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

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

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.

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

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

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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.

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

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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.

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.

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)

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.

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.

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.

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.

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.

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

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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.

Preparation and characterization of the Li(17)Pb(83) eutectic alloy and the LiPb intermetallic compound

International Nuclear Information System (INIS)

Jauch, U.; Karcher, V.; Schulz, B.

1986-01-01

Li(17)Pb(83) and LiPb were prepared from the pure elements in amounts of several hundred grams. The resolidified samples were characterized by melting points (eutectic temperature), chemical analysis and metallography. Using differential thermal analysis the heats of fusion were determined and the behaviour of the intermetallic phase LiPb in vacuum and high purified He was studied. The results from these investigations were applied to characterize Li(17)Pb(83) prepared in high amounts for technical application as a potential liquid breeder material. (orig.)

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)

Shape memory effect of Fe-17%Mn-X alloys

International Nuclear Information System (INIS)

Lee, S.-H.; Kim, H.-J.; Choi, C.-S.; Baik, S.-H.

2000-01-01

SME of Fe-17%Mn-X alloy decreased with increasing Ni and Cr contents. This is because the occurrence of stress-induced martensite transformation of γ to ε is difficult due to the increase in stability of retained austenite with increasing Ni and Cr contents. SME of Fe-17%Mn-X alloy increased with increasing the number of thermal cycles. The reason is that the prior bending deformation for SME is associated with coalescence of the pre-existing ε plates due to their rearrangement, thereby the more the ε content, the greater the SME. (orig.)

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.

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

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)

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

Magnetic and structural properties of the Nd2(Fe100-xNbx)14B system prepared by arc melting

International Nuclear Information System (INIS)

Oyola Lozano, D.; Zamora, L. E.; Perez Alcazar, G. A.; Rojas, Y. A.; Bustos, H.; Greneche, J. M.

2006-01-01

In this work the magnetic and structural properties are investigated by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd 2 (Fe 100-x Nb x ) 14 B powdered alloys with x = 0, 2 and 4 prepared by arc melting. The Moessbauer spectra of the samples were fitted with several contributions from: Nd 2 Fe 14 B, α-Fe and a paramagnetic phase associated with Nd 1.1 Fe 4 B 4 for x = 0 and additionally from NbFeB and Nd 2 Fe 17 for x = 2 and x = 4. The relative fractions of α-Fe and Nd 2 Fe 14 B are smaller for x = 4 than for x = 0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd 2 Fe 17 increases. The α-Fe grain size slightly decreases while that of the Nd 2 Fe 14 B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization.

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.

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.

Perspectives for tritium recovery from liquid Pb83Li17 alloy

International Nuclear Information System (INIS)

Pierini, G.

1983-01-01

A preliminary analysis has been made on the perspectives of tritium recovery from a blanket constituted by liquid Pb 83 Li 17 alloy, by investigating the Tsub(2g) 2T alloy thermodynamic behaviour and trying to individuate those chemico-physical characteristics of which knowledge is useful for the effective design of the apparatus. In the light of the recent work carried out on the systems, hydrogen and its isotopes with molten Li-Pb eutectics, it has been possible to individuate a fair reliability of the Sieverts constant for the T 2 -Pb 83 Li 17 system. As far as the kinetics of the tritium desorption process from the liquid phase are concerned, the hydrogen (and its isotopes) transfer rates across the liquid interphase have been evaluated. Even though in first approximation the diffusion coefficient of tritium in the molten alloy at 400 0 C has been found. Then, the processing equations of attractive tritium recovery systems have been presented, individuating the fundamental parameters and reporting an example of applied engineering of the desorption system in a packed column. None of these tritium recovery systems seem incompatible at the actual state of the research

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

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

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.

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

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.)

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

Metallic glasses of the type Fe80B17X3

International Nuclear Information System (INIS)

Riedel, M.; Gnaser, H.; Ruedenauer, F.G.

1981-08-01

Absolute and relative practical sensitivities for Osub2sup+ - bombardement of 14 elements, present as a 3% admixture in a Fe80B17X3 metallic glass matrix, were determined by SIMS. The variation of sensitivity data between elements is similar to that found for pure element samples. The 3% admixture causes a small but statistically significant matrix effect on the matrix elements Fe and B. Comparison with yield data of the same minor impurity elements in other matrices (stainless steel, silicon) shows, that sensitivities in different matrices are within 30% for most elements, indicating the possibility of transferring relative sensitivity factor data determined on metallic glasses to other Fe-based alloys and thereby obtaining a semi- quantitative analysis. (author)

Design, processing and characterization of mechanically alloyed galfenol & lightly rare-earth doped FeGa alloys as smart materials for actuators and transducers

Science.gov (United States)

Taheri, Parisa

of Er/Gd-doped [110]-textured polycrystalline alloys of nominal composition, Fe83Ga17Erx (0 In the second part of this work, we report for the first time, experimental results pertaining to successful fabrication and advanced characterization of a series of Er/Gd-doped [110]-textured polycrystalline alloys of nominal composition, Fe83Ga 17Erx (0.

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

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)

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.

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.

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

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.)

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)

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.

Fe-based composite materials with improved mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Werniewicz, Katarzyna [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland); Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland)

2008-07-01

Following a previous study by the authors two new compositions (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 91}C{sub 9} and (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} have been developed with the aim of improving the ductility of Fe{sub 65.5}Cr{sub 4}Mo{sub 4}Ga{sub 4}P{sub 12}C{sub 5}B{sub 5.5} bulk metallic glass (BMG). In contrast to the alloys in that study, the recently prepared Fe-based materials are Ga-free. It was expected that the variations in the composition will lead to the changes in the phase formation and, hence, in the mechanical response of the investigated alloys. It was recognized that in-situ formed Fe-based composites show superior plasticity ({epsilon}{sub pl}{approx}37%) for the alloy with lower C content and ({epsilon}{sub pl}{approx}4%) for the alloy with higher C content compared to monolithic glass ({epsilon}{sub pl}{approx}0.2%). Furthermore, on the basis of present as well as previous investigations it has been shown that the Ga addition is beneficial for the plasticity of these Fe-based alloys. It was observed that the (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} alloy exhibits a significantly smaller fracture strain ({epsilon}{sub f}{approx}5%) compared to its Ga-containing counterpart ({epsilon}{sub f}{approx}16%). Therefore, it can be concluded that appropriate alloying additions are crucial in enhancing the mechanical properties of the complex Fe-based materials developed here.

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.)

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

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%.

Magnetic and structural properties of the Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B system prepared by arc melting

Energy Technology Data Exchange (ETDEWEB)

Oyola Lozano, D., E-mail: doyola@ut.edu.co [University of Tolima, Department of Physics (Colombia); Zamora, L. E.; Perez Alcazar, G. A. [University of Valle, Department of Physics (Colombia); Rojas, Y. A.; Bustos, H. [University of Tolima, Department of Physics (Colombia); Greneche, J. M. [Universite du Maine, Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087 (France)

2006-04-15

In this work the magnetic and structural properties are investigated by Moessbauer spectrometry, Vibrating Sample Magnetometry and X-ray diffraction of Nd{sub 2}(Fe{sub 100-x}Nb{sub x}){sub 14}B powdered alloys with x = 0, 2 and 4 prepared by arc melting. The Moessbauer spectra of the samples were fitted with several contributions from: Nd{sub 2}Fe{sub 14}B, {alpha}-Fe and a paramagnetic phase associated with Nd{sub 1.1}Fe{sub 4}B{sub 4} for x = 0 and additionally from NbFeB and Nd{sub 2}Fe{sub 17} for x = 2 and x = 4. The relative fractions of {alpha}-Fe and Nd{sub 2}Fe{sub 14}B are smaller for x = 4 than for x = 0, indicating that the amount of these two phases is reduced with increasing Nb content, while the relative fraction of Nd{sub 2}Fe{sub 17} increases. The {alpha}-Fe grain size slightly decreases while that of the Nd{sub 2}Fe{sub 14}B phase is increasing, when the Nb content increases. The hysteresis loops indicate that these samples behave as hard ferromagnets, with a coercive field which decreases when the Nb content increases, but with rather low remanent magnetization.

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)

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.

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)

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)

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. .

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

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.

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.

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.

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.)

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.

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.

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.

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

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

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

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

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.)

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.

High-temperature electrochemical performance of low-cost La–Ni–Fe based hydrogen storage alloys with different preparation methods

Energy Technology Data Exchange (ETDEWEB)

Wang, Qiannan [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhu, Ding [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China); Zhou, Wanhai; Zhong, Chenglin; Wu, Chaoling [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Yungui, E-mail: ygchen60@aliyun.com [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China)

2016-04-15

Highlights: • Effects of four different preparation processes were studied at 20/60 °C. • All NS + HT, RS and RS + HT processes can optimize the thermodynamic performance. • The HT process can provoke the precipitation of A{sub 2}B{sub 7} and leads to a poor cycling life. • Al exhibits the most remarkable dissolution for all the alloys, especially at 60 °C. - Abstract: In order to optimize the microstructure and high temperature electrochemical performances of low-cost AB{sub 5}-type Ml(NiMnAl){sub 4.2}Co{sub 0.3}Fe{sub 0.5} hydrogen storage electrode alloys, four different preparation methods including normal solidification (NS), normal solidification and 900 °C heat treatment (NS + HT), rapid solidification (RS), rapid solidification and 900 °C heat treatment (RS + HT) were adopted in this work. All alloys exhibit CaCu{sub 5} type hexagonal structure and there is a small amount of A{sub 2}B{sub 7} phase in NS + HT and RS + HT alloys. It is found the using of HT process can decrease the hydrogen equilibrium plateau pressure, the plateau slope and hysteresis at 40, 60 and 80 °C. The NS + HT and RS + HT alloys also possess better activation, high rate discharge performance, larger discharge capacity, but poor cycling performance due to the existence of A{sub 2}B{sub 7} phase which can accelerate dissolution of Ni, Mn and Fe elements in KOH alkaline electrolyte. The RS process can make alloy exhibit the best cycling performance especially at 60 °C.

Evaluation of Pb–17Li compatibility of ODS Fe-12Cr-5Al alloys

Energy Technology Data Exchange (ETDEWEB)

Unocic, Kinga A., E-mail: unocicka@ornl.gov; Hoelzer, David T.

2016-10-15

The Dual Coolant Lead Lithium (DCLL: eutectic Pb–17Li and He) blanket concept requires improved Pb–17Li compatibility with ferritic steels in order to demonstrate acceptable performance in fusion reactors. As an initial step, static Pb-17at.%Li (Pb-17Li) capsule experiments were conducted on new oxide dispersion strengthened (ODS) FeCrAl alloys ((1) Y{sub 2}O{sub 3} (125Y), (2) Y{sub 2}O{sub 3} + ZrO{sub 2} (125YZ), (3) Y{sub 2}O{sub 3} + HfO{sub 2} (125YH), and (4) Y{sub 2}O{sub 3} + TiO{sub 2} (125YT)) produced at ORNL via mechanical alloying (MA). Tests were conducted in static Pb–17Li for 1000 h at 700 °C. Alloys showed promising compatibility with Pb–17Li with small mass change after testing for 125YZ, 125YH and 125YT, while the 125Y alloy experienced the highest mass loss associated with some oxide spallation and subsequent alloy dissolution. X-ray diffraction methods identified the surface reaction product as LiAlO{sub 2} on all four alloys. A small decrease (∼1 at.%) in Al content beneath the oxide scale was observed in all four ODS alloys, which extended 60 μm beneath the oxide/metal interface. This indicates improvements in alloy dissolution by decreasing the amount of Al loss from the alloy. Scales formed on 125YZ, 125YH and 125YT were examined via scanning transmission electron microscopy (S/TEM) and revealed incorporation of Zr-, Hf-, and Ti-rich precipitates within the LiAlO{sub 2} product, respectively. This indicates an inward scale growth mechanism. Future work in flowing Pb–17Li is needed to further evaluate the effectiveness of this strategy in a test blanket module. - Highlights: • Investigation of Pb-17Li compatibility of new ODS Fe-12Cr5Al. • Promising small mass change after static Pb-17Li exposure. • LiAlO{sub 2} formed on the surface during Pb-17Li exposure. • Oxide precipitates incorporated within the LiAlO{sub 2} product. • An inward scale growth mechanism was identified.

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

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

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

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

Preparation of NiFe binary alloy nanocrystals for nonvolatile memory applications

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

In this work,an idea which applies binary alloy nanocrystal floating gate to nonvolatile memory application was introduced.The relationship between binary alloy’s work function and its composition was discussed theoretically.A nanocrystal floating gate structure with NiFe nanocrystals embedded in SiO2 dielectric layers was fabricated by magnetron sputtering.The micro-structure and composition deviation of the prepared NiFe nanocrystals were also investigated by TEM and EDS.

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.)

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 ...

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.

Site populations analysis of the Sm2(Co,Fe)17 alloys using Moessbauer spectroscopy

International Nuclear Information System (INIS)

Nagamine, L.C.C.M.

1990-01-01

Moessbauer measurements were carried out at room temperature for Sm 2 (Co 1-x Fe x ) 17 alloys with x=0,1 to 0,6 and Sm 2 (Co 0.9-v Fe v Cu 0.08 Zr 0.02 ) 8.35 , with v=0.23 to 0.27. All samples were characterized by x-ray diffraction. They showed rhombohedral structure of Th 2 Zn 17 type (R 3-bar m), where Fe atoms occupy four crystallographic sites. All spectra showed magnetic splitting and a high complexity resulting from the superposition of four Fe sites. Hyperfine parameters and site populations were obtained by least-squares fitting of the spectra. (author)

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.

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.

Crystal structure and magnetic properties of a nitrogenated melt-spun Sm[sub 2]Fe[sub 17] compound

Energy Technology Data Exchange (ETDEWEB)

Yang, Choong-Jin [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Lee, Woo-Young [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Choi, Seung-Duck [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of)

1994-05-15

Sm[sub 2]Fe[sub 17]N[sub 2.9] compound powders were prepared from parent alloys of Sm[sub 2]Fe[sub 17] which were made by both arc melting and rapid solidification processes. The cast Sm[sub 2]Fe[sub 17] contained mixed phases of SmFe[sub 3] and [alpha]-Fe, and correspondingly formed less Sm[sub 2]Fe[sub 17]N[sub x] with a rather large amount of residual [alpha]-Fe after nitrogenation. The melt-spun Sm[sub 2]Fe[sub 17] compound, however, was single phase and exhibited a negligible amount of residual [alpha]+Fe after nitrogenation. The residual amount of free iron was found to increase as a function of milling time and to impede the development of promising permanent magnetic properties. The melt-spun Sm[sub 2]Fe[sub 17]N[sub x] compound powders exhibited a coercivity value [sub i]H[sub c] of 5 kOe, which is double that of the as-cast Sm[sub 2]Fe[sub 17]N[sub x] powders and a high remanence B[sub r]=60 e.m.u. g[sup -1]. The average magnetic moment of Fe atoms in the crystal is estimated to be 2.29 [mu][sub B] and the Fe atom in the 6c site exhibits the highest magnetic moment of 2.65 [mu][sub B]. The expansion in the c axial direction of the nitrogenated crystal was found to be mainly due to extension of Sm(6c)-Fe(c) and Fe(18f)-Fe(18f) distances. ((orig.))

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.

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.

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.

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.

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.

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

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

Science.gov (United States)

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

2016-11-30

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

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

Science.gov (United States)

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

2016-01-01

In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al15(Fe,Cr)3Si2 or α-Al15(Fe,Mn)3Si2 phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5. PMID:28774094

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

Structure and magnetic properties of nanocrystalline Fe75Si25 powders prepared by mechanical alloying

International Nuclear Information System (INIS)

Kalita, M.P.C.; Perumal, A.; Srinivasan, A.

2008-01-01

Nanocrystalline Fe 75 Si 25 powders were prepared by mechanical alloying in a planetary ball mill. The evolution of the microstructure and magnetic properties during the milling process were studied by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. The evolution of non-equilibrium solid solution Fe (Si) during milling was accompanied by refinement of crystallite size down to 10 nm and the introduction of high density of dislocations of the order of 10 17 m -2 . During the milling process, Fe sites get substituted by Si. This structural change and the resulting disorder are reflected in the lattice parameters and average magnetic moment of the powders milled for various time periods. A progressive increase of coercivity was also observed with increasing milling time. The increase of coercivity could be attributed to the introduction of dislocations and reduction of powder particle size as a function of milling time

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.

A Cost-Effective Approach to Optimizing Microstructure and Magnetic Properties in Ce17Fe78B₆ Alloys.

Science.gov (United States)

Tan, Xiaohua; Li, Heyun; Xu, Hui; Han, Ke; Li, Weidan; Zhang, Fang

2017-07-28

Optimizing fabrication parameters for rapid solidification of Re-Fe-B (Re = Rare earth) alloys can lead to nanocrystalline products with hard magnetic properties without any heat-treatment. In this work, we enhanced the magnetic properties of Ce 17 Fe 78 B₆ ribbons by engineering both the microstructure and volume fraction of the Ce₂Fe 14 B phase through optimization of the chamber pressure and the wheel speed necessary for quenching the liquid. We explored the relationship between these two parameters (chamber pressure and wheel speed), and proposed an approach to identifying the experimental conditions most likely to yield homogenous microstructure and reproducible magnetic properties. Optimized experimental conditions resulted in a microstructure with homogeneously dispersed Ce₂Fe 14 B and CeFe₂ nanocrystals. The best magnetic properties were obtained at a chamber pressure of 0.05 MPa and a wheel speed of 15 m·s -1 . Without the conventional heat-treatment that is usually required, key magnetic properties were maximized by optimization processing parameters in rapid solidification of magnetic materials in a cost-effective manner.

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.)

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.)

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

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

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.

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.

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

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.)

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 ).

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.

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

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.)

Preparation and properties of [(NdFeB)x/(Nb)z]n multi-layer films

International Nuclear Information System (INIS)

Tsai, J.-L.; Chin, T.-S.; Yao, Y.-D.; Melsheimer, A.; Fisher, S.; Drogen, T.; Kelsch, M.; Kronmueller, H.

2003-01-01

Multi-layer [(NdFeB) x /(Nb) z ] n films with 200 nm≥x≥10 nm, 10 nm≥z≥0, 40≥n≥2, prepared by ion beam sputtering and subsequent annealing, show significantly enhanced coercivity due to the reduced grain size that enhances the anisotropy of individual grains. After annealing at 630 deg. C, some Nd 2 Fe 14 B grains were enriched with Nb and isolated as the thickness of the Nb spacer layer increases. For multi-layer (NdFeB x /Nb z ) n films with 100 nm ≥x≥25 nm, 5 nm≥z≥2 nm, their coercivity and remanence ratio are better than that of a single NdFeB film. Up to 17.8 kOe room temperature coercivity has been obtained for a sample with x=25 nm, z=5 nm and n=16

Crystallization behavior and the thermal properties of Zr63Al7.5Cu17.5Ni10B2 bulk amorphous alloy

International Nuclear Information System (INIS)

Jang, J.S.C.; Chang, L.J.; Jiang, Y.T.; Wong, P.W.

2003-01-01

The ribbons of amorphous Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloys with 0.1 mm thickness were prepared by melt spinning method. The thermal properties and micro structural development during the annealing of amorphous alloy have been investigated by a combination of differential thermal analysis, differential scanning calorimetry, high-temperature optical microscope, X-ray diffractometry and TEM. The glass transition temperature for the Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloys are measured about 645 K (372 C). This alloy also obtains a large temperature interval ΔT x about 63 K. Meanwhile, the calculated T rg for Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloy presents the value of 0.57. The activation energy of crystallization for the alloy Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 was about 370± 10 kJ/mole as determined by the Kissinger and Avrami plot, respectively. These values are about 20% higher than the activation energy of crystallization for the Zr 65 Al 7.5 Cu 17.5 Ni 10 alloy (314 kJ/mol.). This implies that the boron additions exhibit the effect of improving the thermal stability for the Zr-based alloy. The average value of the Avrami exponent n were calculated to be 1.75±0.15 for Zr 63 Al 7.5 Cu 17.5 Ni 10 B 2 alloy. This indicates that this alloy presents a crystallization process with decreasing nucleation rate. (orig.)

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

Preparation, mechanical strengths, and thermal stability of Ni-Si-B and Ni-P-B amorphous wires

International Nuclear Information System (INIS)

Inoue, A.; Furukawa, S.; Hagiwara, M.; Masumoto, T.

1987-01-01

Ni-based amorphous wires with good bending ductility have been prepared for Ni/sub 75/Si/sub 8/B/sub 17/ and Ni/sub 78/P/sub 12/B/sub 10/ alloys containing 1 to 2 at. pct Al or Zr by melt spinning in rotating water. The enhancement of the wire-formation tendency by the addition of Al has been clarified to be due to the increase in the stability of the melt jet through the formation of a thin Al/sub 2/O/sub 3/ film on the outer surface. The maximum wire diameter is about 190 to 200 μm for the Ni-Si (or P)-B-Al alloys and increases to about 250 μm for the Ni-Si-B-Al-Cr alloys containing 4 to 6 at. pct Cr. The tensile fracture strength and fracture elongation are 2730 MPa and 2.9 pct for (N/sub 0.75/Si/sub 0.08/B/sub 0.17/)/sub 99/Al/sub 1/ wire and 2170 MPa and 2.4 pct for (Ni/sub 0.78/P/sub 0.12/B/sub 0.1/)/sub 99/Al/sub 1/ wire. These wires exhibit a fatigue limit under dynamic bending strain in air with a relative humidity of 65 pct; this limit is 0.50 pct for a NiSi-B-Al wire, which is higher by 0.15 pct than that of a Fe/sub 75/Si/sub 10/B/sub 15/ amorphous wire. Furthermore, the Ni-base wires do not fracture during a 180-deg bending even for a sample annealed at temperatures just below the crystallization temperature, in sharp contrast to high embrittlement tendency for Fe-base amorphous alloys. Thus, the Ni-based amorphous wires have been shown to be an attractive material similar to Fe- and Co-based amorphous wires because of its high static and dynamic strength, high ductility, high stability to thermal embrittlement, and good corrosion resistance

Preparation of Cu–Ni–Fe alloy coating and its evaluation on corrosion behavior in 3.5% NaCl solution

International Nuclear Information System (INIS)

Zhou, Qiongyu; Jiang, Jibo; Zhong, Qingdong; Wang, Yi; Li, Ke; Liu, Huijuan

2013-01-01

Highlights: ► An uniform Cu–Ni–Fe alloy coating constituted of homogenous γ-phases was prepared on the surface of low-carbon steel. ► The increase of Ni has a significant promotion to produce a uniform and homogenous Cu–Ni–Fe alloy coating. ► Electrochemical test results indicated the excellent corrosion resistance of the coating with high Ni content. ► EIS test and results demonstrated the surface homogeneity or compactness of the coating with high Ni content. -- Abstract: In this paper, an attempt had been made to prepare a Cu–Ni–Fe alloy coating for improving the corrosion resistance of the low-carbon steel. The surface heat treatment of coated low-carbon steel was performed at 1000 °C for 3 h under hydrogen atmosphere. The structure and microstructure of coatings was separately analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The corrosion resistance of the samples was evaluated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS). Results indicated that a compact alloy coating was formed on the surface of low-carbon steel and the Ni content had a prodigious impact to the microstructure, composition and structure of Cu–Ni–Fe alloy coating. Apart from that, significant improvements in corrosion resistance were achieved by using the Cu–Ni–Fe alloy coating, which constituting of homogeneous γ-phases

Effect of niobium addition to the Fe-17% Cr alloy on the resistance to generalized corrosion in sulfuric acid

International Nuclear Information System (INIS)

Alonso, Neusa; Wolynec, Stephan

1992-01-01

The aim of present work was to investigate the influence of Nb upon the corrosion resistance to o.5 M H2 SO 4 cf 17% Cr ferritic stainless steels, to which it was added in amounts larger than those necessary for the stabilization of interstitial elements. The performance of Fe-17% Cr alloys containing 0.31%, 0.58%, 1.,62% Nb was compared to that of two other Fe-17% Cr alloys containing 0.31%, 0.58% and 1.62% Nb was compared to that of two other Fe-175 Cr alloys, one without additions and another containing 0.93% Nb. Through weight and electrochemical measurements and through morphologic examination of corroded surface it was found that in o.5 M H 2 SO 4 solution the corrosion of these alloys, with the exception of that containing molybdenum, products in two different stages. In the first stage (up to about 60 minutes the rate practically does not change with time, the lower rates being displayed by alloys containing larger mounts of Nb. In the second stage (for immersion times larger than 60 minutes) the corrosion rate increases with time. the corrosion rate of Mo containing alloy is constant with time so that for longer immersion times this alloy becomes the most resistant. The first stage was discussed in terms of electromechanical properties of Nb and its ability to combine with steel impurities, while the second stage was considered as affected by corrosion products formed on the surface of these alloys after certain time of immersion. (author)

Formation of modified TbCu{sub 7} and Th{sub 2}Zn{sub 17} type structures during annealing of mechanical-alloyed Sm-Fe powders

Energy Technology Data Exchange (ETDEWEB)

Teresiak, A.; Kubis, M.; Mattern, N.; Wolf, M.; Mueller, K.-H. [Inst. fuer Festkoerper- und Werkstofforschung, Dresden (Germany)

1998-06-26

Compounds with the nominal composition near Sm{sub 2}Fe{sub 17} were prepared by mechanical alloying starting from the elemental powders and subsequent annealing at temperatures, T{sub A}, between 600 C and 900 C. For crystal structure investigations of the non-equilibrium phases formed at various temperatures, XRD methods with following Rietveld analysis were applied. For T{sub A} between 600 C and 750 C a modified TbCu{sub 7}-type structure of space group P6/mmm was found, in which the Fe(2c) site is replaced by the partially (1/3) and randomly occupied Fe(6l) site. Its approximate composition is SmFe{sub 8.8-9.0}. For T{sub A} between 800 C to 900 C a disordered modified Th{sub 2}Zn{sub 17} structure (space group R anti 3m) was found that is formed by introducing additional randomly occupied Fe (6c) and Sm(3a) positions, respectively. The degree of order of Sm atoms and Fe-dumbbells along the c-direction increases with increasing T{sub A}. A decrease in the Fe concentration in the cell is observed for increasing T{sub A}. The completely ordered stoichiometric Th{sub 2}Zn{sub 17}-type structure could not be reached by annealing samples prepared from the ball-milled elemental powders. (orig.) 20 refs.

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.)

Surface coating and magnetic properties of Sm2Fe17Nx materials

International Nuclear Information System (INIS)

Noguchi, K.; Machida, K.; Nishimura, M.; Adachi, G.

1998-01-01

Surface coating for finely ground Sm 2 Fe 17 N x (x=-3) powders (diameter 2 Fe 17 N x and (Zn,In)/Cu/Sm 2 Fe 17 N x , showed good oxidation-resistivity and thermal stability compared with the samples prepared without the Cu metal pre-coating, Zn/Sm 2 Fe 17 N x . The epoxy resin- or In metal-bonded magnets produced from the above coated powders, Zn/Cu/Sm 2 Fe 17 N x and (Zn,In)/Cu/Sm 2 Fe 17 N x , under warm molding conditions provided a flux loss of around -15% after standing in air at 120 C for 1000 h, but 30-40% for the conventional injection-type resin-bonded magnets prepared from Nd-Fe-B powders. (orig.)

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.

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.

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

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...

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.)

Investigation of phase stability of novel equiatomic FeCoNiCuZn based-high entropy alloy prepared by mechanical alloying

Science.gov (United States)

Soni, Vinay Kumar; Sanyal, S.; Sinha, S. K.

2018-05-01

The present work reports the structural and phase stability analysis of equiatomic FeCoNiCuZn High entropy alloy (HEA) systems prepared by mechanical alloying (MA) method. In this research effort some 1287 alloy combinations were extensively studied to arrive at most favourable combination. FeCoNiCuZn based alloy system was selected on the basis of physiochemical parameters such as enthalpy of mixing (ΔHmix), entropy of mixing (ΔSmix), atomic size difference (ΔX) and valence electron concentration (VEC) such that it fulfils the formation criteria of stable multi component high entropy alloy system. In this context, we have investigated the effect of novel alloying addition in view of microstructure and phase formation aspect. XRD plots of the MA samples shows the formation of stable solid solution with FCC (Face Cantered Cubic) after 20 hr of milling time and no indication of any amorphous or intermetallic phase formation. Our results are in good agreement with calculation and analysis done on the basis of physiochemical parameters during selection of constituent elements of HEA.

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.

Corrosion of martensitic steels in flowing 17Li83Pb alloy

International Nuclear Information System (INIS)

Flament, T.; Fauvet, P.; Hocde, B.; Sannier, J.

1988-01-01

Corrosion of three martensitic steels - 1.4914, HT9 and T91 - in the presence of flowing 17Li83Pb is investigated in thermal convection loops Tulip entirely made of 1.4914 steel. Two 3000-hour tests were performed at maximal temperatures of respectively 450 and 475 0 C with a δT of 60 0 C and an alloy velocity of about 0.08 m.s -1 . In both tests, corrosion is characterized by an homogeneous dissolution of the steel without formation of a corrosion layer. Corrosion rate is constant and very temperature dependent: the sound-metal loss of 1.4914 steel is 22 μm. year -1 at 450 0 C and 40 μm.year -1 at 475 0 C. Behaviours of 1.4914 and HT9 steels are very similar whereas T91 steel is about 20% less corroded

Structural and magnetic properties of Fe60Al40 alloys prepared by means of a magnetic mill

International Nuclear Information System (INIS)

Bernal-Correa, R.; Rosales-Rivera, A.; Pineda-Gomez, P.; Salazar, N.A.

2010-01-01

A study on synthesis, structural and magnetic characterization of Fe 60 Al 40 (at.%) alloys prepared by means of mechanical alloying process is presented. The mechanical alloying was performed using a milling device with magnetically controlled ball movement (Uni-Ball-Mill 5 equipment) at several milling times. The characterization was carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The effects of milling time on the structural state, morphological evolution and magnetic behaviour of the Fe 60 Al 40 (at.%) alloys are discussed. Besides, in this current study we emphasize the result that indicating a ferro-para-ferromagnetic transition from a correlation between X-ray diffraction and magnetization data.

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.

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.

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)

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

Nd2Fe14C-based magnet with better permanent magnetic properties prepared by a simple mechanochemical method

Science.gov (United States)

Geng, Hongmin; Ji, Yuan; Zhang, Jingjing; Gao, Yuchao; Yan, Yu; Wang, Wenquan; Su, Feng; Du, Xiaobo

2017-11-01

Nd2Fe14C-based magnet is prepared by a mechanochemical method, namely high-energy ball-milling Nd2Fe11Bx (x = 0-0.15) alloy in heptane (C7H16), followed by annealing to 850 °C in vacuum. Under the action of high-energy ball-milling, Nd2Fe11Bx react with heptane to form NdH2+δ, Fe-(CB), C, etc. H2 is released and Nd2Fe17, Nd2Fe17Cx (x = 0-3), Nd2Fe14C, Nd carbides and α-Fe are formed in the subsequent annealing. C amount depends on ball-milling time t. Long time ball milling or high C content suppresses the formation of 2:17 phase and favors the formation of 2:14:1 phase in the final products. Excessive ball-milling results in the quick increase of α-Fe. The maximum of magnetically hard Nd2Fe14C is obtained at t = 4 h. For Nd2Fe11 samples, there exists considerable quantity of Nd carbides and α-Fe phase appears earlier and increases rapidly with extending the ball-milling time t. The addition of B element shortens the ball-milling time of the formation of maximum Nd2Fe14C and prominently suppresses the formation of Nd carbide and α-Fe. The optimum magnetic properties, coercivity iHc of 1193.7 kA/m, remanence Mr of 580.9 kA/m, maximum magnetic energy product (BH)max of 91.7 kJ/m3 is approaching to its theoretic value of 99.2 kJ/m3 for isotropic Nd2Fe14C magnet, are obtained in Nd2Fe11B0.06 alloy ball milled for 3.5 h.

Preparation, thermal stability, and magnetic properties of Fe-Zr-Mo-W-B bulk metallic glass

International Nuclear Information System (INIS)

Liu, D.Y.; Sun, W.S.; Wang, A.M.; Zhang, H.F.; Hu, Z.Q.

2004-01-01

A bulk metallic glass (BMG) cylinder of Fe 60 Co 8 Zr 10 Mo 5 W 2 B 15 with a diameter of 1.5 mm was prepared by copper mould casting of industrial raw materials. The amorphous state and the crystallization behavior were investigated by X-ray diffraction (XRD). The thermal stability parameters, such as glass transition temperature (T g ), crystallization temperature (T x ), supercooled liquid region (ΔT x ) between T g and T x , and reduced glass transition temperature T rg (T g /T m ) were measured by differential scanning calorimetry (DSC) to be 891, 950, 59 K, and 0.62, respectively. The crystallization process took place through a single stage, and involved crystallization of the phases α-Fe, ZrFe 2 , Fe 3 B, MoB 2 , Mo 2 FeB 2 , and an unknown phase, as determined by X-ray analysis of the sample annealed for 1.5 ks at 1023 K, 50 K above the DSC peak temperature of crystallization. Moessbauer spectroscopy was studied for this alloy. The spectra exhibit a broadened and asymmetric doublet-like structure that indicated paramagnetic behavior and a fully amorphous structure. α-Fe was found in the amorphous matrix for a cylinder with a diameter of 2.5 mm. The success of synthesis of the Fe-based bulk metallic glass from industrial materials is important for the future progress in research and practical application of new bulk metallic glasses

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

Directory of Open Access Journals (Sweden)

Lin Chong

2013-05-01

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

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

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.

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.

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)

NdFeB nanoparticles prepared by wet-milling

Energy Technology Data Exchange (ETDEWEB)

Thielsch, Juliane; Lyubina, Julia; Woodcock, Thomas; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden (Germany)

2010-07-01

Since the prediction of a giant energy product of textured nanocomposite magnets those materials where believed to be the next generation of permanent magnets. For effective exchange-coupling in such two-phase magnets grain sizes need to be in the range of the domain wall width of the hard magnetic phase. That makes a homogenous phase distribution and a microstructure with nanograins necessary. One option of preparing such materials is the synthesis of magnetic nanoparticles which further could be aligned and compacted to a bulk magnet. For this we performed wet-milling experiments of a NdFeGaNbB alloy. XRD studies revealed that by using a surfactant and a solvent during the high energy ball milling process amorphization sets in later than compared to dry milling experiments under the same conditions. Dynamic Light Scattering investigations showed a Gauss distribution of the particle size with a mean diameter of about 12nm which was also proven by TEM. Magnetic properties were measured with SQUID and showed so far rather poor coercivity values.

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.

PREPARATION AND MAGNETIC-PROPERTIES OF AMORPHOUS FE1-XBX (15-LESS-THAN-OR-EQUAL-TO X LESS-THAN-40 ATMOSPHERIC PERCENT) ALLOY PARTICLES

DEFF Research Database (Denmark)

Linderoth, Søren; Mørup, S.

1992-01-01

Amorphous Fe1-xBx alloy particles have been prepared in aqueous solutions by reduction of Fe2+ ions to the metallic state by the use of NaBH4. It is demonstrated, that by changing the pH of the aqueous metal ion solution the amount of boron incorporated in the alloy particles can be varied between...... 15 and 28 at.%. Fe-57 Mossbauer spectra have been obtained at 10, 80 and 295 K. The hyperfine parameters for amorphous particles have been found to be similar to those found for ribbons and films prepared by the liquid-quench and sputtering techniques, respectively, though with a tendency...... for the magnetic hyperfine fields for the chemically prepared and sputter prepared alloys to deviate slightly from those for melt-spun samples. The magnetic hyperfine fields decrease linearly as a function of T3/2....

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

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....

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)

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

Development of FeCoB/Graphene Oxide based microwave absorbing materials for X-Band region

International Nuclear Information System (INIS)

Das, Sukanta; Chandra Nayak, Ganesh; Sahu, S.K.; Oraon, Ramesh

2015-01-01

This work explored the microwave absorption capability of Graphene Oxide and Graphene Oxide coated with FeCoB for stealth technology. Epoxy based microwave absorbing materials were prepared with 30% loading of Graphene Oxide, FeCoB alloy and Graphene Oxide coated with FeCoB. Graphene Oxide and FeCoB were synthesized by Hummer's and Co-precipitation methods, respectively. The filler particles were characterized by FESEM, XRD and Vibrating Sample Magnetometer techniques. Permittivity, permeability and reflection loss values of the composite absorbers were measured with vector network analyzer which showed a reflection loss value of −7.86 dB, at 10.72 GHz, for single layered Graphene Oxide/Epoxy based microwave absorbers which can be correlated to the absorption of about 83.97% of the incident microwave energy. Reflection loss value of FeCoB/Epoxy based microwave absorber showed −13.30 dB at 11.67 GHz, which corresponded to maximum absorption of 93.8%. However, reflection loss values of Graphene Oxide coated with FeCoB/Epoxy based single-layer absorber increased to −22.24 dB at 12.4 GHz which corresponds to an absorption of 99% of the incident microwave energy. - Highlights: • FeCoB coated Graphene Oxide (GO) was synthesized by co-precipitation method. • GO, FeCoB and GO@FeCoB based microwave absorbers were developed with Epoxy matrix. • GO and FeCoB/Epoxy absorbers showed −7.86 & −13.30 dB reflection loss, respectively. • Maximum Reflection loss of −22.24 dB was achieved with GO@FeCoB/Epoxy absorber

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

Influence of annealing and nitrogenation on structure and magnetic properties of mechanically alloyed Sm-Fe powders

International Nuclear Information System (INIS)

Teresiak, A.; Kubis, M.; Mattern, N.; Wolf, M.; Mueller, K.-H.

1998-01-01

Sm-Fe-N compounds were prepared by mechanical alloying, subsequent annealing and nitrogenation. For crystal structure investigations of the non-equilibrium phases Sm 2 Fe 17+x and Sm 2 Fe 17+x N y , respectively, formed at the various annealing temperatures T A , XRD with following Rietveld analysis was used. For T A between 600 C and 750 C a modified hexagonal TbCu 7 structure (space group P6/mmm) was found in which the Fe(2c) site is replaced by the partially (1/3) and randomly occupied Fe(61) site. The approximated composition is SmFe 8.8-9.0 . The nitrogenated alloys crystallize in the same structure for 600 C A A ≤ 900 C a disordered modified Th 2 Zn 17 structure (space group R anti 3m) was found that is formed by introducing additional Fe (6c) and Sm(3a) positions. The degree of order of the Sm- and Fe-atoms in c-direction increases with increasing annealing temperature. The completely ordered stoichiometric Sm 2 Fe 17 structure could not be reached by annealing the ball milled elemental powders. The nitrided alloys already form this intermediate structure at T A = 750 C. The interstitial nitrogen occupies the 9e site. The estimated nitrogen content is higher in the hexagonal phases than in the rhombohedral phase. Optimum magnetic properties, in particular a coercitivity μ 01 H C = 3.7 T and a good squareness of the demagnetization curve, were obtained for T A = 750 C. Here we found a nitrogen content of y = 3 for Sm 2 Fe 17+x N y . (orig.)

Heat treatment influence on the structural and magnetic properties of the intermetallic Fe56.25Al43.75 alloy prepared by mechanical alloying and arc-melted

Science.gov (United States)

Trujillo Hernández, J. S.; Tabares, J. A.; Pérez Alcázar, G. A.

2014-04-01

Alloys of the Fe56.25Al43.75 system were prepared by mechanical alloying (MA) using a high energy planetary ball mill, with milling times in the range from 12 up to 96 h named MA0 samples. The sample milled for 48 hours was heat treated at 700 °C for 9 days. Then this sample was milled for times of 1, 4, 8, 12, 24, and 48 h, named MA1 samples. Additionally, and for comparison, it was prepared a Fe56.25Al43.75 sample by arc-melting method. For all samples, the structural and magnetic study was conducted by X-rays diffraction (XRD) and Mössbauer spectrometry (MS). The XRD results show that the system is nanostructured and the MA0 samples present only the BCC disordered phase, whose lattice parameter remains relatively constant with milling time. For MA1 samples it was identify the FeAl, Fe3Al, FeO and α-Fe phases. The Mössbauer spectra for all samples were fitted by using a hyperfine magnetic field distribution (HMFD), and a paramagnetic site for all the times used here. The ferromagnetism increases when milling time increases, and this is a consequence of the structural disorder induced by mechanical alloying.

Effect of hydrogenation disproportionation conditions on magnetic anisotropy in Nd-Fe-B powder prepared by dynamic hydrogenation disproportionation desorption recombination

Directory of Open Access Journals (Sweden)

Masao Yamazaki

2017-05-01

Full Text Available Various anisotropic Nd-Fe-B magnetic powders were prepared by the dynamic hydrogenation disproportionation desorption recombination (d-HDDR treatment with different hydrogenation disproportionation (HD times (tHD. The resulting magnetic properties and microstructural changes were investigated. The magnetic anisotropy was decreased with increasing tHD. In the d-HDDR powders with higher magnetic anisotropy, fine (200–600 nm and coarse (600–1200 nm Nd2Fe14B grains were observed. The coarse Nd2Fe14B grains showed highly crystallographic alignment of the c-axis than fine Nd2Fe14B grains. In the highly anisotropic Nd2Fe14B d-HDDR powder, a large area fraction of lamellar-like structures consisting of NdH2 and α-Fe were observed after HD treatment. Furthermore, the mean diameter of the lamellar-like regions, where lamellar-like structures orientate to the same direction in the HD-treated alloys was close to that of coarse Nd2Fe14B grains after d-HDDR treatment. Thus, the lamellar-like regions were converted into the crystallographically aligned coarse Nd2Fe14B grains during desorption recombination treatment, and magnetic anisotropy is closely related to the volume fraction of lamellar-like regions observed after HD treatment.

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.

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.

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.

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

The investigation of Fe-Mn-based alloys with shape memory effect by small-angle scattering of polarized neutrons

International Nuclear Information System (INIS)

Kopitsa, G.P.; Runov, V.V.; Grigoriev, S.V.; Bliznuk, V.V.; Gavriljuk, V.G.; Glavatska, N.I.

2003-01-01

The small-angle polarized neutron scattering (SAPNS) technique has been used to study a nuclear and magnetic homogeneity in the distribution of both substituent (Si, Cr, Ni) and interstitial (C, N) alloying elements on the mesoscopic range in Fe-Mn-based alloys with shape memory effect (SME). The four groups of alloys with various basic compositions: FeMn 18 (wt%), FeMn 20 Si 6 , FeMn 20 Cr 9 N 0.2 and FeMn 17 Cr 9 Ni 4 Si 6 were investigated. It was found that the small-angle scattering of neutrons and depolarization on these alloys are very small altogether. The scattering did not exceed 1.5% from the incident beam and depolarization ∼2% for all samples. It means that these alloys are well nuclear and magnetically homogeneous on the scale of 10-1000 A. However, the difference in the homogeneity depending on the compositions still takes place. Thus, the adding of Si in FeMn 18 and FeMn 20 Cr 9 N 0.2 alloys improves the homogeneity pronouncedly. At once, the effect of the doping by C or N atoms on the homogeneity in FeMn 20 Si 6 and FeMn 17 Cr 9 Ni 4 Si 6 alloys is multivalued and depend on the presence of substitutional atoms (Ni and Cr). The capability of SAPNS as a method for the study of mesoscopic homogeneity in materials with SME and testing of the quality of their preparation is discussed

In situ Investigation of Magnetism in Metastable Phases of Levitated {\mathrm{<span\; class="hlt">Fe</span>}}_{\mathrm{<span\; class="hlt">83</span>}}{{<span\; class="hlt">B</span>}}_{\mathrm{<span\; class="hlt">17</span>}} During Solidification

Energy Technology Data Exchange (ETDEWEB)

Quirinale, D.G.; Messina, D.; Rustan, G.E.; Kreyssig, A.; Prozorov, R.; Goldman, A.I. (Ames); (Iowa State)

2017-11-01

In situ measurements of structure, density, and magnetization on samples of Fe 83 B 17 using an electrostatic levitation furnace allow us to identify and correlate the magnetic and structural transitions in this system during its complex solidification process. In particular, we identify magnetic ordering in the metastable Fe 23 B 6 / fcc Fe coherently grown structures and primitive tetragonal Fe 3 B metastable phase in addition to characterizing the equilibrium Fe 2 B phase. Our measurements demonstrate that the incorporation of a tunnel-diode oscillator circuit within an electrostatic levitation furnace enables investigations of the physical properties of high-temperature metastable structures.

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

Joule heating of Fe-B metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Miglierini, M.; Sitek, J.; Lipka, J. (Dept. of Nuclear Physics and Technology, Slovak Technical Univ., Bratislava, Slovak Republic (Czechoslovakia))

1993-04-01

Amorphous Fe[sub 80]B[sub 20] and Fe[sub 83]B[sub 17] ribbons were heated in air and in vacuum, respectively, by a dc electric current passing through the specimen. During the Joule heating, [sup 57]Fe transmission Moessbauer spectra were recorded. Ribbons of the same geometrical dimensions, cut from a natural iron foil, were treated in the same way as a reference. The influence of the current-induced magnetic field in addition to the Joule heating is supposed to cause fluctuations in a short-range order observed. Changes in the hyperfine magnetic fields are compared with those obtained by a conventional heating in a vacuum furnace. (orig.).

Joule heating of Fe-B metallic glasses

International Nuclear Information System (INIS)

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

1993-01-01

Amorphous Fe 80 B 20 and Fe 83 B 17 ribbons were heated in air and in vacuum, respectively, by a dc electric current passing through the specimen. During the Joule heating, 57 Fe transmission Moessbauer spectra were recorded. Ribbons of the same geometrical dimensions, cut from a natural iron foil, were treated in the same way as a reference. The influence of the current-induced magnetic field in addition to the Joule heating is supposed to cause fluctuations in a short-range order observed. Changes in the hyperfine magnetic fields are compared with those obtained by a conventional heating in a vacuum furnace. (orig.)

Preparation and properties of Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} bulk metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ling; Ma, XiuHua [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Li, Qiang, E-mail: qli@xju.edu.cn [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Zhang, Jijun [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Dong, Yaqiang; Chang, Chuntao [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

2014-09-01

Highlights: • Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20–50 at.%) BMGs were prepared by fluxing and J-quenching techniques. • The highest GFA is reached at x = 40 and the corresponding critical diameter is up to 2.5 mm. • The present FeNi-based BMGs exhibit very large ε{sub p} and the ε{sub p} of Fe{sub 30}Ni{sub 50}P{sub 14}B{sub 6} BMG is 11.7%. • The present FeNi-based BMGs have much higher corrosion resistance than stainless steel. - Abstract: Bulk Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20, 30, 40, 50 at.%) glassy alloy rods with the diameters of 1.0–2.5 mm were synthesized by combining fluxing technique and J-quenching technique. The glassy alloy rods were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). It is found that the range of supercooled liquid region (ΔT{sub x}) is 27–32 K. The saturation magnetization of Fe{sub 80−x}Ni{sub x}P{sub 14}B{sub 6} (x = 20, 30, 40, 50 at.%) bulk glassy alloys gradually decreases from 1.13 T to 0.58 T with increasing Ni content from x = 20 to x = 50. More importantly, the present quaternary FeNiPB bulk metallic glasses (BMGs) shows a significant plastic strain, in particular, the plastic strain of Fe{sub 30}Ni{sub 50}P{sub 14}B{sub 6} BMG reaches as high as 11.7%. The corrosion resistance of the present FeNiPB BMGs was studied by weight-loss method, potentiodynamic polarization curves and scanning electron microscopy (SEM). It is shown that the corrosion resistance of the present FeNiPB BMGs in 0.5 M NaCl and 1 M HCl solution increases with Ni content, and further the present FeNiPB BMGs exhibit larger E{sub corr} values and lower I{sub corr} values, i.e. higher corrosion resistances, than that of stainless steel.

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

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.

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.)

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)

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.

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

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

Effect of niobium addition to the Fe-17% Cr alloy on the resistance to generalized corrosion in sulfuric acid; Efeito da adicao de niobio a liga Fe-17% Cr sobre a resistencia a corrosao generalizada em acido sulfurico

Energy Technology Data Exchange (ETDEWEB)

Alonso, Neusa; Wolynec, Stephan

1993-12-31

The aim of present work was to investigate the influence of Nb upon the corrosion resistance to o.5 M H2 SO{sub 4} cf 17% Cr ferritic stainless steels, to which it was added in amounts larger than those necessary for the stabilization of interstitial elements. The performance of Fe-17% Cr alloys containing 0.31%, 0.58%, 1.,62% Nb was compared to that of two other Fe-17% Cr alloys containing 0.31%, 0.58% and 1.62% Nb was compared to that of two other Fe-175 Cr alloys, one without additions and another containing 0.93% Nb. Through weight and electrochemical measurements and through morphologic examination of corroded surface it was found that in o.5 M H{sub 2} SO{sub 4} solution the corrosion of these alloys, with the exception of that containing molybdenum, products in two different stages. In the first stage (up to about 60 minutes) the rate practically does not change with time, the lower rates being displayed by alloys containing larger mounts of Nb. In the second stage (for immersion times larger than 60 minutes) the corrosion rate increases with time. the corrosion rate of Mo containing alloy is constant with time so that for longer immersion times this alloy becomes the most resistant. The first stage was discussed in terms of electromechanical properties of Nb and its ability to combine with steel impurities, while the second stage was considered as affected by corrosion products formed on the surface of these alloys after certain time of immersion. (author) 24 refs., 1 fig., 3 tabs.

Stress-induced phase transformation and room temperature aging in Ti-Nb-Fe alloys

Energy Technology Data Exchange (ETDEWEB)

Cai, S.; Schaffer, J.E. [Fort Wayne Metals Research Products Corp, 9609 Ardmore Ave., Fort Wayne, IN 46809 (United States); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

2017-01-05

Room temperature deformation behavior of Ti-17Nb-1Fe and Ti-17Nb-2Fe alloys was studied by synchrotron X-ray diffraction and tensile testing. It was found that, after proper heat treatment, both alloys were able to recover a deformation strain of above 3.5% due to the Stress-induced Martensite (SIM) phase transformation. Higher Fe content increased the beta phase stability and onset stress for SIM transformation. A strong {110}{sub β} texture was produced in Ti-17Nb-2Fe compared to the {210}{sub β} texture that was observed in Ti-17Nb-1Fe. Room temperature aging was observed in both alloys, where the formation of the omega phase increased the yield strength (also SIM onset stress), and decreased the ductility and strain recovery. Other metastable beta Ti alloys may show a similar aging response and this should draw the attention of materials design engineers.

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.

Surface modification and its role in the preparation of FeSi gradient alloys with good magnetic property and ductility

Science.gov (United States)

Yu, Haiyuan; Bi, Xiaofang

2018-04-01

Realization of the effective Si penetration at a lower processing temperature is a challenge, but of significance in reducing the strict requirements for the equipment and realizing cost-cutting in production. In this work, we have modified the surface microstructure of Fe-3 wt%Si alloy by using surface mechanical attrition treatment. The modified surface microstructure is characteristic of nanocrystalline, which is found to significantly enhance the efficiency of subsequent Si penetration into the alloy, and successively leading to the decrease of penetration temperature up to 200 °C. As a consequence, the Si gradient distribution across thickness can be readily controlled by changing penetration time, and FeSi alloys with various gradients are prepared by chemical vapor deposition along with subsequent annealing process. The dependence of magnetic and mechanical properties on Si gradient for demonstrates that the increase of Si gradient reduces core losses, especially at higher frequencies, and meanwhile improves ductility of FeSi alloys as well. The mechanism underlying the effect of Si gradient is clarified by combining magnetostriction measurement and domain structure observations. This work provides a facile and effective way for achieving gradient FeSi alloys with good magnetic property and ductility.

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

Phase composition of iron-rich R-Fe-Si (R=Dy, Ho, Er) alloys

International Nuclear Information System (INIS)

Ivanova, G.V.; Makarova, G.M.; Shcherbakova, E.V.; Belozerov, E.V.

2005-01-01

Phase composition is studied in iron-rich alloys of R-Fe-Si (R=Dy, Ho, Er). In the as-cast state R 2 (Fe, Si) 17 of type Th 2 Ni 17 and R(Fe, Si) 12 compounds are observed; in the alloys of rated composition of R(Fe 0.85 Si 0.15 ) 8.5 (R=Dy, Er) a compound R 2 (Fe, Si) 17 of Th 2 Zn 17 -type is revealed as well. The annealing at 1273 K results in formation of Dy 3 (Fe, Si) 29 and also the compounds with the presumed composition of Dy 4 (Fe, Si) 41 and Ho 4 (Fe, Si) 41 . As this takes place the alloys contain a transition structure as well that represents a set of small-sized areas with various type short-range order in mutual displacement of Fe-Fe(Si) dumpbell chains. The process of phase formation at 1273 K is faced with difficulties. Even the annealing for 1000 h does not result in the state of equilibrium [ru

Structural and magnetic properties of Fe{sub 60}Al{sub 40} alloys prepared by means of a magnetic mill

Energy Technology Data Exchange (ETDEWEB)

Bernal-Correa, R. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Rosales-Rivera, A., E-mail: arosalesr@unal.edu.c [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Pineda-Gomez, P. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Universidad de Caldas, Manizales (Colombia); Salazar, N.A. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia)

2010-04-16

A study on synthesis, structural and magnetic characterization of Fe{sub 60}Al{sub 40} (at.%) alloys prepared by means of mechanical alloying process is presented. The mechanical alloying was performed using a milling device with magnetically controlled ball movement (Uni-Ball-Mill 5 equipment) at several milling times. The characterization was carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The effects of milling time on the structural state, morphological evolution and magnetic behaviour of the Fe{sub 60}Al{sub 40} (at.%) alloys are discussed. Besides, in this current study we emphasize the result that indicating a ferro-para-ferromagnetic transition from a correlation between X-ray diffraction and magnetization data.

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...

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.)

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.

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.

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.

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

Czech Academy of Sciences Publication Activity Database

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

2002-01-01

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

A novel high-strength and highly corrosive biodegradable Fe-Pd alloy: Structural, mechanical and in vitro corrosion and cytotoxicity study.

Science.gov (United States)

Čapek, Jaroslav; Msallamová, Šárka; Jablonská, Eva; Lipov, Jan; Vojtěch, Dalibor

2017-10-01

Recently, iron-based materials have been considered as candidates for the fabrication of biodegradable load-bearing implants. Alloying with palladium has been found to be a suitable approach to enhance the insufficient corrosion rate of iron-based alloys. In this work, we have extensively compared the microstructure, the mechanical and corrosion properties, and the cytotoxicity of an FePd2 (wt%) alloy prepared by three different routes - casting, mechanical alloying and spark plasma sintering (SPS), and mechanical alloying and the space holder technique (SHT). The properties of the FePd2 (wt%) were compared with pure Fe prepared in the same processes. The preparation route significantly influenced the material properties. Materials prepared by SPS possessed the highest values of mechanical properties (CYS~750-850MPa) and higher corrosion rates than the casted materials. Materials prepared by SHT contained approximately 60% porosity; therefore, their mechanical properties reached the lowest values, and they had the highest corrosion rates, approximately 0.7-1.2mm/a. Highly porous FePd2 was tested in vitro according to the ISO 10993-5 standard using L929 cells, and two-fold diluted extracts showed acceptable cytocompatibility. In general, alloying with Pd enhanced both mechanical properties and corrosion rates and did not decrease the cytocompatibility of the studied materials. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Application of a dynamic-nanoindentation method to analyze the local structure of an Fe-18 at.% Gd cast alloy

Energy Technology Data Exchange (ETDEWEB)

Choi, Yong; Baik, Youl [Dept. of Materials Science and Technology, Dankook University, Cheonan(Korea, Republic of); Moon, Byung M. [Liquid Processing and Casting Technology R and D Group, KITECH, Incheon (Korea, Republic of); Sohn, Dong Seong [Nuclear Engineering Department, UNIST, Ulsan (Korea, Republic of)

2017-04-15

A dynamic nanoindentation method was applied to study an Fe-18 at.% Gd alloy as a neutron-absorbing material prepared by vacuum arc-melting and cast in a mold. The Fe-18 at.% Gd cast alloy had a microstructure with matrix phases and an Fe-rich primary dendrite of Fe9Gd. Rietveld refinement of the X-ray spectra showed that the Fe-18 at.% Gd cast alloy consisted of 35.84 at.% Fe3Gd, 6.58 at.% Fe5Gd, 16.22 at.% Fe9Gd, 1.87 at.% Fe2Gd, and 39.49 at.% β-Fe17Gd2. The average nanohardness of the primary dendrite phase and the matrix phases were 8.7 GPa and 9.3 GPa, respectively. The fatigue limit of the matrix phase was approximately 37% higher than that of the primary dendrite phase. The dynamic nanoindentation method is useful for identifying local phases and for analyzing local mechanical properties.

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)

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.

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.

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

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.

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.

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.

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)

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.

Curie temperature rising by fluorination for Sm2Fe17

Directory of Open Access Journals (Sweden)

Matahiro Komuro

2013-02-01

Full Text Available Fluorine atoms can be introduced to Sm2Fe17 using XeF2 below 423 K. The resulting fluorinated Sm2Fe17 powders have ferromagnetic phases containing Sm2Fe17FY1(0Fe17FY2 (1Fe17, and α-Fe. The unit cell for Sm2Fe17 is elongated by the fluorination. The largest unit cell volume among the rhombohedral Sm2Fe17 compounds is 83.8 nm3, which is 5.8% larger than Sm2Fe17. The rhombohedral Sm2Fe17 with the largest unit cell volume is dissociated above 873 K, and fluorination increases Curie temperature from 403 K for Sm2Fe17 to 675 K. This increase can be explained by the magneto-volume effect.

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

The microstructure and magnetic properties of Nd8.5Tb1.5Fe83Zr1B6 ribbons obtained at various cooling rates

Directory of Open Access Journals (Sweden)

Dośpiał Marcin

2015-03-01

Full Text Available The paper presents results of microstructure and magnetic properties studies of Nd8.5Tb1.5Fe83Zr1B6 ribbons obtained by melt-spinning technique. The samples were produced using the rapid cooling of liquid alloy on the copper wheel, by applying three different linear velocities 20, 30, and 35 m/s. The microstructure of obtained ribbons was examined using X-ray diffractometry and Mössbauer spectroscopy. Magnetic measurements were performed using LakeShore vibrating sample magnetometer. The microstructure measurements were used for quantitative and qualitative analysis of phase composition. Basing on results of structure studies combined with magnetic measurements, the influence of phase composition on hysteresis loop behavior was described.

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

High anisotropic NdFeB submicro/nanoflakes prepared by surfactant-assisted ball milling at low temperature

Science.gov (United States)

An, Xiaoxin; Jin, Kunpeng; Abbas, Nadeem; Fang, Qiuli; Wang, Fang; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

2017-11-01

Hard magnetic NdFeB submicro/nanoflakes were successfully prepared by surfactant-assisted ball milling at low temperature (SABMLT) by specially using 2-methyl pentane and trioctylamine (TOA) as solvent and surfactant, respectively. Influences of the amount of TOA and milling temperature on the crystal structure, morphology and magnetic performances of the as-prepared NdFeB powders were investigated systematically. There is significant difference on morphology between the NdFeB powders milled at room and low temperature. The NdFeB powders with flaky morphology could be obtained even with a small amount of TOA by SABMLT, which could not be achieved by surfactant-assisted ball milling at room temperature (SABMRT). The better crystallinity, better grain alignment, higher coercivity, larger saturation magnetization and remanence ratio were achieved in the samples prepared by SABMLT. Furthermore, the final NdFeB powders prepared by SABMLT possessed a lower amount of residual TOA than those prepared by SABMRT. It was demonstrated that SABMLT is a promising way to fabricate rare-earth-transition metal nanoflakes with high anisotropy for permanent magnetic materials. The effective method of preparing NdFeB flakes by lowering temperature will be also useful to fabricate flakes of other functional materials.

Microstructure and Tensile Behavior of Al8Co17Cr17Cu8Fe17Ni33 (at.%) High-Entropy Alloy

Science.gov (United States)

Daoud, H. M.; Manzoni, A.; Völkl, R.; Wanderka, N.; Glatzel, U.

2013-12-01

Microstructure evolution and tensile behavior of the high-entropy alloy Al8Co17Cr17Cu8Fe17Ni33 (at.%) are investigated at room temperature and at 500°C in the as-cast state and under different heat-treatment conditions. Detailed microstructural characterizations are carried out using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The equilibrium phase evolution as a function of temperature was calculated using the Thermo-Calc software (Thermo-Calc Software, Stockholm, Sweden) integrated with TTNi-7 database. The observed majority phase is a face-centered cubic solid solution for all tested specimens. Tensile ductility at room temperature and at elevated temperature is enhanced by heat treatment at 1150°C. An embrittlement phenomenon has been observed after a heat treatment at 700°C resulting in significant degradation in tensile properties.

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)

Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

Directory of Open Access Journals (Sweden)

Talijan Nadežda M.

2005-01-01

Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

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.

Influence of annealing and nitrogenation on structure and magnetic properties of mechanically alloyed Sm-Fe powders

Energy Technology Data Exchange (ETDEWEB)

Teresiak, A.; Kubis, M.; Mattern, N.; Wolf, M.; Mueller, K.-H. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany)

1998-07-01

Sm-Fe-N compounds were prepared by mechanical alloying, subsequent annealing and nitrogenation. For crystal structure investigations of the non-equilibrium phases Sm{sub 2}Fe{sub 17+x} and Sm{sub 2}Fe{sub 17+x}N{sub y}, respectively, formed at the various annealing temperatures T{sub A}, XRD with following Rietveld analysis was used. For T{sub A} between 600 C and 750 C a modified hexagonal TbCu{sub 7} structure (space group P6/mmm) was found in which the Fe(2c) site is replaced by the partially (1/3) and randomly occupied Fe(61) site. The approximated composition is SmFe{sub 8.8-9.0}. The nitrogenated alloys crystallize in the same structure for 600 C < T{sub A} < 700 C. In this case the interstitial nitrogen randomly occupies the 3f site partially (1/3). For 800 C {<=} T{sub A} {<=} 900 C a disordered modified Th{sub 2}Zn{sub 17} structure (space group R anti 3m) was found that is formed by introducing additional Fe (6c) and Sm(3a) positions. The degree of order of the Sm- and Fe-atoms in c-direction increases with increasing annealing temperature. The completely ordered stoichiometric Sm{sub 2}Fe{sub 17} structure could not be reached by annealing the ball milled elemental powders. The nitrided alloys already form this intermediate structure at T{sub A} = 750 C. The interstitial nitrogen occupies the 9e site. The estimated nitrogen content is higher in the hexagonal phases than in the rhombohedral phase. Optimum magnetic properties, in particular a coercitivity {mu}{sub 01}H{sub C} = 3.7 T and a good squareness of the demagnetization curve, were obtained for T{sub A} = 750 C. Here we found a nitrogen content of y = 3 for Sm{sub 2}Fe{sub 17+x}N{sub y}. (orig.)

Microstructure and Room-Temperature Mechanical Properties of FeCrMoVTi x High-Entropy Alloys

Science.gov (United States)

Guo, Jun; Huang, Xuefei; Huang, Weigang

2017-07-01

FeCrMoVTi x ( x values represent the molar ratio, where x = 0, 0.5, 1.0, 1.5, and 2.0) high-entropy alloys were prepared by a vacuum arc melting method. The effects of Ti element on the microstructure and room-temperature mechanical properties of the as-cast FeCrMoVTi x alloys were investigated. The results show that the prepared alloys exhibited typical dendritic microstructure and the size of the microstructure became fine with increasing Ti content. The FeCrMoV alloy exhibited a single body-centered cubic structure (BCC1) and the alloys prepared with Ti element exhibited BCC1 + BCC2 mixed structure. The new BCC2 phase is considered as (Fe, Ti)-rich phase and was distributed in the dendrite region. With the increase of Ti content, the volume fraction of the BCC2 phase increased and its shape changed from a long strip to a network. For the FeCrMoV alloy, the fracture strength, plastic strain, and hardness reached as high as 2231 MPa, 28.2%, and 720 HV, respectively. The maximum hardness of 887 HV was obtained in the FeCrMoVTi alloy. However, the fracture strength, yield stress, and plastic strain of the alloys decreased continuously as Ti content increased. In the room-temperature compressive test, the alloys showed typical brittle fracture characteristics.

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.

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.

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.)

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.)

Microstructural characterization of spray formed Fe-based amorfizable alloy; Caracterizacao microestrutural de ligas ferrosas amorfizaveis processadas por conformacao por spray

Energy Technology Data Exchange (ETDEWEB)

Gabriel, A.H.G.; Ananias, M.Jr. da S.; Lucena, F.A.; Santos, L.S. dos; Bolfarini, C.; Botta, W.J.; Kiminami, C.S.; Afonso, C.R.M., E-mail: guimaraes.andreh@gmail.com [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil)

2014-07-01

Iron-based amorphous alloys show outstanding characteristics such as high hardness and wear resistance, with microstructure partially amorphous, making them favorable to spray forming process (SF), which has cooling rates between 10{sup 3}-10{sup 5} K/s. Thus, this work aims to use the SF in one of the alloy cast iron present in this project, being chosen the alloy with a better set of results, through the performed characterizations. The alloys studied in this project were: (Fe{sub 65}Cr{sub 17}Mo{sub 2}C{sub 14}Si{sub 1}Cu{sub 1}){sub 100-x}B{sub x} (x = 5, 8 and 12% at) and (Fe{sub 65}Cr{sub 17}Mo{sub 2}C{sub 14}Si{sub 1}Cu{sub 1}){sub 88}Nb{sub 4}B{sub 8} (at.%), being all processed through Discovery® Plasma and 'melt- spinning' and characterized using: TEM, SEM, DSC, XRD and microhardness test. The cast iron alloy selected were (Fe{sub 65}Cr{sub 17}Mo{sub 2}C{sub 14}Si{sub 1}Cu{sub 1}){sub 88}Nb{sub 4}B+8, getting by the spray forming process, deposit and overspray powder. With them, were realized almost the same characterizations, except for the TEM. The results showed 1044±102 (HV1) in Vickers microhardness and nanocrystalline overspray powder from 20-45 μm to > 180 μm. (author)

Structure and soft magnetic properties of the bulk samples prepared by compaction of the mixtures of Co-based and Fe-based powders

International Nuclear Information System (INIS)

Fuezer, J.; Bednarcik, J.; Kollar, P.; Roth, S.

2007-01-01

Ball milling of CoFeZrB ribbons and subsequent compaction of the resulting powders were used to prepare bulk amorphous samples. Further, two sets of powder samples were prepared by cryomilling of FeCuNbMoSiB alloy in amorphous and nanocrystalline state. Amorphous and nanocrystalline FeCuNbMoSiB powders were blended with CoFeZrB powder at different concentrations. Such powder mixtures were consolidated and several bulk nanocomposites have been synthesized. An addition of nanocrystalline or amorphous FeCuNbMoSiB powder to amorphous CoFeZrB powder caused a decrease of the magnetostriction of the resultant bulk samples, while the coercivity shows an opposite behavior. Our results show that the powder consolidation by hot pressing is an alternative method for the preparation of bulk metallic glasses, which are difficult to prepare by casting methods

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)

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

Directory of Open Access Journals (Sweden)

J. Piątkowski

2011-10-01

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

Properties of nanoparticles prepared from NdFeB-based compound for magnetic hyperthermia application.

Science.gov (United States)

Périgo, E A; Silva, S C; de Sousa, E M B; Freitas, A A; Cohen, R; Nagamine, L C C M; Takiishi, H; Landgraf, F J G

2012-05-04

Nanoparticles were prepared from a NdFeB-based alloy using the hydrogen decrepitation process together with high-energy ball milling and tested as heating agent for magnetic hyperthermia. In the milling time range evaluated (up to 10 h), the magnetic moment per mass at H = 1.59 MA m(-1) is superior than 70 A m(2) kg(-1); however, the intrinsic coercivity might be inferior than 20 kA m(-1). The material presents both ferromagnetic and superparamagnetic particles constituted by a mixture of phases due to the incomplete disproportionation reaction of Nd(2)Fe(14)BH(x) during milling. Solutions prepared with deionized water and magnetic particles exposed to an AC magnetic field (H(max) ~ 3.7 kA m(-1) and f = 228 kHz) exhibited 26 K ≤ ΔT(max) ≤ 44 K with a maximum estimated specific absorption rate (SAR) of 225 W kg(-1). For the pure magnetic material milled for the longest period of time (10 h), the SAR was estimated as ~2500 W kg(-1). In vitro tests indicated that the powders have acceptable cytotoxicity over a wide range of concentration (0.1-100 µg ml(-1)) due to the coating applied during milling.

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...

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.)

Soft magnetic properties of FeRuGaSi alloy films: SOFMAX

International Nuclear Information System (INIS)

Hayashi, K.; Hayakawa, M.; Ishikawa, W.; Ochiai, Y.; Iwasaki, Y.; Aso, K.

1988-01-01

To advance new soft magnetic materials of an FeGaSi alloy into the commercial world, improvements on various properties were designed by introducing additive elements without sacrificing its high saturation magnetic induction. The detailed studies on the diversified properties, such as saturation magnetic induction, film internal stress, wear resistivity, and so on, were performed. High-frequency permeability of the laminated structure film was also investigated. As a result, the Ru-added FeRuGaSi alloy films, whose typical compositions are Fe 72 Ru 4 Ga 7 Si 17 and Fe 68 Ru 8 Ga 7 Si 17 (at. %), prove to be excellent soft magnetic materials especially appropriate for the magnetic recording/playback head core use

Preparation and Characterization of TiB2-(Supra-Nano-Dual-Phase High-Entropy Alloy Cermet by Spark Plasma Sintering

Directory of Open Access Journals (Sweden)

Shulei Zhang

2018-01-01

Full Text Available This paper introduces the preparation method and characterization results of TiB2 ceramics with CoCrFeNiAl high-entropy alloy (HEA as a sintering aid by Spark Plasma Sintering (SPS. Good wettability between HEA and TiB2 was proved by the sessile drop method, indicating promising prospects for this composite. The sintering results showed that the addition of HEA could dramatically promote the sinterability of TiB2. TiB2-5 wt. % HEA dense ceramics prepared at the optimal temperature of 1650 °C showed fine morphology without formation of brittle phases. The liquid phase in the ceramics was highly consistent with the so-called “supra-nano-dual-phase materials (SNDPM”, with near-ideal strength. This study represents the first time that a ceramic-SNDPM composite has been fabricated since the invention of such structures.

Thermophysical properties of the Li(17)Pb(83) eutectic alloy

International Nuclear Information System (INIS)

Jauch, U.; Haase, G.; Schulz, B.

1986-01-01

Methods of measurements and results for the following properties of Li(17)Pb(83) are presented: density, specific heat, latent heat of fusion, surface energy, thermal conductivity and diffusivity, electrical conductivity and viscosity. The range of the temperature for extrapolation of the physical properties is discussed. (orig.)

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.)

Isotropic and anisotropic nanocrystalline NdFeB-based magnets prepared by spark plasma sintering and hot deformation

International Nuclear Information System (INIS)

Liu, Z.W.; Huang, Y.L.; Huang, H.Y.; Zhong, X.C.; Yu, Y.H.; Zeng, D.C.

2011-01-01

Isotropic and anisotropic NdFeB permanent magnets were prepared by Spark Plasma Sintering (SPS) and SPS followed hot deformation (HD), respectively, using melt spun NdFeB ribbons with various compositions as starting materials. It is found that, based on RE-rich composition, SPSed magnets sintered at low temperatures (<700 C) almost maintained the uniform fine grain structure inherited from rapid quenching. At higher temperatures, a distinct two-zone (coarse grain and fine grain zones) structure was formed in the SPSed magnets. The SPS temperature and pressure have important effects on the grain structure, which led to the variations in the magnetic properties. By employing low SPS temperature and high pressure, high-density magnets with negligible coarse grain zone and an excellent combination of magnetic properties can be obtained. For single phase NdFeB alloy, because of the deficiency of Nd-rich phases, it is relatively difficult to consolidate micro-sized melt spun powders into high density bulk magnet, but generally a larger particle size is beneficial to achieve better magnetic properties. Anisotropic magnets with a maximum energy product of approx. equal to 38 MGOe were produced by the SPS+HD process. HD did not lead to obvious grain growth and the two-zone structure still existed in the hot deformed magnets. The results indicated that nanocrystalline NdFeB magnets without significant grain growth and with excellent properties could be obtained by SPS and HD processes. (author)

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.

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

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.

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.

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

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

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)

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.

Effect of Ag micro-alloying on the microstructure and properties of Cu-14Fe in situ composite

International Nuclear Information System (INIS)

Liu, K.M.; Lu, D.P.; Zhou, H.T.; Atrens, A.; Zou, J.; Yang, Y.L.; Zeng, S.M.

2010-01-01

This paper studied Ag micro-alloying in the deformation-processed Cu-14Fe in situ composite, by a comparison of Cu-14Fe and Cu-14Fe-0.06Ag. Each alloy was prepared by casting and processed into an in situ composite by hot and cold working. The microstructures were documented using light microscopy and scanning electron microscopy (SEM). The mechanical properties were measured with a tensile-testing machine. The electrical conductivity was measured with a micro-ohmmeter. For both alloys, the as-cast microstructure consisted of a Cu matrix and Fe dendrites; after hot and cold working the microstructure consisted of a Cu matrix containing Fe fibres elongated in the working direction. The as-cast Ag-containing alloy contained finer Fe dendrites. The Ag-containing in situ composite had thinner Fe fibres, higher tensile strength, higher ductility, and higher conductivity. The cold worked Cu-14Fe-0.06Ag in situ composite with cumulative cold deformation strain η = 7.8 (where η = ln(A 0 /A) and A 0 and A are the original and final cross-section areas, respectively), achieved a tensile strength of 930 MPa and a conductivity of 56%IACS (International Annealed Copper Standard; 17.241 nΩ m is defined as 100%IACS). The Ag micro-alloyed in situ composite had a combination of properties comparable to that of a much more expensive alloy containing much more Ag. After 1 h heat treatment at 300 deg. C, the tensile strength was increased to 950 MPa and the conductivity was increased to 56.4%IACS.

Microstructural and magnetic behavior of nanostructured soft alloys prepared by mechanical grinding and gas atomization

International Nuclear Information System (INIS)

Marin, P.; Lopez, M.; Garcia-Escorial, A.; Lieblich, M.

2007-01-01

Nanocrystalline powder of Fe-Si-B-Cu-Nb has been obtained by means of mechanical milling of the corresponding nanocrystalline ribbons. Gas atomization technique has been used to minimize the magnetic hardening due to stress effects observed in ball-milled samples. Fe-Si-B-Cu-Nb and Fe-Si nanocrystalline samples have been prepared by gas atomization. The aim of our work is to analyse the particle size dependence of coercivity in this nanostructured alloys and to show the analogies and differences between ball-milled and gas atomized samples

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

4 CFR 83.17 - Fees.

Science.gov (United States)

2010-01-01

... 4 Accounts 1 2010-01-01 2010-01-01 false Fees. 83.17 Section 83.17 Accounts GOVERNMENT ACCOUNTABILITY OFFICE RECORDS PRIVACY PROCEDURES FOR PERSONNEL RECORDS § 83.17 Fees. (a) Generally, GAO's policy... discretion may charge a fee when the cost for copying the record (at a rate of 20 cents per page) would be in...

Effect of Ni Addition on the Wear and Corrosion Resistance of Fe-20Cr-1.7C-1Si Hardfacing Alloy

International Nuclear Information System (INIS)

Lee, Sung Hoon; Kim, Ki Nam; Kim, Seon Jin

2011-01-01

In order to improve the corrosion resistance of Fe-20Cr-1.7C-1Si hardfacing alloy without a loss of wear resistance, the effect of Ni addition was investigated. As expected, the corrosion resistance of the alloy increased with increasing Ni concentration. The wear resistance of the alloy did not decrease, even though the hardness decreased, up to Ni concentration of 5 wt.%. This was attributed to the fact that the decrease in hardness was counterbalanced by the strain-induced martensitic transformation. The wear resistance of the alloy, however, decreased abruptly with increases of the Ni concentration over 5 wt.%.

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.

Low-temperature electron properties of Heusler alloys Fe2VAl and Fe2CrAl: Effect of annealing

International Nuclear Information System (INIS)

Podgornykh, S. M.; Svyazhin, A. D.; Shreder, E. I.; Marchenkov, V. V.; Dyakina, V. P.

2007-01-01

We present the results of measurements of low-temperature heat capacity, as well as electrical and magnetic properties of Heusler alloys Fe 2 VAl and Fe 2 CrAl prepared in different ways using various heat treatment regimes. The density of states at the Fermi level is estimated. A contribution of ferromagnetic clusters in the low-temperature heat capacity of the Fe 2 VAl alloy is detected. The change in the number and volume of clusters as a result of annealing of an alloy affects the behavior of their low-temperature heat capacity, resistivity, and magnetic properties

Mechanical properties and bio-tribological behaviors of novel beta-Zr-type Zr-Al-Fe-Nb alloys for biomedical applications.

Science.gov (United States)

Hua, Nengbin; Chen, Wenzhe; Zhang, Lei; Li, Guanghui; Liao, Zhenlong; Lin, Yan

2017-07-01

The present study prepares novel Zr 70+x Al 5 Fe 15-x Nb 10 (x=0, 5) alloys by arc-melting for potential biomedical application. The mechanical properties and bio-tribological behaviors of the Zr-based alloys are evaluated and compared with biomedical pure Zr. The as-prepared alloys exhibit a microstructure containing a micrometer-sized dendritic beta-Zr phase dispersed in a Zr 2 Fe-typed matrix. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high compressive strength. The wear resistance of the Zr-Al-Fe-Nb alloys in air and phosphate buffer saline (PBS) solution is superior to that of pure Zr. The wear mechanism of Zr-based alloys sliding in air is controlled by oxidation and abrasive wear whereas that sliding in PBS is controlled by synergistic effects of the abrasive and corrosive wear. Electrochemical measurements demonstrate that the Zr-based alloys are corrosion resistant in PBS. Their bio-corrosion resistance is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. The Zr 75 Al 5 Fe 10 Nb 10 exhibits the best corrosion resistance in PBS, which contributes to its superior wear resistance in a simulated body environment. The combination of good mechanical properties, corrosion resistance, and biotribological behaviors of the Zr-Al-Fe-Nb alloys offers them potential advantages in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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.

Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

International Nuclear Information System (INIS)

Ma, Y.L.; Liu, X.B.; Nguyen, V.V.; Poudyal, N.; Yue, M.; Liu, J.P.

2016-01-01

Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd 2 Fe 14 B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH) max of 10 MGOe was obtained at NdFeB content of 50 wt%.

Preparation and magnetic properties of anisotropic bulk MnBi/NdFeB hybrid magnets

Energy Technology Data Exchange (ETDEWEB)

Ma, Y.L. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); College of Metallurgical and Materials Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Liu, X.B.; Nguyen, V.V.; Poudyal, N. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Yue, M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Liu, J.P., E-mail: pliu@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

2016-08-01

Anisotropic hybrid bulk magnets of MnBi/NdFeB with different composition ratio have been prepared with starting MnBi and Nd{sub 2}Fe{sub 14}B powders as well as epoxy resin as a binder in case it is needed to form bulk samples. It has been found that the ratio between the two phases in content has a remarkable influence on the magnetic properties, the thermal stability and the density of the bulk magnets. With increasing MnBi content the binder addition can be reduced. When the MnBi content is larger than 30 wt%, no binder is needed. On the other hand, the coercivity and saturation magnetization were increased significantly with increasing NdFeB content. When the NdFeB content was increased from 0% to 50%, the maximum energy product was enhanced from 4.7 to 10.0 MGOe, respectively. The energy product then decreased gradually with the NdFeB content due to the reduced density of the hybrid magnet. The thermal stability measurements showed that the temperature coefficient of coercivity grew with the MnBi content and became positive with MnBi=80 wt%. - Highlights: • Anisotropic bulk hybrid MnBi/NdFeB magnets were prepared. • MnBi content affected the density and coercivity temperature coefficient positively. • An energy product (BH){sub max} of 10 MGOe was obtained at NdFeB content of 50 wt%.

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.

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.

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.

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.

NdFeB thick films prepared by tape casting

International Nuclear Information System (INIS)

Pawlowski, B.; Schwarzer, S.; Rahmig, A.; Toepfer, J.

2003-01-01

NdFeB films of thickness between 100 and 800 μm were prepared by tape casting of a slurry containing 84-95 wt% of commercial NdFeB powder (MQP-B, -Q and -S). After curing the flexible green tapes at 120 deg. C non-porous magnetic films are obtained. The remanence of the films is in the range of 350-450 mT and the coercivity is between 300 and 800 kA/m depending on the type of MQP powder used. The magnetic properties of the films are discussed in relation to film composition and type of magnetic material. For MEMS applications the thick films are magnetized with a multi-pole stripe pattern with 1 mm pole pitch. The induction at the surface of the films was measured with a Hall probe and compared to theoretical calculations. The results indicate that the films are completely magnetized regardless of the film thickness. Tape-casted NdFeB thick films are promising candidates for applications in micro-systems or actuators. Miniaturization of the magnet components is one of the key issues in the development of electromagnetic micro-systems, thus creating a need for replacement of small sintered magnets by magnetic thick film components. Other applications include encoders

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.

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.

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

Magnetic Properties of Nanocrystalline Fe{sub x}Cu{sub 1-x} Alloys Prepared by Ball Milling

Energy Technology Data Exchange (ETDEWEB)

Yousif, A.; Bouziane, K., E-mail: bouzi@squ.edu.om; Elzain, M. E. [Sultan Qaboos University, Physics Department, College of Science (Oman); Ren, X.; Berry, F. J. [The Open University, Department of Chemistry (United Kingdom); Widatallah, H. M. [Sudan Atomic Energy Commission, Institute of Nuclear Research (Sudan); Al Rawas, A.; Gismelseed, A.; Al-Omari, I. A. [Sultan Qaboos University, Physics Department, College of Science (Oman)

2004-12-15

X-ray diffraction, Moessbauer and magnetization measurements were used to study Fe{sub x}Cu{sub 1-x} alloys prepared by ball-milling. The X-ray data show the formation of a nanocrystalline Fe-Cu solid solution. The samples with x{>=}0.8 and x{<=}0.5 exhibit bcc or fcc phase, respectively. Both the bcc and fcc phases are principally ferromagnetic for x{>=}0.2, but the sample with x=0.1 remains paramagnetic down to 78 K. The influence of the local environment on the hyperfine parameters and the local magnetic moment are discussed using calculations based on the discrete-variational method in the local density approximation.

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.

Comparative study on microstructures and mechanical properties of the heat-treated Al–5.0Cu–0.6Mn–xFe alloys prepared by gravity die casting and squeeze casting

International Nuclear Information System (INIS)

Lin, Bo; Zhang, WeiWen; Lou, ZhaoHui; Zhang, DaTong; Li, YuanYuan

2014-01-01

Highlights: • Only two kind Fe-rich intermetallics are found in the heat-treated Al–5.0Cu–0.6Mn–xFe alloys. • Squeeze cast Al–5.0Cu–0.6Mn alloys containing 1.5% Fe have desirable mechanical properties. • The difference between gravity die cast and squeeze cast Al–5.0Cu–0.6Mn–xFe alloys. - Abstract: The Al–5.0 wt% Cu–0.6 wt% Mn alloys with different Fe contents were prepared by gravity die casting and squeeze casting. The difference in microstructures and mechanical properties of the T5 heat-treated alloys was examined by tensile test, optical microscopy, deep etching technique, scanning electron microscope and electron probe micro-analyzer. The results show that both β-Fe and α (CuFe) are observed in T5 heat-treated gravity die cast alloy and only α (CuFe) appears in the squeeze cast alloy when the Fe content is 0.5 wt%. When the Fe content is more than 1.0 wt%, the main Fe-rich intermetallics is α (CuFe) in both squeeze cast and gravity die cast alloys. The mechanical properties of both the gravity die cast and squeeze cast alloys decrease gradually with the increase of Fe content due to the decreased volume fraction of precipitation particles, the increased volume fraction of Fe-rich intermetallics and the increased size of α (Al) dendrites. The squeeze cast alloys with different Fe contents have superior mechanical properties compared to the gravity die cast alloys, which is mainly attributed to the reduction of porosity and refinement of Fe-rich intermetallics and α (Al) dendrite. In particularly, the elongation of the squeeze cast alloys is less sensitive to the Fe content than that of the gravity die cast alloys. An elongation level of 13.7% is obtained in squeeze cast alloy even when the Fe content is as high as 1.5%, while that of the gravity die cast alloy is only 5.3%

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.

On the phase evolution of AlCoCrCuFeMnSix high entropy alloys prepared by mechanical alloying and arc melting route

Science.gov (United States)

Kumar, Anil; Chopkar, Manoj

2018-05-01

Effect of Si addition on phase formation of AlCoCrCuFeMnSix (x=0, 0.3, 0.6 and 0.9) high entropy alloy have been investigated in this work. The alloys are prepared by mechanical alloying and vacuum arc melting technique. The X-ray diffraction results reveals the formation of mixture of face centered and body centered cubic solid solution phases in milled powders. The addition of Si favours body centered cubic structure formation during milling process. Whereas, after melting the milled powders, body centered phases formed during milling is partial transformed into sigma phases. XRD results were also correlated with the SEM elemental mapping of as casted samples. Addition of Si favours σ phase formation in the as cast samples.

High coercivity microcrystalline Nd-rich Nd–Fe–Co–Al–B bulk magnets prepared by direct copper mold casting

Energy Technology Data Exchange (ETDEWEB)

Zhao, L.Z.; Hong, Y. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Fang, X.G. [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510640 (China); Qiu, Z.G.; Zhong, X.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, X.S. [Institute for Advanced Materials and Laboratory of Quantum Engineering and Quantum Materials, South China Normal University, Guangzhou 510640 (China); Liu, Z.W., E-mail: zwliu@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China)

2016-06-15

High coercivity Nd{sub 25}Fe{sub 40}Co{sub 20}Al{sub 15−x}B{sub x} (x=7–15) hard magnets were prepared by a simple process of injection casting. Different from many previous investigations on nanocomposite compositions, the magnets in this work contain hard magnetic Nd{sub 2}(FeCoAl){sub 14}B, Nd-rich, and Nd{sub 1+ε}(FeCo){sub 4}B{sub 4} phases. The magnetic properties, phase evolution, and microstructure of the as-cast and annealed magnets were investigated. As the boron content increased from 7 to 11 at%, the intrinsic coercivity H{sub cj} of the as-cast magnet increased from 816 to 1140 kA/m. The magnets annealed at 750 °C have shown more regular and smaller grains than the as-cast alloys, especially for the x=11 alloy. The high intrinsic coercivities for the annealed alloys with x=8~11 result from the presence of small-sized grains in the microstructure. The highest H{sub cj} of 1427 kA/m was obtained for the heat treated alloy with x=10. This work provides an alternative approach for preparing fully dense Nd-rich bulk hard magnets with relatively good properties. - Highlights: • 2 mm hard magnetic Nd{sub 25}Fe{sub 40}Co{sub 20}Al{sub 15−x}B{sub x} rods were prepared by direct casting. • High coercivity of 1.78 T was achieved in x=11 sample after heat treatment. • Small grains are responsible for the significant increase in H{sub C} after annealing. • Nd{sub 2}Fe{sub 14}B grains with two different sizes lead to two-step demagnetization process.

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

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

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

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

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.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2013-01-10

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

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.

Phase formation and crystallization behavior of melt spun Sm-Fe-based alloys

International Nuclear Information System (INIS)

Shield, J.E.

1999-01-01

The phase formation and microstructures of Sm-Fe alloys have been investigated at Sm levels of 11 and 17 atomic percent and with alloying additions of Ti and C. At lower Sm content, virtually phase pure SmFe 7 formed, while higher Sm content resulted in the formation of SmFe 7 , SmFe 2 and amorphous phases. The addition of Ti and C resulted in greater stability and a larger volume fraction of the amorphous phase. The binary Sm-Fe alloys at both Sm levels had tremendously variable microstructures, with large discrepancies in grain size and phase distribution from region to region. The addition of Ti and C tended to result in a more homogeneous microstructure, as well as a refinement in the microstructural scale. (orig.)

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.

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.

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.

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Corrosion of ferrous alloys exposed to thermally convective Pb-17 at. % Li

International Nuclear Information System (INIS)

Tortorelli, P.F.; DeVan, J.H.

1986-01-01

A type 316 stainless steel thermal convection loop with type 316 stainless steel coupons and a Fe-9 Cr-1 Mo steel loop containing Fe-12 Cr-1 MoVW steel specimens circulated molten Pb-17 at. % Li at a maximum temperature of 500 0 C. Specimens were exposed for greater than 6000 h. Mass loss and surface characterization data were compared for these two alloys. At any particular exposure time, the corrosion of type 316 stainless steel by Pb-17 at. % Li was more severe, and of a different type than that of similarly exposed Fe-12 Cr-1 MoVW steel. The austenitic alloy suffered nonuniform penetration and dissolution by the lead-lithium, whereas the Fe-12 Cr-1 MoVW steel tended to be more uniformly corroded. The presence of a ferritic layer on the type 316 stainless steel, and its susceptibility to spalling during specimen cleaning, were shown to be important in evaluating the data and in comparing corrosion losses for the type types of alloys. A model for the nonuniform penetration of type 316 stainless steel by Pb-17 at. % Li was suggested

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.

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

Directory of Open Access Journals (Sweden)

Andrea Školáková

2017-11-01

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

Influence of cooling rate on microstructure of NdFeB strip casting flakes

Energy Technology Data Exchange (ETDEWEB)

Binglin Guo; Bo Li; Dongling Wang; Xiaojun Yu [Central Iron and Steel Research Inst., Beijing, BJ (China); Jifan Hu [Shandong Univ., Jinan (China)

2005-07-01

In this paper, flakes of NdFeB cast alloys were prepared by using the strip casting technique. Microstructure and composition of phases in NdFeB SC flakes were studied by SEM and energy spectra. Especially, the influences of cooling rate on the microstructure of SC flakes were discussed, helping us to master strip casting technology. The results show that the cooling rate plays an important role in obtaining the perfect microstructure of SC flakes, which thickness is supposed not less than 0.32mm in these studies. (orig.)

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.)

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.

Influence of nitrogenation on structure development and magnetic properties of mechanically alloyed and annealed Sm-Fe powders

International Nuclear Information System (INIS)

Teresiak, A.; Kubis, M.; Mattern, N.; Wolf, M.; Gruner, W.; Mueller, K.-H.

1999-01-01

Sm-Fe-N compounds were prepared by mechanical alloying, subsequent annealing and nitrogenation. For crystal structure investigations of the non-equilibrium phases Sm 2 Fe 17+y N x , formed at various annealing temperatures T A for 1 h, X-ray diffraction with following Rietveld analysis was used. A volume expansion of 6.2% was observed after nitrogenation. As for the non-nitrided Sm-Fe alloys a modified TbCu 7 -type structure (space group P6/mmm) and a modified Th 2 Zn 17 -type structure (space group R anti 3m) have been observed. However, for nitrogenated Sm-Fe samples the modified Th 2 Zn 17 -type structure forms already for annealing at T A =750 C prior to nitrogenation. For samples annealed, prior to nitrogenation, between T A =600 and 700 C the modified TbCu 7 -type structure was found, in which the nitrogen occupies randomly the 3f position with an occupancy larger than 1/3. The partially ordered, modified Th 2 Zn 17 -type structure formed for 750 C A 2 Zn 17 -type structure by introducing additional Fe(6c) and Sm(3a) positions. The degree of order of the Sm atoms and Fe-dumbbells increases with increasing T A . The nitrogen occupies the octahedral interstitial positions 9e in the latter cases. The nitrogen content is higher in the hexagonal phase than in the rhombohedral phase. Optimum magnetic properties were obtained for T A =750 C. Here we found a coercivity μ 0J H c =3.7 T and a good squareness of the demagnetization curve. (orig.)

Magnetic properties of the Ce2Fe17-x Mn x helical magnets up to high magnetic fields

International Nuclear Information System (INIS)

Kuchin, A.G.; Mushnikov, N.V.; Bartashevich, M.I.; Prokhnenko, O.; Khrabrov, V.I.; Lapina, T.P.

2007-01-01

Magnetic properties of the Ce 2 Fe 17- x Mn x , x=0-2, alloys in magnetic fields up to 40 T are reported. The compounds with x=0.5-1 are helical antiferromagnets and those with 1 B that couple antiparallelly to the Fe moments. Easy-plane magnetic anisotropy in the Ce 2 Fe 17- x Mn x compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce 2 Fe 17- x Mn x helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce 2 Fe 17- x Mn x , x=0.5-2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short-range order (SRO) magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimated

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.

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

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.

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....

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

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

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)

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.

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

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

OpenAIRE

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

2017-01-01

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

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.)

Preparation, mechanical strengths, and thermal

Science.gov (United States)

Inoue, A.; Furukawa, S.; Hagiwara, M.; Masumoto, T.

1987-05-01

Ni-based amorphous wires with good bending ductility have been prepared for Ni75Si8B17 and Ni78P12B10 alloys containing 1 to 2 at. pct Al or Zr by melt spinning in rotating water. The enhancement of the wire-formation tendency by the addition of Al has been clarified to be due to the increase in the stability of the melt jet through the formation of a thin A12O3 film on the outer surface. The maximum wire diameter is about 190 to 200 μm for the Ni-Si (or P)-B-Al alloys and increases to about 250 μm for the Ni-Si-B-Al-Cr alloys containing 4 to 6 at. pct Cr. The tensile fracture strength and fracture elongation are 2730 MPa and 2.9 pct for (Ni0.75Si0.08B0.17 99Al1) wire and 2170 MPa and 2.4 pct for (Ni0.78P0.12B0.1)99Al1 wire. These wires exhibit a fatigue limit under dynamic bending strain in air with a relative humidity of 65 pct; this limit is 0.50 pct for a Ni-Si-B-Al wire, which is higher by 0.15 pct than that of a Fe75Si10B15 amorphous wire. Furthermore, the Ni-base wires do not fracture during a 180-deg bending even for a sample annealed at temperatures just below the crystallization temperature, in sharp contrast to high embrittlement tendency for Fe-base amorphous alloys. Thus, the Ni-based amorphous wires have been shown to be an attractive material similar to Fe- and Co-based amorphous wires because of its high static and dynamic strength, high ductility, high stability to thermal embrittlement, and good corrosion resistance.

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.

Performance enhancement of NdFeB nanoflakes prepared by surfactant-assisted ball milling at low temperature by using different surfactants

Science.gov (United States)

An, Xiaoxin; Jin, Kunpeng; Wang, Fang; Fang, Qiuli; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

2017-02-01

Hard magnetic NdFeB submicron and nanoflakes were successfully prepared by surfactant-assisted ball milling at room temperature (SABMRT) and low temperature (SABMLT) by using oleic acid (OA), oleylamine (OLA) and trioctylamine (TOA) as surfactant, respectively. Among the surfactants used, OA and OLA have similar effects on the morphology of the NdFeB nanoflakes milled at both room and low temperature. In the case of TOA, irregular micron-sized particles and submirco/nanoflakes were obtained for the NdFeB powders prepared by SABMRT and SABMLT, respectively. Samples prepared by SABMLT show better crystallinity and better degree of grain alignment than that prepared by SABMRT with the same surfactant. Comparing with the samples milled at RT, higher coercivity and larger remanence ratio were achieved in the NdFeB samples prepared at LT. The amounts of residual surfactants in final NdFeB powders were also calculated, which reveals that the final NdFeB powders milled at LT possess lower amount of residual surfactants than those milled at RT. It was found that lowering milling temperature of SABM would be a promising way for fabricating permanent magnetic materials with better hard magnetic properties.

Formation of bulk metallic glasses in the Fe-M-Y-B (M = transition metal) system

Energy Technology Data Exchange (ETDEWEB)

Huang, X.M. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chang, C.T. [Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Chang, Z.Y.; Wang, X.D.; Cao, Q.P. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Shen, B.L.; Inoue, A. [Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Jiang, J.Z. [International Center for New-Structured Materials (ICNSM) and Laboratory of New-Structured Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)], E-mail: jiangjz@zju.edu.cn

2008-07-28

In this work, quaternary Fe{sub 72-x}M{sub x}Y{sub 6}B{sub 22} (M = Ni, Co and Mo) bulk metallic glasses (BMGs) have been developed. It is found that a fully amorphous Fe{sub 68}Mo{sub 4}Y{sub 6}B{sub 22} cylindrical rod with 6.5 mm in diameter can be prepared by copper mold injection. These alloys have a high glass transition temperature of about 900 K with high fracture strengths up to about 3 GPa although they are still brittle. Magnetic measurements reveal that they are ferromagnetic at ambient temperature with low coercive force of about 2 A/m, saturation magnetization of about 0.7 T and effective permeability of about 7000 at 100 kHz. The newly developed Fe-based quaternary alloys exhibit excellent combination properties: superior glass forming ability (GFA), high glass transition temperature, and soft magnetic properties, which could have potential applications in electronic industries. Furthermore, the effect of Mo addition on GFA in the Fe-Y-B BMG system has been discussed compared with those of Ni and Co additions.

Structural relaxations in the bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}

Energy Technology Data Exchange (ETDEWEB)

Błoch, K., E-mail: 23kasia1@wp.pl; Nabiałek, M.; Gondro, J.

2017-05-01

The paper presents studies of annealing effect on the disaccommodation phenomenon in bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}. The investigated sample was prepared by suction-casting method in the form of rod. The annealing process has been performed at temperature well below the crystallisation temperature. The amorphous structure has been confirmed using X-ray diffractometer. The susceptibility and its disaccommodation were determined using completely automated set up. The disaccommodation curve was decomposed into three elementary processes, each of them was described by Gaussian distribution of relaxation times. The obtained results indicate that the disaccommodation phenomenon in studied alloy is related with directional ordering of atom pairs near the free volumes; this is in agreement with H. Kronmüller's theorem.

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)

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

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.