studied from 2K to 300K. The Fe-poor (x x(,c)) samples have distinctive differences in (rho)(T) at low temperature (below 30K). All the magnetic samples

  10. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gente, C.; Bormann, R.

    1998-01-01

    The studies of mechanical alloying on the Fe-Cu system, as a model system for those with positive heats of mixing, are reviewed. Several problems involved in the mechanical alloying process are discussed. For example, (1) whether alloying occurs on an atomic level; (2) what the solid solubility...... in the Fe-Cu system is; (3) where the positive energy is stored in the alloys; (4) what the decomposition process of the supersaturated alloys is; and (5) what type of magnetic properties the new materials have. The elucidation of these problems will shed light on the understanding of the mechanisms...... for the preparation of materials under highly non-equilibrium conditions in systems with positive heats of mixing by mechanical alloying....

  11. Study of U - Pu - Fe alloys (Masurca critical experiment)

    International Nuclear Information System (INIS)

    Barthelemy, P.; Boucher, R.

    1965-01-01

    Three compositions have been studied: 73.5 U - 25 Pu - 1.5 Fe (weight %) 74 U - 25 Pu - 1 Fe 74.5 U - 25 Pu - 0.5 Fe Elaboration and Casting are easy. After two weeks in air 74.5 U - 25 Pu - 0.5 Fe alloys are reduced in powder. As-cast alloys containing 1 and 1,5% Fe are kept undamaged during several months. A rapid oxidisation of the alloys is however observed when the samples undergo the phase transformation (at 595 deg. C and 590 deg. C respectively). Ignition tests in the presence of air show that the oxidisation starts at about 250 deg. C and that the reaction does not spread. Ignition is not observed during heating from 20 to 660 deg. C. The transformation temperature, the melting temperature and the thermal expansion coefficients have been determined by dilatometry. Below the transformation temperature, the principal phases are U-Pu zeta and (U, Pu) 6 Fe. Thermal conductibility, Young modulus, density and heat of fusion have been measured. Compatibility tests show that between U-Pu-Fe and stainless steel a phase of (U, Pu) 6 Fe type is formed. The 74 U - 25 Pu - 1% Fe alloy seems to behave better than 73.5 U - 25 Pu - 1.5% Fe alloy because the (U, Pu) 6 Fe layer is two or three times smaller. Finally, the thermal stability has been studied with the 74 U - 25 Pu - 1% Fe alloy. A dilatometric anomaly (very weak expansion) occurs when the sample is heated above transformation temperature and cooled. But there is no anomaly by thermal cycling from 50 deg. C to 400 deg. C and there is no deterioration of alloys by heat treatments at 100 deg. C, 200 deg. C, 300 deg. C during 5 months under vacuum. (authors) [fr

  12. Mechanical alloying of the FeNi-Ag system

    International Nuclear Information System (INIS)

    Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

    2007-01-01

    The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

  13. Study of intergranular embrittlement in Fe-12Mn alloys

    International Nuclear Information System (INIS)

    Lee, H.J.

    1982-06-01

    A high resolution scanning Auger microscopic study has been performed on the intergranular fracture surfaces of Fe-12Mn steels in the as-austenitized condition. Fracture mode below the ductile-brittle transition temperature was intergranular whenever the alloy was quenched from the austenite field. The intergranular fracture surface failed to reveal any consistent segregation of P, S, As, O, or N. The occasional appearance of S or O on the fracture surface was found to be due to a low density precipitation of MnS and MnO 2 along the prior austenite boundaries. An AES study with Ar + ion-sputtering showed no evidence of manganese enrichment along the prior austenite boundaries, but a slight segregation of carbon which does not appear to be implicated in the tendency toward intergranular fracture. Addition of 0.002% B with a 1000 0 C/1h/WQ treatment yielded a high Charpy impact energy at liquid nitrogen temperature, preventing the intergranular fracture. High resolution AES studies showed that 3 at. % B on the prior austenite grain boundaries is most effective in increasing the grain boundary cohesive strength in an Fe-12Mn alloy. Trace additions of Mg, Zr, or V had negligible effects on the intergranular embrittlement. A 450 0 C temper of the boron-modified alloys was found to cause tempered martensite embrittlement, leading to intergranular fracture. The embrittling treatment of the Fe-12Mn alloys with and without boron additions raised the ductile-brittle transition by 150 0 C. This tempered martensite embrittlement was found to be due to the Mn enrichment of the fracture surface to 32 at. % Mn in the boron-modified alloy and 38 at. % Mn in the unmodified alloy. The Mn-enriched region along the prior austenite grain boundaries upon further tempering is believed to cause nucleation of austenite and to change the chemistry of the intergranular fracture surfaces. 61 figures

  14. Irradiation-induced softening of Ni3P and (Ni, Fe, Cr)3P alloys

    International Nuclear Information System (INIS)

    Schumacher, G.; Miekeley, W.; Wahi, R.P.

    1993-01-01

    Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M 3 P type of brazing alloys (M: Metal) is attractive because of the following reason: In brazed joints of candidate structural materials like 316L stainless steel for applications in fusion reactors, crystalline intermetallic phases have been detected which are unstable relative to the amorphous state when irradiated at moderate temperatures with fast particles. It is expected that the transition to the amorphous state is accompanied by changes of the mechanical properties, which are of fundamental interest in this context. Until now, only a few studies on the evolution of mechanical properties during amorphization have been performed. Measurements of microhardness of the crystalline and the corresponding amorphous phase do not exist to the authors knowledge. In this communication, the authors present results on changes of microhardness, due to amorphization by fast ions. The measurements have been performed on a model alloy Ni 3 P and on the brazed joint of stainless steel 316L, containing M 3 P (M: Ni, Fe, Cr) as one of the phases. Though microhardness is not a fundamental property of materials, it is a manifestation of several related properties, such as yield stress, ductility, work-hardening, elastic modulus and residual stress states. It represents a resistance for indentation and is, therefore, appropriate for comparative purposes

  15. On the Correlation between Morphology of alpha and Its Crystallographic Orientation Relationship with TiB and Beta in Boron Containing Ti-5Al-5Mo-5V-3Cr-0.5Fe Alloy (Preprint)

    Science.gov (United States)

    2012-01-01

    orientation microscopy studies on a boron containing version of the commercial Ti- 5Al-5Mo-5V-3Cr-0.5Fe ( Ti5553 ) alloy. 15. SUBJECT TERMS Ti5553 ...of the commercial Ti-5Al-5Mo-5V-3Cr-0.5Fe ( Ti5553 ) alloy. Keywords: Ti5553 , TiB, EBSD, crystallography, orientation relationship. Paper There has...absence of orientation relationships between the α, β and TiB phases, on the morphology of α nucleating from TiB in the Ti5553 alloy.. The base

  16. Effect of Y addition on crystallization behavior and soft-magnetic properties of Fe{sub 78}Si{sub 9}B{sub 13} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zhanwei, Liu; Dunbo, Yu, E-mail: yudb2008@126.com; Kuoshe, Li; Yang, Luo; Chao, Yuan; Zilong, Wang; Liang, Sun; Kuo, Men

    2017-08-15

    Highlights: • Thermal stability of Fe-Si-B amorphous alloy is enhanced by Y addition. • Y addition can improve soft magnetic properties of Fe-Si-B amorphous alloy. • Decomposition of metastable Fe{sub 3}B phase is related to Y content in Fe-Si-B matrix. - Abstract: A series of amorphous Fe-Si-B ribbons with various Y addition were prepared by melt-spinning. The effect of Y addition on crystallization behavior, thermal and magnetic properties was systematically investigated. With the increase of Y content, the initial crystallization temperature shifted to a higher temperature, indicating that the thermal stability of amorphous state in Fe-Si-B-Y ribbon is enhanced compared to that of Fe-Si-B alloy. Meanwhile, compared to the two exothermic peaks in the samples with lower Y content, a new exothermic peak was found in the ribbons with Y content higher than 1 at%, which corresponded to the decomposition of metastable Fe{sub 3}B phase. Among all the alloys, Fe{sub 76.5}Si{sub 9}B{sub 13}Y{sub 1.5} alloy exhibits optimized magnetic properties, with high saturation magnetization M{sub s} of 187 emu/g and low coercivity H{sub cJ} of 7.6 A/m.

  17. Electronic structure of disordered Fe-V alloys

    International Nuclear Information System (INIS)

    Krause, J.C.; Paduani, C.; Schaff, J.; Costa, M.I. Jr. da

    1998-01-01

    The first-principles discrete variational method is employed to investigate the electronic structure and local magnetic properties of disordered Fe-V alloys. The spin-polarized case is considered in the formalism of the local-spin-density approximation, with the exchange-correlation term of von Barth endash Hedin. The effect on the local magnetic properties of adding V atoms in the immediate neighborhood of iron atoms is investigated. The partial density of states, hyperfine field (H c ), magnetic moment (μ), and isomer shift are obtained for the central atom of the cluster. For the impurity V atom in the bcc iron host the calculated values for H c and μ are -203 kG and -0.86μ B , respectively. The isolated Fe atom in a bcc vanadium host exhibits a collapsed moment and acts as a receptor for electrons. In ordered alloys the calculations indicate also a vanishing moment at iron sites. copyright 1998 The American Physical Society

  18. Nanocrystalline NdFeB magnet prepared by mechanically activated disproportionation and desorption-recombination in-situ sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoya, Liu; Yuping, Li [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Lianxi, Hu, E-mail: hulx@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2013-03-15

    The process of mechanically activated disproportionation and desorption-recombination in-situ sintering was proposed to synthesize highly densified nanocrystalline NdFeB magnet, and its validity was demonstrated by experimental investigation with the use of a Nd{sub 16}Fe{sub 76}B{sub 8} (atomic ratio) alloy. Firstly, the as-cast alloy was disproportionated by mechanical milling in hydrogen, with the starting micron-sized Nd{sub 2}Fe{sub 14}B phase decomposed into an intimate mixture of nano-structured NdH{sub 2.7}, Fe{sub 2}B and {alpha}-Fe phases. The as-disproportionated alloy powders were compacted by cold pressing and then subjected to desorption-recombination in-situ sintering. The microstructure of both the as-disproportionated and the subsequently sintered samples was characterized by X-ray diffraction and electron transmission microscopy, respectively. The magnetic properties of the sintered samples were measured by using vibrating sample magnetometer. The results showed that, by vacuum sintering, not only was the powder compact consolidated, but also the as-disproportionated microstucture transformed into nanocrystalline Nd{sub 2}Fe{sub 14}B phase via the well-known desorption-recombination reaction, thus giving rise to nanocrystalline NdFeB magnet. In the present study, the optimal sintering parameters were found to be 780 Degree-Sign C Multiplication-Sign 30 min. In this case, the coercivity, the remanence, and maximum energy product of the magnet sample achieved 0.8 T, 635.3 kA/m, and 106.3 kJ/m{sup 3}, respectively. - Highlights: Black-Right-Pointing-Pointer Nano-structured disproportionated NdFeB alloy powders by mechanical milling in hydrogen. Black-Right-Pointing-Pointer Highly densified green magnet compact by cold pressing of as-disproportionated NdFeB alloy powders. Black-Right-Pointing-Pointer Nanocrystalline NdFeB magnets by desorption-recombination in-situ sintering under vacuum. Black-Right-Pointing-Pointer Magnetic properties significantly

  19. Alloying behavior, microstructure and mechanical properties in a FeNiCrCo0.3Al0.7 high entropy alloy

    International Nuclear Information System (INIS)

    Chen, Weiping; Fu, Zhiqiang; Fang, Sicong; Xiao, Huaqiang; Zhu, Dezhi

    2013-01-01

    Highlights: • FeNiCrCo 0.3 Al 0.7 high entropy alloy is prepared via MA and SPS. • Two BCC phases and one FCC phase were obtained after SPS. • The two BCC phases are enriched in Fe–Cr (A2 structure) and enriched in Ni–Al (B2 structure). • Bulk FeNiCrCo 0.3 Al 0.7 HEA exhibits excellent mechanical properties. - Abstract: The present paper reports the synthesis of FeNiCrCo 0.3 Al 0.7 high entropy alloy (HEA) by mechanical alloying (MA) and spark plasma sintering (SPS) process. Alloying behavior, microstructure, mechanical properties and detailed phases of the alloy were investigated systematically. During MA, the formation of a supersaturated solid solution with body-centered cubic (BCC) structure occurred. However, partial BCC structure phase transformed into a face-center cubic (FCC) structure phase during SPS. Two BCC phases with nearly the same lattice parameter of 3.01 Å and one FCC phase with the lattice parameter of 3.72 Å were characterized in the transmission electron microscope (TEM) images. The two BCC phases which are evidently deviated from the definition of high entropy alloys (HEAs) are enriched in Fe–Cr and enriched in Ni–Al, respectively. Moreover, the FCC phase agrees well with the definition of HEAs. Bulk FeNiCrCo 0.3 Al 0.7 alloy with little porosity exhibits much better mechanical properties except compression ratio compared with other typical HEAs of FeNiCrCoAl HEA system. The yield strength, compressive strength, compression ratio and Vickers hardness of FeNiCrCo 0.3 Al 0.7 alloy are 2033 ± 41 MPa, 2635 ± 55 MPa, 8.12 ± 0.51% and 624 ± 26H v , respectively. The fracture mechanism of bulk FeNiCrCo 0.3 Al 0.7 alloy is dominated by intercrystalline fracture and quasi-cleavage fracture

  20. Single-crystalline LiFePO4 nanosheets for high-rate Li-ion batteries.

    Science.gov (United States)

    Zhao, Yu; Peng, Lele; Liu, Borui; Yu, Guihua

    2014-05-14

    The lithiation/delithiation in LiFePO4 is highly anisotropic with lithium-ion diffusion being mainly confined to channels along the b-axis. Controlling the orientation of LiFePO4 crystals therefore plays an important role for efficient mass transport within this material. We report here the preparation of single crystalline LiFePO4 nanosheets with a large percentage of highly oriented {010} facets, which provide the highest pore density for lithium-ion insertion/extraction. The LiFePO4 nanosheets show a high specific capacity at low charge/discharge rates and retain significant capacities at high C-rates, which may benefit the development of lithium batteries with both favorable energy and power density.

  1. 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.

  2. Effect of niobium on microstructure and magnetic properties of bulk anisotropic NdFeB/{alpha}-Fe nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Li Jun [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Liu Ying, E-mail: Liuying5536@163.com [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China) and Key Laboratory of Advanced Special Material and Technology, Ministry of Education, Chengdu 610065 (China); Ma Yilong [School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2012-07-15

    Bulk anisotropic NdFeB/{alpha}-Fe nano-composites were obtained directly from alloys of Nd{sub 11}Dy{sub 0.5}Fe{sub 82.4-x}Nb{sub x}B{sub 6.1} (x=0,0.5,1.0,1.5). High resolution transmission electron microscopy images showed the existence of Nb-rich amorphous grain boundary phase in the alloys with Nb doped. Field emission scanning electron microscope morphologies and X-ray diffraction patterns revealed the grain size and grain alignment of hot pressed and hot deformed nanocomposites. It was found that Nb could refine the grain size and grain texture in hot worked ribbons. Vibrating sample magnetometer results showed that the magnetic properties of the anisotropic nanocomposites were improved with increased Nb doping. The remanence, coercivity and maximum energy product of the bulk anisotropic Nd{sub 11}Dy{sub 0.5}Fe{sub 80.4}Nb{sub 2}B{sub 6.1} nanocomposites were 1.04 T, 563 kA/m and 146 kJ/m{sup 3}, respectively. - Highlights: Black-Right-Pointing-Pointer Nb has great influence on the microstructure and magnetic properties of (NdDy){sub 11.5}Fe{sub 82.4-x}Nb{sub x}B{sub 6.1} (x=0-2.0) nanocomposites. Black-Right-Pointing-Pointer Most of Nb atoms gather in the grain boundary to form Nb-rich amorphous intergranular phase, not NbFeB boride. Black-Right-Pointing-Pointer Furthermore, grain alignment can be prompt by the Nb-rich solid intergranular phase during deform. Black-Right-Pointing-Pointer Remanence, coercivity and (BH){sub m} of deformed (NdDy){sub 11.5}Fe{sub 80.4}Nb{sub 2}B{sub 6.1} nanocomposite is 1.04T, 563 kA/m and 146 kJ/m{sup 3} respectively. Black-Right-Pointing-Pointer This study provides an alternative method for prepare anisotropic nanocomposite direct from Nd-lean alloys with low cost.

  3. Development of crystal texture in R-lean RFeCoNbB (R = Nd, Pr) alloy during melt spinning processes

    International Nuclear Information System (INIS)

    Li, Wei; Li, Lanlan; Liu, Yanguo; Zhang, Xiangyi

    2012-01-01

    Highlights: ► We study the texture development during the melt spinning processes of R-lean alloys. ► A strong (0 0 l) texture parallel to the ribbon plane for (Nd,Pr) 2 Fe 14 B is obtained. ► The texture for R 2 Fe 14 B crystals can develop by a seeding effect of α-Fe texture. ► The anisotropic nanocomposite magnet yields M r = 0.78M s and large (BH) max = 25.2 MGOe. - Abstract: The formation of crystal texture of R 2 Fe 14 B nanocrystals in R–Fe–B (R = rare earth) alloys with low R content ( 2 Fe 14 B nanocrystals during the melt spinning processes of Nd 3.6 Pr 5.4 Fe 80 Co 3 NbB 7 by effectively employing the seeding effect of α-Fe nanocrystal texture. The (Nd,Pr) 2 Fe 14 B nanocrystals produced from the R-lean alloy at a wheel speed of 18 m/s show a strong (0 0 l) texture parallel to the ribbon plane, which yields a high remanence M r = 0.78M s and a large energy product (BH) max = 25.2 MGOe for the α-Fe/(Nd,Pr) 2 Fe 14 B nanocomposite ribbons. The present study provides a promising approach to prepare anisotropic nanocomposite magnets from R-lean alloys.

  4. External influence on magnetic properties of Fe-based nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, Jozef [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)]. E-mail: jozef.sitek@stuba.sk; Degmova, Jarmila [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Sedlackova, Katarina [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Butvin, Pavol [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    2006-09-15

    Amorphous and nanocrystalline ribbons of NANOPERM, FINEMET and HITPERM were studied by Moessbauer spectroscopy (MS) after the influence of external factors: different annealing atmospheres, tensile stress and several kinds of corrosion. MS is a suitable tool for such studies because the spectral parameters are very sensitive to changes in the vicinity of the probe -{sup 57}Fe nuclei. The most sensitive parameters were hyperfine magnetic field in crystalline component, average hyperfine field in amorphous component and direction of net magnetic moments. Influence of external factors modified also the structure of the alloys, i.e. new or modified phases were identified by MS phase analysis.

  5. Effect of Co content on structure and magnetic behaviors of high induction Fe-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Rajat K., E-mail: rajat@nmlindia.org; Panda, Ashis K.; Mitra, Amitava

    2016-11-15

    The replacement of Fe with Co is investigated in the (Fe{sub 1−x}Co{sub x}){sub 79}Si{sub 8.5}B{sub 8.5}Nb{sub 3}Cu{sub 1} (x=0, 0.05, 0.2, 0.35, 0.5) amorphous alloys. The alloys are synthesized in the forms of ribbons by single roller melt spinning technique, and the structural and magnetic properties of annealed ribbons are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), B–H curve tracer, respectively. All as-cast alloys are structurally amorphous, however, their magnetic properties are varying with Co addition. The Co addition within 5–20 at% results in moderate thermal stability, saturation induction, Curie temperature and lowest coercivity, while 35 at% Co causes highest saturation induction, coercivity, Curie temperature and lowest thermal stability. On devitrification, the magnetic properties change with the generation of α-FeCo nanocrystallites and (FeCo){sub 23}B{sub 6}, Fe{sub 2}B phases during primary and secondary crystallization stages, respectively. A small amount Co is advantageous for maintaining finer nanocrystallites in amorphous matrix even after annealing at 600 °C, leading to high saturation magnetization (>1.5 T) and low coercivity (~35 A/m). The improved magnetic properties at elevated temperatures indicate these alloys have a potential for high frequency transformer core applications. - Highlights: • The structural and magnetic behaviors of Fe based amorphous alloys have been investigated with the effect of Co content. • The Co has no adverse effect on amorphization of alloys. • A small amount Co causes the superior improvement of magnetic properties at elevated temperatures. • Therefore, it is important not only for academic research but also for industrial applied research.

  6. Parametric Study of Amorphous High-Entropy Alloys formation from two New Perspectives: Atomic Radius Modification and Crystalline Structure of Alloying Elements

    Science.gov (United States)

    Hu, Q.; Guo, S.; Wang, J. M.; Yan, Y. H.; Chen, S. S.; Lu, D. P.; Liu, K. M.; Zou, J. Z.; Zeng, X. R.

    2017-01-01

    Chemical and topological parameters have been widely used for predicting the phase selection in high-entropy alloys (HEAs). Nevertheless, previous studies could be faulted due to the small number of available data points, the negligence of kinetic effects, and the insensitivity to small compositional changes. Here in this work, 92 TiZrHfM, TiZrHfMM, TiZrHfMMM (M = Fe, Cr, V, Nb, Al, Ag, Cu, Ni) HEAs were prepared by melt spinning, to build a reliable and sufficiently large material database to inspect the robustness of previously established parameters. Modification of atomic radii by considering the change of local electronic environment in alloys, was critically found out to be superior in distinguishing the formation of amorphous and crystalline alloys, when compared to using atomic radii of pure elements in topological parameters. Moreover, crystal structures of alloying element were found to play an important role in the amorphous phase formation, which was then attributed to how alloying hexagonal-close-packed elements and face-centered-cubic or body-centered-cubic elements can affect the mixing enthalpy. Findings from this work not only provide parametric studies for HEAs with new and important perspectives, but also reveal possibly a hidden connection among some important concepts in various fields.

  7. Coercivity and induced magnetic anisotropy by stress and/or field annealing in Fe- and Co- based (Finemet-type) amorphous alloys

    International Nuclear Information System (INIS)

    Miguel, C.; Zhukov, A.; Val, J.J. del; Gonzalez, J.

    2005-01-01

    Uniaxial magnetic anisotropy has been induced in amorphous Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 (Fe-rich) and (Co 77 Si 13.5 B 9.5 ) 90 Fe 7 Nb 3 (Co-rich) ferromagnetic alloys by annealing under stress and/or magnetic field. Such anisotropy plays a crucial role on the magnetization process and, consequently, determine the future applications of these materials. The mechanisms involved on the origin of such induced magnetic anisotropy showed significant differences between Fe-rich and Co-rich amorphous alloys. This work provides a comparative study of the coercive field and induced magnetic anisotropy in Fe-rich and Co-rich (Finemet) amorphous alloys treated by stress and/or field

  8. Hydrogen solubility in austenite of Fe-Ni-Cr alloys

    International Nuclear Information System (INIS)

    Zhirnova, V.V.; Mogutnov, B.M.; Tomilin, I.A.

    1981-01-01

    Hydrogen solubility in Fe-Ni-Cr alloys at 600-1000 deg C is determined. Hydrogen solubility in ternary alloys can not be predicted on the basis of the data on its solubility in binary Fe-Ni, Fe-Cr alloys. Chromium and nickel effect on hydrogen solubility in iron is insignificant in comparison with the effect of these elements on carbon or nitrogen solubility [ru

  9. Atomic scale study of grain boundary segregation before carbide nucleation in Ni-Cr-Fe Alloys

    Science.gov (United States)

    Li, Hui; Xia, Shuang; Liu, Wenqing; Liu, Tingguang; Zhou, Bangxin

    2013-08-01

    Three dimensional chemical information concerning grain boundary segregation before carbide nucleation was characterized by atom probe tomography in two Ni-Cr-Fe alloys which were aged at 500 °C for 0.5 h after homogenizing treatment. B, C and Si atoms segregation at grain boundary in Alloy 690 was observed. B, C, N and P atoms segregation at grain boundary in 304 austenitic stainless steel was observed. C atoms co-segregation with Cr atoms at the grain boundaries both in Alloy 690 and 304 austenitic stainless steel was found, and its effect on the carbide nucleation was discussed. The amount of each segregated element at grain boundaries in the two Ni-Cr-Fe alloys were analyzed quantitatively. Comparison of the grain boundary segregation features of the two Ni-Cr-Fe alloys were carried out based on the experimental results. The impurity and solute atoms segregate inhomogeneously in the same grain boundary both in 304 SS and Alloy 690. The grain boundary segregation tendencies (Sav) are B (11.8 ± 1.4) > P (5.4 ± 1.4) > N (4.7 ± 0.3) > C (3.7 ± 0.4) in 304 SS, and B (6.9 ± 0.9) > C (6.7 ± 0.4) > Si (1.5 ± 0.2) in Alloy 690. Cr atoms may co-segregate with C atoms at grain boundaries before carbide nucleation at the grain boundaries both in 304 SS and Alloy 690. Ni atoms generally deplete at grain boundary both in 304 SS and Alloy 690. The literature shows that the Ni atoms may co-segregate with P atoms at grain boundaries [28], but the P atoms segregation do not leads to Ni segregation in the current study. In the current study, Fe atoms may segregate or deplete at grain boundary in Alloy 690. But Fe atoms generally deplete at grain boundary in 304 SS. B atoms have the strongest grain boundary segregation tendency both in 304 SS and Alloy 690. The grain boundary segregation tendency and Gibbs free energy of B in 304 SS is higher than in Alloy 690. C atoms are easy to segregate at grain boundaries both in 304 SS and Alloy 690. The grain boundary segregation

  10. First-principles study of electronic properties of FeSe{sub 1-x}S{sub x} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sandeep, E-mail: sandeep@phy.iitb.ac.in; Singh, Prabhakar P. [Department of Physics, Indian Institute of Technology-Bombay, Mumbai-400076 (India)

    2016-05-06

    We have studied the electronic and superconducting properties of FeSe{sub 1-x}S{sub x} (x = 0.0, 0.04) alloys by first-principles calculations using the Korringa-Kohn-Rostoker Atomic Sphere Approximation within the coherent potential approximation (KKR-ASA-CPA). The electronic structure calculations show the ground states of S-doped FeSe to be nonmagnetic. We present the results of our unpolarized calculations for these alloys in terms of density of states (DOS), band structures, Fermi surfaces and the superconducting transition temperature of FeSe and FeSe{sub 0.96}S{sub 0.04} alloys. We find that the substitution of S at Se site into FeSe exhibit the subtle changes in the electronic structure with respect to the parent FeSe. We have also estimated bare Sommerfeld constant (γ{sub b}), electron-phonon coupling constant (λ) and the superconducting transition temperature (T{sub c}) for these alloys, which were found to be in good agreement with experiments.

  11. Secondary particles precipitates in Be-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Petrov, V. I.; Martynenko, S. S.; Salomasov, V. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    Mössbauer spectra of monocrystalline Be-Fe alloy (0.85 % Fe) were obtained with the use of resonant detector after isothermal annealing at 600 °C for total duration of 2659 hours, and Mössbauer spectra of coarse-grained Be-Fe alloys (0,09-0,80 % Fe) samples were obtained after annealing at 500-600 °C for different durations. The alloys were prepared from the beryllium of different purity. Spectra of phases were fitted by a convolution equation of the three Lorentz lines. The coherent analysis of the solid solution decomposition process by means of the kinetic law classification and the secondary particles precipitate growth processes based on the diffusion models has been implemented. Nucleation on the numerous dislocation clusters and diffusion growth of the FeBe {sub 11} nano-particles are the dominant processes in the analyzed materials. The phase distribution, the incubation period and the diffusion path were obtained. The dependence between the impurity concentration and Mössbauer parameters of the phases is discussed.

  12. Secondary particles precipitates in Be-Fe alloys

    International Nuclear Information System (INIS)

    Filippov, V. P.; Petrov, V. I.; Martynenko, S. S.; Salomasov, V. A.

    2016-01-01

    Mössbauer spectra of monocrystalline Be-Fe alloy (0.85 % Fe) were obtained with the use of resonant detector after isothermal annealing at 600 °C for total duration of 2659 hours, and Mössbauer spectra of coarse-grained Be-Fe alloys (0,09-0,80 % Fe) samples were obtained after annealing at 500-600 °C for different durations. The alloys were prepared from the beryllium of different purity. Spectra of phases were fitted by a convolution equation of the three Lorentz lines. The coherent analysis of the solid solution decomposition process by means of the kinetic law classification and the secondary particles precipitate growth processes based on the diffusion models has been implemented. Nucleation on the numerous dislocation clusters and diffusion growth of the FeBe _1_1 nano-particles are the dominant processes in the analyzed materials. The phase distribution, the incubation period and the diffusion path were obtained. The dependence between the impurity concentration and Mössbauer parameters of the phases is discussed.

  13. Synthesis, characterization and electromagnetic properties of SnO-coated FeNi alloy nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingling; Li, Honglin; Xu, Taotao; Nie, Yu, E-mail: lml771212@163.com [College of Chemistry and Material Engineering, Chaohu University (China)

    2016-11-15

    SnO-coated FeNi alloy nanocapsules have been synthesized by an arc-discharge method. High resolution transmission electron microscopy and x-ray photoelectron spectroscopy analysis show that the nanocapsules have a shell/core structure with FeNi alloy nanoparticles as the core and amorphous SnO as the shell. Dielectric relaxation of SnO shell and the interfacial relaxation between SnO shell and FeNi core lead to the dual nonlinear dielectric resonance. The natural resonance in the SnO coated FeNi nanocapsules shifts to 14.0 GHz. Reflection loss (RL) reaches -46.1 dB at 14.8 GHz for a matching thickness of 1.95 mm, while it exceeds-20 dB over the 13.6 -16.7 GHz range and it exceeds -10 dB in the whole Ku-band (12.4-18 GHz). In addition, the optimal RL values at 5.0-7.6 GHz with the absorbing thickness of 3.4-5.0 mm just exhibit a slight fluctuation. (author)

  14. Study on magnetic properties of (Nd{sub 0.8}Ce{sub 0.2}){sub 2−x}Fe{sub 12}Co{sub 2}B (x = 0–0.6) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tan, G.S.; Xu, H., E-mail: huixu8888@shu.edu.cn; Yu, L.Y.; Tan, X.H.; Zhang, Q.; Gu, Y.; Hou, X.L.

    2017-09-01

    Highlights: • (Nd{sub 0.8}Ce{sub 0.2}){sub 2−x}Fe{sub 12}Co{sub 2}B alloys are prepared by melt-spinning method with simultaneously decreasing of Nd, Ce concentration. • The magnetic properties B{sub r}, (BH){sub max} and squareness are all improved with an appropriate reduction of Nd, Ce concentration. • Magnetic field heat treatment offers a significant improvement in B{sub r}, (BH){sub max} and squareness. - Abstract: In the present work, (Nd{sub 0.8}Ce{sub 0.2}){sub 2−x}Fe{sub 12}Co{sub 2}B (x = 0–0.6) permanent alloys are prepared by melt-spinning method. The hard magnetic properties of (Nd{sub 0.8}Ce{sub 0.2}){sub 2−x}Fe{sub 12}Co{sub 2}B (x = 0–0.6) alloys annealed at optimum temperatures have been investigated systematically. Depending on the Nd, Ce concentration, the maximum energy product ((BH){sub max}) and remanence (B{sub r}) increase gradually with x in the range of 0 ≤ x ≤ 0.4, whereas decrease gradually in the alloys with 0.4 < x ≤ 0.6. It is found that the optimum magnetic properties are obtained at x = 0.4: H{sub ci} = 4.9 kOe, B{sub r} = 10.1 kG, (BH){sub max} = 13.7 MGOe. Specifically, magnetic field heat treatment below the Curie temperature is applied for (Nd{sub 0.8}Ce{sub 0.2}){sub 1.6}Fe{sub 12}Co{sub 2}B (x = 0.4) annealed ribbons. The magnetic properties B{sub r}, (BH){sub max} and squareness are all enhanced after the magnetic field heat treatment. The (BH){sub max} shows a substantial increase from 13.7 MGOe to 16.0 MGOe after the heat treatment at 623 K with a magnetic field of 1 T, which gets 17% improvement compared with that of the sample without a magnetic field heat treatment. We demonstrate that the magnetic field heat treatment plays a certain role in the magnetization reversal behavior and can improve the microstructure of (Nd{sub 0.8}Ce{sub 0.2}){sub 1.6}Fe{sub 12}Co{sub 2}B alloy.

  15. Upgrade Fe-50%Ni alloys for open-loop DC current sensor: Design and alloy-potential characteristics

    International Nuclear Information System (INIS)

    Waeckerle, Thierry; Fraisse, Herve; Furnemont, Quentin; Bloch, Frederic

    2006-01-01

    This paper deals with the DC current sensor with open loop and high accuracy, and describes the relationship between the latter and the core-material magnetic properties in the case of Fe-50%Ni alloys. It is pointed out that air-gap precision, nonlinearity B-H and hysteresis are the main sources of accuracy; the influences of mechanical stress and temperature on coercive field are quantified and have to be taken into account in the design of the sensor. It is shown by dedicated choice of grades and annealing that Fe-50%Ni alloys may vary their coercive field from 4-6 A/m down to 1.5-4 A/m depending on the final annealing treatment used

  16. Effects of Zn additions to highly magnetoelastic FeGa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lograsso, Thomas A., E-mail: lograsso@ameslab.gov [Division of Materials Sciences and Engineering, Ames Laboratory, Ames, Iowa 50011 (United States); Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States); Jones, Nicholas J.; Wun-Fogle, Marilyn; Restorff, James B. [Metallurgy and Fasteners Branch, Naval Surface Warfare Center, Carderock Division, Maryland 20817 (United States); Schlagel, Deborah L. [Division of Materials Sciences and Engineering, Ames Laboratory, Ames, Iowa 50011 (United States); Petculescu, Gabriela [University of Louisiana at Lafayette, Louisiana 70504 (United States); Clark, Arthur E. [Clark Associates, Adelphi, Maryland 20783 (United States); Hathaway, Kristl B. [Spectrum Technology Group, Inc., Gaithersburg, Maryland 20877 (United States)

    2015-05-07

    Fe{sub 1−x}M{sub x} (M = Ga, Ge, Si, Al, Mo and x ∼ 0.18) alloys offer an extraordinary combination of magnetoelasticity and mechanical properties. They are rare-earth-free, can be processed using conventional deformation techniques, have high magnetic permeability, low hysteresis, and low magnetic saturation fields, making them attractive for device applications such as actuators and energy harvesters. Starting with Fe-Ga as a reference and using a rigid-band-filling argument, Zhang et al. predicted that lowering the Fermi level by reducing the total number of electrons could enhance magnetoelasticity. To provide a direct experimental validation for Zhang's hypothesis, elemental additions with lower-than-Ga valence are needed. Of the possible candidates, only Be and Zn have sufficient solubility. Single crystals of bcc Fe-Ga-Zn have been grown with up to 4.6 at. % Zn in a Bridgman furnace under elevated pressure (15 bars) in order to overcome the high vapor pressure of Zn and obtain homogeneous crystals. Single-crystal measurements of magnetostriction and elastic constants allow for the direct comparison of the magnetoelastic coupling constants of Fe-Ga-Zn with those of other magnetoelastic alloys in its class. The partial substitution of Ga with Zn yields values for the magnetoelastic coupling factor, −b{sub 1}, comparable to those of the binary Fe-Ga alloy.

  17. Structure of nanocomposites of Al–Fe alloys prepared by ...

    Indian Academy of Sciences (India)

    Wintec

    This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP. Keywords. Nanocomposites; Al–Fe; mechanical alloying; rapid solidification; quasicrystalline. 1. Introduction. Al–Fe alloys are attractive for applications at temperatures beyond those normally associated with ...

  18. Initial stages of solid solution decomposition in Fe-Ti and Fe-Nb alloys

    International Nuclear Information System (INIS)

    Ustinovshchikov, Yu.I.; Chen Shiren; Shirobokova, M.S.

    1993-01-01

    Structural analysis of Fe-Ti and Fe-Nb systems is performed. Formation of Laves phases proceed through the stage of the formation of a structure representing a periodic sequence of the regions enriched and depleted in alloying element. Abnormal changes in the properties of alloys of the given systems are noted; there changes reside in a decrease of alloy hardness during the formation of the above structure

  19. Mechanical behaviour of Zn-Fe alloy coated mild steel

    International Nuclear Information System (INIS)

    Panagopoulos, C.N.; Georgiou, E.P.; Agathocleous, P.E.; Giannakopoulos, K.I.

    2009-01-01

    Zinc alloy coatings containing various amounts of Fe were deposited by electrodeposition technique on a mild steel substrate. The concentration of Fe in the produced alloy coatings ranged from 0 to 14 wt.%, whereas the thickness of the coatings was about 50 μm. Structural and metallurgical characterization of the produced coatings was performed with the aid of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. This study aims in investigating the mechanical behaviour of Zn-Fe coated mild steel specimens, as no research investigation concerning the tensile behaviour of Zn alloy coated ferrous alloys has been reported in the past. The experimental results indicated that the ultimate tensile strength of the Zn-Fe coated mild steel was lower than the bare mild steel. In addition, the ductility of the Zn-Fe coated mild steel was found to decrease significantly with increasing Fe content in the coating.

  20. Structural and magnetic properties of rapidly quenched and as-cast bulk NdFeBCu alloys

    International Nuclear Information System (INIS)

    Sanchez Ll, J.L.; Bustamante S, R.; Barthem, V.M.T.S.; Miranda, P.E.V. de

    2005-01-01

    A study of the structural and magnetic properties of as-cast and melt spun (x)Nd 2 Fe 14 B(100-x)Nd 70 Cu 30 alloys (x=10, 50 and 75%wt.) is presented. In as-cast alloys for x=10wt%. the formation of a high coercivity phase, referred to as N (T C =240 deg. C, i H C =4.9kOe) is found. N is a (Nd-Fe)-based phase with a Fe/Nd ratio lower than that of phase Nd 2 Fe 14 B (φ). It is suggested that this phase is related to the A 1 phase found in binary Nd-Fe alloys. In melt-spun alloys, at the same x value of 10wt%, another hard phase is found which is suggested to be the Nd 6 Fe 13 Cu δ-phase (T C =192 deg. C, i H C =4.8kOe). Transmission electron microscope (TEM) micrographs of the ribbons with x=10wt% shows the formation of nanograins with a non-uniform grain size distribution. In cast alloys with x=50 and 75wt% large slab-like grains of φ are formed, in the inter-granular region a Nd-Cu eutectic phase and Nd grains, are observed. High coercivities are obtained in ribbons with x=50wt% ( i H C =19.7kOe) and 75wt% ( i H C =13.0kOe). A slight reduction in the Curie temperature of the φ-phase with respect to the bulk value is found in these ribbons

  1. Acoustic properties of TiNiMoFe base alloys

    International Nuclear Information System (INIS)

    Gyunter, V.Eh.; Chernyshev, V.I.; Chekalkin, T.L.

    2000-01-01

    The regularity of changing the acoustic properties of the TiNi base alloys in dependence on the alloy composition and impact temperature is studied. It is shown that the oscillations of the TiNiMoFe base alloys within the temperature range of the B2 phase existence and possible appearance of the martensite under the load differ from the traditional materials oscillations. After excitation of spontaneous oscillations within the range of M f ≤ T ≤ M d there exists the area of long-term and low-amplitude low-frequency acoustic oscillations. It is established that free low-frequency oscillations of the TH-10 alloy sample are characterized by the low damping level in the given temperature range [ru

  2. Crystallization study of amorphous system Fe84-xWxB16 (x = 3;5)

    International Nuclear Information System (INIS)

    Novakova, A.A.; Sidorova, G.V.; Kiseleva, T.Yu.; Szasz, A.

    1992-01-01

    A complex study of the crystallization process of the amorphous system was carried out by Moessbauer spectroscopy, X-ray diffraction and DTA. Alloy samples crystallized at 600deg C contain the following phases: α-Fe, Fe 3 B and solid solution (Fe, W) 3 B. (orig.)

  3. Structure and magnetic properties of Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al, (0 ≤ x ≤ 1) Heusler alloys prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Yogesh, E-mail: 123209001_yogesh@manit.ac.in [Department of Materials Science & Metallurgical Engineering, Ceramic & Powder Metallurgy Laboratory, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Vajpai, Sanjay Kumar, E-mail: vajpaisk@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Srivastava, Sanjay, E-mail: s.srivastava.msme@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India)

    2017-07-01

    Highlights: • A series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy by powder metallurgy. • Effect of substitution of Fe for Cr on the microstructure and magnetic properties. • Increasing amounts of B2 type disordered structure with increasing Fe content. • Enhanced Ms, Mr, Hc, and Tc with increasing Fe content. • Relative magnetic anisotropy decreased with increasing Fe content. - Abstract: In the present study, a series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders were successfully prepared by high energy ball milling and the effect of substitution of Fe for Cr on the microstructure and magnetic properties was investigated in detail. The Co{sub 2}CrAl alloy powder consisted of only A2 type disordered structure whereas the substitution of Cr by Fe led to the appearance of increasing amounts of B2 type disordered structure along with A2 type structure. All the Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders demonstrated high spontaneous magnetization together with a very small hysteresis losses. The saturation magnetization, remanence, coercivity, and Curie temperature increased with increasing Fe content. The increasing magnetization with increasing Fe content was attributed to the replacement of antiferromagnetic Cr by strongly ferromagnetic Fe and an increasing amounts of relatively more ordered, atomically as well as ferromagnetically, B2 structure as compared to that of A2 phase. The increment in remanence and coercivity with increasing Fe content were associated with the variation in microstructural characteristics, such as grain size, lattice defects, and the presence of small amounts of magnetic/nonmagnetic secondary phases. The increment in Curie temperature with increasing Fe content was attributed to the enhancement of d-d exchange interaction due to the possible occupancy of vacant sites by Fe atoms. All the Heusler alloys indicated extremely low magnetic anisotropy and the

  4. Crystallisation kinetics of amorphous Fe72.5-xCu1Nb4.5Si10+x+yB12-y alloy

    International Nuclear Information System (INIS)

    Miglierini, M.; Lipka, J.; Sitek, J.

    1994-01-01

    Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 and Fe 72.5-x Cu 1 Nb 4.5 Si 10+x+y B 12-y alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 C for x = 0.5, y = 3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder. (orig.)

  5. Surface modification of 5083 Al alloy by electrical discharge alloying processing with a 75 mass% Si-Fe alloy electrode

    Energy Technology Data Exchange (ETDEWEB)

    Stambekova, Kuralay [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan (China); Lin, Hung-Mao [Department of Mechanical Engineering, Far East University, No. 49, Zhonghua Rd., Xinshi Dist., Tainan City 74448, Taiwan (China); Uan, Jun-Yen, E-mail: jyuan@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan (China)

    2012-03-01

    This study experimentally investigates the surface modification of 5083 Al alloy by the electrical discharge alloying (EDA) process with a Si-Fe alloy as an electrode. Samples were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), micro-hardness and corrosion resistance tests. The micro-hardness of EDA alloyed layer was evidently higher than that of the base metal (5083 Al alloy). The TEM results show that the matrix of the alloyed layer has an amorphous-like structure; the matrix contains fine needle-like Si particles, block-like Si particles and nano-size Al{sub 4.5}FeSi and Al{sub 13}Fe{sub 4} particles. The TEM results support experimental results for the high hardness of the alloyed layer. Moreover, the EDA alloyed layer with composite microstructures has good corrosion resistance in NaCl aqueous solution.

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

    Science.gov (United States)

    Hadef, Fatma

    2016-12-01

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

  7. Structure and grindability of cast Ti-5Cr-xFe alloys

    International Nuclear Information System (INIS)

    Hsu, H.-C.; Pan, C.-H.; Wu, S.-C.; Ho, W.-F.

    2009-01-01

    The purpose of this study was to investigate the structure, microhardness and grindability of Ti-5Cr and a series of ternary Ti-5Cr-xFe alloys with 0.1, 0.5, 1, 3 and 5 wt.% Fe, respectively. This study evaluated the phase and structure of Ti-5Cr and Ti-5Cr-xFe alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. In addition, grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min at each of the four rotational speeds of the wheel (500, 750, 1000 or 1200 m/min), with the goal of developing a titanium alloy with better machinability than commercially pure titanium (c.p. Ti). The results showed that the structure of Ti-5Cr-xFe alloys is sensitive to the Fe content. With Fe contents higher than 0.5 wt.%, the equi-axed β phase is entirely retained, while ω phase was found in the Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The largest quantity of ω phase and highest microhardness were found in Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The grinding rates of the Ti-5Cr and Ti-5Cr-xFe alloys showed a similar tendency to the microhardness. The Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys exhibited the best grindability, especially at 500, 750 and 1000 m/min. Furthermore, the grindability of the tested metals increased in proportion to grinding speed up to 1000 m/min, with a decrease after 1200 m/min. This study concluded that Fe may be used to harden titanium and improve the grindability

  8. Cl K-edge XANES spectra of atmospheric rust on Fe, Fe-Cr and Fe-Ni alloys exposed to saline environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2004-01-01

    Cl K-edge XANES measurements of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys in chloride pollution have been performed using synchrotron radiation in order to clarify roles of anticorrosive alloying elements and of Cl in the corrosion resistance of weathering steel. The spectra of binary alloys show a shoulder structure near the absorption edge. The intensity of the shoulder peak depends on the kind and amount of the alloying element, whereas the energy position is invariant. This indicates that Cl is not combined directly with alloying elements in the rust. (author)

  9. Local atomic order in nanocrystalline Fe-based alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Jartych, E.

    2003-01-01

    Using the 57 Fe Moessbauer spectroscopy, a local atomic order in nanocrystalline alloys of iron with Al, Ni, W and Mo has been determined. Alloys were prepared by mechanical alloying method. Analysis of Moessbauer spectra was performed on the basis of the local environment model in terms of Warren-Cowley parameters. It was shown that impurity atoms are not randomly distributed in the volume of the first and the second co-ordination spheres of 57 Fe nuclei and they form clusters

  10. Pressure-induced preferential growth of nanocrystals in amorphous Nd{sub 9}Fe{sub 85}B{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Wu Wei; Li Wei; Sun Hongyu; Li Hui; Zhang Xiangyi [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, 066004 Qinhuangdao (China); Li Xiaohong; Liu Baoting [College of Physics Science and Technology, Hebei University, 071002 Baoding (China)], E-mail: xyzh66@ysu.edu.cn

    2008-07-16

    Control over the growth and crystallographic orientation of nanocrystals in amorphous alloys is of particular importance for the development of advanced nanocrystalline materials. In the present study, Nd{sub 2}Fe{sub 14}B nanocrystals with a strong crystallographic texture along the [410] direction have been produced in Nd-lean amorphous Nd{sub 9}Fe{sub 85}B{sub 6} under a high pressure of 6 GPa at 923 K. This is attributed to the high pressure inducing the preferential growth of Nd{sub 2}Fe{sub 14}B nanocrystals in the alloy. The present study demonstrates the potential application of high-pressure technology in controlling nanocrystalline orientation in amorphous alloys.

  11. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    International Nuclear Information System (INIS)

    Lavorato, G.C.; Fiore, G.; Castellero, A.; Baricco, M.; Moya, J.A.

    2012-01-01

    Amorphous alloys with composition (at%) Fe 48 Cr 15 Mo 14 C 15 B 6 Gd 2 (alloy A) and Fe 48 Cr 15 Mo 14 C 15 B 6 Y 2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness (∼13 GPa) and the Young modulus (∼180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  12. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    Energy Technology Data Exchange (ETDEWEB)

    Lavorato, G.C. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Fiore, G.; Castellero, A.; Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [IESIING, Facultad de Ingenieria e Informatica, UCASAL, Salta (Argentina); CONICET (Argentina)

    2012-08-15

    Amorphous alloys with composition (at%) Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Gd{sub 2} (alloy A) and Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Y{sub 2} (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness ({approx}13 GPa) and the Young modulus ({approx}180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  13. The role of Mg interface layer in MgO magnetic tunnel junctions with CoFe and CoFeB electrodes

    Directory of Open Access Journals (Sweden)

    Hyunsoo Yang

    2012-03-01

    Full Text Available The tunneling spin polarization (TSP is directly measured from reactively sputter deposited crystalline MgO tunnel barriers with various CoFe(B compositions using superconducting tunneling spectroscopy. We find that the Mg interface layer thickness dependence of TSP values for CoFeB/Mg/MgO junctions is substantially different from those for CoFe/Mg/MgO especially in the pre-annealed samples due to the formation of boron oxide at the CoFeB/MgO interface. Annealing depletes boron at the interface thus requiring a finite Mg interface layer to prevent CoFeOx formation at the CoFeB/MgO interface so that the TSP values can be optimized by controlling Mg thickness.

  14. Inhibited Aluminization of an ODS FeCr Alloy

    International Nuclear Information System (INIS)

    Vande Put Ep Rouaix, Aurelie; Pint, Bruce A.

    2012-01-01

    Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small (∼ 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

  15. Influence of an Fe cap layer on the structural and magnetic properties of Fe49Pt51/Fe bi-layers

    International Nuclear Information System (INIS)

    Chao-Yang, Duan; Bin, Ma; Zong-Zhi, Zhang; Qing-Yuan, Jin; Fu-Lin, Wei

    2009-01-01

    The influences of an Fe cap layer on the structural and magnetic properties of FePt/Fe bi-layers are investigated. Compared with single FePt alloy films, a thin Fe layer can affect the crystalline orientation and improve the chemical ordering of L1 0 FePt films. Moreover, the coercivity increases when a thin Fe layer covers the FePt layer. Beyond a critical thickness, however, the Fe cover layer quickens the magnetization reversal of Fe 49 Pt 51 /Fe bi-layers by their exchange coupling

  16. Alloying Solid Solution Strengthening of Fe-Ga Alloys: A First-Principle Study

    National Research Council Canada - National Science Library

    Chen, Kuiying; Cheng, Leon M

    2006-01-01

    ... and Co in cubic solid solution of Fe-Ga alloys. Mayer bond order "BO" values were used to evaluate the atomic bond strengths in the alloys, and were then used to assess the alloying strengthening characteristics...

  17. Study of the structural, electronic and magnetic properties of ScFeCrT (T=Si, Ge) Heusler alloys by first principles approach

    Energy Technology Data Exchange (ETDEWEB)

    Rasool, Muhammad Nasir [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Hussain, Altaf, E-mail: altafiub@yahoo.com [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan); Javed, Athar, E-mail: athar.physics@pu.edu.pk [Department of Physics, University of the Punjab, Lahore 54590 (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur (Pakistan)

    2017-03-15

    Spin polarized structural, electronic, magnetic and bonding properties of ScFeCrT (T=Si, Ge) Heusler alloys are studied by employing density functional theory. The total energy calculation (for a static lattice) shows that both alloys are structurally stable in ferromagnetic phase with compressibility C{sub ScFeCrSi}>C{sub ScFeCrGe}. The electronic and band structure analysis show that the ScFeCrT alloys exhibit half-metallic ferromagnetic (HMF) behaviour for spin ↑ channel while semiconducting behaviour in spin ↓ channel. Both alloys exhibit total magnetic moment, M{sub Total}=3.0 µ{sub B}/cell obeying the Slater Pauling rule, M{sub SPR}=(N{sub v} –18)μ{sub B}. For ScFeCrSi and ScFeCrGe alloys, the charge density and interatomic bonding character show highly covalent and polar covalent character, respectively. For both alloys, 100% spin polarization (for spin ↑ state) is expected which is an indication of their suitability for applications in spintronic devices. - Highlights: • Heusler alloys ScFeCrT (T= Si, Ge) are studied by first principles approach. • Structural, electronic, magnetic and bonding properties are reported. • Both alloys show half-metallicity and ferromagnetic behaviour. • Combination of properties shows the suitability of alloys in spintronic devices.

  18. 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...

  19. Local order dynamics: its application to the study of atomic mobility, of point defects in crystalline alloys, and of structural relaxation in amorphous alloys

    International Nuclear Information System (INIS)

    Balanzat, Emmanuel

    1983-01-01

    This research thesis addressed the study of the atomic mobility mechanism and of the atom movement dynamics in the case of crystalline alloys and of amorphous alloys. The first part is based on a previous study performed on an α-Cu 70 -Zn 30 crystalline alloy, and addresses the case of an α-Au 70 -Ni 30 alloy. The specificity of this case relies in the fact that the considered solid solution is metastable and susceptible to de-mixing in the considered temperature range. This case of off-equilibrium crystalline alloy is at the crossroad between steady crystalline alloys and metallic glasses which are studied in the second part. The third part addresses the irradiation of metallic amorphous alloys by fast particles (neutrons or electrons). The author tried to characterise atomic defects induced by irradiation and to compare them with pre-existing ones. He studied how these defects may change atomic mobility, and, more generally, to which extent the impact of energetic particles could modify local order status

  20. 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

  1. 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.

  2. Study of structural, electronic and magnetic properties of CoFeIn and Co2FeIn Heusler alloys

    International Nuclear Information System (INIS)

    El Amine Monir, M.; Khenata, R.; Baltache, H.; Murtaza, G.; Abu-Jafar, M.S.; Bouhemadou, A.; Bin Omran, S.

    2015-01-01

    The structural, electronic and magnetic properties of half-Heusler CoFeIn and full-Heusler Co 2 FeIn alloys have been investigated by using the state of the art full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential was treated with the generalized gradient approximation (PBE-GGA) for the calculation of the structural properties, whereas the PBE-GGA+U approximation (where U is the Hubbard Coulomb energy term) is applied for the computation of the electronic and magnetic properties in order to treat the “d” electrons. The structural properties have been calculated in the paramagnetic and ferromagnetic phases where we have found that both the CoFeIn and Co 2 FeIn alloys have a stable ferromagnetic phase. The obtained results of the spin-polarized band structure and the density of states show that the CoFeIn alloy is a metal and the Co 2 FeIn alloy has a complete half-metallic nature. Through the obtained values of the total spin magnetic moment, we conclude that in general, the Co 2 FeIn alloy is half-metallic ferromagnet material whereas the CoFeIn alloy has a metallic nature. - Highlights: • Based on DFT calculations, CoFeIn and Co2FeIn Heusler alloys were investigated. • The magnetic phase stability was determined from the total energy calculations. • Electronic properties reveal the metallic (half-metallic) nature for CoFeIn (Co2FeIn)

  3. Development of NdFeB magnet through hydrogen decrepitation

    International Nuclear Information System (INIS)

    Akhtar, S.; Farooque, M.; Haider, A.; Ahmad, Z.

    2009-01-01

    Neodymium based magnets are the powerful permanent magnet of today. This paper will discuss iron based rare earth magnets. NdFeB sintered magnet material has been developed. The magnets are produced by powder metallurgy route involving hydrogen decrepitation technique for making fine powder. After melting and casting, the NdFeB alloy is subject to hydrogen atmosphere. Hydrogen slowly absorbs into the solid alloy and makes it brittle, which upon milling becomes fine powder. Hydrogen is then removed by placing the powder at temperature around 800 deg. C under vacuum. Then the powders are pressed under isostatic conditions and sintered at temperature range of 1020-1050 deg. C. Post sintering is done at 800 deg. C and 580 deg. C followed by quenching. Energy product in the range of 8 MGOe is achieved. (author)

  4. Magnetoimpedance effect in Nanoperm alloys

    International Nuclear Information System (INIS)

    Hernando, B.; Alvarez, P.; Santos, J.D.; Gorria, P.; Sanchez, M.L.; Olivera, J.; Perez, M.J.; Prida, V.M.

    2006-01-01

    The influence of isothermal annealing (1 h at 600 deg. C in Ar atmosphere) on the soft magnetic properties and magnetoimpedance (MI) effect has been studied in ribbons of the following Nanoperm alloys: Fe 91 Zr 7 B 2 , Fe 88 Zr 8 B 4 , Fe 87 Zr 6 B 6 Cu 1 and Fe 8 Zr 1 B 1 . A maximum MI ratio of about 27% was measured for the nanocrystalline alloy Fe 87 Zr 6 B 6 Cu 1 at a driving frequency of 0.2 MHz. The thermal annealing led to magnetic softening for this alloy, while a hardening is observed for the Fe 8 Zr 1 B 1 alloy

  5. Magnetic domain size effect on resistivity and Hall effect of amorphous Fe83-xZr7B10Mx (M=Ni, Nb) alloys

    International Nuclear Information System (INIS)

    Rhie, K.; Lim, W.Y.; Lee, S.H.; Yu, S.C.

    1997-01-01

    Studies of effective permeability, core loss and saturation magnetostriction of Fe 83-x Zr 7 B 10 M x (M=Ni, Nb) alloys revealed that the domain width is smallest around x=0.10. We measured the resistivity and low field Hall coefficients of these alloys and found that the maxima of resistivity and Hall coefficients occurred roughly at the same concentrations. Larger surface area of smaller domains is considered the reason. copyright 1997 American Institute of Physics

  6. Coercivity enhancement in hot deformed Nd2Fe14B-type magnets by doping low-melting RCu alloys (R = Nd, Dy, Nd + Dy)

    Science.gov (United States)

    Lee, Y. I.; Huang, G. Y.; Shih, C. W.; Chang, W. C.; Chang, H. W.; You, J. S.

    2017-10-01

    Magnetic properties of the anisotropic NdFeB magnets prepared by hot pressing followed by die-upsetting NdFeB MQU-F powders doped with low-melting RCu alloy powders were explored, where RCu stands for Nd70Cu30, Dy70Cu30 and (Nd0.5Dy0.5)70Cu30, respectively. In addition, the post-annealing at 600 °C was employed to modify the microstructures and the magnetic properties of the hot deformed magnets. It is found that doping RCu alloy powders is effective in enhancing the coercivity of the hot deformed NdFeB magnets from 15.1 kOe to 16.3-19.5 kOe. For Nd70Cu30-doped magnets, the increment of coercivity is only 1.2 kOe. Meanwhile, Dy70Cu30-doped and (Nd0.5Dy0.5)70Cu30-doped magnets show an almost identical enhancement of coercivity of about 4.4 kOe. Importantly, the latter magnet shows a beneficial effect of reducing the usage of Dy from 1.6 wt% to 0.8 wt%. TEM analysis shows that nonmagnetic Nd, Dy and Cu appear at grain boundary and isolate the magnetic grains, leading to an enhancement of coercivity. Doping lower melting point Dy-lean (Nd0.5Dy0.5)70Cu30 powders into commercial MQU-F powders for making high coercivity hot deformed NdFeB magnets might be a potential and economic way for mass production.

  7. Formation and stability of aluminum-based metallic glasses in Al-Fe-Gd alloys

    International Nuclear Information System (INIS)

    He, Y.; Poon, S.J.; Shiflet, G.J.

    1988-01-01

    Metallic glasses, a class of amorphous alloys made by rapid solidification, have been studied quite extensively for almost thirty years. It has been recognized for a long time that metallic glasses are usually very strong and ductile, and exhibit high corrosion resistance relative to crystalline alloys with the same compositions. Recently, metallic glasses containing as much as 90 atomic percent aluminum have been discovered independently by two groups. This discovery has both scientific and technological implications. The formability of these new glasses have been found to be unusual. Studies of mechanical properties in these new metallic glasses show that many of them have tensile strengths over 800MPa, greatly exceeding the strongest commercial aluminum alloys. The high strengths of aluminum-rich metallic glasses can be of significant importance in obtaining high strength low density materials. Therefore, from both scientific and technological standpoints, it is important to understand the formation and thermal stability of these metallic glasses. Al-Fe-Gd alloys were chosen for a more detailed study since they exhibit high tensile strengths

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-09-15

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

  9. MFM study of NdFeB and NdFeB/Fe/NdFeB thin films

    International Nuclear Information System (INIS)

    Gouteff, P.C.; Folks, L.; Street, R.

    1998-01-01

    Domain structures of NdFeB thin films, ranging in thickness between 1500 and 29 nm, have been studied qualitatively by magnetic force microscopy (MFM). Samples were prepared using a range of sputtering conditions resulting in differences in properties such as texture, coercivity and magnetic saturation. MFM images of all the films showed extensive interaction domain structures, similar to those observed in nanocrystalline bulk NdFeB. An exchange-coupled NdFeB/Fe/NdFeB trilayer with layer thicknesses 18 nm/15 nm/18 nm, respectively, was also examined using MFM. (orig.)

  10. Temperature dependence of diffuse satellites in Ti–(50 − x)Pd–xFe (14 ⩽ x ⩽ 20 (at.%)) alloys

    International Nuclear Information System (INIS)

    Todai, Mitsuharu; Fukuda, Takashi; Kakeshita, Tomoyuki

    2014-01-01

    Highlights: • Diffuse satellites of Ti–(50 − x)Pd–xFe alloys have been investigated. • Diffuse satellites appear at g B2 + 〈ζζ ¯ 0〉 * below T min . • The peak position of diffuse satellites at T min agree with the length of the nesting vector. • The present result implies that the nesting effect of Fermi surface originates diffuse satellites in Ti–(50 − x)Pd–xFe alloys. - Abstract: Diffuse satellites appearing in electron diffraction pattern of shape memory Ti–(50 − x)Pd–xFe (14, 16, 18, 19 and 20, in at.%) alloys have been investigated. The satellites appear in each alloy below T min , where its electrical resistivity shows a local minimum. The positions of satellites are g B2 + 〈ζ ζ ¯ 0〉 * , where g B2 is a reciprocal lattice vector of the B2-phase. The value of ζ is smaller than 1/5 at T min for all the alloys; it increases with decreasing temperature and decreases with increasing iron content. The value of ζ at T min agrees with the length of the nesting vector previously calculated by the present authors. This result implies that Fermi surface nesting is the origin of diffuse satellites in Ti–(50 − x)Pd–xFe alloys

  11. 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.

  12. High damping Fe-Mn martensitic alloys for engineering applications

    International Nuclear Information System (INIS)

    Baik, S.-H.

    2000-01-01

    Conventional methods for reducing vibration in engineering designs (i.e. by stiffening or detuning) may be undesirable or inadequate in conditions where size or weight must be minimized or where complex vibration spectra exist. Alloys which combine high damping capacity with good mechanical properties can provide attractive technical and economic solutions to problems involving seismic, shock and vibration isolation. To meet these trends, we have developed a new high damping Fe-17%Mn alloy. Also, the alloy has advantages of good mechanical properties and is more economical than any other known damping alloys (a quarter the cost of non-ferrous damping alloy). Thus, the high damping Fe-17%Mn alloy can be widely applied to household appliances, automobiles, industrial facilities and power plant components with its excellent damping capacity (SDC, 30%) and mechanical property (T.S. 700 MPa). It is the purpose of this paper to introduce the characterization of the high damping Fe-17%Mn alloy and the results of retrofit of several such applications. (orig.)

  13. Progress of HDDR NdFeB powders modulated by the diffusion of low melting point elements and their alloys

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available The hydrogenation-disproportionation-desorption-recombination (HDDR process is the main technique for the fabrication of anisotropic NdFeB magnetic powder.But the intrinsic coercivity (HC of HDDR magnetic powder is low.The addition of heavy rare earth element Dy could improve its HC.It was found that the added Dy is mainly distributed in the grain boundary of HDDR magnets,which regulates grain boundary phase and increases the thickness of grain boundary to improve the anisotropy field (HA and HC of the magnets.However,Dy becomes scarcer and more expensive,which limits the practical application of HDDR magnets.To reduce the dependence on heavy rare earth elements and cost,researchers replaced the heavy rare earth element Dy by low melting point elements and their alloys through grain boundary diffusion technique.During diffusion process low melting point metal exists as liquid phase that increases the diffusion coefficient of diffusion medium as well as its contact area with grain boundary phases of HDDR magnets,and benefits its diffusion along grain boundaries and regulation of grain boundary phase.The modified grain boundary in magnets improve HC.This review paper focuses on the research progress in improving HC of HDDR NdFeB magnets by low melting point elements and their alloys.

  14. Extrinsic Curie temperature and spin reorientation changes in Nd2Fe14B/α-Fe nanocomposites

    International Nuclear Information System (INIS)

    Lewis, L.H.; Panchanathan, V.

    1998-05-01

    The Curie temperatures and spin reorientation temperatures of a series of four melt-spun nanocomposite materials comprised of Nd 2 Fe 1 4B and varying amounts of α-Fe were measured using independent techniques. The phase constitution and grain size was assessed with synchrotron x-ray diffraction; the Curie temperatures were measured by differential thermal analysis (DTA) and dc SQUID magnetometry in the temperature range 375 K ≤ T ≤ 800 K, whereas the spin reorientation transition temperature was determined from ac susceptibility measurements taken in the range 10 K ≤ T ≤ 300 K. The Curie temperature increases with increasing excess iron content, resulting in a 18 degree enhancement over the Curie temperature of pure Nd 2 Fe 14 B for 27 wt% excess α-Fe. The spin reorientation temperatures are depressed from the single-crystal value by an average of 10 degrees. Both anomalous effects are attributed to intergranular exchange coupling present in the alloys, although the effects of uncompensated stress between the constituent phases cannot be ruled out The experimental results suggest that while the Curie temperature of the Nd 2 Fe 14 B phase may be extrinsically enhanced significantly beyond the bulk value, possibly extending the range of applications of this compound, the anisotropy may be simultaneously lowered, impeding the attainment of high coercivities in these alloys

  15. Moessbauer effect study on mechanically alloyed amorphous Fe1-xTix alloys

    International Nuclear Information System (INIS)

    Chen Hong; Xu Zuxiong; Ma Ruzhang; Zhao Zhongtao; Ping Jueyun

    1994-01-01

    Amorphous Fe 1-x Ti x (x = 0.50, 0.60) powders were produced by mechanical alloying from pure elemental powders in a vibratory ball-mill. X-ray diffraction (XRD) and Moessbauer effect (ME) were used to study the progress of amorphization and the property of hydrogen absorption in Fe-Ti alloys. The amorphization process and the properties of the amorphous phase are discussed. (orig.)

  16. 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

  17. Mechanism of magnetic recovery in the disorder-order transformation of Fe70Al30 mechanically deformed alloys

    International Nuclear Information System (INIS)

    Rodriguez, D. Martin; Apinaniz, E.; Plazaola, F.; Garitaonandia, J.S.; Jimenez, J.A.; Schmool, D.S.; Cuello, G.J.

    2005-01-01

    The degree of order in Fe-Al intermetallic alloys has an important influence on their magnetic properties. Moreover, the deformation of ordered alloys causes a dramatic increase of magnetization. If deformed alloys are heated, their magnetic properties decrease again. The reordering process was monitored by neutron diffraction, Moessbauer spectroscopy, and calorimetric measurements on the Fe 70 Al 30 crushed alloy. This indicates that the reordering process occurs in two stages. In the first (150-200 deg. C) new small B2 phase domains are nucleated due to vacancy migration. A second reordering stage occurs between 300 and 450 deg. C, where dislocation motion induces B2 domain growth and A2 phase elimination. The main mechanism responsible for this decrease of magnetization during the reordering process is the decrease of the disordered A2 phase content in the alloy

  18. Microstructural characterisation of high-entropy alloy AlCoCrFeNi fabricated by laser engineered net shaping

    Energy Technology Data Exchange (ETDEWEB)

    Kunce, I., E-mail: ikunce@wat.edu.pl [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Polanski, M.; Karczewski, K. [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Plocinski, T.; Kurzydlowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw (Poland)

    2015-11-05

    Laser engineered net shaping (LENS) was used to produce thin-walled samples of the high-entropy alloy AlCoCrFeNi from a prealloyed powder. To determine the effect of the cooling rate during solidification on the microstructure of the alloy, different laser scanning rates were used. A microstructural study of the surfaces of the sample walls was performed using X-ray diffraction analysis and optical and scanning/transmission electron microscopy. The crystal structure of the alloy was determined to be a body-centred cubic (bcc)-derivative B2-ordered type. The microstructure of the alloy produced by LENS was dendritic. Further, it was found that with an increase in the laser scanning rate from 2.5 to 40 mm s{sup −1}, the average grain size decreased from 108.3 ± 32.4 μm to 30.6 ± 9.2 μm. The maximum cooling rate achieved during the laser cladding of the alloy was 44 × 10{sup 3} K s{sup −1}. The electron microscopy study of the alloy showed the presence of precipitates. The morphology of the disordered bcc (Fe, Cr)-rich precipitates in the ordered B2 (Al, Ni)-rich matrix changed in the dendritic and interdendritic regions from fine and spherical (with a diameter of less 100 nm) to spinodal (with the thickness being less than 100 nm). The LENS- produced AlCoCrFeNi alloy exhibited an average microhardness of approximately 543 HV0.5; this was approximately 13% higher than the hardness in the as-cast state and can be attributed to the grain refinemet in the LENS- produced alloy. Moreover, it was found that increasing the cooling rate during laser cladding increasess the microhardness of the alloy. - Highlights: • Laser-engineered net shaping is used to produce samples of AlCoCrFeNi alloy. • The alloy has a body-centred cubic (bcc)-derivative B2-ordered crystal structure. • Electron microscopy images of the alloy show the presence of precipitates. • The microhardness of the laser-clad alloy is higher than that of the as-cast alloy. • The cooling rate

  19. Nd-Fe-B sintered magnets fabrication by using atomized powders

    International Nuclear Information System (INIS)

    Goto, R; Sugimoto, S; Matsuura, M; Tezuka, N; Une, Y; Sagawa, M

    2011-01-01

    Nd-Fe-B sintered magnets are required to achieve high coercivity for improvement of their thermal stability. Dy is added to increase coercivity, however, this element decrease magnetization and energy products. Therefore, Dy-lean Nd-Fe-B sintered magnets with high coercivity are strongly demanded. To increase coercivity, it is necessary that microstructure of sintered magnets is consisted of both fine main phase particles and homogeneously distributed Nd-rich phases around the main phase. To meet those requirements, Nd-Fe-B atomized powders were applied to the fabrication process of sintered magnets. Comparing with the case of using strip casting (SC) alloys, jet-milled powders from atomized powders show homogeneous distribution of Nd-rich phase. After optimized thermal treatment, coercivities of sintered magnets from atomized powders and SC alloys reach 1050 kA·m-1 and 1220 kA·m-1, respectively. This difference in coercivity was due to initial oxygen concentration of starting materials. Consequently, Nd-rich phases became oxides with high melting points, and did not melt and spread during sintering and annealing.

  20. Plastic anomaly of the B2 ordered Fe-40Al alloy; Anomalie plastique de l'alliage Fe-40Al ordonne B2

    Energy Technology Data Exchange (ETDEWEB)

    Calonne, O

    2002-05-01

    The plastic behaviour of Fe-40Al (B2-ordered) alloys was studied. This material has the particularly of exhibiting a yield stress that increases in a given temperature range ('yield stress anomaly'). This anomaly is usually associated with a zero strain rate sensitivity in the very same temperature range. These two peculiarities can be explained as a whole by a thermally activated exhaustion of the mobile dislocations. In this work, the macroscopic mechanical behaviour of the FeAl alloys was first characterised. Then, slip geometry was studied in a large temperature range using oriented single crystals. Finally, the elementary deformation processes were studied through an analysis of dislocation structures in deformed materials using TEM post-mortem and in-situ techniques. Our results show that the yield stress anomaly stems from superdislocations exhaustion through the formation of antiphase boundary tubes, due to vacancy absorption. The number of antiphase boundary tubes produced during dislocation motion depends on vacancy concentration, that in turn increases with temperature. This is believed to be the main reason for thermally activated exhaustion. In addition, the anomaly peak and the related stress fall-off at higher temperatures can be ascribed to superdislocation decomposition, which provides the material with ordinary dislocations that cannot generate antiphase boundary tubes. Superdislocations exhaustion seems to be the catalyzing factor for decomposition. We have proposed a basis for an exhaustion/multiplication model. Considering a classical Frank-Read type multiplication mechanism, we express the yield stress as a function of temperature and we show that this results in an anomaly. Moreover, supposing that boron modifies vacancy migration energy, we suggest that the influence of boron on the stress anomaly stems from an increase of vacancy capture radius by mobile superdislocations. (authors)

  1. The Generation of AlmFe in Dilute Aluminium Alloys with Different Grain Refining Additions

    Science.gov (United States)

    Meredith, M. W.; Greer, A. L.; Evans, P. V.; Hamerton, R. G.

    Al13Fe4, Al6Fe and AlmFe are common intermetallics in commercial AA1XXX series Al alloys. Grain-refining additions (based on either Al-Ti-B or Al-Ti-C) are usually added to such alloys during solidification processing to aid the grain structure development. They also influence the favoured intermetallic and, hence, can affect the materials' properties. This work simulates commercial casting practices in an attempt to determine the mechanisms by which one intermetallic phase is favoured over another by the introduction of grain-refining additions. Directional solidification experiments on Al-0.3wt.%Fe-0.15wt.%Si with and without grain refiner are conducted using Bridgman apparatus. The type, amount and effectiveness of the grain-refining additions are altered and the resulting intermetallic phase selection followed. The materials are characterised using optical microscopy, scanning electron microscopy and X-ray diffraction. AlmFe is seen to form when Al-Ti-B grain-refiner is introduced but only when the refinement is successful; reducing the effectiveness of the refiner led to Al6Fe forming under all conditions. Al-Ti-C refiners are seen to promote AlmFe at lower solidification velocities than when Al-Ti-B was used even though the grain structure was not as refined. These trends can be explained within existing eutectic theory, by considering growth undercooling.

  2. About oxide dispersion particles chemical compatibility with areas coherent dissipation/sub-grains of bcc-alloys in Fe - (Cr, V, Mo, W systems

    Directory of Open Access Journals (Sweden)

    Udovsky A.

    2016-01-01

    Full Text Available A concept of partial magnetic moments (PMM of the iron atoms located in the first ч four coordination spheres (1÷4 CS for bcc lattice have been introduced based on analysis of results obtained by quantum-mechanical calculations (QMC for volume dependence of the average magnetic moment ferromagnetic (FM Fe. The values of these moments have been calculated for pure bcc Fe and bcc - Fe-Cr alloys. This concept has been used to formulate a three sub-lattice model for binary FM alloys of the Fe-M systems (M is an alloying paramagnetic element. Physical reason for sign change dependence of the short-range order and mixing enthalpy obtained by QMCs for Fe-(Cr, V bcc phases has been found. Using this model it has been predicted that static displacements of Fe - atoms in alloy matrix increase with increasing the of CS number and result in reducing of the area of coherent dissipation (ACD size with growth of the dimension factor (DF in the Fe-(Cr, V, Mo, W systems in agreement with the X-ray experiments. It has been shown theoretically that anisotropy of spin- density in bcc lattice Fe and DF in binary Fe - (Cr, V, Mo, W systems is main factor for origins of segregations on small angle boundaries of ACD and sub-grains boundaries To prevent the coagulation of both ACD and sub-grains, and to increase the strength of alloys, it is advisable to add oxide dispersion particles into ferrite steel taking into account their chemical compatibility and coherent interfacing with the crystalline lattice of a ferrite matrix. Application of phase diagrams for binary and ternary the Fe-(Y, Zr-O systems to verify chemical compatibility of oxide dispersion particles with ferrite matrix have been discussed

  3. Effect of cobalt on microstructure and properties of AlCr1.5CuFeNi2Cox high-entropy alloys

    Science.gov (United States)

    Kukshal, Vikas; Patnaik, Amar; Bhat, I. K.

    2018-04-01

    The present paper investigates the effect of Co addition on the alloying behaviour, microstructure and the resulting properties of cast AlCr1.5CuFeNi2Cox high-entropy alloys intended to be used for high temperature applications. The elements Al, Cr, Cu, Fe, Ni and Co (Purity > 99) weighing approximately 800 g was melted in a high temperature vacuum induction furnace. The microstructure, phase transformation, density, microhardness and compressive strength of the samples were analysed using x-ray diffraction (XRD), scanning electron microscopes (SEM), Vickers microhardness tester and universal Testing machine. The crystalline structure of the alloys exhibits simple FCC and BCC phases. The microstructures investigation of the alloys shows the segregation of copper in the interdendritic region resulting in Cu-rich FCC phase. The addition of Co further enhances the formation of FCC phase resulting in the decrease in micro hardness value of the alloys, which varies from 471 HV to 364 HV with increase in the cobalt content from x = 0 to x = 1 (molar ratio). The similar decreasing trend is also observed for the compressive strength of the alloys.

  4. Texturing for bulk α-Fe/Nd2Fe14B nanocomposites with enhanced magnetic properties

    International Nuclear Information System (INIS)

    Lou, L.; Hou, F.C.; Wang, Y.N.; Cheng, Y.; Li, H.L.; Li, W.; Guo, D.F.; Li, X.H.; Zhang, X.Y.

    2014-01-01

    In the present study, the texturing of bulk α-Fe/Nd 2 Fe 14 B nanocomposites produced from Nd-lean amorphous Nd x Fe 92.5−x Cu 1.5 B 6 (x=9 to 11.5 at%) via a hot deformation under a uniaxial stress of ∼350 MPa at 973 K has been studied. An enhanced (00l) texture of the hard phase is observed with increasing Nd content, which results in an increase in the magnetic anisotropy of the nanocomposite magnets. As a result, both the coercivity and the remanence of the magnets increase simultaneously with increasing Nd content from x=9–11.5 at%, yielding a significant enhancement of the maximum energy product from (BH) max =13.2 to 17.5 MGOe in the direction parallel to stress axis. - Highlights: • Textured bulk α-Fe/Nd 2 Fe 14 B nanocomposites have been produced from Nd-lean alloys. • Nd content has an effect on the texturing of α-Fe/Nd 2 Fe 14 B nanocomposite magnets. • An enhanced (00l) texture of hard phase is observed with increasing Nd content. • Both the coercivity and remanence increase simultaneously with Nd content

  5. Magnetic susceptibility of CoFeBSiNb alloys in liquid state

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V., E-mail: vesidor@mail.ru [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Hosko, J. [Institute of Physics SAS, Bratislava (Slovakia); Mikhailov, V.; Rozkov, I.; Uporova, N. [Ural State Pedagogical University, Ekaterinburg (Russian Federation); Svec, P.; Janickovic, D.; Matko, I.; Svec Sr, P. [Institute of Physics SAS, Bratislava (Slovakia); Malyshev, L. [Ural Federal University, Ekaterinburg (Russian Federation)

    2014-03-15

    The influence of small additions of gallium and antimony on magnetic susceptibility of the bulk glass forming Co{sub 47}Fe{sub 20.9}B{sub 21.2}Si{sub 4.6}Nb{sub 6.3} alloy was studied in a wide temperature range up to 1830 K by the Faraday’s method. The undercooling for all the samples was measured experimentally. Both Ga and Sb additions were found to increase liquidus and solidification temperatures. However, gallium atoms strengthen interatomic interaction in the melts, whereas antimony atoms reduce it. - Highlights: • Bulk metallic glasses from CoFeBSiNb-based alloys were produced as in situ composites. • Magnetic susceptibility of these alloys was measured in a wide temperature range including liquid state. • Undercooling of these melts was measured experimentally. • Ga additions strengthen interatomic interaction in BMG melts, whereas Sb atoms reduce it.

  6. Hyperfine interactions in dilute Se doped Fe{sub x}Sb{sub 1−x} bulk alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Mitesh, E-mail: miteshsarkar-msu@yahoo.com; Agrawal, Naveen [The M. S. University of Baroda, Department of Physics (India); Chawda, Mukesh [Polytechnic, The M. S. University of Baroda, Department of Applied Physics (India)

    2016-12-15

    Hyperfine Interaction technique like Moessbauer spectroscopy is a very sensitive tool to study the local probe interactions in Iron doped alloys and compounds. We report here the Moessbauer study of the effect of Fe concentration variations in dilute magnetic semiconducting Se{sub 0.004}Fe{sub x}Sb{sub 1−x} alloys for x = 0.002, 0.004 and 0.008. The materials were characterized using X-ray diffraction technique (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Neutron depolarization and Moessbauer spectroscopy. The FTIR result shows the semiconducting behavior of the alloys with band gap of 0.18 eV. From Moessbauer spectroscopy two magnetic sites (A and B) were observed. The value of hyperfine magnetic fields (HMF) of ∼ 308 kOe (site A) and 270 kOe (site B) was constant with increase in Fe concentration. A nonmagnetic interaction was also observed with quadrupole splitting (QS) of 1.26 mm/sec (site C) for x = 0.004 and x = 0.008. The Neutron depolarization studies indicate that the clusters of Fe or Fe based compounds having net magnetic moments with a size greater than 100 Å is absent.

  7. 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.

  8. Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

  9. 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.

  10. Positron lifetime measurements on electron irradiated amorphous alloys

    International Nuclear Information System (INIS)

    Moser, P.; Hautojaervi, P.; Chamberod, A.; Yli-Kauppila, J.; Van Zurk, R.

    1981-08-01

    Great advance in understanding the nature of point defects in crystalline metals has been achieved by employing positron annihilation technique. Positrons detect vacancy-type defects and the lifetime value of trapped positrons gives information on the size of submicroscopic vacancy aglomerates and microvoids. In this paper it is shown that low-temperature electron irradiations can result in a considerable increase in the positron lifetimes in various amorphous alloys because of the formation of vacancy-like defects which, in addition of the pre-existing holes, are able to trap positrons. Studied amorphous alloys were Fe 80 B 20 , Pd 80 Si 20 , Cu 50 Ti 50 , and Fe 40 Ni 40 P 14 B 6 . Electron irradiations were performed with 3 MeV electrons at 20 K to doses around 10 19 e - /cm 2 . After annealing positron lifetime spectra were measured at 77 K

  11. Magnetron Sputtering as a Fabrication Method for a Biodegradable Fe32Mn Alloy

    Directory of Open Access Journals (Sweden)

    Till Jurgeleit

    2017-10-01

    Full Text Available Biodegradable metals are a topic of great interest and Fe-based materials are prominent examples. The research task is to find a suitable compromise between mechanical, corrosion, and magnetic properties. For this purpose, investigations regarding alternative fabrication processes are important. In the present study, magnetron sputtering technology in combination with UV-lithography was used in order to fabricate freestanding, microstructured Fe32Mn films. To adjust the microstructure and crystalline phase composition with respect to the requirements, the foils were post-deposition annealed under a reducing atmosphere. The microstructure and crystalline phase composition were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, for mechanical characterization, uniaxial tensile tests were performed. The in vitro corrosion rates were determined by electrochemical polarization measurements in pseudo-physiological solution. Additionally, the magnetic properties were measured via vibrating sample magnetometry. The foils showed a fine-grained structure and a tensile strength of 712 MPa, which is approximately a factor of two higher compared to the sputtered pure Fe reference material. The yield strength was observed to be even higher than values reported in literature for alloys with similar composition. Against expectations, the corrosion rates were found to be lower in comparison to pure Fe. Since the annealed foils exist in the austenitic, and antiferromagnetic γ-phase, an additional advantage of the FeMn foils is the low magnetic saturation polarization of 0.003 T, compared to Fe with 1.978 T. This value is even lower compared to the SS 316L steel acting as a gold standard for implants, and thus enhances the MRI compatibility of the material. The study demonstrates that magnetron sputtering in combination with UV-lithography is a new concept for the fabrication of already in situ

  12. Study of the oxidation of Fe-Cr alloys at high temperatures; Estudo da oxidacao de ligas Fe-Cr a altas temperaturas

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, J.F.; Sabioni, A.C.S. [Universidade Federal de Ouro Preto (LDM/DF/UFOP), MG (Brazil). Dept. de Fisica. Lab. de Difusao em Materiais; Trindade, V.B. [Universidade Federal de Ouro Preto (DEMM/UFOP), MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais; Ji, V. [Laboratoire d' Etude des Materiaux Hors-Equilibre (LEMHE), Orsay (France)

    2010-07-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1{mu}g. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10{sup -9}g{sup 2}.cm{sup -4}.s{sup -1}, for the alloy Fe-1.5% Cr, to 1.18 x 10-14g{sup 2}.cm{sup -4}.s{sup -1} for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  13. Corrosion behaviour of Nd-Fe-B magnets containing Co and Cr

    International Nuclear Information System (INIS)

    Pawlowska, G.; Bala, H.; Szymura, S.

    1993-01-01

    The effect of partial substitution of iron by Co and Cr on corrosion behaviour of Nd 16 Fe 76 B 8 permanent magnets has been investigated. Small additions of Cr (1 to 4%at) are enough to ensure maximal corrosion inhibition. Greater amount of Cr into Nd-Fe-B alloy (>8%at), against expectations, practically do not affect the corrosion behaviour and additionally, considerably worsen its magnetic properties. Corrosion tests have shown a distinct effect of cobalt addition on the inhibition of both acid corrosion and the abnormal dissolution process of the Nd-Fe-Co-B magnets. Cobalt additions inhibit the atmosphere corrosion of Nd-Fe-B permanent magnets, especially a salt-spray environment. (author). 6 refs, 4 figs, 1 tab

  14. Effects of Fe and Cr on corrosion behavior of ZrFeCr alloys in 500 oC steam

    International Nuclear Information System (INIS)

    Wang Jun; Fan Hongyuan; Xiong Ji; Liu Hong; Miao Zhi; Ying Shihao; Yang Gang

    2011-01-01

    Research highlights: Amount and size of SPP will effect the corrosion resistance of Zr alloy at 500 o C/10.3 MPa. - Abstract: A study of the corrosion behaviors of ZrFeCr alloy and the influence of microstructure on corrosion resistance are described by X-ray diffraction and scanning electron microscope in this paper. The results show that several ZrFeCr alloys exhibit protective behavior throughout the test and oxide growth is stable and protective. The best alloy has the composition Zr1.0Fe0.6Cr. Fitting of the weight gain curves for the protective oxide alloys in the region of protective behavior, it showed nearly cubic behavior for the most protective alloys. The Zr1.0Fe0.6Cr has the more laves Zr(Fe,Cr) 2 precipitate in matrix and it has the better corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, the biggest hydrogen absorption and the worst corrosion resistance. The number of precipitates and the amount of hydrogen absorption in Zr alloy plays an important role on corrosion resistance behaviors in 500 o C/10.3 MPa steam.

  15. Preparation of Pr-Fe-Co-B-Nb-M (M= Al, P, Cu, Ga and/or Gd) HDDR magnets and alloys and characterization of their magnetic properties and corrosion resistance

    International Nuclear Information System (INIS)

    Oliveira, Mara Cristina Lopes de

    2009-01-01

    HDDR process has attracted great interest for producing polymer- bonded rare earth based magnets. It presents commercial advantages when compared with conventional sintered magnets owing to easy and low cost manufacturing. With the development of anisotropic powders using praseodymium, the expectations about this process grow e also the need for studying new compositions and alloy additions. In this work the magnetic properties of polymer-bonded magnets prepared with PrFeB magnetic alloys using HDDR process have been studied. Pr 14 Fe bal Co 16 B 6 Nb 0,1 was used as the reference alloy Phosphorus, copper, aluminium, gallium and gadolinium additions have been performed to increase the magnetic properties of the reference alloy. The microstructural characterization of the magnets has been carried out through optical microscopy and SEM. The complex microstructure influences the electrochemical behavior of the magnetic alloys. The literature about this subject is scarce. Thus, the corrosion resistance of the different alloys prepared during this work was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization curves. A correlation between the microstructural features and the electrochemical behavior of the alloys has been established. The results showed that phosphorus and aluminium additions up to 1.0wt% had a beneficial effect on the magnetic properties and corrosion resistance of the alloys. Copper additions, on the other hand, strongly diminished the magnetic properties of the reference alloy. (author)

  16. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness; Tratamiento termico de la aleacion amorfa base Fe 2605SA1, analisis de sus defectos y microdureza

    Energy Technology Data Exchange (ETDEWEB)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. El Cerillo Piedras Blancas, 50000 Toluca, Estado de Mexico (Mexico)

    2007-07-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  17. Amorphization of C-implanted Fe(Cr) alloys

    International Nuclear Information System (INIS)

    Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

    1991-01-01

    The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

  18. Study of structural, electronic and magnetic properties of CoFeIn and Co{sub 2}FeIn Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    El Amine Monir, M. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Baltache, H. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Abu-Jafar, M.S., E-mail: mabujafar@najah.edu [Dipartimento di Fisica Universita di Roma ' La Sapienza' , Roma (Italy); Department of Physics, An-Najah N. University, Nablus, Palestine (Country Unknown); Bouhemadou, A. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); and others

    2015-11-15

    The structural, electronic and magnetic properties of half-Heusler CoFeIn and full-Heusler Co{sub 2}FeIn alloys have been investigated by using the state of the art full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential was treated with the generalized gradient approximation (PBE-GGA) for the calculation of the structural properties, whereas the PBE-GGA+U approximation (where U is the Hubbard Coulomb energy term) is applied for the computation of the electronic and magnetic properties in order to treat the “d” electrons. The structural properties have been calculated in the paramagnetic and ferromagnetic phases where we have found that both the CoFeIn and Co{sub 2}FeIn alloys have a stable ferromagnetic phase. The obtained results of the spin-polarized band structure and the density of states show that the CoFeIn alloy is a metal and the Co{sub 2}FeIn alloy has a complete half-metallic nature. Through the obtained values of the total spin magnetic moment, we conclude that in general, the Co{sub 2}FeIn alloy is half-metallic ferromagnet material whereas the CoFeIn alloy has a metallic nature. - Highlights: • Based on DFT calculations, CoFeIn and Co2FeIn Heusler alloys were investigated. • The magnetic phase stability was determined from the total energy calculations. • Electronic properties reveal the metallic (half-metallic) nature for CoFeIn (Co2FeIn)

  19. A study of the process of Nd{sub 15} Fe{sub 77} B{sub 8} magnetic alloy preparation by calciothermic reduction diffusion (R/D); Estudo do processo de obtencao da liga magnetica Nd{sub 15} Fe{sub 77} B{sub 8} por reducao-difusao (R/D) calciotermica

    Energy Technology Data Exchange (ETDEWEB)

    Graca Guilherme, Eneida da; Paschoal, Jose O.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1992-12-31

    In this work the manufacturing of Nd{sub 15}, Fe{sub 77}, B{sub 8} alloy powder for high-performance permanent magnets by reduction-diffusion process was investigated. The effect of variables such as the excess amount of neodymium oxide, the removal of calcium oxide by selective leaching and milling of alloy was examined. (author). 8 refs., 8 figs., 5 tab.s.

  20. Investigation of structural relaxation, crystallization process and magnetic properties of the Fe-Ni-Si-B-C amorphous alloy

    International Nuclear Information System (INIS)

    Kalezic-Glisovic, A.; Novakovic, L.; Maricic, A.; Minic, D.; Mitrovic, N.

    2006-01-01

    The differential scanning calorimetry method was used for investigating the crystallization process of the Fe 89.8 Ni 1.5 Si 5.2 B 3 C 0.5 amorphous alloy. It was shown that the examined alloy crystallizes in three stages. The first crystallization stage occurs at 799 K, the second at 820 K and the third at 888 K. Temperature dependence of the magnetic susceptibility relative change was investigated by the modified Faraday method in the temperature region from room temperature up to 900 K. It has been established that the Curie temperature is about 700 K for amorphous state. The magnetic susceptibility increases by 30% after the first heating up to 710 K. During the second heating up to 840 K the alloy loses its ferromagnetic features in the temperature region from 710 to 750 K, upon which it again regains the same. After the second heating magnetic susceptibility decreases by 23% as compared to the amorphous starting value and by 53% as compared to the value before the second heating. The crystallized alloy maintains ferromagnetic features in the whole temperature region during the heating up to 900 K

  1. Investigation of structural relaxation, crystallization process and magnetic properties of the Fe-Ni-Si-B-C amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kalezic-Glisovic, A. [Joint Laboratory for Advanced Materials of SASA, Section for Amorphous Systems, Technical Faculty Cacak, Svetog Save 65, 32000 Cacak (Serbia and Montenegro)]. E-mail: aleksandrakalezic@eunet.yu; Novakovic, L. [Faculty of Physics, Studentski trg 16, 11000 Belgrade (Serbia and Montenegro); Maricic, A. [Joint Laboratory for Advanced Materials of SASA, Section for Amorphous Systems, Technical Faculty Cacak, Svetog Save 65, 32000 Cacak (Serbia and Montenegro); Minic, D. [Faculty of Physical Chemistry, Studentski trg 16, 11000 Belgrade (Serbia and Montenegro); Mitrovic, N. [Joint Laboratory for Advanced Materials of SASA, Section for Amorphous Systems, Technical Faculty Cacak, Svetog Save 65, 32000 Cacak (Serbia and Montenegro)]. E-mail: nmitrov@tfc.kg.ac.yu

    2006-07-15

    The differential scanning calorimetry method was used for investigating the crystallization process of the Fe{sub 89.8}Ni{sub 1.5}Si{sub 5.2}B{sub 3}C{sub 0.5} amorphous alloy. It was shown that the examined alloy crystallizes in three stages. The first crystallization stage occurs at 799 K, the second at 820 K and the third at 888 K. Temperature dependence of the magnetic susceptibility relative change was investigated by the modified Faraday method in the temperature region from room temperature up to 900 K. It has been established that the Curie temperature is about 700 K for amorphous state. The magnetic susceptibility increases by 30% after the first heating up to 710 K. During the second heating up to 840 K the alloy loses its ferromagnetic features in the temperature region from 710 to 750 K, upon which it again regains the same. After the second heating magnetic susceptibility decreases by 23% as compared to the amorphous starting value and by 53% as compared to the value before the second heating. The crystallized alloy maintains ferromagnetic features in the whole temperature region during the heating up to 900 K.

  2. Gamma→alpha transformation during cooling of Fe-Mn alloys

    International Nuclear Information System (INIS)

    Shtejnberg, M.M.; Mirzaev, D.A.; Ponomareva, T.N.

    1977-01-01

    Consideration is given to the effect of the cooling rate on the temperatures of γ→α transformation initiation, the structure and microhardness of Fe-Mn alloys. The general principles governing phase transformations in these alloys are similar to those which have been the subject of earlier investigations for Fe-Ni, Fe-Cr, Fe-Mo systems. It has been found that the higher manganese content results in a more intensive temperature drop for all the stages and elimination of stage 111 at a relatively low manganese content. Support is provided for the existence of the four stages of γ→α transformation in the iron alloys. The yield point, ultimate strength and microhardness of each alloy are related by Petch's relations to the size of the martensite packet which at the given grain size of the γsup(')-phase is defined by a transformation stage and a cooling rate at the given stage

  3. Solution-phase synthesis of single-crystalline Fe3O4 magnetic nanobelts

    International Nuclear Information System (INIS)

    Li Lili; Chu Ying; Liu Yang; Wang Dan

    2009-01-01

    Single-crystalline Fe 3 O 4 nanobelt was first synthesized on a large scale by a facile and efficient hydrothermal process. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The SAED pattern obtained from a typical individual nanobelt has a highly symmetrical dotted lattice, which reveals the single-crystalline nature of belt-like Fe 3 O 4 . The saturation magnetization of the Fe 3 O 4 nanobelt is higher than the wire, hollow sphere and octahedral structure. Such methods are easy and mild, and could synthesize other metal oxide in such experiment situation

  4. Effect of site disorder on the electronic properties of Fe2VAl Heusler alloy

    International Nuclear Information System (INIS)

    Venkatesh, Ch.; Srinivas, V.; Rao, V.V.; Srivastava, S.K.; Babu, P. Sudheer

    2013-01-01

    Highlights: •The role of site-disorder on physical properties of Fe 2 VAl has been investigated through experiments as well as DFT calculations. •Metal to semiconductor-like behaviour in electrical transport of anti-site disordered Fe 2 VAl was consistently explained. •Both itinerant and localized magnetic behaviours of anti-site disordered Fe 2 VAl are discussed. •Justification of metallic-like transition in site-disordered Fe 2 VAl is given. -- Abstract: Ab initio calculations on ordered L2 1 structure of Fe 2 VAl alloy have been carried out by introducing B2, DO 3 , A2′ and XY–XZ type disorders in order to understand the role of anti-site disorder on magnetic and transport properties. These studies show an enhancement of individual spin moments of anti-site Fe atoms in DO 3 , A2′ and XY–XZ type anti-site disorder, making the Fe 2 VAl alloy magnetically active. These calculations also show that hybridization due to covalent distribution of valance states among the atoms is important in Fe 2 VAl, defining its unusual physical properties. From the density of states spectrum obtained near the Fermi level, we have noticed formation of intermediate defect-like states that couple the edges of the pseudo gap on both sides of the Fermi level, driving the material from semi-metallic to metallic type in electrical transport. We also present experimental results on structural, magnetic and electrical properties of Fe 2 VAl Heusler alloy. A comparison of present experimental data with calculations shows an existence of DO 3 type anti-site disorder due to the Al-deficiency in Fe 2 VAl alloy which causes deviations in theoretical results on the magnetic and transport behaviour of pure Fe 2 VAl. The temperature dependence of electrical transport and magnetic data analysed on the basis of impurity band model which provides convincing evidence for itinerant character of this alloy system with an anti-site disorder

  5. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

    International Nuclear Information System (INIS)

    Jin, Y.; O'Connell, A.; Kharel, P.; Lukashev, P.; Staten, B.; Tutic, I.; Valloppilly, S.; Herran, J.; Mitrakumar, M.; Bhusal, B.; Huh, Y.; Yang, K.; Skomski, R.; Sellmyer, D. J.

    2016-01-01

    The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2 1 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T C ) significantly above room temperature. The measured T C for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ B /f.u. and 2.78 μ B /f.u., respectively, which are close to the theoretically predicted value of 3 μ B /f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

  6. Preparation and characterisation of Co–Fe–Ni–M-Si–B (M = Zr, Ti) amorphous powders by wet mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

    2016-07-15

    Co-based amorphous alloys were prepared via wet mechanical alloying process starting from elemental powders. The reference alloy Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 9} (at. %) as well as the alloys derived from this composition by the substitution of 5 at.% of Zr or Ti for Si or B (Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 4}Zr{sub 5}, Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 4}Ti{sub 5}, Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 10}B{sub 9}Zr{sub 5} and Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 10}B{sub 9}Ti{sub 5}) are obtained in amorphous state, according to X-ray diffraction (XRD) investigation, after 40 h of milling. The calculated amount of amorphous fraction reaches 99% after 40 h of milling. The largest increase of the crystallisation temperature was induced by the substitution of Zr or Ti for Si while, regardless of the type of substitution, an important increase of the Curie temperature of the alloy was obtained. A Co-based solid solution, with Co{sub 2}Si and Co{sub 2}B phases, result after crystallisation of the amorphous alloys as proved by XRD investigations. Saturation magnetisation of the alloys decreases upon increasing milling time, however it remains larger than the saturation magnetisation of the reference alloy. This was discussed in correlation with the specificity of the wet mechanical alloying process and the influence of the chemical bonding between Co and metalloids atoms over the magnetic moment of Co. - Highlights: • Co–Fe–Ni–M-Si–B (M = Zr, Ti) amorphous powders were prepared by wet MA. • Amorphisation of the alloy is reached after 40 h of wet MA for any composition. • Magnetisation decrease upon increasing milling time. • Substituting 5% Zr/Ti for Si increases significantly the alloy's thermal stability. • Substitution of 5 at. % Zr/Ti for Si increases the saturation magnetisation by 20%.

  7. Magnetic x-ray linear dichroism of ultrathin Fe-Ni alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, F.O.; Willis, R.F. [Pennsylvania State Univ., University Park, PA (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have studied the magnetic structure of ultrathin Fe-Ni alloy films as a function of Fe concentration by measuring the linear dichroism of the 3p-core levels in angle-resolved photoemission spectroscopy. The alloy films, grown by molecular-beam epitaxy on Cu(001) surfaces, were fcc and approximately four monolayers thick. The intensity of the Fe dichroism varied with Fe concentration, with larger dichroisms at lower Fe concentrations. The implication of these results to an ultrathin film analogue of the bulk Invar effect in Fe-Ni alloys will be discussed. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  8. Corrosion behavior of amorphous and crystalline Cu50Ti50 and Cu50Zr50 alloys

    International Nuclear Information System (INIS)

    Naka, M.; Hoshimoto, K.; Masumoto, T.

    1978-01-01

    Corrosion rates and anodic polarization curves of amorphous and crystalline Cu 50 Ti 50 and Cu 50 Zr 50 alloys have been examined in various acidic, neutral and alkaline solutions. The amorphous alloys are very stable in acidic and alkaline solutions, but unstable in agressive chloride solutions. The corrosion resistance of these amorphous alloys is higher than that of the crystallized alloys. The high corrosion resistance of amorphous alloys is attributable to the high chemical homogeneity of amorphous alloys without localized crystalline defects such as precipitates, segregates, grain boundaries, etc. Metalloid elements play an important role in the corrosion behavior of amorphous alloys; the addition of phosphorus to amorphous Cu-Ti alloy greatly increases the corrosion resistance, even in 1N HCl. (Auth.)

  9. A novel sandwich Fe-Mn damping alloy with ferrite shell prepared by vacuum annealing

    Science.gov (United States)

    Qian, Bingnan; Peng, Huabei; Wen, Yuhua

    2018-04-01

    To improve the corrosion resistance of high strength Fe-Mn damping alloys, we fabricated a novel sandwich Fe-17.5Mn damping alloy with Mn-depleted ferrite shell by vacuum annealing at 1100 °C. The formation behavior of the ferrite shell obeys the parabolic law for the vacuum annealed Fe-17.5Mn alloy at 1100 °C. The sandwich Fe-17.5Mn alloy with ferrite shell exhibits not only better corrosion resistance but also higher damping capacity than the conventional annealed Fe-17.5Mn alloy under argon atmosphere. The existence of only ferrite shell on the surface accounts for the better corrosion in the sandwich Fe-17.5Mn alloy. The better damping capacity in the sandwich Fe-17.5Mn alloy is owed to more stacking faults inside both ɛ martensite and γ austenite induced by the stress from ferrite shell. Vacuum annealing is a new way to improve the corrosion resistance and damping capacity of Fe-Mn damping alloys.

  10. Nanocomposite Nd-Y-Fe-B-Mo bulk magnets prepared by injection casting technique

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Shan [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Ahmad, Zubair [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Pengyue [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China); Yan, Mi, E-mail: mse_yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zheng, Xiaomei [Magnetism Key Laboratory of Zhejiang Province, China Jiliang University, Hangzhou 310018 (China)

    2017-09-01

    Highlights: • Nanocomposite Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets were synthesized by injection casting. • High coercivity of 1289 kA/m was obtained for the directly casted magnet. • Magnetic properties arise from magnetically exchange coupled soft and hard phases. - Abstract: The phase composition, magnetic and microstructural properties of Nd{sub 2}Fe{sub 14}B/(α-Fe, Fe{sub 3}B) nanocomposite magnets produced by injection casting technique have been studied. Magnetic hysteresis loop of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} permanent magnet demonstrates the coercivity as high as 1289 kA/m. Electron microscopy elucidates a microstructure composed of magnetically soft α-Fe, Fe{sub 3}B and hard Nd{sub 2}Fe{sub 14}B/Y{sub 2}Fe{sub 14}B nanograins (20–50 nm) separated by ultra-thin grain boundary layer. The Henkel plot curve of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} magnet yields the existence of exchange coupling interactions between soft and hard phases. Macroscopically large size sheet magnet is obtained due to high glass forming ability of the Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} alloy derived from large atomic radius mismatch and negative enthalpy of alloy constituent elements. The high coercivity of the magnet is attributed to the magnetically hard phase increment, nucleation of reverse domains and the presence of thin grain boundary phase. Good magnetic properties such as remanence of 0.51 T, coercivity of 1289 kA/m and maximum energy product of 46.2 kJ/m{sup 3} are obtained in directly casted Nd{sub 7}Y{sub 6}Fe{sub 61}B{sub 22}Mo{sub 4} sheet magnets.

  11. Phase martensitic transformation study in mechanically alloyed Ti{sub 50}Ni{sub 25}Fe{sub 25} alloy via high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Joao Cardoso de; Ferreira, Ailton da Silva, E-mail: joao.cardoso.lima@ufsc.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis (Brazil); Rovani, Pablo Roberto; Pereira, Altair Soria [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil)

    2016-07-01

    Full text: Alloys based on titanium and nickel with shape memory effect (SME) have been widely investigated due to potential use in different areas of science and technology, such as electronics, medicine, and space.1 Among them, the superalloys Ti-Ni-Fe show high corrosion resistance and good mechanical properties even at high temperatures that make them suitable for use in applications such as power plant components that work under aggressive conditions. At room temperature, the TiNi alloy has a monoclinic (B19'), known as the martensitic phase. With increasing temperature, the B19' phase transforms into a trigonal/hexagonal (B19) phase, known as the R- or pre martensitic phase, which, in its turn, transforms into a cubic (B2) structure, known as the austenitic phase. On cooling to room temperature, the reverse B2→B19→B19' phase transformations are observed. Since the B19↔B19' transformation occurs at a temperature low enough to inhibit diffusion-controlled processes, it belongs to a class of diffusionless phase transformations known as martensitic transformations. For this study, a Ti{sub 50}Ni{sub 25}Fe{sub 25} (B2) alloy was prepared by mechanical alloying, and the effects of high pressures up to 18 GPa will be presented. The structural changes with increasing pressure were followed by recording in situ angle-dispersive X-ray diffraction (ADXRD) diffractograms, in transmission geometry, using a long fine focus Mo X-ray tube and an imaging plate detector. The obtained results were already reported in Ref [1]. (1) A. S. Ferreira, P. R. Rovani, J. C. de Lima, A. S. Pereira, J. Appl. Phys. 117 (2015). (author)

  12. Preparation of nanocrystalline Ce1-xSmx(Fe,Co)11Ti by melt spinning and mechanical alloying

    Science.gov (United States)

    Wuest, H.; Bommer, L.; Huber, A. M.; Goll, D.; Weissgaerber, T.; Kieback, B.

    2017-04-01

    Permanent magnetic materials based on Ce(Fe, Co)12-xTix with the ThMn12 structure are promising candidates for replacing NdFeB magnets. Its intrinsic magnetic properties are not far below the values of Nd2Fe14B, and the high amount of Fe and the fact that Ce is much more abundant and less expensive than Nd encourages the reasonable interest in these compounds. Nanocrystalline magnetic material of the composition Ce1-xSmxFe11-yCoyTi (x=0-1 and y=0; 1.95) has been produced by both melt spinning and mechanical alloying. Alloys containing only Ce as rare earth element (x=0) show coercivities below 77 kA/m, while for x=1 Hc,J values up to 392 kA/m are reached. Coercivity shows rather an exponential than a linear dependence on the gradual substitution of Ce by Sm.

  13. Wetting behavior of liquid Fe-C-Ti alloys on sapphire

    International Nuclear Information System (INIS)

    Gelbstein, M.; Froumin, N.; Frage, N.

    2008-01-01

    Wetting behavior in the (Fe-C-Ti)/sapphire system was studied at 1823 K. The wetting angle between sapphire and Fe-C alloys is higher than 90 deg. (93 deg. and 105 deg. for the alloys with 1.4 and 3.6 at.% C, respectively). The presence of Ti improves the wetting of the iron-carbon alloys, especially for the alloys with carbon content of 3.6 at.%. The addition of 5 at.% Ti to Fe-3.6 at.% C provides a contact angle of about 30 deg., while the same addition to Fe-1.4 at.% C decreases the wetting angle to 70 deg. only. It was established that the wetting in the systems is controlled by the formation of a titanium oxicarbide layer at the interface, which composition and thickness depend on C and Ti contents in the melt. The experimental observations are well accounted for by a thermodynamic analysis of the Fe-Ti-Al-O-C system

  14. Thermal treatment of the Fe78Si9B13 alloy in it amorphous phase studied by means of Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Cabral P, A.; Lopez, A.; Garcia S, F.

    2003-01-01

    The magnetic and microhardness changes, dependents of the temperature that occur in the Fe 78 Si 9 B 13 alloy in it amorphous state were studied by means of the Moessbauer spectroscopy and Vickers microhardness. According to the Moessbauer parameters and in particular that of the hyperfine magnetic field, this it changes according to the changes of the microhardness; i.e. if the microhardness increases, the hyperfine magnetic field increases. The registered increment of hardness in the amorphous state of this alloy should be considered as anomalous, according to the prediction of the Hall-Petch equation, the one that relates negative slopes with grain sizes every time but small. (Author)

  15. Hydrogen storage performance of Ti-V-based BCC phase alloys with various Fe content

    International Nuclear Information System (INIS)

    Yu, X.B.; Feng, S.L.; Wu, Z.; Xia, B.J.; Xu, N.X.

    2005-01-01

    The effect of Fe content on hydrogen storage characteristics of Ti-10Cr-18Mn-(32-x)V-xFe (x = 0, 2, 3, 4, 5) alloys has been investigated at 353 K. The X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images of the alloys present BCC and C14 two-phase structures for all of the Fe-containing alloys. With the increasing Fe content, the lattice parameters of the BCC phase decrease, which results in an increase of the hydrogen desorption plateau pressure of the alloys. Among the studied alloys, Ti-10Cr-18Mn-27V-5Fe alloy exhibits the smallest PCT plateau slope and a more suitable plateau pressure (0.1 MPa equ <1 MPa). The maximum and effective capacities of the alloy are 3.32 wt.% and 2.26 wt.%, respectively, which are higher than other reported Fe-containing BCC phase alloys. In addition, the V/Fe ratio in this alloy is close to that of (VFe) alloy, whose cost is much lower than that of pure V

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

    Science.gov (United States)

    Apparao, K. Ch; Birru, Anil Kumar

    2018-01-01

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

  17. Nanocrystalline Fe-Pt alloys. Phase transformations, structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, J.V.

    2006-12-21

    This work has been devoted to the study of phase transformations involving chemical ordering and magnetic properties evolution in bulk Fe-Pt alloys composed of nanometersized grains. Nanocrystalline Fe{sub 100-x}Pt{sub x} (x=40-60) alloys have been prepared by mechanical ball milling of elemental Fe and Pt powders at liquid nitrogen temperature. The as-milled Fe-Pt alloys consist of {proportional_to} 100 {mu}m sized particles constituted by randomly oriented grains having an average size in the range of 10-40 nm. Depending on the milling time, three major microstructure types have been obtained: samples with a multilayer-type structure of Fe and Pt with a thickness of 20-300 nm and a very thin (several nanometers) A1 layer at their interfaces (2 h milled), an intermediate structure, consisting of finer lamellae of Fe and Pt (below approximately 100 nm) with the A1 layer thickness reaching several tens of nanometers (4 h milled) and alloys containing a homogeneous A1 phase (7 h milled). Subsequent heat treatment at elevated temperatures is required for the formation of the L1{sub 0} FePt phase. The ordering develops via so-called combined solid state reactions. It is accompanied by grain growth and thermally assisted removal of defects introduced by milling and proceeds rapidly at moderate temperatures by nucleation and growth of the ordered phases with a high degree of the long-range order. In a two-particle interaction model elaborated in the present work, the existence of hysteresis in recoil loops has been shown to arise from insufficient coupling between the low- and the high-anisotropy particles. The model reveals the main features of magnetisation reversal processes observed experimentally in exchange-coupled systems. Neutron diffraction has been used for the investigation of the magnetic structure of ordered and partially ordered nanocrystalline Fe-Pt alloys. (orig.)

  18. 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.

  19. Strengthening of the brazed joint for single-crystalline molybdenum by using Mo-40%Ru-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hiraoka, Y. [Okayama Univ. of Science (Japan). Department of Applied Physics; Igarashi, T. [Tokyo Tungsten Co. Ltd., Toyama (Japan). Research and Development Division

    1998-12-01

    In this study, the bend properties of the single-crystalline molybdenum brazed by using Mo-40%Ru alloys containing boron of 1-6 mass%Ru alloy for the improvement of the joint strength was determined. (orig.) [Deutsch] Durchgefuehrt wurde die Herstellung von Verbindungen aus einkristallinem Molybdaen. Hierbei kamen Mo-40%Ru-Legierungen mit 1 bis 6 Gew.-% Bor als Lotmaterialien zum Einsatz. Festigkeit und Duktilitaet der Verbindungen wurden mittels 3-Punkt-Biegepruefung bei Raumtemperatur und unter fluessigem Stickstoff ermittelt. Die Bruchflaechen der Proben wurden mit Hilfe eines Rasterelektronenmikroskopes untersucht. Die Ergebnisse lassen sich wie folgt zusammenfassen: Der optimale Borgehalt bezueglich Festigkeit und Duktilitaet der geloeteten Verbindung liegt bei 2 Gew.-%. Die entsprechende Probe hat bei einem Biegewinkel von 100 bei Raumtemperatur nicht versagt. Auch unter fluessigem Stickstoff zeigte diese Probe eine Festigkeit in der Groessenordnung des einkristallinen Vollmaterials. (orig.)

  20. Martensitic Transformation and Superelasticity in Fe-Mn-Al-Based Shape Memory Alloys

    Science.gov (United States)

    Omori, Toshihiro; Kainuma, Ryosuke

    2017-12-01

    Ferrous shape memory alloys showing superelasticity have recently been obtained in two alloy systems in the 2010s. One is Fe-Mn-Al-Ni, which undergoes martensitic transformation (MT) between the α (bcc) parent and γ' (fcc) martensite phases. This MT can be thermodynamically understood by considering the magnetic contribution to the Gibbs energy, and the β-NiAl (B2) nanoprecipitates play an important role in the thermoelastic MT. The temperature dependence of critical stress for the MT is very small (about 0.5 MPa/°C) due to the small entropy difference between the parent and martensite phases in the Fe-Mn-Al-Ni alloy, and consequently, superelasticity can be obtained in a wide temperature range from cryogenic temperature to about 200 °C. Microstructural control is of great importance for obtaining superelasticity, and the relative grain size is among the most crucial factors.

  1. Measurement of thermoelectric power of Fe-Cu binary alloys

    International Nuclear Information System (INIS)

    Joubouji, Katsuo

    2007-01-01

    In INSS, non-destructive evaluation (NDE) of irradiation embrittlement of low alloy steel using thermoelectric power (TEP) measurement has been considered, as well as NDE of thermal aging of cast duplex stainless steel which has been studied in recent years. Material degradation is evaluated based on a relation between progress of the degradation and change in TEP due to change in material structure caused by the degradation event. So it is necessary for NDE of irradiation embrittlement to measure the change in TEP due to precipitation of Cu contained as an impurity, which is known as one of the reasons for the embrittlement. In this study, TEP of Fe-Cu binary alloys with different Cu content was measured for investigation of the relationship between TEP of the alloys and Cu content. In addition, appropriateness of measuring TEP of Fe-Cu binary alloy in the same way to measure TEP of duplex stainless steel was examined. It was found that increment of Cu contained in the alloys changed TEP in a negative direction and the rate was evaluated as -6.6μV/K/wt%Cu. There were the cases that it took 20 minutes for measurement values to become stable in measurement of Fe-Cu binary alloys. It was much longer than the time taken in measurement of duplex stainless steel. So the measurement time per a point was extended to 60 minutes in case of Fe-Cu binary alloys. (author)

  2. Effect of Nb on magnetic and mechanical properties of TbDyFe alloys

    Science.gov (United States)

    Wang, Naijuan; Liu, Yuan; Zhang, Huawei; Chen, Xiang; Li, Yanxiang

    2018-03-01

    The intrinsic brittleness in giant magnetostrictive material TbDyFe alloy has devastating influence on the machinability and properties of the alloy, thus affecting its applications. The purpose of this paper is to study the mechanical properties of the TbDyFe alloy by alloying with Nb element. The samples (Tb0.3Dy0.7)xFe2xNby (y = 0, 0.01, 0.04, 0.07, 0.1; 3x + y = 1) were melted in an arc melting furnace under high purity argon atmosphere. The microstructure, magnetostrictive properties and mechanical performance of the alloys were studied systematically. The results showed that NbFe2 phases were observed in the alloys with the addition of Nb. Moreover, both the NbFe2 phases and rare earth (RE)-rich phases were increased with the increasing of Nb element. The mechanical properties results revealed that the fracture toughness of the alloy with the addition of Nb enhanced 1.5-5 times of the Nb-free alloy. Both the NbFe2 phase and the RE-rich phase had the ability to prevent crack propagation, so that they can strengthen the REFe2 body. However, NbFe2 phase is a paramagnetic phase, which can reduce the magnetostrictive properties of the alloy by excessive precipitation.

  3. Amorphous and nanocrystalline Fe-Ni-Zr-B ribbons as sensing elements in magnetic field sensors

    International Nuclear Information System (INIS)

    Vertesy, G.; Idzikowski, B.

    2006-01-01

    Fe 81-x Ni x Zr 7 B 12 (x=20, 30, 40) melt-spun alloys were investigated as potential new material applied as a sensing element of a fluxgate-type high-sensitivity magnetic field sensor. The sensitivity of the magnetometer was increased by about 60% by using the amorphous or nanocrystalline Fe 41 Ni 40 Zr 7 B 12 alloy, compared with a standard reference sensing material. Application of this material can also extend the temperature range of the operation of the device

  4. Doping effects on structural and magnetic properties of Heusler alloys Fe2Cr1-xCoxSi

    Science.gov (United States)

    Liu, Yifan; Ren, Lizhu; Zheng, Yuhong; He, Shikun; Liu, Yang; Yang, Ping; Yang, Hyunsoo; Teo, Kie Leong

    2018-05-01

    In this work, 30nm Fe2Cr1-xCoxSi (FCCS) magnetic films were deposited on Cr buffered MgO (100) substrates by sputtering. Fe2Cr0.5Co0.5Si exhibits the largest magnetization and optimal ordered L21 cubic structure at in-situ annealing temperature (Tia) of 450°C. The Co composition dependence of crystalline structures, surface morphology, defects, lattice distortions and their correlation with the magnetic properties are analyzed in detail. The Co-doped samples show in-plane M-H loops with magnetic squareness ratio of 1 and increasing anisotropy energy density with Co composition. Appropriate Co doping composition promotes L21 phase but higher Co composition converts L21 to B2 phase. Doping effect and lattice mismatch both are proved to increase the defect density. In addition, distortions of the FCCS lattice are found to be approximately linear with Co composition. The largest lattice distortion (c/a) is 0.969 for Fe2Cr0.25Co0.75Si and the smallest is 0.983 for Fe2CrSi. Our analyses suggest that these tetragonal distortions mainly induced by an elastic stress from Cr buffer account for the large in-plane anisotropy energy. This work paves the way for further tailoring the magnetic and structural properties of quaternary Heusler alloys.

  5. First principles study on the magnetocrystalline anisotropy of Fe–Ga magnetostrictive alloys

    International Nuclear Information System (INIS)

    Lei, Zheng; Cheng-Bao, Jiang; Jia-Xiang, Shang; Hui-Bin, Xu

    2009-01-01

    This paper investigates the electronic structure and magnetocrystalline anisotropy of Fe-Ga magnetostrictive material by means of the full potential-linearized augmented plane-wave method within the generalized gradient approximation. The 3d-orbit splitting of Fe atoms in D0 3 , B2-like and L1 2 crystalline structures of Fe–Ga is calculated with consideration of the crystal field as well as the spin–orbit coupling effect. Because of the frozen orbital angular momenta of the 3d-orbit for Fe atoms in Fe–Ga magnetostrictive alloys and the spin–orbit coupling, the distribution of the electron cloud is not isotropic, which leads to the anisotropy of exchange interaction between the different atoms. A method on estimating the magnetocrystalline anisotropy of Fe–Ga alloys by means of calculating orbit-projected density of states for Fe atoms is performed. The anisotropic distribution of the electron cloud of Fe atoms in these three crystalline structures of Fe–Ga is studied based on the above method showing the highest magnetic anisotropy for B2-like structure. This qualitative method comes closer to physical reality with a vivid physical view, which can evaluate the anisotropy of electron cloud for 3d transition atoms directly. The calculated results are in good agreement with both the previous theoretical computation and the tested value on the magnetic anisotropy constant, which confirms that the electron cloud anisotropy of Fe atoms could well characterize the magnetocrystalline anisotropy of Fe–Ga magnetostrictive material. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

    International Nuclear Information System (INIS)

    Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching; Lee, Chih-Jhan; Ho, Wen-Fu

    2010-01-01

    In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable β phase began. However, when 4 mass% Fe or greater was added, the β phase was entirely retained with a bcc crystal structure. Moreover, the ω phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of ω phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9 o ) and Ti-5Nb-5Fe (29.5 o ) alloys were greater than that of c.p. Ti (2.7 o ) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

  7. Structure and mechanical properties of as-cast Ti-5Nb-xFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Hsu, Shih-Kuang; Wu, Shih-Ching [Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung 40605, Taiwan (China); Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Changhua 51591, Taiwan (China); Lee, Chih-Jhan [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China); Ho, Wen-Fu, E-mail: fujii@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Changhua 51591, Taiwan (China)

    2010-09-15

    In this study, as-cast Ti-5Nb and a series of Ti-5Nb-xFe alloys were investigated and compared with commercially pure titanium (c.p. Ti) in order to determine their structure and mechanical properties. The series of Ti-5Nb-xFe alloys contained an iron content ranging from 1 to 5 mass% and were prepared by using a commercial arc-melting vacuum-pressure casting system. Additionally, X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer, and three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). The experimental results indicated that these alloys possessed a range of different structures and mechanical properties dependent upon the various additions of Fe. With an addition of 1 mass% Fe, retention of the metastable {beta} phase began. However, when 4 mass% Fe or greater was added, the {beta} phase was entirely retained with a bcc crystal structure. Moreover, the {omega} phase was only detected in the Ti-5Nb-2Fe, Ti-5Nb-3Fe and Ti-5Nb-4Fe alloys. The largest quantity of {omega} phase and the highest bending modulus were found in the Ti-5Nb-3Fe alloy. The Ti-5Nb-2Fe alloy had the lowest bending modulus, which was lower than that of c.p. Ti by 20%. This alloy exhibited the highest bending strength/modulus ratio of 26.7, which was higher than that of c.p. Ti by 214%, and of the Ti-5Nb alloy (14.4 ) by 85%. Additionally, the elastically recoverable angles of the ductile Ti-5Nb-1Fe (19.9{sup o}) and Ti-5Nb-5Fe (29.5{sup o}) alloys were greater than that of c.p. Ti (2.7{sup o}) by as much as 637% and 993%, respectively. Furthermore, the preliminary cell culturing results revealed that the Ti-5Nb-xFe alloys were not only biocompatible, but also supported cell attachment.

  8. Formation of metastable phases and nanocomposite structures in rapidly solidified Al-Fe alloys

    International Nuclear Information System (INIS)

    Nayak, S.S.; Chang, H.J.; Kim, D.H.; Pabi, S.K.; Murty, B.S.

    2011-01-01

    Highlights: → Structures of nanocomposites in rapidly solidified Al-Fe alloys were investigated. → Nanoquasicrystalline, amorphous and intermetallics phases coexist with α-Al. → Nanoquasicrystalline phase was observed for the first time in the dilute Al alloys. → Thermodynamic driving force plays dominant role in precipitation of Fe-rich phases. → High hardness (3.57 GPa) was observed for nanocomposite of Al-10Fe alloy. - Abstract: In the present work the structure and morphology of the phases of nanocomposites formed in rapidly solidified Al-Fe alloys were investigated in details using analytical transmission electron microscopy and X-ray diffraction. Nanoquasicrystalline phases, amorphous phase and intermetallics like Al 5 Fe 2 , Al 13 F 4 coexisted with α-Al in nanocomposites of the melt spun alloys. It was seen that the Fe supersaturation in α-Al diminished with the increase in Fe content and wheel speed indicating the dominant role of the thermodynamic driving force in the precipitation of Fe-rich phases. Nanoquasicrystalline phases were observed for the first time in the dilute Al alloys like Al-2.5Fe and Al-5Fe as confirmed by high resolution TEM. High hardness (3.57 GPa) was measured in nanocomposite of Al-10Fe alloy, which was attributed to synergistic effect of solid solution strengthening due to high solute content (9.17 at.% Fe), dispersion strengthening by high volume fraction of nanoquasicrystalline phase; and Hall-Petch strengthening from finer cell size (20-30 nm) of α-Al matrix.

  9. Moessbauer spectroscopy of Fe-Mn-Cu alloys

    International Nuclear Information System (INIS)

    Paduani, Clederson; Krause, Joao Carlos; Yoschida, M.I. Soares

    2004-01-01

    Full text: Although a continuous series of solid solutions exists between Cu and Mn, Fe and Cu are miscible only a few percent at higher temperatures. In moderately concentrated Cu-Mn alloys the Mn moments are bound to the long ranged antiferromagnetic order and the perpendicular components form an X-Y spin glass. Copper alloys are largely employed in various industrial applications. In this work we study the magnetic properties of iron-rich disordered Fe-Mn-Cu alloys with the bcc structure with the experimental techniques of X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and thermogravimetry (TGA). We investigate the formation of a solid solution with the bcc structure as well as the effect of the composition on the structural and magnetic properties of these alloys. A Rietveld analysis of the XRD diffractograms indicate that all prepared samples are single phase and are well crystallized with a bcc structure. (author)

  10. Crystallographic parameters of magnetic Pr{sub 2}Fe{sub 14−x}Co{sub x}B-type alloys determined using anomalous x-ray diffraction with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Galego, E., E-mail: egalego@ipen.br; Serna, M.M.; Ramanathan, L.V.; Faria, R.N.

    2017-02-15

    Anomalous x-ray synchrotron diffraction was used to determine the crystallographic parameters of PrFeCoB-based magnetic alloys. The effect of cobalt concentration on the crystallographic parameters of the magnetically hard Pr{sub 2}Fe{sub 14−x}Co{sub x}B phase was studied. The results indicate that addition of cobalt has a marked effect on crystal structure. Variation of the c parameter decreased twice as much as the a parameter with increase in Co content. The positions of inequivalent atoms of the magnetically hard matrix phase ϕ in the Pr-based alloys were determined using Rietveld refinement. This permitted determination of the relative distance of each inequivalent atom from its nearest neighbors. Cobalt occupied the 16k{sub 2} site and Fe had a tendency to occupy the 8j{sub 2} sites located between the Kagomé layers. - Highlights: • Good magnetics properties can be achieved with addition of 4% and 8% Co. • Rietveld refinement is proposed for crystallographic parameters studies. • Co has preference to substitute Fe in 16k{sub 2} site and avoid the 8j{sub 2} site.

  11. Nuclear Magnetic Resonance (NMR) study of the nanocrystalline alloy Fe73.5 Cu1 Nb3 Si13.5 B9

    International Nuclear Information System (INIS)

    Aliaga-Guerra, D.; Iannarella, L.; Fontes, M.B.; Guimaraes, A.P.; Skorvanek, I.

    1994-05-01

    Nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloys were studied with spin echo NMR at 4.2 K, from 15 to 100 MHz. Several lines are observed, with signals from domains and domain walls. Signals at 50-90 MHz appear to arise from 93 Nb nuclei in the amorphous matrix and in the interface of the crystallites. (author). 5 refs, 3 figs

  12. 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.

  13. Effect of alloying Mo on mechanical strength and corrosion resistance of Zr-1% Sn-1% Nb-1% Fe alloy

    International Nuclear Information System (INIS)

    Sugondo

    2011-01-01

    It had been done research on Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy. The ingot was prepared by means of electrical electrode technique. The chemical analysis was identified by XRF, the metallography examination was perform by an optical microscope, the hardness test was done by Vickers microhardness, and the corrosion test was done in autoclave. The objective of this research were making Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy with Mo concentration; comparing effect of Mo concentration to metal characteristics of Zr-1%Sn-1%Nb-1%Fe which covered microstructure; composition homogeneity, mechanical strength; and corrosion resistance in steam, and determining the optimal Mo concentration in Zr-1%Sn-1%Nb-1%Fe-(x)% Mo alloy for nuclear fuel cladding which had corrosion resistance and high hardness. The results were as follow: The alloying Mo refined grains at concentration in between 0,1%-0,3% and the concentration more than that could coarsened grains. The hardness of the Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was controlled either by the flaw or the dislocation, the intersection of the harder alloying element, the solid solution of the alloying element and the second phase formation of ZrMo 2 . The corrosion rate of the Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was controlled by the second phase of ZrMo 2 . The 0.3% Mo concentration in Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was the best for second phase formation. The Mo concentration in between 0,3-0,5% in Zr-1%Sn-1%Nb-1%Fe-(x)%Mo alloy was good for the second phase formation and the solid solution. (author)

  14. Magnetic properties of amorphous alloys of Fe with La, Lu, Y, and Zr

    International Nuclear Information System (INIS)

    Heiman, N.; Kazama, N.

    1979-01-01

    In order to study the systematics of the Fe-Fe exchange in amorphous rare-earth--Fe alloys, without the complications associated with the magnetic characteristics of the rare-earth elements, amorphous films of Fe alloyed with La, Lu, Y, and Zr have been prepared with a wide range of Fe concentrations. Magnetization and Moessbauer-effect measurements were made. The magnetic properties of the alloys depended critically on the choice of rare earth (or rare-earth-like element). YFe and LuFe alloys were found to have spin-glass characteristics while LaFe and ZrFe alloys were found to be ferromagnetic, but with evidence that exchange fluctuations were nearly as large as the average exchange. Thus the nature of the Fe-Fe exchange interaction depends critically upon the species of the rare earth. The most important parameter in determining the magnetic behavior of these alloys appears to be the size of the rare-earth atom, with large rare-earth atoms resulting in a smaller ratio of exchange fluctuations to exchange. The same dependence of the magnetic properties upon rare-earth size appears to be important in the case of magnetic-rare-earth atoms; however, the effect of rare-earth--Fe exchange also becomes important and these effects are discussed

  15. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-13

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

  16. Influence of Al addition on the thermal stability and mechanical properties of Fe76.5-xCu1Si13.5b9Alx amorphous alloys

    Directory of Open Access Journals (Sweden)

    Sun Y.Y.

    2012-01-01

    Full Text Available This paper fabricated Fe76.5-xCu1Si13.5B9Alx (x=0,1,2,3,5,7 at.% amorphous ribbons using singleroller melt-spinning method. The effect of Al content on the thermal stability and mechanical properties was investigated. The results indicated that Al addition have little effect on the amorphous formation ability of the alloys. On the other hand, increasing the Al content can substantially increase Tx2, which corresponds to the crystallization of Fe borides. Nanoindentation tests indicated that hardness of the alloys increase slightly with increasing the Al content, and Young’s modulus has a complicated relationship with the Al content.

  17. 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.

  18. Investigation on the formation of Cu-Fe nano crystalline super-saturated solid solution developed by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Mojtahedi, M., E-mail: m.mojtahedi@gmail.com [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Goodarzi, M.; Aboutalebi, M.R. [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Ghaffari, M. [Department of Electrical and Electronics Engineering, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Soleimanian, V. [Department of Physics, Faculty of Science, Shahrekord University, P.O. Box 115, Shahrekord (Iran, Islamic Republic of)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer The deformation of the mechanically alloyed Cu-Fe powder is anisotropic. Black-Right-Pointing-Pointer The Rietveld method is more proper and results in smaller crystallite size than the Scherer and Williamson-Hall methods. Black-Right-Pointing-Pointer A dual phase super saturated solid solution achieved after 96 h of milling of the mixtures with 30, 50 and 70 wt.% of Iron. Black-Right-Pointing-Pointer A final proportion of approximately 85% FCC and 15% BCC structure obtained in all of the applied compositions. - Abstract: In this study, the formation of super saturated solid solution in the binary Cu-Fe system was investigated. Three powder blends with 30, 50 and 70 wt.% of Fe were milled for different times to 96 h. The variations of lattice parameter and inter-planar spacing were calculated and analyzed using X-ray diffraction analysis (XDA). The anisotropy of lattice deformation in the FCC phase was studied and the obtained results were compared to milled pure Cu powder. Furthermore, crystallite size was calculated using Scherer formula in comparison with Rietveld full profile refinement method. Considering the previous studies about the formation of non-equilibrium FCC and BCC phases, the phase evolution has been discussed and the proportion of each phase was calculated using Rietveld refinement method. Supplementary studies on the evolution of microstructure and formation of solid solution were carried out using high resolution transmission electron microscopy (HRTEM). Finally, high angle annular dark field (HAADF) imaging was utilized to find out the level of homogeneity in the resulting phases. While true alloying takes place in each phase, the final structure consists of both FCC and BCC nano-crystallites.

  19. Impact of Ion Bombardment on the Structure and Magnetic Properties of Fe78Si13B9 Amorphous Alloy

    Science.gov (United States)

    Wu, Yingwei; Peng, Kun

    2018-06-01

    Amorphous Fe78Si13B9 alloy ribbons were bombarded by ion beams with different incident angles ( θ ). The evolution of the microstructure and magnetic properties of ribbons caused by ion beam bombardment was investigated by x-ray diffraction, transmission electron microscope and vibrating sample magnetometer analysis. Low-incident-angle bombardment led to atomic migration in the short range, and high-incident-angle bombardment resulted in the crystallization of amorphous alloys. Ion bombardment induces magnetic anisotropy and affects magnetic properties. The effective magnetic anisotropy was determined by applying the law of approach to saturation, and it increased with the increase of the ion bombardment angle. The introduction of effective magnetic anisotropy will reduce the permeability and increase the relaxation frequency. Excellent high-frequency magnetic properties can be obtained by selecting suitable ion bombardment parameters.

  20. Studies on electrodeposition and characterization of the Ni–W–Fe alloys coatings

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Aldrighi Luiz M.; Costa, Josiane D.; Sousa, Mikarla B. de; Alves, José Jailson N. [Department of Chemical Engineering, Federal University of Campina Grande, Av. Aprígio Veloso, 882, 58429-970 Campina Grande (Brazil); Campos, Ana Regina N.; Santana, Renato Alexandre C. [Department of Education, Federal University of Campina Grande, R. Olho da Água da Bica, S. N., 58175-000 Cuité-Pb (Brazil); Prasad, Shiva, E-mail: prasad@deq.ufcg.edu.br [Department of Education, Federal University of Campina Grande, R. Olho da Água da Bica, S. N., 58175-000 Cuité-Pb (Brazil)

    2015-01-15

    Highlights: • Ni–W–Fe alloy resistant to corrosion has been obtained by electrodeposition. • Optimal temperature and current density for Ni–W–Fe alloy electrodeposition has been found. • Experimental design has been used as optimization tool. • Amorphous Ni–W–Fe alloy has been obtained. - Abstract: Corrosion has been responsible for industrial maintenance cost as well as for industrial accidents. A key to prevent corrosion is to develop advanced materials with highly anti-corrosive properties. The electrodeposition has been one of the most important techniques for obtaining these materials. The objective of this work is to develop and optimize the parameters to obtain a new Ni–W–Fe alloy with high resistance to corrosion. A factorial design 2{sup 2} with 2 center points was used to find the optimal current density and bath temperature for Ni–W–Fe electrodeposition. The influence of such variables on the cathodic current efficiency and polarization resistance were obtained. The alloys obtained with the highest current density (125 mA/cm{sup 2}) and the highest bath temperature (70 °C) had the best anticorrosive properties, which are superior to anticorrosive properties of Ni–W–Fe available in the literature. The obtained alloys had the highest tungsten content compared with other alloys studied of about 46 wt.%. The highest cathodic current efficiency was 34% for the alloy with a chemical composition of 3 wt.% Fe, 29 wt.% W and 68 wt.% Ni.

  1. A novel method combining additive manufacturing and alloy infiltration for NdFeB bonded magnet fabrication

    Science.gov (United States)

    Li, Ling; Tirado, Angelica; Conner, B. S.; Chi, Miaofang; Elliott, Amy M.; Rios, Orlando; Zhou, Haidong; Paranthaman, M. Parans

    2017-09-01

    In this paper, binder jetting additive manufacturing technique is employed to fabricate NdFeB isotropic bonded magnets, followed by an infiltration process with low-melting point eutectic alloys [i.e., Nd3Cu0.25Co0.75 (NdCuCo) and Pr3Cu0.25Co0.75 (PrCuCo)]. Densification and mechanical strength improvement are achieved for the as-printed porous part. Meanwhile, the intrinsic coercivity Hci is enhanced from 732 to 1345 kA/m and 1233 kA/m after diffusion of NdCuCo and PrCuCo, respectively. This study presents a novel method for fabricating complex-shaped bonded magnets with promising mechanical and magnetic properties.

  2. Production of NdFeB powders by HDDR from sintered magnets; Obtencao de pos de NdFeB por HDDR a partir de imas sinterizados

    Energy Technology Data Exchange (ETDEWEB)

    Janasi, S.R.; Rodrigues, D.; Landgraf, F.J.G. [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil). Lab. de Metalurgia e Materiais Ceramicos; Silva, B.F.A. da; Takiishi, H [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Campos, M.F. de [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2010-07-01

    The production of NdFeB powders by the HDDR process from metallic alloys has been widely investigated. Different HD and DR conditions have been used to induce anisotropy and to improve the intrinsic coercivity of the obtained powders. The purpose of this study is to apply the HDDR process in the reprocessing of NdFeB sintered magnet scraps. There were investigated different processing conditions as temperature and time of desorption and recombination (DR). The results of X ray diffraction show the formation of the magnetic phase Nd{sub 2}Fe{sub 14}B in all the investigated conditions. Magnetic measurements by vibrating sample magnetometer indicate that powders with intrinsic coercivity up to 790 kA/m were obtained. (author)

  3. Degradable and porous Fe-Mn-C alloy for biomaterials candidate

    Science.gov (United States)

    Pratesa, Yudha; Harjanto, Sri; Larasati, Almira; Suharno, Bambang; Ariati, Myrna

    2018-02-01

    Nowadays, degradable implants attract attention to be developed because it can improve the quality of life of patients. The degradable implant is expected to degrade easily in the body until the bone healing process already achieved. However, there is limited material that could be used as a degradable implant, polymer, magnesium, and iron. In the previous study, Fe-Mn-C alloys had succesfully produced austenitic phase. However, the weakness of the alloy is degradation rate of materials was considered below the expectation. This study aimed to produce porous Fe-Mn-C materials to improve degradation rate and reduce the density of alloy without losing it non-magnetic properties. Potassium carbonate (K2CO3) were chosen as filler material to produce foam structure by sintering and dissolution process. Multisteps sintering process under argon gas environment was performed to generate austenite phase. The product showed an increment of the degradation rate of the foamed Fe-Mn-C alloy compared with the solid Fe-Mn-C alloy without losing the Austenitic Structure

  4. Amorphous Al–Mn coating on NdFeB magnets: Electrodeposition from AlCl3–EMIC–MnCl2 ionic liquid and its corrosion behavior

    International Nuclear Information System (INIS)

    Chen Jing; Xu Bajin; Ling Guoping

    2012-01-01

    Amorphous Al–Mn coating was electrodeposited on NdFeB magnets from AlCl 3 –EMIC–MnCl 2 ionic liquid with the pretreatment of anodic electrolytic etching in AlCl 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 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: ► Amorphous Al–Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. ► To remove the surface oxides of NdFeB, anodic etching pretreatment is used. ► The deposited Al–Mn alloy coating shows high adhesion to the NdFeB substrate. ► Corrosion tests show that amorphous Al–Mn alloy coating is anodic coating for NdFeB magnet.

  5. Nitrogen versus helium: effects of the choice of the atomizing gas on the structures of Fe50Ni30Si10B10 and Fe32Ni36Ta7Si8B17 powders

    International Nuclear Information System (INIS)

    Zambon, A.

    2004-01-01

    Gas atomization can produce, besides a possible significant degree of undercooling, high cooling rates, whose extent depends on the size of the droplets, on their velocity with respect to the surrounding medium, on the thermo-physical properties of both the alloy and the gas, and of course on the operating conditions such as melt overheating and gas-to-metal flow ratio. In this respect it is well-known that the atomizing gas can play a significant role in determining both the powder size distribution and the kind and mix of phases which result from the solidification and cooling processes. The microstructures and solidification morphologies of powders obtained from nitrogen and helium sonic gas atomization of two iron-nickel base glass forming alloys, Fe 50 Ni 30 Si 10 B 10 and Fe 32 Ni 36 Ta 7 Si 8 B 17 , were investigated by means of light microscopy, X-ray diffraction (XRD) and differential thermal analysis (DTA). The Fe 32 Ni 36 Ta 7 Si 8 B 17 alloy exhibits a higher proneness to the development of amorphous phase than the Fe 50 Ni 30 Si 10 B 10 alloy, while the effect of the higher speed attainable by the stream of helium with respect to that of nitrogen, affords not only to obtain a larger amount of particles in the finer size ranges, but also to affect the relative amounts of phases within the different size fractions

  6. 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.

  7. Amorphous and nanocrystalline Fe-Ni-Zr-B ribbons as sensing elements in magnetic field sensors

    Energy Technology Data Exchange (ETDEWEB)

    Vertesy, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1525 Budapest, P.O.B. 49 (Hungary)]. E-mail: vertesyg@mfa.kfki.hu; Idzikowski, B. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, PL 60-179 Poznan (Poland)

    2006-04-15

    Fe{sub 81-x}Ni{sub x}Zr{sub 7}B{sub 12} (x=20, 30, 40) melt-spun alloys were investigated as potential new material applied as a sensing element of a fluxgate-type high-sensitivity magnetic field sensor. The sensitivity of the magnetometer was increased by about 60% by using the amorphous or nanocrystalline Fe{sub 41}Ni{sub 40}Zr{sub 7}B{sub 12} alloy, compared with a standard reference sensing material. Application of this material can also extend the temperature range of the operation of the device.

  8. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

    2000-01-01

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  9. Production of NdFeB powders by HDDR from sintered magnets

    International Nuclear Information System (INIS)

    Janasi, S.R.; Rodrigues, D.; Landgraf, F.J.G.; Campos, M.F. de

    2010-01-01

    The production of NdFeB powders by the HDDR process from metallic alloys has been widely investigated. Different HD and DR conditions have been used to induce anisotropy and to improve the intrinsic coercivity of the obtained powders. The purpose of this study is to apply the HDDR process in the reprocessing of NdFeB sintered magnet scraps. There were investigated different processing conditions as temperature and time of desorption and recombination (DR). The results of X ray diffraction show the formation of the magnetic phase Nd 2 Fe 14 B in all the investigated conditions. Magnetic measurements by vibrating sample magnetometer indicate that powders with intrinsic coercivity up to 790 kA/m were obtained. (author)

  10. 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.

  11. Characterization of crystallization kinetics of a Ni- (Cr, Fe, Si, B, C, P) based amorphous brazing alloy by non-isothermal differential scanning calorimetry

    International Nuclear Information System (INIS)

    Raju, S.; Kumar, N.S. Arun; Jeyaganesh, B.; Mohandas, E.; Mudali, U. Kamachi

    2007-01-01

    The thermal stability and crystallization kinetics of a Ni- (Cr, Si, Fe, B, C, P) based amorphous brazing foil have been investigated by non-isothermal differential scanning calorimetry. The glass transition temperature T g , is found to be 720 ± 2 K. The amorphous alloy showed three distinct, yet considerably overlapping crystallization transformations with peak crystallization temperatures centered around 739, 778 and 853 ± 2 K, respectively. The solidus and liquidus temperatures are estimated to be 1250 and 1300 ± 2 K, respectively. The apparent activation energies for the three crystallization reactions have been determined using model free isoconversional methods. The typical values for the three crystallization reactions are: 334, 433 and 468 kJ mol -1 , respectively. The X-ray diffraction of the crystallized foil revealed the presence of following compounds Ni 3 B (Ni 4 B 3 ), CrB, B 2 Fe 15 Si 3 , CrSi 2 , and Ni 4.5 Si 2 B

  12. Laboratory scale fabrication of Nd-Fe-B sintered magnets; Fabricacao de imas sinterizados de Nd-Fe-B em escala piloto

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Daniel; Beneduce Neto, Flavio; Landgraf, Fernando Jose Gomes; Neiva, Augusto Camara; Romero, Sergio; Missell, Frank Patrick

    1993-12-31

    Results are presented on magnetic properties of Nd-Fe-B sauntered magnets produced from 1 kg of alloy caste in vacuum induction furnace. The fabrication viability of these magnets, with properties similar to the commercial magnets, and the influence of particle size in the energy product, through the effect on the H{sub k} field, is confirmed 12 refs., 7 figs., 1 tab.

  13. Synthesis and characterization of iron-cobalt (FeCo) alloy nanoparticles supported on carbon

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Barfod, Rasmus; Eriksen, Kim Michael

    2017-01-01

    of the alloy nanoparticles differed depending on the preparation method. When the wet impregnation technique of acetate precursor salts of Fe and Co were used for the synthesis, the size of FeCo alloy nanoparticles was approximately 13 nm. FeCo alloy nanoparticles were characterized by crystallography (XRD...

  14. Effect of γ-(Fe,Ni) crystal-size stabilization in Fe-Ni-B amorphous ribbon

    Science.gov (United States)

    Gorshenkov, M. V.; Glezer, A. M.; Korchuganova, O. A.; Aleev, A. A.; Shurygina, N. A.

    2017-02-01

    The effect of stabilizing crystal size in a melt-quenched amorphous Fe50Ni33B17 ribbon is described upon crystallization in a temperature range of 360-400°C. The shape, size, volume fraction, and volume density have been investigated by transmission electron microscopy and X-ray diffraction methods. The formation of an amorphous layer of the Fe50Ni29B21 compound was found by means of atomic-probe tomography at the boundary of the crystallite-amorphous phase. The stabilization of crystal sizes during annealing is due to the formation of a barrier amorphous layer that has a crystallization temperature that exceeds the crystallization temperature of the matrix amorphous alloy.

  15. Mössbauer and XRD study of the Fe65Si35 alloy obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Vélez, G. Y.; Rodríguez, R. R.; Melo, C. A.; Pérez Alcázar, G. A.; Zamora, Ligia E.; Tabares, J. A.

    2011-01-01

    A study was made on the alloy Fe 65 Si 35 using x-ray diffraction and Mössbauer spectrometry. The alloy was obtained by mechanical alloying in a high energy planetary mill, with milling times of 15, 30, 50, 75 and 100 h. The results show that in the alloys two structural phases are present, a Fe-Si BCC disordered phase and ferromagnetic, and a Fe-Si SC phase, whose nature is paramagnetic and which decreases with milling time. In the temporal evolution of the milling two stages are differentiated: one between 15 and 75 h of milling, in which silicon atoms diffuse into the bcc matrix of iron and its effect is to reduce the hyperfine magnetic field; the other, after 75 h of milling, where the alloy is consolidated, the effect of the milling is only to increase the disorder of the system, increasing the magnetic order.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-02-23

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

  17. Temperature dependence of the magnetostriction in polycrystalline PrFe1.9 and TbFe2 alloys: Experiment and theory

    International Nuclear Information System (INIS)

    Tang, Y. M.; Chen, L. Y.; Huang, H. F.; Xia, W. B.; Zhang, S. Y.; Wei, J.; Tang, S. L.; Du, Y. W.; Zhang, L.

    2014-01-01

    A remarkable magnetostriction λ 111 as large as 6700 ppm was found at 70 K in PrFe 1.9 alloy. This value is even larger than the theoretical maximum of 5600 ppm estimated by the Steven's equivalent operator method. The temperature dependence of λ 111 for PrFe 1.9 and TbFe 2 alloys follows well with the single-ion theory rule, which yields giant estimated λ 111 values of about 8000 and 4200 ppm for PrFe 1.9 and TbFe 2 alloys, respectively, at 0 K. The easy magnetization direction of PrFe 1.9 changes from [111] to [100] as temperature decreases, which leads to the abnormal decrease of the magnetostriction λ. The rare earth sublattice moment increases sharply in PrFe 1.9 alloy with decreasing temperature, resulting in the remarkably largest estimated value of λ 111 at 0 K according to the single-ion theory

  18. Influence of microstructural change of the interface between Nd2Fe14B and Nd-O phases on coercivity of Nd-Fe-B films by oxidation and subsequent low-temperature annealing

    International Nuclear Information System (INIS)

    Matsuura, Masashi; Tezuka, Nobuki; Sugimoto, Satoshi; Goto, Ryota

    2011-01-01

    This study provides the influence of microstructural change of the interface between Nd 2 Fe 14 B and Nd-O phases on coercivity of Nd-Fe-B thin films during annealing at low temperature (∼350 deg. C). All films were prepared by using ultra high vacuum (UHV) magnetron sputtering, and the Nd-Fe-B layer was oxidized under Ar gas atmosphere (O 2 content; ∼2 Vol.ppm). Then, the films were annealed at 250-350 deg. C under UHV condition. After oxidation, the coercivity of Nd-Fe-B film decreased to around 40% of the coercivity of as-deposited Nd-Fe-B film. The Nd-rich phase changed from α-Nd to amorphous Nd(-O), and the interface of Nd 2 Fe 14 B/Nd(-O) became rough. In the Nd-Fe-B films oxidized and subsequent annealed at 350 deg. C, the coercivity decreased to around 20%. In the films, poly crystalline hcp Nd 2 O 3 phase crystallized in Nd-rich phase, and there were some steps at the surface of Nd 2 Fe 14 B phase contacting with hcp Nd 2 O 3 phase. Regardless of crystal orientation of Nd 2 Fe 14 B, the microstructural changes of the interface described above were observed.

  19. Investigation of Ti-Fe-Co bulk alloys with high strength and enhanced ductility

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.; Louzguina-Luzgina, Larissa V.; Kato, Hidemi; Inoue, Akihisa

    2005-01-01

    High-strength Ti-Fe-Co alloys were produced in the shape of arc-melted ingots with the dimensions of about 20-25mm in diameter and 7-10mm in height. The structure of the Ti-Fe-Co alloys (at Fe/Co ratio >1) studied by X-ray diffractometry and scanning electron microscopy consisted of an ordered Pm3-bar m Ti(FeCo) compound and a disordered body-centered cubic Im3-bar m β-Ti solid solution. The optimization of the Ti-Fe-Co alloy composition is performed from the viewpoint of both high strength and ductility. The strongest Ti-Fe-Co alloys have a hypereutectic structure and exhibit a high strength of about 2000MPa and a plastic deformation of 15%. The high strength and ductility values can be achieved without using the injection mould casting or rapid solidification procedure. The deformation behavior and the fractography of Ti-Fe-Co alloys are studied in detail

  20. Photoelectron spectroscopy study of Fe-diluted Au-Fe alloys

    CERN Document Server

    Nahm, T U; Choi, B; Park, J S; Oh, S J; Cho, E J

    2003-01-01

    The electronic structure of Fe-diluted Au-Fe alloys has been studied by taking core-level and valence-band spectra using x-ray photoemission spectroscopy and synchrotron radiation. From the core-level spectroscopy, we found that the Fe 2p spectrum is composed of d sup 6 and d sup 7 multiplets from Fe impurity atoms. This behaviour is qualitatively discussed within the context of electron-electron interaction. In order to explore the electron-correlation effects in the valence band, we obtained Fe 3d partial spectral weights by taking advantage of the Cooper-minimum phenomenon of an Au 5d photoionization cross section. It was found that the spin-down states have an appreciable amount of spectral weights throughout the host Au 5d band, contrary to previous one-electron calculations predicting two-peak structure of the Fe 3d states. We suggest that this discrepancy results from the correlation effect of the Fe 3d electrons.

  1. 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.

  2. 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

  3. Crystallization study of amorphous system Fe[sub 84-x]W[sub x]B[sub 16] (x = 3; 5)

    Energy Technology Data Exchange (ETDEWEB)

    Novakova, A.A.; Sidorova, G.V.; Kiseleva, T.Yu.; Szasz, A. (Dept. of Physics, State Univ., Moscow (Russia) Inst. of Metallurgy, Academy of Science, Moscow (Russia) Eoetvoes Univ., Budapest (Hungary))

    1992-10-01

    A complex study of the crystallization process of the amorphous system was carried out by Moessbauer spectroscopy, X-ray diffraction and DTA. Alloy samples crystallized at 600deg C contain the following phases: [alpha]-Fe, Fe[sub 3]B and solid solution (Fe, W)[sub 3]B. (orig.).

  4. Characterization and properties of sintered WC–Co and WC–Ni–Fe hard metal alloys

    International Nuclear Information System (INIS)

    Chang, Shih-Hsien; Chen, Song-Ling

    2014-01-01

    Highlights: • WC–Ni–Fe alloy sintered at 1400 °C had the highest hardness (HRA 85.3 ± 0.5). • The optimal WC–Ni–Fe sintered alloy possessed the highest TRS value (2524.5 ± 1.0 MPa). • The fracture toughness of the sintered WC–Ni–Fe alloys is mainly provided by the Ni–Fe binders. • WC–Ni–Fe sintered alloy possessed the highest fracture toughness of K IC (15.1 MPa m 1/2 ). • The WC–Ni–Fe sintered alloy had the much better corrosion resistance in 0.15 M HCl solution. -- Abstract: The aim of this study is to explore two different tungsten carbide binders (Co and Ni–Fe) and then impose various sintering temperature treatments. Experimental results show that the optimal sintering temperatures for WC–Co and WC–Ni–Fe hard metal alloys are 1350 °C and 1400 °C for 1 h, respectively. Meanwhile, the WC–Co and WC–Ni–Fe alloys undergo a well liquid-phase sintering and, thus, exhibit excellent mechanical properties. In addition, the sintered WC–Co and WC–Ni–Fe alloys show that when the relative density reached 99.76% and 99.68%, the hardness was enhanced to HRA 84.4 ± 0.5 and 85.3 ± 0.5, and the TRS increased to 2471.2 ± 1.0 and 2524.5 ± 1.0 MPa, respectively. Moreover, the corrosion test results show that the WC–Ni–Fe alloy sintered at 1400 °C had the lowest corrosion current (I corr ) of 1.11 × 10 −5 A cm −2 and the highest polarization resistance (R p ) of 2464.61 Ω cm 2 in 0.15 M HCl solution. Simultaneously, the fracture toughness of K IC increased to 15.1 MPa m 1/2 . Compared with sintered WC–Co alloys, the sintered WC–Ni–Fe hard metal alloys possessed much better corrosion resistance and mechanical properties

  5. Molecular dynamics study on threshold displacement energies in Fe-Cr alloys

    Science.gov (United States)

    Fu, Jiawei; Ding, Wenyi; Zheng, Mingjie; Mao, Xiaodong

    2018-03-01

    The threshold displacement energies (Ed) of Fe and Cr atoms in Fe-Cr alloys with Cr contents ranging from 0% to 21% have been obtained with molecular dynamics (MD) method. The values of Ed have been calculated along the three high-symmetry crystallographic directions [0 0 1], [0 1 1] and [1 1 1], a slightly 2° tilt from these directions, and a high-index crystallographic directions [1 3 5]. The results showed that [0 1 1] crystallographic direction had the highest Ed among the three high-symmetry directions in each Cr content alloy. Fe-9Cr had higher weighted average Ed than the other Cr content alloys for both Fe and Cr PKA due to its statistically high Ed along the [0 1 1] crystallographic direction up to 44.3 eV. And the statistical analysis on the primary damage configuration demonstrated that 〈1 1 0〉Fe-Fe dumbbells were the dominant defect structures after relaxation. These data can enrich the database of Ed in Fe-Cr alloys and have potential applications in guiding the optimization design of radiation-resistant RAFM steels.

  6. Effect of different factors on phase transformations in Fe-Mn alloys

    International Nuclear Information System (INIS)

    Balychev, Yu.M.; Tkachenko, F.K.

    1983-01-01

    Phase transformations proceeding under Fe-Mn alloy heating are studied and the effect of previous working conditions, particularly, cooling rate on these transformations is investigated. Investigations have been conducted on pure Fe-Mn alloys with 2-15% Mn. Phase transformations are shown to proceed according to α → #betta# and epsilon → #betta# reaction in Fe-Mn alloys containing 2-15% Mn under heating. Cooling rate in the range of approximately 5-1000 deg/min in preliminary working essentially affects phase transformations under subsequent heating

  7. Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

    2015-07-01

    The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

  8. Intermediate phases in the hydrogen disproportionated state of NdFeB-type powders

    International Nuclear Information System (INIS)

    Yi, G.; Chapman, J. N.; Brown, D. N.; Harris, I. R.

    2001-01-01

    Transmission electron microscopy studies have been carried out on partially disproportionated NdFeB-type alloys. A new intermediate magnetic (NIM) phase has been identified. Moreover, the lamella structure which subsequently develops from the tetragonal NIM phase comprises a tetragonal NdFe-containing (IL) phase and α-Fe. The experimental data show strong evidence of a well-defined crystallographic relation between both the NIM and lamella phases and between the IL phase and α-Fe. These observations give insight into how crystallographic texture, and hence anisotropy, can be developed in NdFeB-type powders processed by the hydrogenation, disproportionation, desorption, and recombination route. copyright 2001 American Institute of Physics

  9. Structural relaxation of FeNiB amorphous alloy

    International Nuclear Information System (INIS)

    Arcondo, B.; Moya, J.; Audebert, F.; Sirkin, H.

    1994-01-01

    Young's modulus was measured in rapidly quenched ribbons of Fe 44 Ni 38 B 18 annealed at a rate of 5 K/min up to different temperatures. An oscillating behavior was observed. Samples annealed up to temperatures that correspond to maxima and minima values of Young's modulus were studied with Moessbauer spectroscopy in order to correlate the macroscopic parameter with the hyperfine field distribution. (orig.)

  10. Response of metallic glasses Fe40Ni40P14B6 and Fe80B20 to irradiation with 800-MeV protons

    International Nuclear Information System (INIS)

    Cost, J.R.; Sommer, W.F.

    1981-01-01

    Metallic glasses with compositions of Fe 40 Ni 40 P 14 B 6 and Fe 80 B 20 were irradiated in the 800 MeV proton beam at the Los Alamos Meson Physics Facility while the electrical resistance and length changes were monitored. The resistance and the length of the first alloy were both found to increase and saturate with dose to ΔR/R approx. = 5 x 10 -3 and ΔL/L approx. = 2 x 10 -3 . For the second alloy the total dose of 1.1 x 10 19 p/cm 2 , which was calculated to give roughly 0.12 dpa, was slightly less than that required for saturation. No annealing of these increases was observed for anneals from room temperature to 250 0 C. These results are interpreted in terms of a model in which collision cascades create small regions of increased atomic disorder which fully overlap each other at saturation

  11. Phase characterisation and mechanical behaviour of Fe–B modified Cu–Zn–Al shape memory alloys

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2017-04-01

    Full Text Available The microstructures, phase characteristics and mechanical behaviour of Cu–Zn–Al alloys modified with Fe, B, and Fe–B mixed micro-alloying additions has been investigated. Cu–Zn–Al alloys were produced by casting with and without the addition of the microelements (Fe, B and Fe–B. The alloys were subjected to a homogenisation – cold rolling – annealing treatment schedule, before the alloys were machined to specifications for tensile test, fracture toughness, and hardness measurement. Optical, scanning electron microscopy and X-ray diffraction analysis were utilised for microstructural and phase characterisation of the alloys. A distinct difference in grain morphology was observed in the alloys produced – the unmodified alloy had predominantly needle-like lath martensite structure with sharp grain edges while significantly larger transverse grain size and curve edged/near elliptical grain shape was observed for the modified Cu–Zn–Al alloys. Cu–Zn with fcc structure was the predominant phase identified in the alloys while Cu–Al with bcc structure was the secondary phase observed. The hardness of the unmodified Cu–Zn–Al alloy was higher than that of the modified alloys with reductions in hardness ranging between 32.4 and 51.5%. However, the tensile strength was significantly lower than that of the modified alloy grades (28.37–52.74% increase in tensile strength was achieved with the addition of micro-alloying elements. Similarly, the percent elongation and fracture toughness (10–23% increase of the modified alloy was higher than that of the unmodified alloy grade. The modified alloy compositions mostly exhibited fracture features indicative of a fibrous micro-mechanism to crack initiation and propagation, characterised by the prevalence of dimpled rupture.

  12. Effect of Nb and Cr incorporation on the structural and magnetic properties of rapidly quenched FeCoSiB microwires

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Partha; Roy, R.K.; Mitra, A. [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Panda, A.K., E-mail: akpanda@nmlindia.org [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Churyukanova, Margarita; Kaloshkin, Sergey [National University of Science and Technology, MISIS, Leninsky Prospect, 4, Moscow 119049 (Russian Federation)

    2012-08-15

    Rapidly quenched microwires with a nominal composition of Fe{sub 39}Co{sub 39}Si{sub 8}B{sub 14} (A{sub O}), Fe{sub 37}Co{sub 37}Nb{sub 4}Si{sub 8}B{sub 14} (A{sub N}) and Fe{sub 36}Co{sub 36}Nb{sub 4}Cr{sub 2}Si{sub 8}B{sub 14} (A{sub NC}) have been investigated. Devitrification of as-quenched microwires showed that crystallization temperatures increased with simultaneous incorporation of Nb and Cr as in A{sub NC} alloy. Addition of these elements also contributed to an increase in activation energy in A{sub N} and A{sub NC} alloys. Nb addition reduced the particle size, which became much finer in the case of the Cr-containing alloy. Although Nb addition did not have much effect on lowering the Curie temperature T{sub C} of the amorphous phase, Cr substitution lowered T{sub C} to 698 K from high values of 785 K and 787 K observed in the no. A{sub O} and A{sub NC} alloys, respectively. However, the Cr addition revealed a better Giant magneto-impedance (GMI) response compared to the other alloys. Such improved GMI properties in the Cr-containing alloy are attributed to lower values of the coercivity and magnetostriction in the alloy containing both Nb and Cr. - Highlights: Black-Right-Pointing-Pointer FeCoSiB based rapidly quenched microwires prepared by in-rotating-water quenching system. Black-Right-Pointing-Pointer Effect of Nb and Cr on the thermal and GMI behavior of FeCoSiB microwires has been investigated. Black-Right-Pointing-Pointer Effect of Nb and Cr on magnetic properties has also been investigated.

  13. An ab initio study on the structural, electronic and mechanical properties of quaternary full-Heusler alloys FeMnCrSn and FeMnCrSb

    Science.gov (United States)

    Erkişi, Aytaç

    2018-06-01

    The quaternary full Heusler alloys FeMnCrSn and FeMnCrSb, which have face-centred cubic (FCC) crystal structure and conform to ? space group with 216 space number, have been investigated using Generalised Gradient Approximation (GGA) in the Density Functional Theory (DFT) as implemented in VASP (Vienna Ab initio Simulation Package) software. These alloys are considered in ferromagnetic (FM) order. After the investigation of structural stability of these alloys, their mechanical and thermal properties and also electronic band structures have been examined. The calculated spin-polarised electronic band structures and total electronic density of states (DOS) within GGA approximation show that these alloys can exhibit both metallic and half-metallic characters in different structural phases. The calculated formation enthalpies and the plotted energy-volume graphs show that Type-III phase is most stable structural phase for these materials. Also, FeMnCrSb alloy in Type-I/Type-III phases and FeMnCrSn alloy in Type-III phase show half-metallic behaviour with integer total magnetic moments almost 2 and 1 μB per formula unit, respectively, since there are band gaps observed in spin-down states, whereas they have metallic behaviour in majority bands. Other structural phases of both systems are also metallic. Moreover, the calculated elastic constants and the estimated anisotropy shear factors indicate that these materials are stable mechanically in all of three phases except FeMnCrSn in Type-I phase that does not satisfy Born stability criteria in this phase and have high anisotropic behaviour.

  14. Wetting behavior of molten In-Sn alloy on bulk amorphous and crystalline Cu40Zr44Al8Ag8

    International Nuclear Information System (INIS)

    Ma, G. F.; Zhang, H. F.; Li, H.; Hu, Z. Q.

    2007-01-01

    Using the sessile-drop method, the wettability of the molten In-Sn alloy on bulk amorphous and crystalline Cu 40 Zr 44 Al 8 Ag 8 alloy was studied at different temperatures. It was found that the equilibrium contact angle of In-Sn alloy melt on bulk amorphous substrate was smaller than that of the crystalline one. An intermetallic compound existed at the interface of In-Sn alloy on amorphous Cu 40 Zr 44 Al 8 Ag 8 , while no intermediate reaction layer was formed at the interface of In-Sn alloy on crystalline Cu 40 Zr 44 Al 8 Ag 8 in the temperature range studied

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-08-01

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

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  17. 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.

  18. A study on the microstructural characteristics of rapidly solidified Al-Fe alloys(I)

    International Nuclear Information System (INIS)

    Kim, D.H.; Lee, H.I.

    1991-01-01

    Solidification microstructures and phases in rapidly solidified Al-5, 10wt% Fe alloys have been investigated by TEM bright field and dark field imaging techniques and electron and x-ray diffraction techniques. Rapid solidification of Al-5, 10wt%Fe alloys produces various metastable and stable phases, such as Al m Fe, Al 6 Fe and Al 13 Fe 4 . In addition to these phases, clusters of randomly oriented few nm scale particles exist in the form of fine cellular network with α-Al or primary spherical particles. Solidification microstructures of the rapidly solidified Al-5, 10wt%Fe alloys consist of various combination of primary phases such as Al 13 Fe 4 , Al m Fe and cluster of nm scale particles, and cellular/dendritic structures such as fine cellular network structure of nm scale particle clusters and α-Al and cellular structure of Al m Fe and α-Al, depending upon alloy compositions and local cooling rates. (Author)

  19. Magnetic characterization of nanocrystalline Fe80−xCrxCo20 (15≤x≤35) alloys during milling and subsequent annealing

    International Nuclear Information System (INIS)

    Rastabi, Reza Amini; Ghasemi, Ali; Tavoosi, Majid; Sodaee, Tahmineh

    2016-01-01

    Magnetic characterization of nanocrystalline Fe–Cr–Co alloys during milling and annealing process was the goal of this study. To formation of Fe 80−x Cr x Co 20 (15≤x≤35) solid solution, different powder mixtures of Fe, Cr and Co elements were mechanically milled in a planetary ball mill. The annealing process was done in as-milled samples at different temperature in the range of 500–640 °C for 2 h. The produced samples were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. Performed mechanical alloying in different powder mixtures lead to the formation of Fe–Cr–Co α-phase solid solution with average crystallite sizes of about 10 nm. The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The coercivity of produced alloys after annealing process decreased and reached to about 40–150 Oe. The highest value of coercivity in as-milled and annealed samples was achieved in alloys with higher Cr contents. - Highlights: • Hc and Ms of produced alloys obtained in the range of 110–200 Oe and 150–220 emu/g. • The highest value of Hc in milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . • Hc of produced alloys after spinodal decomposition decreased to about 40–150 Oe. • The effect of crystalline defects and residual strain on magnetic fields pinning in milled samples is higher than spinodal decomposition in annealed samples. • The highest value of Hc in as-milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . The coercivity of produced alloys after annealing process decreased and reach to about 40–150 Oe. • The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively.

  20. Thermal, magnetic, and structural properties of soft magnetic FeCrNbCuSiB alloy ribbons

    International Nuclear Information System (INIS)

    Rosales-Rivera, A.; Valencia, V.H.; Quintero, D.L.; Pineda-Gomez, P.; Gomez, M.

    2006-01-01

    The thermal, magnetic and structural properties of amorphous magnetic Fe 73.5-x Cr x Nb 3 Cu 1 Si 13.5 B 9 alloy ribbons, with x=0, 2, 4, 6, 8, and 10, were studied by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magneto-impedance measurements and X-ray diffraction (XRD). The ribbons exhibit ultrasoft magnetic behavior, especially giant magneto-impedance effect, GMI. A three-peak behavior was observed in GMI curves. Particular attention has been given to observation of crystallization kinetics via DSC and TGA. The primary crystallization T pcr , and Curie T c , temperatures were determined from DSC and TGA data, respectively. The effect of partial substitution of iron by Cr on the thermal and magnetic properties is discussed

  1. 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.

  2. Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

    International Nuclear Information System (INIS)

    Maziasz, P.J.; Klueh, R.L.

    1988-01-01

    Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some σ phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs

  3. Thermal stability, thermal expansion and grain-growth in exchange-coupled Fe-Pt-Ag-B bulk nanocomposite magnets

    International Nuclear Information System (INIS)

    Nicula, R.; Crisan, O.; Crisan, A.D.; Mercioniu, I.; Stir, M.; Vasiliu, F.

    2015-01-01

    Highlights: • Formation of the L10 FePt hard-magnetic phase (>90%) directly in the as-cast state. • Specific alternating hard/soft nanostructure is stable to 600 °C without grain growth. • Anisotropic and non-linear thermal expansion effects. • The FePtAgB alloy behaves like a single magnetic phase (full exchange coupling). - Abstract: Rare-earth free (RE-free) exchange coupling nanocomposite magnets are intensively studied nowadays due to their potential use in applications demanding stable high-temperature operation and corrosion resistance. In this respect, the FePt alloy system is one of the most actively addressed potential permanent magnet solutions. In FePt alloys, promising magnetic features arise from the co-existence of hard magnetic L1 0 FePt and soft magnetic L1 2 Fe 3 Pt phases emerged from the same metastable precursor. The present work deals with an in-situ temperature-resolved synchrotron radiation study of the thermal stability, thermal expansion and microstructure evolution in exchange-coupled FePtAgB alloys. The as-cast microstructural state as well as the optimized magnetic behavior are given as reference and correlated to the observed microstructural evolution with temperature. The melt-spun Fe 48 Pt 28 Ag 6 B 18 alloy ribbons were examined in situ by synchrotron X-ray powder diffraction from ambient temperature up to 600 °C. The FePt-Fe 3 Pt exchange-coupled microstructure achieved by rapid solidification is not significantly altered during the high temperature exposure. The thermal expansion of the FePt L1 0 unit cell has been found to be strongly anisotropic, being essentially an in-plane expansion which may be seen as an anisotropic invar effect. For the FePt L1 0 phase, a significant deviation from linear thermal expansion is observed at the Curie temperature T C = 477 °C. This non-linear behavior above T C is tentatively linked to a diffusion/segregation mechanism of Ag. The promising hard magnetic properties as well as the

  4. Study of the magnetic and structural properties of nanostructured powders of Nd{sub 2}Fe{sub 14}B mechanically alloyed

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, L.E.; Perez Alcazar, G.A. [Department of Physics, University of Valle, A.A. 25360, Cali (Colombia); Rojas, Y.A.; Bustos, H. [Department of Physics, University of Tolima, A.A. 546, Ibague (Colombia); Greneche, J.M. [Laboratoire de Physique de l' Etat Condense, UMR CNRS6087, 72085 Le Mans Cedex 9 (France); Oyola Lozano, D.

    2007-07-01

    In this work we report the magnetic and structural properties obtained by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction, of powder of Nd{sub 2}Fe{sub 14}B prepared by mechanical alloying. The mixtures were ball milled during 48 hours and submitted to heat treatments between 500 and 900 C under an argon atmosphere. Structural parameters were derived from high statistics X-ray patterns. The Moessbauer spectra registered at 300 K for samples without heat treatment were fitted by means of a sextet and a hyperfine field distribution, associated to a residual pure iron phase ({alpha}-Fe) and a disordered iron-based phase, respectively. From the spectra at 300 K the formation of the Fe{sub 3}C phase is observed for samples heat treated at 900 C. A quenching above 900 C accelerates the formation of the Fe{sub 3}C phase. The hysteresis loops allow to conclude that these samples behave as soft ferromagnets. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. 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.

  6. A review of the irradiation evolution of dispersed oxide nanoparticles in the b.c.c. Fe-Cr system: Current understanding and future directions

    Energy Technology Data Exchange (ETDEWEB)

    Wharry, Janelle P., E-mail: jwharry@purdue.edu [Purdue University, 400 Central Drive, West Lafayette, IN 47907 (United States); Swenson, Matthew J.; Yano, Kayla H. [Boise State University, 1910 University Drive, Boise, ID 83725 (United States)

    2017-04-01

    Thus far, a number of studies have investigated the irradiation evolution of oxide nanoparticles in b.c.c. Fe-Cr based oxide dispersion strengthened (ODS) alloys. But given the inconsistent experimental conditions, results have been widely variable and inconclusive. Crystal structure and chemistry changes differ from experiment to experiment, and the total nanoparticle volume fraction has been observed to both increase and decrease. Furthermore, there has not yet been a comprehensive review of the archival literature. In this paper, we summarize the existing studies on nanoparticle irradiation evolution. We note significant observations with respect to oxide nanoparticle crystallinity, composition, size, and number density. We discuss four possible contributing mechanisms for nanoparticle evolution: ballistic dissolution, Ostwald ripening, irradiation-enhanced diffusion, and homogeneous nucleation. Finally, we propose future directions to achieve a more comprehensive understanding of irradiation effects on oxide nanoparticles in ODS alloys.

  7. Structural and magnetic characterization of Fe2CrSi Heusler alloy nanoparticles as spin injectors and spin based sensors

    Science.gov (United States)

    Saravanan, G.; Asvini, V.; Kalaiezhily, R. K.; Parveen, I. Mubeena; Ravichandran, K.

    2018-05-01

    Half-metallic ferromagnetic [HMF] nanoparticles are of considerable interest in spintronics applications due to their potential use as a highly spin polarized current source. HMF exhibits a semiconductor in one spin band at the Fermi level Ef and at the other spin band they poses strong metallic nature which shows 100 % spin polarization at Ef. Fe based full Heusler alloys are primary interest due to high Curie temperature. Fe2CrSi Heusler alloys are synthesized using metallic powders of Fe, Cr and Si by mechanical alloying method. X-Ray diffractions studies were performed to analyze the structural details of Fe2CrSi nanoparticles with High resolution scanning electron microscope (HRSEM) studies for the morphological details of nanoparticles and magnetic properties were studied using Vibrating sample magnetometer (VSM). XRD Data analysis conforms the Heusler alloy phase showing the existence of L21 structure. Magnetic properties are measured for synthesized samples exhibiting a soft magnetic property possessing low coercivity (HC = 60.5 Oe) and saturation magnetic moment of Fe2CrSi is 3.16 µB, which is significantly higher than the ideal value of 2 µB from the Slater-Pauling rule due to room temperature measurement. The change in magnetic properties are half-metallic nature of Fe2CrSi is due to the shift of the Fermi level with respect to the gap were can be used as spin sensors and spin injectors in magnetic random access memories and other spin dependent devices.

  8. Amorphous Fe-B alloys in B-Fe-Ag multilayers studied by magnetization and Mössbauer measurements

    DEFF Research Database (Denmark)

    Kiss, L. F.; Balogh, J.; Bujdoso, L.

    2011-01-01

    Bulk and local magnetic properties were studied in [1 nm B + 1 nm 57Fe + x nm Ag]5, x = 1, 2, 4, 5 and 10, multilayer samples. Although Ag does not mix with either of the other two elements the magnetic properties of the multilayers are strongly influenced by the Ag thickness below x = 5, whereas...

  9. Thermal treatment of the Fe{sub 78} Si{sub 9} B{sub 13} alloy and the analysis of it magnetic properties through Moessbauer spectroscopy and Positronium annihilation; Tratamiento termico de la aleacion Fe{sub 78} Si{sub 9} B{sub 13} y el analisis de sus propiedades magneticas mediante Espectroscopia de Moessbauer y Aniquilacion de positronio

    Energy Technology Data Exchange (ETDEWEB)

    Lopez M, A

    2005-07-01

    The present work is divided in five chapters. In the first one a general vision of the amorphous alloys is given from antecedents, structure, obtaining methods, properties and problems that at the moment, focusing us in a certain moment to the iron base alloys and the anomalous problem of hardness that it presents the alloy Fe{sub 78}Si{sub 9}B{sub 13} like previously mention us. The second chapter tries on the basic theory of the techniques of Moessbauer spectroscopy and Positron Annihilation spectroscopy, used for the characterization of our alloy as well as the complementary technique of X-ray diffraction (XRD) to observe that the amorphous phase was even studying. The third chapter describes the experimental conditions that were used to study the alloy Fe{sub 78}Si{sub 9}B{sub 13} in each one of their thermal treatments. In the fourth chapter the obtained results and their discussion are presented. In the fifth chapter the conclusions to which were arrived after analyzing the results are presented. (Author)

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Phase and magnetic studies of the high-energy alloyed Ni-Fe

    Czech Academy of Sciences Publication Activity Database

    Jirásková, Yvonna; Buršík, Jiří; Turek, Ilja; Hapla, Miroslav; Titov, A.; Životský, O.

    2014-01-01

    Roč. 594, May (2014), s. 133-140 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/1350 Grant - others:VŠB(CZ) CZ.1.07/2.3.00/20.0074 Institutional support: RVO:68081723 Keywords : Ni-Fe * mechanical alloying * magnetic properties * microstructure * particle interactions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  15. Coercivity enhancement in Nd-Fe-B sintered permanent magnet by Dy nanoparticles doping

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.Q., E-mail: liuweiqiang77@hotmail.co [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Sun, H. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yi, X.F. [Anhui Earth-panda Advance Magnetic Material Co., Ltd., Anhui 231500 (China); Liu, X.C.; Zhang, D.T. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Yue, M., E-mail: yueming@bjut.edu.c [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Zhang, J.X. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

    2010-07-02

    Nd-Fe-B permanent magnets with a small amount of Dysprosium (Dy) nanoparticles doping were prepared by conventional sintered method, and the microstructure and magnetic properties of the magnets were studied. Investigation shows that the coercivity rises gradually, while the remanence decreases simultaneously with increased Dy doping amount. As a result, the magnet with 1.5 wt.% Dy exhibits optimal magnetic properties. Further investigation presumed that Dy is enriched as (Nd, Dy){sub 2}Fe{sub 14}B phase in the surface region of the Nd{sub 2}Fe{sub 14}B matrix grains indicated by the enhancement of the magneto-crystalline anisotropy field of the Nd{sub 2}Fe{sub 14}B phase. As a result, the magnet doped with a small amount of Dy nanoparticles possesses remarkably enhanced coercivity without sacrificing its magnetization noticeably.

  16. 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.

  17. Effect of alloying elements on σ phase formation in Fe-Cr-Mn alloys

    International Nuclear Information System (INIS)

    Okazaki, Yoshimitsu; Miyahara, Kazuya; Hosoi, Yuzo; Tanino, Mitsuru; Komatsu, Hazime.

    1989-01-01

    Alloys of Fe-(8∼12%) Cr-(5∼30%) Mn were solution-treated at 1373 K for 3.6 ks, followed by cold-working of 50% reduction. Both solution-treated and 50% cold-worked materials were aged in the temperature range from 773 to 973 K for 3.6 x 10 3 ks. The identification of σ phase formation was made by using X-ray diffraction from the electrolytically extracted residues of the aged specimens. The region of σ phase formation determined by the present work is wider than that on the phase diagram already reported. It is to be noted that Mn promotes markedly the σ phase formation, and that three different types of σ phase formation are observed depending on Mn content: α→γ + α→γ + α + σ in 10% Mn, α→γ + σ in 15 to 20% Mn alloys, α→χ(Chi) →χ + σ + γ in 25 to 30% Mn alloys. An average electron concentration (e/a) in the σ phase was estimated by quantitative analysis of alloying elements using EPMA. The e/a value in the σ phase formed in Fe-(12∼16%) Cr-Mn alloys aged at 873 K for 3.6 x 10 3 ks is about 7.3, which is independent of Mn content. In order to prevent σ phase formation in Fe-12% Cr-15% Mn alloy, the value of Ni * eq of 11 (Ni * eq = Ni + 30(C) + 25(N)) is required. (author)

  18. Investigation of electrochemical behaviour and structure of oxide films on Ni60Nb40 alloy in amorphous and crystalline states

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Skvortsova, I.B.; Gorodetskij, A.E.; Bogomolov, D.B.

    1987-01-01

    Electrochemical properties of Ni 60 Nb 40 alloy in amorphous and crystalline states as well as structure of oxide films forming during anode polarization in electrolytes on the surface of this alloy in both its states are investigated. It is stated that increased passive ability of Ni 60 Nb 40 alloys in amorphous state and high efficiency of chlorine evolution (2 n NaCl+HCl up to pH=0) anode process in comparison with crystalline state are defined by increased homogeneity and uniformity of passive films forming on amorphous alloy and their increased electron conductivity, that is in direct dependence on different structure of passive films forming on alloys in amorphous and crystalline states

  19. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys

    International Nuclear Information System (INIS)

    Geribola, Gulherme Altomari

    2014-01-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H 2 /2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  20. Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

    International Nuclear Information System (INIS)

    Auger, M.A.; Leguey, T.; Munoz, A.; Monge, M.A.; Castro, V. de; Fernandez, P.; Garces, G.; Pareja, R.

    2011-01-01

    Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y 2 O 3 alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y 2 O 3 developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y 2 O 3 free alloy. Strengthening induced by the Y 2 O 3 dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

  1. Hysteresis properties of conventionally annealed and Joule-heated nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloys

    International Nuclear Information System (INIS)

    Tiberto, P.; Basso, V.; Beatrice, C.; Bertotti, G.

    1996-01-01

    The dependence of magnetic properties on the thermal treatment used to induce the amorphous-to-nanocrystalline transformation in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloy has been studied. Quasi-static hysteresis loops and initial permeability measurements were performed on nanocrystalline samples obtained by conventional annealing and Joule heating. A comparison between the magnetic properties of nanocrystalline samples obtained by the two heating procedures is presented. (orig.)

  2. Alloy Design Data Generated for B2-Ordered Compounds

    Science.gov (United States)

    Noebe, Ronald D.; Bozzolo, Guillermo; Abel, Phillip B.

    2003-01-01

    Developing alloys based on ordered compounds is significantly more complicated than developing designs based on disordered materials. In ordered compounds, the major constituent elements reside on particular sublattices. Therefore, the addition of a ternary element to a binary-ordered compound is complicated by the manner in which the ternary addition is made (at the expense of which binary component). When ternary additions are substituted for the wrong constituent, the physical and mechanical properties usually degrade. In some cases the resulting degradation in properties can be quite severe. For example, adding alloying additions to NiAl in the wrong combination (i.e., alloying additions that prefer the Al sublattice but are added at the expense of Ni) will severely embrittle the alloy to the point that it can literally fall apart during processing on cooling from the molten state. Consequently, alloying additions that strongly prefer one sublattice over another should always be added at the expense of that component during alloy development. Elements that have a very weak preference for a sublattice can usually be safely added at the expense of either element and will accommodate any deviation from stoichiometry by filling in for the deficient component. Unfortunately, this type of information is not known beforehand for most ordered systems. Therefore, a computational survey study, using a recently developed quantum approximate method, was undertaken at the NASA Glenn Research Center to determine the preferred site occupancy of ternary alloying additions to 12 different B2-ordered compounds including NiAl, FeAl, CoAl, CoFe, CoHf, CoTi, FeTi, RuAl, RuSi, RuHf, RuTi, and RuZr. Some of these compounds are potential high temperature structural alloys; others are used in thin-film magnetic and other electronic applications. The results are summarized. The italicized elements represent the previous sum total alloying information known and verify the computational

  3. Low temperature behavior of hyperfine fields in amorphous and nanocrystalline FeMoCuB

    Czech Academy of Sciences Publication Activity Database

    Kohout, J.; Kříšťan, P.; Kubániová, D.; Kmječ, T.; Závěta, K.; Štěpánková, H.; Lančok, Adriana; Sklenka, L.; Matúš, P.; Miglierini, M.

    2015-01-01

    Roč. 117, č. 17 (2015), "17B718-1"-"17B718-4" ISSN 0021-8979 R&D Projects: GA ČR(CZ) GA14-12449S Institutional support: RVO:61388980 Keywords : rapidly quenched crystalline * nanocrystalline alloy s * magnetic microstructure * metallic glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.101, year: 2015

  4. Application of damping mechanism model and stacking fault probability in Fe-Mn alloy

    International Nuclear Information System (INIS)

    Huang, S.K.; Wen, Y.H.; Li, N.; Teng, J.; Ding, S.; Xu, Y.G.

    2008-01-01

    In this paper, the damping mechanism model of Fe-Mn alloy was analyzed using dislocation theory. Moreover, as an important parameter in Fe-Mn based alloy, the effect of stacking fault probability on the damping capacity of Fe-19.35Mn alloy after deep-cooling or tensile deformation was also studied. The damping capacity was measured using reversal torsion pendulum. The stacking fault probability of γ-austenite and ε-martensite was determined by means of X-ray diffraction (XRD) profile analysis. The microstructure was observed using scanning electronic microscope (SEM). The results indicated that with the strain amplitude increasing above a critical value, the damping capacity of Fe-19.35Mn alloy increased rapidly which could be explained using the breakaway model of Shockley partial dislocations. Deep-cooling and suitable tensile deformation could improve the damping capacity owning to the increasing of stacking fault probability of Fe-19.35Mn alloy

  5. Low temperature irradiation effects on iron boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, A.

    1982-09-01

    Three Fe-B amorphous alloys (Fe 80 B 20 , Fe 27 Mo 2 B 20 and Fe 75 B 25 ) and the crystallized Fe 3 B alloy have been irradiated at the temperature of liquid hydrogen. Electron irradiation and irradiation by 10 B fission fragments induce point defects in amorphous alloys. These defects are characterized by an intrinsic resistivity and a formation volume. The threshold energy for the displacement of iron atoms has also been calculated. Irradiation by 235 U fission fragments induces some important structural modifications in the amorphous alloys [fr

  6. Crystallographic orientation analysis in HDDR process of anisotropic Nd-Fe-B magnet powders

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Rina, E-mail: 3ES15002M@s.kyushu-u.ac.jp [Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Science and Engineering, Kyushu University, 6-1 Kasugakoen, Kasuga 816-8580 (Japan); Itakura, Masaru [Department of Applied Science for Electronics and Materials, Faculty of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Katayama, Nobuhiro; Morimoto, Koichiro [R& D Division, Toda Kogyo Corp., 1-4 Meijishinkai, Otake, Hiroshima 739-0652 (Japan)

    2017-07-01

    Highlights: • Over 70% of the Nd{sub 2}Fe{sub 14}B grains after the HDDR process are aligned within 30°. • The c-axis alignment of Nd{sub 2}Fe{sub 14}B slightly deteriorates by the Nd-rich phase formation. • α-Fe grains possess a uniaxial and 〈1 1 3〉 oriented texture in the decomposed stage. • α-Fe is most likely to induce the texture development of recombined Nd{sub 2}Fe{sub 14}B. - Abstract: Microstructural changes and crystallographic orientation information in the hydrogenation-decomposition-desorption-recombination (HDDR) process of Nd-Fe-B alloy were investigated using electron backscatter diffraction (EBSD) and precession electron diffraction (PED) in order to understand the mechanism of anisotropy inducement in the HDDR process. Recombined Nd{sub 2}Fe{sub 14}B grains were found to nucleate at the interfaces between NdH{sub 2} and α-Fe grains and to have a [0 0 1]-oriented texture from the beginning of the recombination reaction. The Fe grains form with alignment of one of the 〈1 1 3〉 directions at decomposed stage. This suggests that α-Fe most likely induces texture development of recombined Nd{sub 2}Fe{sub 14}B.

  7. 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

  8. Point defect properties of ternary fcc Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wróbel, J.S., E-mail: jan.wrobel@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D.; Dudarev, S.L. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland)

    2017-02-15

    Highlights: • Properties of point defects depend on the local atomic environment. • As the degree of chemical order increases, the formation energies increase, too. • Relaxation volumes are larger for the more ordered structures. - Abstract: The properties of point defects in Fe-Cr-Ni alloys are investigated, using density functional theory (DFT), for two alloy compositions, Fe{sub 50}Cr{sub 25}Ni{sub 25} and Fe{sub 55}Cr{sub 15}Ni{sub 30}, assuming various degrees of short-range order. DFT-based Monte Carlo simulations are applied to explore short-range order parameters and generate representative structures of alloys. Chemical potentials for the relevant structures are estimated from the minimum of the substitutional energy at representative atoms sites. Vacancies and 〈1 0 0〉 dumbbells are introduced in the Fe{sub 2}CrNi intermetallic phase as well as in two Fe{sub 55}Cr{sub 15}Ni{sub 30} alloy structures: the disordered and short range-ordered structures, generated using Monte Carlo simulations at 2000 K and 300 K, respectively. Formation energies and relaxation volumes of defects as well as changes of magnetic moments caused by the presence of defects are investigated as functions of the local environment of a defect.

  9. Adhesive and Cohesive Strength in FeB/Fe2B Systems

    Science.gov (United States)

    Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

    2018-05-01

    In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

  10. Laboratory scale fabrication of Nd-Fe-B sintered magnets

    International Nuclear Information System (INIS)

    Rodrigues, Daniel; Beneduce Neto, Flavio; Landgraf, Fernando Jose Gomes; Neiva, Augusto Camara; Romero, Sergio; Missell, Frank Patrick

    1992-01-01

    Results are presented on magnetic properties of Nd-Fe-B sauntered magnets produced from 1 kg of alloy caste in vacuum induction furnace. The fabrication viability of these magnets, with properties similar to the commercial magnets, and the influence of particle size in the energy product, through the effect on the H k field, is confirmed

  11. Oxide Morphology of a FeCrAl Alloy, Kanthal APMT, Following Extended Aging in Air at 300 °C to 600 °C

    Science.gov (United States)

    Li, Nan; Parker, Stephen S.; Wood, Elizabeth S.; Nelson, Andrew T.

    2018-05-01

    Iron-chromium-aluminum (FeCrAl) alloys are of interest to the nuclear materials community due to their resistance to high-temperature steam oxidation under accident conditions. The present work investigates oxide formation at temperatures relevant to light water reactor cladding operation following extended aging to assess growth kinetics, chemical composition, and microstructure of oxide formation on a commercial FeCrAl alloy, Fe-21 wt pct Cr-5 wt pct Al-3 wt pct Mo (Kanthal APMT). Aging treatments were performed for 100 to 1000 hours in stagnant air at 300 °C, 400 °C, 500 °C, and 600 °C, respectively. Oxide growth behavior under the investigated conditions follows a logarithmic time dependence. When the oxidization temperature is 400 °C or below, the oxide is amorphous. At 500 °C, isolated crystalline regions start to appear during short period aging time and expand with extended exposures. Crystalline α-Al2O3 oxide film develops at 600 °C and the correlated logarithmic rate constant decreases significantly, indicating enhanced oxidation resistance of the formed oxide film. In addition, Mo segregation at grain boundaries has been observed when the aging temperature exceeds 500 °C. The results of this study can be viewed as an upper bounding result for potential oxide coarsening during reactor operation.

  12. Mn and Fe Impurities in Si$_{1-x}$ Ge$_{x}$ alloys

    CERN Multimedia

    2002-01-01

    Following our investigations of Mn and Fe impurities in elemental semiconductors and in silicon in particular by means of on-line $^{57}$Fe Mössbauer spectroscopy, utilizing radioactive $^{57}$Mn$^{+}$ ion beams at ISOLDE, we propose to extend these studies to bulk and epitaxially-grown Si$_{1-x}$Ge$_{x}$ alloys. In these materials, although already successfully employed in electronic devices, little is known about point defects and important harmful 3d impurities. The experiments aim to determine a variety of fundamental properties: The lattice location of ion-implanted Mn/Fe, the electronic and vibrational properties of dilute Fe impurities in different lattice sites, the charge-state and composition dependence of the diffusivity of interstitial Fe on an atomic scale, the reactions and formation of complexes with lattice defects created by the $^{57}$Mn implantation or by the recoil effect in the nuclear decay to the Mössbauer state of $^{57m}$Fe. Feasibility studies in 2003 indicate that these aims can b...

  13. Mössbauer spectroscopy study of the disordering process of Fe{sub 70}Si{sub 30} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E., E-mail: estibaliz.legarra@ehu.es [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Apiñaniz, E. [Dpto. Fisica Aplicada I, Universidad del Pais Vasco, Nieves Cano 12, 01006 Vitoria (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain)

    2014-12-05

    Highlights: • Ball milled Fe{sub 70}Si{sub 30} alloy has three different structure (D0{sub 3}, D8{sub 8} and B20). • The amount of D8{sub 8} and B20 structures varies the Si content of the D0{sub 3} structure. • The disordering process has three different stages. • The behavior of the magnetization with milling time can be explained in terms of the behavior of the different structures. - Abstract: In this work we study systematically the influence of mechanical attrition on the magnetic and structural properties of annealed Fe{sub 70}Si{sub 30} alloy by means of Mössbauer spectroscopy, X-ray diffraction measurements and magnetic measurements. In order to obtain different stages of disorder the annealed (ordered) alloys were deformed by ball milling during different number of hours. The annealed alloy presents two different structures (D0{sub 3} and D8{sub 8}) and the deformation of the annealed sample with ball milling induces the appearance of B20 structure. The variation of the amount of D8{sub 8} and B20 structures makes the Si content of the D0{sub 3} structure vary, which affects the magnetic properties. The disordering process has three different stages, characterized with different magnetic behaviors.

  14. μ+ studies of dilute PdFe alloys

    International Nuclear Information System (INIS)

    Nagamine, K.; Nishida, N.; Yamazaki, T.; British Columbia Univ., Vancouver

    1976-08-01

    In order to investigate the ordering mechanism among giant moments around Fe impurities in Pd, μ + was used to probe the conduction electron polarization in PdFe alloys above and below the critical concentration of 0.1 at. % with reference to pure Pd. Below the ordering temperatures the broadening of the μ + field for 0.015 at. % Fe is substantially larger than that for 0.28 at. % Fe, when normalized to the bulk magnetization. The results can be explained in terms of an RKKY spin oscillation in the region outside the giant moment. (author)

  15. Changes in cluster magnetism and suppression of local superconductivity in amorphous FeCrB alloy irradiated by Ar"+ ions

    International Nuclear Information System (INIS)

    Okunev, V.D.; Samoilenko, Z.A.; Szymczak, H.; Szewczyk, A.; Szymczak, R.; Lewandowski, S.J.; Aleshkevych, P.; Malinowski, A.; Gierłowski, P.; Więckowski, J.; Wolny-Marszałek, M.; Jeżabek, M.; Varyukhin, V.N.; Antoshina, I.A.

    2016-01-01

    We show that cluster magnetism in ferromagnetic amorphous Fe_6_7Cr_1_8B_1_5 alloy is related to the presence of large, D=150–250 Å, α-(Fe Cr) clusters responsible for basic changes in cluster magnetism, small, D=30–100 Å, α-(Fe, Cr) and Fe_3B clusters and subcluster atomic α-(Fe, Cr, B) groupings, D=10–20 Å, in disordered intercluster medium. For initial sample and irradiated one (Φ=1.5×10"1"8 ions/cm"2) superconductivity exists in the cluster shells of metallic α-(Fe, Cr) phase where ferromagnetism of iron is counterbalanced by antiferromagnetism of chromium. At Φ=3×10"1"8 ions/cm"2, the internal stresses intensify and the process of iron and chromium phase separation, favorable for mesoscopic superconductivity, changes for inverse one promoting more homogeneous distribution of iron and chromium in the clusters as well as gigantic (twice as much) increase in density of the samples. As a result, in the cluster shells ferromagnetism is restored leading to the increase in magnetization of the sample and suppression of local superconductivity. For initial samples, the temperature dependence of resistivity ρ(T)~T"2 is determined by the electron scattering on quantum defects. In strongly inhomogeneous samples, after irradiation by fluence Φ=1.5×10"1"8 ions/cm"2, the transition to a dependence ρ(T)~T"1"/"2 is caused by the effects of weak localization. In more homogeneous samples, at Φ=3×10"1"8 ions/cm"2, a return to the dependence ρ(T)~T"2 is observed. - Highlights: • The samples at high dose of ion irradiation become more homogeneous. • Gigantic increase in density of the samples (twice as much) is observed. • Ferromagnetism in large Fe–Cr clusters is restored. • Ferromagnetism of Fe–Cr clusters suppresses local superconductivity in them. • The participation of quantum defects in scattering of electrons is returned.

  16. 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.

  17. Corrosion resistance of Mo-Fe-Ti alloy for overpack in simulating underground environment

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Toshiyasu, E-mail: NISHIMURA.Toshiyasu@nims.go.jp [Structural metals Center, National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Aging heat-treated Mo-Fe-Ti alloy showed lower corrosion resistance than solution treated one, but much higher than pure Ti in EIS measurement. Black-Right-Pointing-Pointer As {alpha}-phases showed lower Mo content by TEM, they were preferentially dissolved from base metal in the corrosion test. Black-Right-Pointing-Pointer As Fe was involved in {beta} (b)-phase with Mo which increased the corrosion resistance, the addition of Fe did not decrease the corrosion resistance. - Abstract: In order to examine the application of Mo-Fe-Ti alloy for overpak, the corrosion resistance of heat-treated its alloys was investigated by electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM). The sample subjected to solution heat treatment (ST) had a single {beta} phase and samples subjected to aging heat treatment at 600-700 Degree-Sign C had {alpha} phase precipitation in {beta} phase. EIS results showed that the corrosion resistance of the aging heat-treated samples was lower than that of the ST sample, but much higher than that of pure Ti in 10% NaCl solution of pH 0.5 at 97 Degree-Sign C which simulating the crevice solution. Laser micrographs of the aging heat-treated samples indicated that {alpha} phase was caused selective dissolution in test solution. The TEM combined with EDAX (energy dispersive X-ray) analyses showed that {beta} phase matrix composed of 2.7 wt.% Mo and 4.8 wt.% Fe, and {alpha} phase composed of 0.7 wt.% Mo and 0.1 wt.% Fe in sample aged at 600 Degree-Sign C. Thus, Mo-poor {alpha} phase was selectively dissolved in a test solution. In EIS, the ST sample of only {beta} phase showed the highest resistance, and aging heat-treated samples containing {alpha} phase (0.7 wt.% Mo) showed higher values than pure Ti in the corrosion test. As Fe was involved in {beta} phase with Mo which increased remarkably the corrosion resistance, the addition of Fe did not decrease the corrosion resistance

  18. Modeling of full-Heusler alloys within tight-binding approximation: Case study of Fe2MnAl

    Science.gov (United States)

    Azhar, A.; Majidi, M. A.; Nanto, D.

    2017-07-01

    Heusler alloys have been known for about a century, and predictions of magnetic moment values using Slater-Pauling rule have been successful for many such materials. However, such a simple counting rule has been found not to always work for all Heusler alloys. For instance, Fe2CuAl has been found to have magnetic moment of 3.30 µB per formula unit although the Slater-Pauling rule suggests the value of 2 µB. On the other hand, a recent experiment shows that a non-stoichiometric Heusler compound Fe2Mn0.5Cu0.5Al possesses magnetic moment of 4 µB, closer to the Slater-Pauling prediction for the stoichiometric compound. Such discrepancies signify that the theory to predict the magnetic moment of Heusler alloys in general is still far from being complete. Motivated by this issue, we propose to do a theoretical study on a full-Heusler alloy Fe2MnAl to understand the formation of magnetic moment microscopically. We model the system by constructing a density-functional-theory-based tight-binding Hamiltonian and incorporating Hubbard repulsive as well as spin-spin interactions for the electrons occupying the d-orbitals. Then, we solve the model using Green's function approach, and treat the interaction terms within the mean-field approximation. At this stage, we aim to formulate the computational algorithm for the overall calculation process. Our final goal is to compute the total magnetic moment per unit cell of this system and compare it with the experimental data.

  19. Investigating the effect of ascorbate on the Fe(II)-catalyzed transformation of the poorly crystalline iron mineral ferrihydrite.

    Science.gov (United States)

    Xiao, Wei; Jones, Adele M; Collins, Richard N; Waite, T David

    2018-05-09

    The inorganic core of the iron storage protein, ferritin, is recognized as being analogous to the poorly crystalline iron mineral, ferrihydrite (Fh). Fh is also abundant in soils where it is central to the redox cycling of particular soil contaminants and trace elements. In geochemical circles, it is recognized that Fh can undergo Fe(II)-catalyzed transformation to form more crystalline iron minerals, vastly altering the reactivity of the iron oxide and, in some cases, the redox poise of the system. Of relevance to both geochemical and biological systems, we investigate here if the naturally occurring reducing agent, ascorbate, can effect such an Fe(II)-catalyzed transformation of Fh at 25 °C and circumneutral pH. The transformation of ferrihydrite to possible secondary Fe(III) mineralization products was quantified using Fourier transform infrared (FTIR) spectroscopy, with supporting data obtained using X-ray absorbance spectroscopy (XAS) and X-ray diffraction (XRD). Whilst the amount of Fe(II) formed in the presence of ascorbate has resulted in Fh transformation in previous studies, no transformation of Fh to more crystalline Fe(III) (oxyhydr)oxides was observed in this study. Further experiments indicated this was due to the ability of ascorbate to inhibit the formation of goethite, lepidocrocite and magnetite. The manner in which ascorbate associated with Fh was investigated using FTIR and total organic carbon (TOC) analysis. The majority of ascorbate was found to adsorb to the Fh surface under anoxic conditions but, under oxic conditions, ascorbate was initially adsorbed then became incorporated within the Fe(III) (oxyhydr)oxide structure (i.e., co-precipitated) over time. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. High field magnetic behavior in Boron doped Fe{sub 2}VAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Ch., E-mail: venkyphysicsiitm@gmail.com [Department of Physics, Indian Institute of Technology, Kharagpur (India); DCMP & MS, Tata Institute of Fundamental Research, Mumbai (India); Vasundhara, M., E-mail: vasu.mutta@gmail.com [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, CSIR, Trivandrum 695019 (India); Srinivas, V. [Department of Physics, Indian Institute of Technology, Chennai (India); Rao, V.V. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur (India)

    2016-11-15

    We have investigated the magnetic behavior of Fe{sub 2}VAl{sub 1−x}B{sub x} (x=0, 0.03, 0.06 and 0.1) alloys under high temperature and high magnetic field conditions separately. Although, the low temperature DC magnetization data for the alloys above x>0 show clear magnetic transitions, the zero field cooled (ZFC) and field cooled (FC) curves indicate the presence of spin cluster like features. Further, critical exponent (γ) deduced from the initial susceptibility above the T{sub c}, does not agree with standard models derived for 3 dimensional long range magnetic systems. The deviation in γ values are consistent with the short range magnetic nature of these alloys. We further extend the analysis of magnetic behavior by carrying the magnetization measurements at high temperatures and high magnetic fields distinctly. We mainly emphasize the following observations; (i) The magnetic hysteresis loops show sharp upturns at lower fields even at 900 K for all the alloys. (ii) High temperature inverse susceptibility do not overlap until T=900 K, indicating the persistent short range magnetic correlations even at high temperatures. (iii) The Arrott's plot of magnetization data shows spontaneous moment (M{sub S}) for the x=0 alloy at higher magnetic fields which is absent at lower fields (<50 kOe), while the Boron doped samples show feeble M{sub S} at lower fields. The origin of this short range correlation is due to presence of dilute magnetic heterogeneous phases which are not detected from the X-ray diffraction method. - Highlights: • Short range magnetic character has been confirmed by the critical exponents analysis. • Magnetoresistace is about −14% with non-saturating tendency even at 150 kOe for Fe{sub 2}VAl alloy. • Boron doped Fe{sub 2}VAl alloys show a weak magnetism even at T=900 K.