Amorphous and nanocrystalline Fe-Ni-Zr-B ribbons as sensing elements in magnetic field sensors

Energy Technology Data Exchange (ETDEWEB)

Vertesy, G. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1525 Budapest, P.O.B. 49 (Hungary)]. E-mail: vertesyg@mfa.kfki.hu; Idzikowski, B. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, PL 60-179 Poznan (Poland)

2006-04-15

Fe{sub 81-x}Ni{sub x}Zr{sub 7}B{sub 12} (x=20, 30, 40) melt-spun alloys were investigated as potential new material applied as a sensing element of a fluxgate-type high-sensitivity magnetic field sensor. The sensitivity of the magnetometer was increased by about 60% by using the amorphous or nanocrystalline Fe{sub 41}Ni{sub 40}Zr{sub 7}B{sub 12} alloy, compared with a standard reference sensing material. Application of this material can also extend the temperature range of the operation of the device.

Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

Energy Technology Data Exchange (ETDEWEB)

Toparli, Cigdem [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Ebin, Burçak [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Nuclear Chemistry and Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey)

2017-02-01

The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size. - Highlights: • Ternary FeNiCo alloy nanocrystalline particles were synthesized in a single step. • Cubic crystalline structure and spherical morphology was observed by XRD, SEM and TEM investigations. • The analysis of magnetic properties indicates the soft magnetic features of particles.

Effect of zirconium on grain growth and mechanical properties of a ball-milled nanocrystalline FeNi alloy

Energy Technology Data Exchange (ETDEWEB)

Kotan, Hasan, E-mail: hkotan@ncsu.edu [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States); Darling, Kris A. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States); Saber, Mostafa; Koch, Carl C.; Scattergood, Ronald O. [Department of Materials Science and Engineering, NC State University, 911 Partners Way, Room 3078, Raleigh, NC 27606-7907 (United States)

2013-02-25

Highlights: Black-Right-Pointing-Pointer Pure Fe, Fe{sub 92}Ni{sub 8}, and Fe{sub 91}Ni{sub 8}Zr{sub 1} powders were hardened up to 10 GPa by ball milling. Black-Right-Pointing-Pointer Annealing of Fe and Fe{sub 92}Ni{sub 8} leads to reduced hardness and extensive grain growth. Black-Right-Pointing-Pointer The addition of Zr to Fe{sub 92}Ni{sub 8} increases its stability and strength by second phases. Black-Right-Pointing-Pointer The second phases are found to promote the stability of Fe{sub 91}Ni{sub 8}Zr{sub 1} by Zener pinning. Black-Right-Pointing-Pointer The Zr-containing precipitates contribute to the overall strength of the material. - Abstract: Grain growth of ball-milled pure Fe, Fe{sub 92}Ni{sub 8}, and Fe{sub 91}Ni{sub 8}Zr{sub 1} alloys has been studied using X-ray diffractometry (XRD), focused ion beam (FIB) microscopy and transmission electron microscopy (TEM). Mechanical properties with respect to compositional changes and annealing temperatures have been investigated using microhardness and shear punch tests. We found the rate of grain growth of the Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy to be much less than that of pure Fe and the Fe{sub 92}Ni{sub 8} alloy at elevated temperatures. The microstructure of the ternary Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy remains nanoscale up to 700 Degree-Sign C where only a few grains grow abnormally whereas annealing of pure iron and the Fe{sub 92}Ni{sub 8} alloy leads to extensive grain growth. The grain growth of the ternary alloy at high annealing temperatures is coupled with precipitation of Fe{sub 2}Zr. A fine dispersion of precipitated second phase is found to promote the microstructural stability at high annealing temperatures and to increase the hardness and ultimate shear strength of ternary Fe{sub 91}Ni{sub 8}Zr{sub 1} alloy drastically when the grain size is above nanoscale.

Effects of Ni content on nanocrystalline Fe–Co–Ni ternary alloys synthesized by a chemical reduction method

Energy Technology Data Exchange (ETDEWEB)

Chokprasombat, Komkrich, E-mail: komkrich28@gmail.com [Department of Physics, Faculty of Science, Thaksin University, Phatthalung 93210 Thailand (Thailand); Pinitsoontorn, Supree [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 Thailand (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 Thailand (Thailand)

2016-05-01

Magnetic properties of Fe–Co–Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe{sub 50}Co{sub 50−x}Ni{sub x} nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe{sub 50}Ni{sub 50} nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300 Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe–Co–Ni alloys could be adjusted by varying the Ni content. - Highlights: • We prepared nanocrystalline Fe–Co–Ni alloys by a novel chemical reduction process. • Elemental compositions could be well controlled by the molar ratio of metal sources. • Particle size and magnetic properties clearly depended on the Ni contents. • Fe{sub 50}Co{sub 10}Ni{sub 40} exhibited high saturation magnetization of 126.3 emu/g.

The electrochemical characteristics of Mg2Ni nanocrystalline hydrogen storage alloy

International Nuclear Information System (INIS)

Zhang Ling; Zhou Xiaosong; Peng Shuming

2008-06-01

The nanocrystalline Mg 2 Ni materials were prepared by mechanical alloying. The cyclic voltametry results indicated that the potential of oxidation peak was shift as the scan rate increased and the absorption property of Mg 2 Ni prepared by mechanical alloying was increased even at ambient temperature. The absorption and desorption of hydrogen in Mg 2 Ni alloy were remarkably accelerated with the rising temperature. Small angel X-ray scattering results indicated that the Mg 2 Ni powder have 1-5 nm and 5-10 nm particle size distribution, which increased the acting sites of hydrogen absorption/desorption reaction and decreased the diffusion path of hydrogen desorption. It was induced to the enhanced performance of Mg 2 Ni nanocrystalline powder. The cycle life investigated results indicated that the activation property of Mg 2 Ni nanocrystal-line hydrogen storage alloy electrode was excellent, the capacitance maintenance ration was 66% after 200 cycles. The coating of epoxy resin on one side of the electrode had no effect on the activation property and the capacitance maintenance ration was better than the uncoating one. But the anode peak current value and the cathodic peak current value were decreased remarkably which indicated that the hydrogen absorption/desorption rate and the charge/discharge degree had decreased. (authors)

Facile directing agent-free synthesis and magnetism of nanocrystalline Fe–Ni alloy with tunable shape

International Nuclear Information System (INIS)

Mohamed, Marwa A.A.

2014-01-01

Highlights: • Simple directing agent-free wet chemical method for high-yield synthesis of nc Fe-Ni particles with tunable shape. • The alloy morphology is controlled by varying synthesis conditions; concentration of metal ions and pH of reaction. • Synthesis conditions control the final shape of alloy particles via controlling their growth rate and capping with OH − ions. • The alloy magnetic behavior is driven away from soft magnetic toward hard one, by particles anisotropy and size reduction. • The branched wires morphology can be considered a new morphology of distinctive magnetic behavior, for nc Fe-Ni alloy. - Abstract: This article reports the synthesis of nanocrystalline (nc) Fe 20 Ni 80 particles with tunable shape, using a heterogeneous directing agent-free aqueous wet chemical method of mild synthesis conditions. The particle morphology has been controlled by varying synthesis conditions. The results demonstrate that the morphology of alloy particles changes from quasi-isotropic to anisotropic architecture by decreasing concentration of metal ions or increasing pH of reaction solution. Deep interpretations of such phenomena are reported. Magnetic behavior of the alloy is driven away from soft magnetic and toward hard magnetic behavior, by anisotropy and size reduction of alloy particles. This broadens practical applications of nc Fe 20 Ni 80 alloy. Overall, the study provides an effective economical way for high-yield synthesis of nc Fe–Ni particles with tailored shape and subsequently magnetic properties for a specific technological application. Additionally, it adds a new morphology, highly branched wires, of distinctive magnetic behavior to the known morphologies of nc Fe–Ni particles

Mechanically alloyed PrFeB nanocrystalline magnets

International Nuclear Information System (INIS)

Kaszuwara, W.; Leonowicz, M.

1998-01-01

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

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

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

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

Science.gov (United States)

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

2017-11-01

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

Resonant Ni and Fe KLL Auger spectra photoexcited from NiFe alloys

International Nuclear Information System (INIS)

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

2005-01-01

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

The effect of process control agent on the structure and magnetic properties of nanocrystalline mechanically alloyed Fe–45% Ni powders

Energy Technology Data Exchange (ETDEWEB)

Gheisari, Kh., E-mail: khgheisari@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz (Iran, Islamic Republic of); Javadpour, S. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)

2013-10-15

In this study, nanocrystalline Fe-45 wt% Ni alloy powders were prepared by mechanical alloying via high-energy ball milling. The effect of adding stearic acid as a process control agent (PCA) on the particle size, structure and magnetic properties of Fe-45 wt% Ni alloy powders have been studied by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. The results show that the addition of 1 wt% PCA causes fine uniform spherical powder particles of the fcc γ-(Fe, Ni) phase to be formed after 48 h milling time. It is also found that crystallite size, lattice strain and content of γ-(Fe, Ni) phase are three of the most important variables that are significantly affected by PCA content and can influence the magnetic properties. - Highlights: • Different amount of stearic acid as a PCA was used during milling. • Particle size and crystallite size decrease with increasing PCA content. • The addition of 1 wt% PCA leads to a good combination of structure and magnetic properties.

The effect of process control agent on the structure and magnetic properties of nanocrystalline mechanically alloyed Fe–45% Ni powders

International Nuclear Information System (INIS)

Gheisari, Kh.; Javadpour, S.

2013-01-01

In this study, nanocrystalline Fe-45 wt% Ni alloy powders were prepared by mechanical alloying via high-energy ball milling. The effect of adding stearic acid as a process control agent (PCA) on the particle size, structure and magnetic properties of Fe-45 wt% Ni alloy powders have been studied by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. The results show that the addition of 1 wt% PCA causes fine uniform spherical powder particles of the fcc γ-(Fe, Ni) phase to be formed after 48 h milling time. It is also found that crystallite size, lattice strain and content of γ-(Fe, Ni) phase are three of the most important variables that are significantly affected by PCA content and can influence the magnetic properties. - Highlights: • Different amount of stearic acid as a PCA was used during milling. • Particle size and crystallite size decrease with increasing PCA content. • The addition of 1 wt% PCA leads to a good combination of structure and magnetic properties

Formation and structure of nanocrystalline Al-Mn-Ni-Cu alloys

International Nuclear Information System (INIS)

Latuch, J.; Krasnowski, M.; Ciesielska, B.

2002-01-01

This paper reports the results of the short investigation on the effect of Cu additions upon the nanocrystallization behaviour of an Al-Mn-Ni alloy. 2 at.% Cu added to the base alloy of Al 85 Mn 10 Ni 5 alloy by substitution for Mn(mischmetal). The control of cooling rate did not cause the formation of nanocrystals of fcc-Al phase. The nanocrystalline structure fcc-Al + amorphous phase in quarternary alloy was obtained by isothermal annealing and continuous heating method, but the last technique is more effective. The volume fraction, lattice parameter, and size of Al-phase were calculated. (author)

Stability of nanocrystalline Ni-based alloys: coupling Monte Carlo and molecular dynamics simulations

Science.gov (United States)

Waseda, O.; Goldenstein, H.; Silva, G. F. B. Lenz e.; Neiva, A.; Chantrenne, P.; Morthomas, J.; Perez, M.; Becquart, C. S.; Veiga, R. G. A.

2017-10-01

The thermal stability of nanocrystalline Ni due to small additions of Mo or W (up to 1 at%) was investigated in computer simulations by means of a combined Monte Carlo (MC)/molecular dynamics (MD) two-steps approach. In the first step, energy-biased on-lattice MC revealed segregation of the alloying elements to grain boundaries. However, the condition for the thermodynamic stability of these nanocrystalline Ni alloys (zero grain boundary energy) was not fulfilled. Subsequently, MD simulations were carried out for up to 0.5 μs at 1000 K. At this temperature, grain growth was hindered for minimum global concentrations of 0.5 at% W and 0.7 at% Mo, thus preserving most of the nanocrystalline structure. This is in clear contrast to a pure Ni model system, for which the transformation into a monocrystal was observed in MD simulations within 0.2 μs at the same temperature. These results suggest that grain boundary segregation of low-soluble alloying elements in low-alloyed systems can produce high-temperature metastable nanocrystalline materials. MD simulations carried out at 1200 K for 1 at% Mo/W showed significant grain boundary migration accompanied by some degree of solute diffusion, thus providing additional evidence that solute drag mostly contributed to the nanostructure stability observed at lower temperature.

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.)

Investigating the Thermal and Phase Stability of Nanocrystalline Ni-W Produced by Electrodeposition, Sputtering, and Mechanical Alloying

Science.gov (United States)

Marvel, Christopher Jonathan

The development of nanocrystalline materials has been increasingly pursued over the last few decades. They have been shown to exhibit superior properties compared to their coarse-grain counterparts, and thus present a tremendous opportunity to revolutionize the performance of nanoscale devices or bulk structural materials. However, nanocrystalline materials are highly prone to grain growth, and if the nanocrystalline grains coarsen, the beneficial properties are lost. There is a strong effort to determine the most effective thermal stability mechanisms to avoid grain growth, but the physical nature of nanocrystalline grain growth is still unclear due to a lack of detailed understanding of nanocrystalline microstructures. Furthermore, the influence of contamination has scarcely been explored with advanced transmission electron microscopy techniques, nor has there been a direct comparison of alloys fabricated with different bulk processes. Therefore, this research has applied aberration-corrected scanning transmission electron microscopy to characterize nanocrystalline Ni-W on the atomic scale and elucidate the physical grain growth behavior. Three primary objectives were pursued: (1) explore the thermal stability mechanisms of nanocrystalline Ni-W, (2) evaluate the phase stability of Ni-W and link any findings to grain growth behavior, and (3) compare the influences of bulk fabrication processing, including electrodeposition, DC magnetron sputtering, and mechanical alloying, on the thermal stability and phase stability of Ni-W. Several thermal stability mechanisms were identified throughout the course of this research. First and foremost, W-segregation was scarcely observed to grain boundaries, and it is unclear if W-segregation improves thermal stability contrary to most reports in the 2 literature. Long-range Ni4W chemical ordering was observed in alloys with more than 20 at.% W, and it is likely Ni4W domains reduce grain boundary mobility. In addition, lattice

Mechanical alloying of the FeNi-Ag system

International Nuclear Information System (INIS)

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

2007-01-01

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

Effect of nanocrystalline phase on the electrochemical behavior of the alloy Ti{sub 60}Ni{sub 40}

Energy Technology Data Exchange (ETDEWEB)

Mathur, Shubhra, E-mail: shubhramathur3@gmail.com [Department of Physics, Jagannath Gupta Institute of Engineering and Technology, Jaipur 303905 (India); Jain, Rohit [Department of Physics, Jagannath Gupta Institute of Engineering and Technology, Jaipur 303905 (India); Kumar, Praveen [Surface Physics and Nanostructure Group, National Physical Laboratory, New Delhi 110012 (India); Sachdev, K.; Sharma, S.K. [Department of Physics, Malaviya National Institute of Technology, JLN-Marg, Jaipur 302017 (India)

2012-10-15

Highlights: Black-Right-Pointing-Pointer Polarization studies carried out on different structural states of the alloy Ti{sub 60}Ni{sub 40}. Black-Right-Pointing-Pointer Nanocrystalline state exhibits superior corrosion resistance as compared to other states of the alloy Ti{sub 60}Ni{sub 40}. Black-Right-Pointing-Pointer XPS results show that nanocrystalline specimen contains only TiO{sub 2} species. Black-Right-Pointing-Pointer It leads to the formation of adherent and stable film and improves the corrosion resistance. - Abstract: Polarization studies were carried out on crystalline, amorphous and nanocrystalline states of the alloy Ti{sub 60}Ni{sub 40} in 1 M NaCl aqueous medium at room temperature. It was observed that nanocrystalline state exhibits superior corrosion resistance as compared to other states of the alloy Ti{sub 60}Ni{sub 40}. Cyclic voltammetry studies and weight loss data corroborates the polarization studies. X-ray photoelectron spectroscopy (XPS) technique was used in order to decipher the nature of the oxide film formed after corrosion test on the specimens of the alloy Ti{sub 60}Ni{sub 40}. The crystalline specimen of the alloy Ti{sub 60}Ni{sub 40} shows the presence of Ti{sup 2+}, Ti{sup 3+} and Ti{sup 4+} species along with some unoxidized Ti in metallic form (Ti{sup 0}) whereas the amorphous specimen consists of Ti{sup 3+} and Ti{sup 4+} species. On the other hand nanocrystalline specimen contains only Ti{sup 4+} species. Thus it is likely that the presence of fewer species and the absence of Ti{sup 3+} in the oxide film formed on nanocrystalline specimen of Ti{sub 60}Ni{sub 40} lead to the formation of a film with greater homogeneity and protective quality in comparison to the films formed on crystalline and amorphous states of the alloy Ti{sub 60}Ni{sub 40} in 1 M NaCl aqueous medium.

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.

Radiation influence on properties of nanocrystalline alloy

International Nuclear Information System (INIS)

Holkova, D.; Sitek, J.; Novak, P.; Dekan, J.

2016-01-01

Our work is focused on the studied of structural changes amorphous and nanocrystalline alloys after irradiation with electrons. For the analysis of these alloy we use two spectroscopic methods: Moessbauer spectroscopy and XRD. Measurements of nanocrystalline (Fe 3 Ni 1 ) 81 Nb 7 B 12 samples before and after electrons irradiation by means of Moessbauer spectroscopy and XRD showed that the electrons causes changes in magnetic structure which is reflected changes of direction of net magnetic moment. Structural changes occurs in the frame of error indicated by both spectroscopic methods. We can confirm that this kind alloys a resistive again electrons irradiation up to doses of 4 MGy. We observed in this frame only beginning of the radiation damage. (authors)

Laser alloyed Al-Ni-Fe coatings

CSIR Research Space (South Africa)

Pityana, SL

2008-10-01

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

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

Nanoindentation and micro-mechanical fracture toughness of electrodeposited nanocrystalline Ni-W alloy films

Energy Technology Data Exchange (ETDEWEB)

Armstrong, D.E.J., E-mail: david.armstrong@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Haseeb, A.S.M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Roberts, S.G.; Wilkinson, A.J. [Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH (United Kingdom); Bade, K. [Institut fuer Mikrostrukturtechnik (IMT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2012-04-30

Nanocrystalline nickel-tungsten alloys have great potential in the fabrication of components for microelectromechanical systems. Here the fracture toughness of Ni-12.7 at.%W alloy micro-cantilever beams was investigated. Micro-cantilevers were fabricated by UV lithography and electrodeposition and notched by focused ion beam machining. Load was applied using a nanoindenter and fracture toughness was calculated from the fracture load. Fracture toughness of the Ni-12.7 at.%W was in the range of 1.49-5.14 MPa {radical}m. This is higher than the fracture toughness of Si (another important microelectromechanical systems material), but considerably lower than that of electrodeposited nickel and other nickel based alloys. - Highlights: Black-Right-Pointing-Pointer Micro-scale cantilevers manufactured by electro-deposition and focused ion beam machining. Black-Right-Pointing-Pointer Nanoindenter used to perform micro-scale fracture test on Ni-13at%W micro-cantilevers. Black-Right-Pointing-Pointer Calculation of fracture toughness of electrodeposited Ni-13at%W thin films. Black-Right-Pointing-Pointer Fracture toughness values lower than that of nanocrystalline nickel.

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)

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-01-15

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

Magnetic induction heating of FeCr nanocrystalline alloys

International Nuclear Information System (INIS)

Gómez-Polo, C.; Larumbe, S.; Pérez-Landazábal, J.I.; Pastor, J.M.; Olivera, J.; Soto-Armañanzas, J.

2012-01-01

In this work the thermal effects of magnetic induction heating in (FeCr) 73.5 Si 13.5 Cu 1 B 9 Nb 3 amorphous and nanocrystalline wires were analyzed. A single piece of wire was immersed in a glass capillary filled with water and subjected to an ac magnetic field (frequency, 320 kHz). The initial temperature rise enabled the determination of the effective Specific Absorption Rate (SAR). Maximum SAR values are achieved for those samples displaying high magnetic susceptibility, where the eddy current losses dominate the induction heating behavior. Moreover, the amorphous sample with Curie temperature around room temperature displays characteristic features of self-regulated hyperthermia. - Highlights: ► Amorphous and nanocrystalline Fe based alloys with tailored Curie temperature of the amorphous phase. ► Induction heating effects under the action of a ac magnetic field. ► Self-regulated characteristics based on the control of the Curie temperature. ► Dominant role of the eddy-current losses in the self-heating phenomena.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-10-25

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

Hydrogen solubility in austenite of Fe-Ni-Cr alloys

International Nuclear Information System (INIS)

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

1981-01-01

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

Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg₂Ni-type Alloy by Melt Spinning.

Science.gov (United States)

Zhang, Yang-Huan; Li, Bao-Wei; Ren, Hui-Ping; Li, Xia; Qi, Yan; Zhao, Dong-Liang

2011-01-18

Mg₂Ni-type Mg₂Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg₂Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio () of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio () from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10 - 11 to 3.88 × 10 - 11 cm²/s and the limiting current density I L from 150.9 to 887.4 mA/g.

Nanocrystalline electrodeposited Ni-Mo-C cathodes for hydrogen production

International Nuclear Information System (INIS)

Hashimoto, K.; Sasaki, T.; Meguro, S.; Asami, K.

2004-01-01

Tailoring active nickel alloy cathodes for hydrogen evolution in a hot concentrated hydroxide solution was attempted by electrodeposition. The carbon addition to Ni-Mo alloys decreased the nanocrystalline grain size and remarkably enhanced the activity for hydrogen evolution, changing the mechanism of hydrogen evolution. The Tafel slope of hydrogen evolution was about 35 mV per decade. This suggested that the rate-determining step is desorption of adsorbed hydrogen atoms by recombination. As was distinct from the binary Ni-Mo alloys, after open circuit immersion, the overpotential, that is, the activity of nanocrystalline Ni-Mo-C alloys for hydrogen evolution was not changed, indicating the sufficient durability in the practical electrolysis

Linear thermal expansion coefficient of cast Fe-Ni invar and Fe-Ni-Co superinvar alloys

International Nuclear Information System (INIS)

Ogorodnikova, O.M.; Chermenskaya, E.V.; Rabinovich, S.V.; Grachev, S.V.

1999-01-01

Cast invar alloys Fe-Ni (28-35 wt. % Ni) are investigated using metallography, dilatometry and X-ray methods as soon as the crystallization is completed and again after low-temperature treatment resulting in martensitic transformation in low nickel alloys. Nickel distribution in a cast superinvar Fe-32% Ni-4% Co is studied by means of X-ray spectrum microanalysis. The results obtained permit the correction of model concepts about cast invars and the estimate of a coefficient of linear expansion depending on phase composition and nickel microsegregation [ru

Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg2Ni-type Alloy by Melt Spinning

Directory of Open Access Journals (Sweden)

Hui-Ping Ren

2011-01-01

Full Text Available Mg2Ni-type Mg2Ni1−xCox (x = 0, 0.1, 0.2, 0.3, 0.4 alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD and transmission electron microscopy (TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1 alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4 alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg2Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s to 30 m/s, the hydrogen absorption saturation ratio ( of the (x = 0.4 alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio ( from 54.5 to 70.2%, the hydrogen diffusion coefficient (D from 0.75 × 10−11 to 3.88 × 10−11 cm2/s and the limiting current density IL from 150.9 to 887.4 mA/g.

Phase separation in equiatomic AlCoCrFeNi high-entropy alloy

Energy Technology Data Exchange (ETDEWEB)

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

2013-09-15

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

Microstructure and strengthening mechanisms in an FCC structured single-phase nanocrystalline Co25Ni25Fe25Al7.5Cu17.5 high-entropy alloy

International Nuclear Information System (INIS)

Fu, Zhiqiang; Chen, Weiping; Wen, Haiming; Zhang, Dalong; Chen, Zhen; Zheng, Baolong; Zhou, Yizhang; Lavernia, Enrique J.

2016-01-01

We report on a study of the design, phase formation, microstructure, mechanical behavior and strengthening mechanisms of a novel single-phase Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 (at.%) high-entropy alloy (HEA). In this investigation, a bulk nanocrystalline (nc) Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA with the face-centered cubic (FCC) crystal structure was fabricated by mechanical alloying (MA) followed by consolidation via spark plasma sintering (SPS). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that a single FCC solid-solution phase with an average grain diameter of 24 nm was produced following MA. Following SPS, bulk samples exhibiting a bimodal microstructure with both nanoscale grains and ultra-fine grains (UFGs) and with an average grain diameter of 95 nm were obtained, possessing a single FCC solid-solution phase identical to that in the milled powders. The single-phase feature of the Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA principally resulted from remarkably high mutual solubility in most binary atom-pairs of the constituent elements, which appears to correspond to a high entropy of mixing. Approximately 5 vol.% of nanoscale twins were observed in the bulk nc samples. The bulk nc Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA exhibits a compressive yield strength of 1795 MPa with a hardness of 454 Hv, which is dramatically higher than the yield strength of most previously reported FCC structured HEAs (∼130–700 MPa). Compared to those of the bulk coarse-grained (CG) Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA fabricated by arc-melting, the yield strength and Vickers hardness values of the bulk nc samples increased by 834.9% and 251.9%, respectively. Quantitative calculations of the respective contributions from each strengthening mechanism demonstrate that grain boundary strengthening and dislocation strengthening are principally responsible for the measured ultra-high strength of the bulk nc Co 25 Ni 25 Fe 25 Al 7.5 Cu 17.5 HEA.

HRTEM study of the nanocrystalline Al85Y10Ni5 alloy

International Nuclear Information System (INIS)

Kozubowski, J.A.; Latuch, J.

1999-01-01

Nanocrystalline alloy Al 85 Y 10 Ni 5 obtained by annealing of the amorphous ribbons formed by melt spinning was studied by transmission electron microscopy and energy dispersive X-ray spectroscopy (EDS). The combined use of electron diffraction, electron microscopy and EDS has revealed the presence of several nano-phases: separate grains of Al(Y) and Al(N) solid solutions Al 3 Y grains and an unidentified phase of composition close to Al 3 (Ni,Y). (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.

Iron-rich (Fe1-x-yNixCoy)88Zr7B4Cu1 nanocrystalline magnetic materials for high temperature applications with minimal magnetostriction

Science.gov (United States)

Martone, Anthony; Dong, Bowen; Lan, Song; Willard, Matthew A.

2018-05-01

As inductor technology advances, greater efficiency and smaller components demand new core materials. With recent developments of nanocrystalline magnetic materials, soft magnetic properties of these cores can be greatly improved. FeCo-based nanocrystalline magnetic alloys have resulted in good soft magnetic properties and high Curie temperatures; however, magnetoelastic anisotropies persist as a main source of losses. This investigation focuses on the design of a new Fe-based (Fe,Ni,Co)88Zr7B4Cu1 alloy with reduced magnetostriction and potential for operation at elevated temperatures. The alloys have been processed by arc melting, melt spinning, and annealing in a protective atmosphere to produce nanocrystalline ribbons. These ribbons have been analyzed for structure, hysteresis, and magnetostriction using X-Ray diffraction, vibrating sample magnetometry (VSM), and a home-built magnetostriction system, respectively. In addition, Curie temperatures of the amorphous phase were analyzed to determine the best performing, high-temperature material. Our best result was found for a Fe77Ni8.25Co2.75Zr7B4Cu1 alloy with a 12 nm average crystallite size (determined from Scherrer broadening) and a 2.873 Å lattice parameter determined from the Nelson-Riley function. This nanocrystalline alloy possesses a coercivity of 10 A/m, magnetostrictive coefficient of 4.8 ppm, and amorphous phase Curie temperature of 218°C.

Solubility of sulfur in Fe-Cr-Ni alloys

International Nuclear Information System (INIS)

Bogolyubskij, S.D.; Petrova, E.F.; Rogov, A.I.; Shvartsman, L.A.

1979-01-01

The solubility of 35 S was determined in Fe-Cr-Ni alloys in the range of temperatures between 910 and 1050 deg C by the method of radiometric analysis. It was found that the solubility of sulfur increases with the concentration of chromium in alloys with 20% Ni

Tailoring and patterning the grain size of nanocrystalline alloys

International Nuclear Information System (INIS)

Detor, Andrew J.; Schuh, Christopher A.

2007-01-01

Nanocrystalline alloys that exhibit grain boundary segregation can access thermodynamically stable or metastable states with the average grain size dictated by the alloying addition. Here we consider nanocrystalline Ni-W alloys and demonstrate that the W content controls the grain size over a very broad range: ∼2-140 nm as compared with ∼2-20 nm in previous work on strongly segregating systems. This trend is attributed to a relatively weak tendency for W segregation to the grain boundaries. Based upon this observation, we introduce a new synthesis technique allowing for precise composition control during the electrodeposition of Ni-W alloys, which, in turn, leads to precise control of the nanocrystalline grain size. This technique offers new possibilities for understanding the structure-property relationships of nanocrystalline solids, such as the breakdown of Hall-Petch strength scaling, and also opens the door to a new class of customizable materials incorporating patterned nanostructures

Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Kabir, L.; Mandal, A.R. [Department of Physics, Visva-Bharati, Santiniketan-731 235 (India); Mandal, S.K., E-mail: sk_mandal@hotmail.co [Department of Physics, Visva-Bharati, Santiniketan-731 235 (India)

2010-04-15

We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni{sup 2+} clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni{sup 2+} clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

Science.gov (United States)

Kabir, L.; Mandal, A. R.; Mandal, S. K.

2010-04-01

We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni 2+ clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni 2+ clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

International Nuclear Information System (INIS)

Kabir, L.; Mandal, A.R.; Mandal, S.K.

2010-01-01

We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni 2+ clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni 2+ clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

Point defect properties of ternary fcc Fe-Cr-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Wróbel, J.S., E-mail: jan.wrobel@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D.; Dudarev, S.L. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland)

2017-02-15

Highlights: • Properties of point defects depend on the local atomic environment. • As the degree of chemical order increases, the formation energies increase, too. • Relaxation volumes are larger for the more ordered structures. - Abstract: The properties of point defects in Fe-Cr-Ni alloys are investigated, using density functional theory (DFT), for two alloy compositions, Fe{sub 50}Cr{sub 25}Ni{sub 25} and Fe{sub 55}Cr{sub 15}Ni{sub 30}, assuming various degrees of short-range order. DFT-based Monte Carlo simulations are applied to explore short-range order parameters and generate representative structures of alloys. Chemical potentials for the relevant structures are estimated from the minimum of the substitutional energy at representative atoms sites. Vacancies and 〈1 0 0〉 dumbbells are introduced in the Fe{sub 2}CrNi intermetallic phase as well as in two Fe{sub 55}Cr{sub 15}Ni{sub 30} alloy structures: the disordered and short range-ordered structures, generated using Monte Carlo simulations at 2000 K and 300 K, respectively. Formation energies and relaxation volumes of defects as well as changes of magnetic moments caused by the presence of defects are investigated as functions of the local environment of a defect.

Nanocrystalline (Fe{sub 60}Al{sub 40}){sub 80}Cu{sub 20} alloy prepared by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Krifa, M.; Mhadhbi, M. [Laboratoire de Chimie Inorganique, 99/UR/12-22, FSS – Université de Sfax, B.P. 1171, Sfax 3018 (Tunisia); Escoda, L.; Güell, J.M. [Dept. de Fisica, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain); Suñol, J.J., E-mail: joanjosep.sunyol@udg.edu [Dept. de Fisica, Universitat de Girona, Campus Montilivi, 17071 Girona (Spain); Llorca-Isern, N.; Artieda-Guzmán, C. [Dept. CMEM, Universitat de Barcelona, Martí Franques 1, 08028 Barcelona (Spain); Khitouni, M. [Laboratoire de Chimie Inorganique, 99/UR/12-22, FSS – Université de Sfax, B.P. 1171, Sfax 3018 (Tunisia)

2013-03-25

Highlights: ► Nanocrystalline Fe(Al, Cu) powdered alloy (10 nm) has been synthesized by MA. ► Decreasing the crystallite size increases coercivity and squareness ratio. ► As low crystallites size stronger hard ferromagnetic material results. -- Abstract: A nanostructured disordered Fe(Al, Cu) solid solution was obtained from prealloyed FeAl and elemental Cu powders using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. The transformation of the phase depends upon the milling time. With the increase of milling time all Cu atoms became dissolved in the bcc Fe and the final product of the MA process was the nanocrystalline Fe(Al, Cu) solid solution with a mean crystallite size of 10 nm. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Magnetic properties were also investigated and were related to the microstructural changes. The system showed hard magnetic behavior.

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.

High-speed jet electrodeposition and microstructure of nanocrystalline Ni-Co alloys

International Nuclear Information System (INIS)

Qiao Guiying; Jing Tianfu; Wang Nan; Gao Yuwei; Zhao Xin; Zhou Jifeng; Wang Wei

2005-01-01

The jet electrodeposition from watts baths with a device of electrolyte jet was carried out to prepare nano-crystalline cobalt-nickel alloys. The influence of the concentration of Co 2+ ions in the electrolyte and electrolysis parameters, such as the cathodic current density, the temperature as well as the electrolyte jet speed, on the chemistry and microstructure of Ni-Co-deposit alloys were investigated. Experimental results indicated that increasing the Co 2+ ions concentration in the bath, the electrolyte jet speed and decreasing of the cathodic current density and decrease of the electrolyte temperature all results in an increase of cobalt content in the alloy. Detailed microstructure changes upon the changes of alloy composition and experimental conditions were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results show the Ni-Co solid solution was formed through the jet electrodeposition. Phase constitution of solid solution changes progressively under different electrolyte concentration. Alloys with low Co concentration exhibit single phase of face-centered cubic (fcc) structure; The Co concentration over 60.39 wt.%, the alloys are composed of face-centered cubic (fcc) phase and hexagonal close-packed (hcp) phase. Furthermore, the formation of the nanostructured Ni-Co alloy deposit is investigated. Increasing the Co 2+ ions concentration in the bath, the cathodic current density, the electrolyte temperature and the electrolyte jet speed all result in the finer grains in the deposits. Additives such as saccharin in the electrolyte also favor the formation of the finer grains in the alloy deposits

Magnetoresistance in ferromagnetic shape memory alloy NiMnFeGa

International Nuclear Information System (INIS)

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

2011-01-01

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

Magnetic x-ray linear dichroism of ultrathin Fe-Ni alloy films

Energy Technology Data Exchange (ETDEWEB)

Schumann, F.O.; Willis, R.F. [Pennsylvania State Univ., University Park, PA (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-04-01

The authors have studied the magnetic structure of ultrathin Fe-Ni alloy films as a function of Fe concentration by measuring the linear dichroism of the 3p-core levels in angle-resolved photoemission spectroscopy. The alloy films, grown by molecular-beam epitaxy on Cu(001) surfaces, were fcc and approximately four monolayers thick. The intensity of the Fe dichroism varied with Fe concentration, with larger dichroisms at lower Fe concentrations. The implication of these results to an ultrathin film analogue of the bulk Invar effect in Fe-Ni alloys will be discussed. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Effect of solute Cu on ductile-to-brittle behavior of martensitic Fe-8% Ni alloy

International Nuclear Information System (INIS)

Junaidi Syarif; Tsuchiyama, Toshihiro; Takaki, Setsuo

2007-01-01

Effect of solute Cu on the ductile-to-brittle (DBT) behaviour of martensitic Fe-8mass%Ni alloy is investigated to understand the effect of solute Cu on mechanical properties of martensitic steel. The DBT behaviours of the Fe-8mass%Ni and the Fe-8mass%Ni-1mass%Cu alloys are almost the same. It is thought to be due to disappearance of the solid solution softening in the martensitic Fe-8mass%Ni-Cu alloys. The solute Cu gives small influence on temperature and strain rate dependences of yield stress and suppressing the twin deformation at lower temperature in the martensitic Fe-8mass%Ni alloy. Therefore, the DBT temperature of the martensitic Fe-8mass%Ni-Cu alloy was not shifted to lower side. (author)

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

Directory of Open Access Journals (Sweden)

Xingjie Jia

2018-05-01

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

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.

Magnetic properties and EXAFS study of nanocrystalline Fe2Mn0.5Cu0.5Al synthesized using mechanical alloying technique

International Nuclear Information System (INIS)

Nanto, Dwi; Yang, Dong-Seok; Yu, Seong-Cho

2014-01-01

Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has been synthesized by the mechanical alloying technique and studied as a function of milling time. Alloy nature of Fe 2 Mn 0.5 Cu 0.5 Al was observed in a sample milled for 96 h. The magnetic saturation is 4.0 μ B /f.u., which coincidently follows Slater–Pauling rule at 5 K. Nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al has enhanced saturate magnetization compared to any other fabrication of Fe 2 MnAl reported. Cu element plays an important role in site competes with other elements and may result in the enhancement of saturate magnetization. In accordance to the magnetic results and EXAFS pattern, it was revealed that the dynamics of magnetic properties were confirmed as structural changes of nanocrystalline Fe 2 Mn 0.5 Cu 0.5 Al

Alloyed Ni-Fe nanoparticles as catalysts for NH₃ decomposition

DEFF Research Database (Denmark)

Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib

2012-01-01

A rational design approach was used to develop an alloyed Ni-Fe/Al2O3 catalyst for decomposition of ammonia. The dependence of the catalytic activity is tested as a function of the Ni-to-Fe ratio, the type of Ni-Fe alloy phase, the metal loading and the type of oxide support. In the tests with high...... temperatures and a low NH3-to-H2 ratio, the catalytic activity of the best Ni-Fe/Al2O3 catalyst was found to be comparable or even better to that of a more expensive Ru-based catalyst. Small Ni-Fe nanoparticle sizes are crucial for an optimal overall NH3 conversion because of a structural effect favoring...

Thermodynamic properties of liquid alloys systems Fe - Ni - O - Me - Si

Directory of Open Access Journals (Sweden)

Н.О. Шаркіна

2008-01-01

Full Text Available  In the isoperabelic calorimeter at 1870 are determined partial and integral enthalpies of mixture of liquid alloys of systems Fe – Ni – O - Me and Fe – Ni – O – Me – Si, where Me – IVb-, Vb-, VIb-metals. The basis of alloy was served invars with the contents of oxygen by 0,06 %. Established, that the melts of systems Fe – Ni – O – IVb- (Vb--metals are characterized by strong interparticle interplay. The components of the maiden portions IVb- (Vb--metals in Fe – Ni – O melts are accompanied by very large exothermal effects (from – 400 up to – 1000 kJ/mol, which one considerably surpass those in double melts Fe(Ni – Me. The subsequent portions IVb- (Vb--metals caused smaller allocation of a heat (in limits from – 100 up to – 30 kJ/mol, that is conditioned by a decrease of the contents of dissolved oxygen. The partial enthalpies of mixture of molybdenum and tungsten in melts Fe – Ni – O are close to those in a nickel, and for a chromium exceed them. Is rotined, that D` HSi in liquid alloys Fe – Ni – O – Mo (– 450 kJ/mol considerably surpass that are characteristic for a nickel (– 50 kJ/mol. It is explained by interplay of silicon with the stayed dissolved oxygen in initial melts of a system Fe – Ni – O – Mo.

Low temperature study of mechanically alloyed Fe{sub 67.5}Ni{sub 32.5} Invar sample

Energy Technology Data Exchange (ETDEWEB)

Valenzuela, J.L. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Valderruten, J.F. [Departamento de Ingeniería, Universidad Cooperativa de Colombia, Bucaramanga (Colombia); Pérez Alcázar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Colorado, H.D. [Departamento de Física, Universidad del Valle, A. A. 25360, Cali (Colombia); Romero, J.J. [Instituto de Microelectrónica de Madrid, CNM, CSIC, C/Isaac Newton 8, Tres Cantos, 28760 Madrid (Spain); González, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, Las Rozas, 28230 Madrid (Spain); Greneche, J.M. [LUNAM, Université du Maine, Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, 72085 Le Mans, Cedex 9 (France); Marco, J.F. [Instituto de Química-Física ' ' Rocasolano' ' , CSIC, C/Serrano 119, 28006 Madrid (Spain)

2015-07-01

The study at low temperatures of powder of the Invar alloy, Fe{sub 67.5}Ni{sub 32.5}, produced by mechanical alloying, shows that the sample presents two structural phases, the Fe–Ni BCC and the Fe–Ni FCC. The {sup 57}Fe Mössbauer spectra obtained in this sample at different temperatures were fitted considering two hyperfine magnetic field distributions. The first one having the larger mean field and only one peak (at ca. 35 T, varying with T), is associated with the BCC phase, and the second one, presenting several broad peaks (distributed between 10 and 35 T), is associated to the FCC phase. A singlet, which is associated to low spin Fe sites of the FCC phase, was also considered. The mean hyperfine magnetic field of the BCC phase increases monotonically as temperature decreases, while that of the FCC phase presents an anomaly near 75 K. The real part of the ac magnetic susceptibility temperature scans presents a peak whose position increases from 31 to 39 K, when the ac field frequency increases from 100 to 5000 Hz. These results permit to associate the detected anomaly to the occurrence of a reentrant spin glass transition. - Highlights: • XRD detect the BCC and FCC nanocrystalline phases in the Invar Fe{sub 67.5}Si{sub 32.5}. • Mössbauer spectra were fitted with two HMFDs and a singlet. • The MHMF and the isomer shift of the FCC structure present a kink near 61 K. • Magnetic susceptibility proved that this anomaly corresponds to a RSG- F transition. • The Invar composition of the MA Fe{sub 67.5}Si{sub 32.5} alloy presents the frustration phenomena.

L1{sub 0} phase formation in ternary FePdNi alloys

Energy Technology Data Exchange (ETDEWEB)

Montes-Arango, A.M. [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115 (United States); Bordeaux, N.C. [Department of Chemical Engineering, Northeastern University, Boston, MA 02115 (United States); Liu, J.; Barmak, K. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 (United States); Lewis, L.H., E-mail: lhlewis@neu.edu [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115 (United States); Department of Chemical Engineering, Northeastern University, Boston, MA 02115 (United States)

2015-11-05

Metallurgical routes to highly metastable phases are required to access new materials with new functionalities. To this end, the stability of the tetragonal chemically ordered L1{sub 0} phase in the ternary Fe–Pd–Ni system is quantified to provide enabling information concerning synthesis of L1{sub 0}-type FeNi, a highly attractive yet highly elusive advanced permanent magnet candidate. Fe{sub 50}Pd{sub 50−x}Ni{sub x} (x = 0–7 at%) samples were arc-melted and annealed at 773 K (500 °C) for 100 h to induce formation of the chemically ordered L1{sub 0} phase. Coupled calorimetry, structural and magnetic investigations allow determination of an isothermal section of the ternary Fe–Pd–Ni phase diagram featuring a single phase L1{sub 0} region near the FePd boundary for x < 6 at%. It is demonstrated that increased Ni content in Fe{sub 50}Pd{sub 50−x}Ni{sub x} alloys systematically decreases the order-disorder transition temperature, resulting in a lower thermodynamic driving force for the ordering phase transformation. The Fe{sub 50}Pd{sub 50−x}Ni{sub x} L1{sub 0} → fcc disordering transformation is determined to occur via a two-step process, with compositionally-dependent enthalpies and transition temperatures. These results highlight the need to investigate ternary alloys with higher Ni content to determine the stability range of the L1{sub 0} phase near the FeNi boundary, thereby facilitating kinetic access to the important L1{sub 0} FeNi ferromagnetic phase. - Highlights: • Chemical ordering in FePdNi enhances intrinsic and extrinsic magnetic properties. • 773 K annealed FePdNi alloys studied show a stable L1{sub 0} phase for Ni ≤ 5.2 at%. • Chemical disordering in FePdNi occurs by a previously unreported two-step process. • Ni additions to FePd dramatically decrease the chemical order-disorder temperature. • The chemical-ordering transformation kinetics are greatly affected by Ni content.

Alloying effect on hardening of martensite stainless steels of the Fe-Cr-Ni and Fe-Cr-Co systems

International Nuclear Information System (INIS)

Fel'dgandler, Eh.G.; Savkina, L.Ya.

1975-01-01

The effect of alloying elements is considered on the γ → a-transformation and hardening of certain compositions of the ternary Fe-Cr-Ni- and Fe-Cr-Co alloy systems with the martensite structure. In martensite Fe-(10 to 14)% Cr base steels the elements Co, Cu, W, Ni, Mo, Si, Cr decrease, Mn, Si, Mo, Cu increase, and Cr, Ni, Co decrease the temperature of α → γ-transition. The tempering of martensite steels of the Fe-Cr-Ni- and Fe-Cr-Co-systems containing 10 to 14% Cr, 4 to 9% Ni, and 7 to 12% Co does not lead to hardening. Alloyage of the martensite Fe-Cr-Ni-, Fe-Cr-Co- and Fe-Cr-Ni-Co base separately with Mo, W, Si or Cu leads to a hardening during tempering, the hardening being the higher, the higher is the content of Ni and, especially, of Co. The increase in the content of Mo or Si produces the same effect as the increase in the Co content. In on Fe-Cr-Co or Fe-Cr-Ni-Co based steels alloyed with Mo or Si, two temperature ranges of ageing have been revealed which, evidently, have different hardening natures. The compositions studied could serve as the base material for producing maraging stainless steels having a complex variety of properties

Insights into the deformation behavior of the CrMnFeCoNi high-entropy alloy revealed by elevated temperature nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Maier-Kiener, Verena [Montanuniversitat Leoben, Leoben (Austria); Schuh, Benjamin [Austrian Academy of Sciences, Leoben (Austria); George, Easo P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Clemens, Helmut [Montanuniversitat Leoben, Leoben (Austria); Hohenwarter, Anton [Austrian Academy of Sciences, Leoben (Austria)

2017-07-27

A CrMnFeCoNi high-entropy alloy was investigated by nanoindentation from room temperature to 400 °C in the nanocrystalline state and cast plus homogenized coarse-grained state. In the latter case a < 100 >-orientated grain was selected by electron back scatter diffraction for nanoindentation. It was found that hardness decreases more strongly with increasing temperature than Young’s modulus, especially for the coarse-grained state. The modulus of the nanocrystalline state was slightly higher than that of the coarse-grained one. For the coarse-grained sample a strong thermally activated deformation behavior was found up to 100–150 °C, followed by a diminishing thermally activated contribution at higher testing temperatures. For the nanocrystalline state, different temperature dependent deformation mechanisms are proposed. At low temperatures, the governing processes appear to be similar to those in the coarse-grained sample, but with increasing temperature, dislocation-grain boundary interactions likely become more dominant. Finally, at 400 °C, decomposition of the nanocrystalline alloy causes a further reduction in thermal activation. Furthermore, this is rationalized by a reduction of the deformation controlling internal length scale by precipitate formation in conjunction with a diffusional contribution.

Study on the Ni Mo alloy nano crystals

International Nuclear Information System (INIS)

Goncalves, Lidice A. Pereira; Pontes, Luiz Renato de Araujo

1996-01-01

Materials with nanocrystalline microstructures are solids that contain such a high density of defects, with the spacings between neighboring defects approaching interatomic distances. As result, nanocrystalline solids exhibit physical and chemical properties different from those usually found in normal crystalline s or amorphous materials with the same chemical composition. In this work, the nanocrystalline Ni Mo alloy was prepared by melt-spinning method. The novelly synthesized nanocrystalline Ni Mo alloy was characterized by X-ray diffraction (XRD), differential scanning calorimetry (D S C) and microscopy. The estimated average crystalline size by the Debye-Scherrer formulas was 20 nm. (author)

External influence on magnetic properties of Fe-based nanocrystalline alloys

International Nuclear Information System (INIS)

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

2006-01-01

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

Kinetic study of the annealing reactions in Cu-Ni-Fe alloys

International Nuclear Information System (INIS)

Donoso, E.

2014-01-01

The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC) and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi 3 phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi 3 phase. (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.

Irradiation effects in Fe-30%Ni alloy during Ar ion implantation

International Nuclear Information System (INIS)

Soukieh, Mohamad; Al-Mohamad, Ali

1993-12-01

The use of metallic thin films for studying the processes which take place during ion irradiation has recently increased. For example, ion implantation is widely used to study the structural defects in transition metallic thin films such as (Fe, Ni, Co), because it can simulate the effects occurring in nuclear reactors during neutron irradiation especially the swelling of reactor materials. The swelling of metals and alloys is strongly related to the material structure and to the irradiation conditions. The general feature of formation of structural defects as a function of irradiation dosage and annealing temperature is well known. However, the detailed mechanisms are still not well understood. For example, the swelling of iron alloy with 30-35% nickel is very small in comparison with other Ni concentrations, and there is no clear information on the possibility of phase transitions in fe-Ni alloys during irradiation. The aim of this work is to study the phase-structural changes in Fe-30% Ni implanted by high dose of argon ions. The effect of irradiation with low energy argon ions (40 KeV, and fluences of 10.E15 to 10.E17 ions/cm) on the deposited thin films of Fe-30% Ni alloy was investigated using RBS and TEM techniques. The thicknesses of these films were about 65+-10 nm deposited on ceramic, KBr, and Be fiols substrates. Gas bubble formation and profile distribution of the implanted argon ions were investigated. Formation of an ordered phase Fe 3 Ni during irradiation appears to inhibit gas bubble formations in the film structure. (author). 17 refs., 15 figs., 7 tabs

A FeNiMnC alloy with strain glass transition

Directory of Open Access Journals (Sweden)

Hui Ma

2018-02-01

Full Text Available Recent experimental and theoretical investigations suggested that doping sufficient point defects into a normal ferroelastic/martensitic alloy systems could lead to a frozen disordered state of local lattice strains (nanomartensite domains, thereby suppressing the long-range strain-ordering martensitic transition. In this study, we attempt to explore the possibility of developing novel ferrous Elinvar alloys by replacing nickel with carbon and manganese as dopant species. A nominal Fe89Ni5Mn4.6C1.4 alloy was prepared by argon arc melting, and XRD, DSC, DMA and TEM techniques were employed to characterize the strain glass transition signatures, such as invariance in average structure, frequency dispersion in dynamic mechanical properties (storage modulus and internal friction and the formation of nanosized strain domains. It is indicated that doping of Ni, Mn and C suppresses γ→α long-range strain-ordering martensitic transformation in Fe89Ni5Mn4.6C1.4 alloy, generating randomly distributed nanosized domains by strain glass transition. Keywords: Strain glass transition, Elinvar alloys, Point defects, Nanosized domains

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

External influence on magnetic properties of Fe-based nanocrystalline alloys

Energy Technology Data Exchange (ETDEWEB)

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

2006-09-15

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

Electrochemical passivation behaviour of nanocrystalline Fe80Si20 ...

Indian Academy of Sciences (India)

Abstract. Passivation behaviour of nanocrystalline coating (Fe80Si20) obtained by in situ mechanical alloying route .... is controlled by the iron oxide film in case of alloys with ..... the surface is covered, thus, producing effective protection of.

Effect of Fe substitution at the Ni and Mn sites on the magnetic properties of Ni50Mn35In15 Heusler alloys

International Nuclear Information System (INIS)

Halder, Madhumita; Suresh, K.G.

2015-01-01

The structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. At room temperature, Ni 48 Fe 2 Mn 35 In 15 has L2 1 cubic structure, whereas Ni 50 Mn 34 FeIn 15 shows a two-phase structure due to the martensitic transition. In the case of Ni 48 Fe 2 Mn 35 In 15 , there is only one magnetic transition at 316 K with no martensitic transition. However, in Ni 50 Mn 34 FeIn 15 , we observe the martensitic transition at about 280 K. The Curie temperatures for austenite and martensite phases are 314 and 200 K, respectively. The maximum magnetic entropy changes are found to be 5.5 and 4.5 J kg −1 K −1 for Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 , respectively, for 50 kOe. Ni 50 Mn 34 FeIn 15 exhibits exchange bias behavior, with a bias field of 130 Oe at 5 K. Both the alloys satisfy the empirical relation between the martensitic transition and the valence electron concentration (e/a) ratio. - Highlights: • Structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. • Ni 48 Fe 2 Mn 35 In 15 does not undergo a martensitic transition, whereas Ni 50 Mn 34 FeIn 15 shows martensitic transition. • Ni 50 Mn 34 FeIn 15 alloy exhibits exchange bias behavior. • Both alloys satisfy the empirical relation between martensitic transition and valence electron concentration (e/a)

Ultrahigh hardness and high electrical resistivity in nano-twinned, nanocrystalline high-entropy alloy films

Science.gov (United States)

Huo, Wenyi; Liu, Xiaodong; Tan, Shuyong; Fang, Feng; Xie, Zonghan; Shang, Jianku; Jiang, Jianqing

2018-05-01

Nano-twinned, nanocrystalline CoCrFeNi high-entropy alloy films were produced by magnetron sputtering. The films exhibit a high hardness of 8.5 GPa, the elastic modulus of 161.9 GPa and the resistivity as high as 135.1 μΩ·cm. The outstanding mechanical properties were found to result from the resistance of deformation created by nanocrystalline grains and nano-twins, while the electrical resistivity was attributed to the strong blockage effect induced by grain boundaries and lattice distortions. The results lay a solid foundation for the development of advanced films with structural and functional properties combined in micro-/nano-electronic devices.

Diffusion of 51Cr along high-diffusivity paths in Ni-Fe alloys

International Nuclear Information System (INIS)

Cermak, J.

1990-01-01

Penetration profiles of 51 Cr in polycrystalline alloys Ni-xFe (x = 0, 20, 40, and 60 wt.% Fe) after diffusion anneals at temperatures between 693 and 1473 K are studied. Sectioning of diffusion zones of samples annealed above 858 K is carried out by grinding, at lower temperatures by DC glow discharge sputtering. The concentration of 51 Cr in depth x is assumed to be proportional to relative radioactivity of individual sections. With help of volume and pipe self-diffusion data taken from literature, the temperature dependence of product P = δD g (δ and D g are grain boundary width and grain boundary diffusion coefficient, respectively) is obtained: P = (2.68 - 0.88 +1.3 ) x 10 -11 exp [-(221.3 ± 3.0) kJ/mol/RT]m 3 /s. This result agrees well with the previous measurements of 51 Cr diffusivity in Fe-18 Cr-12 Ni and Fe-21 Cr-31 Ni. It indicates that the mean chemical composition of Fe-Cr-Ni ternary alloys is not a dominant factor affecting the grain boundary diffusivity of Cr in these alloys. (author)

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...

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

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

International Nuclear Information System (INIS)

Manghnani, Murli H.; Balogh, John; Hong Xinguo; Newville, Matthew; Amulele, G.

2007-01-01

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

Nickel recovery from electronic waste II Electrodeposition of Ni and Ni–Fe alloys from diluted sulfate solutions

Energy Technology Data Exchange (ETDEWEB)

Robotin, B. [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, RO-400028 Cluj-Napoca (Romania); Ispas, A. [Fachgebiet Elektrochemie und Galvanotechnik II, Technische Universität Ilmenau, D-98693 Ilmenau (Germany); Coman, V. [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, RO-400028 Cluj-Napoca (Romania); Bund, A. [Fachgebiet Elektrochemie und Galvanotechnik II, Technische Universität Ilmenau, D-98693 Ilmenau (Germany); Ilea, P., E-mail: pilea@chem.ubbcluj.ro [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, RO-400028 Cluj-Napoca (Romania)

2013-11-15

Highlights: • Ni can be recovered from EG wastes as pure Ni or as Ni–Fe alloys. • The control of the experimental conditions gives a certain alloy composition. • Unusual deposits morphology shows different nucleation mechanisms for Ni vs Fe. • The nucleation mechanism was progressive for Ni and instantaneous for Fe and Ni–Fe. - Abstract: This study focuses on the electrodeposition of Ni and Ni–Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni{sup 2+}/Fe{sup 2+} ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits’ thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni–Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni–Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni–Fe, the obtained data points are best fitted to an instantaneous nucleation model.

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

Intermartensitic transitions in Ni-Mn-Fe-Cu-Ga Heusler alloys

International Nuclear Information System (INIS)

Khan, Mahmud; Gautam, Bhoj; Pathak, Arjun; Dubenko, Igor; Stadler, Shane; Ali, Naushad

2008-01-01

A series of Fe doped Ni 2 Mn 0.75-x Fe x Cu 0.25 Ga Heusler alloys have been investigated by means of x-ray diffraction, magnetizations, thermal expansion, and electrical resistivity measurements. In Ni 2 Mn 0.75 Cu 0.25 Ga, martensitic and ferromagnetic transitions occur at the same temperature. Partial substitution of Mn by Fe results in a decrease of the martensitic transition temperature, T M , and an increase of the ferromagnetic transition temperature, T C , resulting in separation of the two transitions. In addition to the martensitic transition, complete thermoelastic intermartensitic transformations have been observed in the Fe doped Ni 2 Mn 0.75-x Fe x Cu 0.25 Ga samples with x>0.04. An unusual transition is observed in the alloy with x = 0.04. The magnetization curve as a function of increasing temperature shows only one first-order transition in the temperature range 5-400 K, which is identified as a typical coupled magnetostructural martensitic transformation. The magnetization curve as a function of decreasing temperature shows three different transitions, which are characterized as the ferromagnetic transition, the martensitic transition and the intermartensitic transition.

Annealing effect on redistribution of atoms in austenite of Fe-Ni-Mo and Fe-Ni-Si alloys

International Nuclear Information System (INIS)

Rodionov, Yu.L.; Isfandiyarov, G.G.; Zambrzhitskij, V.N.

1980-01-01

Using the Moessbauer spectrum method, studied has been the change in the fine atomic structure of the Fe-(28-36)%Ni austenite alloys with Mo and Si additives during annealing in the 200-800 deg C range. Also, the energy of the activation of processes, occurring at the annealing temperatures of below 500 deg C has been researched. On the basis of the obtained results a conclusion is drawn that the annealing of the investigated alloys at 300-500 deg C is conducive to the redistribution of the atoms of the alloying element and to the formation of regions with a higher content of Ni and Mo(Si) atoms

Magnetic characterization of nanocrystalline Fe80−xCrxCo20 (15≤x≤35) alloys during milling and subsequent annealing

International Nuclear Information System (INIS)

Rastabi, Reza Amini; Ghasemi, Ali; Tavoosi, Majid; Sodaee, Tahmineh

2016-01-01

Magnetic characterization of nanocrystalline Fe–Cr–Co alloys during milling and annealing process was the goal of this study. To formation of Fe 80−x Cr x Co 20 (15≤x≤35) solid solution, different powder mixtures of Fe, Cr and Co elements were mechanically milled in a planetary ball mill. The annealing process was done in as-milled samples at different temperature in the range of 500–640 °C for 2 h. The produced samples were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. Performed mechanical alloying in different powder mixtures lead to the formation of Fe–Cr–Co α-phase solid solution with average crystallite sizes of about 10 nm. The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The coercivity of produced alloys after annealing process decreased and reached to about 40–150 Oe. The highest value of coercivity in as-milled and annealed samples was achieved in alloys with higher Cr contents. - Highlights: • Hc and Ms of produced alloys obtained in the range of 110–200 Oe and 150–220 emu/g. • The highest value of Hc in milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . • Hc of produced alloys after spinodal decomposition decreased to about 40–150 Oe. • The effect of crystalline defects and residual strain on magnetic fields pinning in milled samples is higher than spinodal decomposition in annealed samples. • The highest value of Hc in as-milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . The coercivity of produced alloys after annealing process decreased and reach to about 40–150 Oe. • The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively.

Forming a structure of the CoNiFe alloys by X-ray irradiation

Science.gov (United States)

Valko, Natalia; Kasperovich, Andrey; Koltunowicz, Tomasz N.

The experimental data of electrodeposition kinetics researches and structure formation of ternary CoNiFe alloys deposited onto low-carbon steel 08kp in the presence of X-rays are presented. Relations of deposit rate, current efficiencies, element and phase compositions of CoNiFe coatings formed from sulfate baths with respect to cathode current densities (0.5-3A/dm2), electrolyte composition and irradiation were obtained. It is shown that, the CoNiFe coatings deposited by the electrochemical method involving exposure of the X-rays are characterized by more perfect morphology surfaces with less developed surface geometry than reference coatings. The effect of the X-ray irradiation on the electrodeposition of CoNiFe coatings promotes formatting of alloys with increased electropositive component and modified phase composition.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-02-15

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

Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

Phase transformation, magnetic property and microstructure of Ni-Mn-Fe-Co-Ga ferromagnetic shape memory alloys

International Nuclear Information System (INIS)

Tsuchiya, K.; Sho, Y.; Kushima, T.; Todaka, Y.; Umemoto, M.

2007-01-01

Effects of addition of Fe and Co on the phase stability, magnetic property and microstructures were investigated for Ni-Mn-Ga. In Ni-Mn 21- x -Fe x -Ga 27 alloys, martensitic transformation temperatures decreased with increasing amount of Fe (x) up to 15 mol%, then slightly increased by the further addition. The crystal structure of martensite phase was 10 M for x 15 mol%. Relatively high martensite stability was obtained for Ni 52 -Mn 16- x -Fe x -Co 5 -Ga 27 alloys. The highest stability of the ferromagnetic martensite phase was achieved in Ni 52 -Mn 6 -Fe 10 -Co 5 -Ga 27 after aging at 773 K for 3.6 ks. Martensite structure was non-modulated 2 M in this series of alloys

Synthesis of FeNi Alloy Nanomaterials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

Directory of Open Access Journals (Sweden)

Cássio Morilla dos Santos

2016-01-01

Full Text Available Proteic Sol-Gel method was used for the synthesis of FeNi alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H2-TPR, SEM, TEM, Mössbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure FeNi alloy in the samples reduced at 600°C (40 mL/min H2 flow and 700°C (25 mL/min H2 flow. The FeNi alloy presented stability against the oxidizing atmosphere up to 250°C. The morphology exhibited agglomerates relatively spherical and particles in the range of 10–40 nm. Mössbauer spectroscopy showed the presence of disordered ferromagnetic FeNi alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

Acoustic properties of TiNiMoFe base alloys

International Nuclear Information System (INIS)

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

2000-01-01

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

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

Directory of Open Access Journals (Sweden)

W. Y. Zhang

2016-05-01

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

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

KAUST Repository

Kolobylina, Natalia

2016-12-21

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

Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

Science.gov (United States)

Steeves, A.F.; Bibb, A.E.

A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

Structural, mechanical and magnetic study on galvanostatic electroplated nanocrystalline NiFeP thin films

Science.gov (United States)

Kalaivani, A.; Senguttuvan, G.; Kannan, R.

2018-03-01

Nickel based alloys has a huge applications in microelectronics and micro electromechanical systems owing to its superior soft magnetic properties. With the advantages of simplicity, cost-effectiveness and controllable patterning, electroplating processes has been chosen to fabricate thin films in our work. The soft magnetic NiFeP thin film was successfully deposited over the surface of copper plate through galvanostatic electroplating method by applying constant current density of 10 mA cm-2 for a deposition rate for half an hour. The properties of the deposited NiFeP thin films were analyzed by subjecting it into different physio-chemical characterization such as XRD, SEM, EDAX, AFM and VSM. XRD pattern confirms the formation of NiFeP particles and the structural analysis reveals that the NiFeP particles were uniformly deposited over the surface of copper substrate. The surface roughness analysis of the NiFeP films was done using AFM analysis. The magnetic studies and the hardness of the thin film were evaluated from the VSM and hardness test. The NiFeP thin films possess lower coercivity with higher magnetization value of 69. 36 × 10-3 and 431.92 Gauss.

Synthesis of Fe Ni Alloy Nano materials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

International Nuclear Information System (INIS)

Santos, C.M.D.; Martins, A.F.N.; Sasaki, J.M.; Costa, B. C.; Ribeiro, T.S.; Braga, T.P.; Soares, J.M.

2016-01-01

Proteic Sol-Gel method was used for the synthesis of Fe Ni alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H_2-TPR, SEM, TEM, Moessbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure Fe Ni alloy in the samples reduced at 600 degree (40 ml/min H_2 flow) and 700 degree (25 ml/min H_2 flow). The Fe Ni alloy presented stability against the oxidizing atmosphere up to 250 degree. The morphology exhibited agglomerates relatively spherical and particles in the range of 10-40 nm. Moessbauer spectroscopy showed the presence of disordered ferromagnetic Fe Ni alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

Electrodeposited nanocrystalline bronze alloys as replacement for Ni

NARCIS (Netherlands)

Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

2008-01-01

Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization

Change of magnetic properties of nanocrystalline alloys under influence of external factors

Science.gov (United States)

Sitek, Jozef; Holková, Dominika; Dekan, Julius; Novák, Patrik

2016-10-01

Nanocrystalline (Fe3Ni1)81Nb7B12 alloys were irradiated using different types of radiation and subsequently studied by Mössbauer spectroscopy. External magnetic field of 0.5 T, electron-beam irradiation up to 4 MGy, neutron irradiation up to 1017 neutrons/cm2 and irradiation with Cu ions were applied on the samples. All types of external factors had an influence on the magnetic microstructure manifested as a change in the direction of the net magnetic moment, intensity of the internal magnetic field and volumetric fraction of the constituent phases. The direction of the net magnetic moment was the most sensitive parameter. Changes of the microscopic magnetic parameters were compared after different external influence and results of nanocrystalline samples were compared with their amorphous precursors.

Hysteresis properties of conventionally annealed and Joule-heated nanocrystalline Fe73.5Cu1Nb3Si13.5B9 alloys

International Nuclear Information System (INIS)

Tiberto, P.; Basso, V.; Beatrice, C.; Bertotti, G.

1996-01-01

The dependence of magnetic properties on the thermal treatment used to induce the amorphous-to-nanocrystalline transformation in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloy has been studied. Quasi-static hysteresis loops and initial permeability measurements were performed on nanocrystalline samples obtained by conventional annealing and Joule heating. A comparison between the magnetic properties of nanocrystalline samples obtained by the two heating procedures is presented. (orig.)

Stress-induced magnetic anisotropy in nanocrystalline alloys

International Nuclear Information System (INIS)

Varga, L.K.; Gercsi, Zs.; Kovacs, Gy.; Kakay, A.; Mazaleyrat, F.

2003-01-01

Stress-annealing experiments were extended to both nanocrystalline alloy families, Finemet and Nanoperm (Hitperm), and, for comparison, to amorphous Fe 62 Nb 8 B 30 alloy. For both Finemet and bulk amorphous, stress-annealing results in a strong induced transversal anisotropy (flattening of hysteresis loop) but yields longitudinal induced anisotropy (square hysteresis loop) in Nanoperm and Hitperm. These results are interpreted in terms of back-stress theory

Evaluation of alloying effect on the formation of Ni-Fe nanosized powders by pulsed wire discharge

International Nuclear Information System (INIS)

Park, Gyu-Hyeon; Lee, Gwang-Yeob; Kim, Hyeon-Ah; Lee, A-Young; Oh, Hye-Ryeong; Kim, Song-Yi; Kim, Do-Hyang; Lee, Min-Ha

2016-01-01

Highlights: • Synthesizing Ni-Fe alloy nano-powder employing Ni-plating layer of Fe wire by PWD process. • The mean particle size is decreased with increasing the charging voltage affecting to the super heating factor (K). • The mean particle size of PWD Ni-Fe nanosized powder is accordance with applied voltage. • Uniformity of mean particel size can be controlled by adjusting charging voltage and super heating factor (K). - Abstract: This study investigates the effects of varying the explosion time and charging voltage of pulsed wire discharge (PWD) on the mean particle size, dispersibility and alloying reliability of powders produced from pure Ni and Ni-plated Fe wires. It was found that with increasing charging voltage, the mean particle size of Ni powders is reduced from 40.11 ± 0.23 to 25.63 ± 0.07 nm, which is attributed to a change in the extent of super heating with particle size. Nanosized powders of Ni-Fe alloy with a mean particle size between 25.91 ± 0.24 and 26.30 ± 0.26 nm were also successfully fabricated and found to consist of particles with a γ-(Ni/Fe) core and FeO shell. The reliability for the optimization of processing parameters to control particle sizes is also evaluated.

Evaluation of alloying effect on the formation of Ni-Fe nanosized powders by pulsed wire discharge

Energy Technology Data Exchange (ETDEWEB)

Park, Gyu-Hyeon [Advanced Functional Materials R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Lee, Gwang-Yeob [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Deparment of Advanced Materials Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Hyeon-Ah [Advanced Functional Materials R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Deparment of Advanced Materials Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, A-Young; Oh, Hye-Ryeong; Kim, Song-Yi [Advanced Functional Materials R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Kim, Do-Hyang [Deparment of Advanced Materials Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Min-Ha, E-mail: mhlee1@kitech.re.kr [Advanced Functional Materials R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of)

2016-10-15

Highlights: • Synthesizing Ni-Fe alloy nano-powder employing Ni-plating layer of Fe wire by PWD process. • The mean particle size is decreased with increasing the charging voltage affecting to the super heating factor (K). • The mean particle size of PWD Ni-Fe nanosized powder is accordance with applied voltage. • Uniformity of mean particel size can be controlled by adjusting charging voltage and super heating factor (K). - Abstract: This study investigates the effects of varying the explosion time and charging voltage of pulsed wire discharge (PWD) on the mean particle size, dispersibility and alloying reliability of powders produced from pure Ni and Ni-plated Fe wires. It was found that with increasing charging voltage, the mean particle size of Ni powders is reduced from 40.11 ± 0.23 to 25.63 ± 0.07 nm, which is attributed to a change in the extent of super heating with particle size. Nanosized powders of Ni-Fe alloy with a mean particle size between 25.91 ± 0.24 and 26.30 ± 0.26 nm were also successfully fabricated and found to consist of particles with a γ-(Ni/Fe) core and FeO shell. The reliability for the optimization of processing parameters to control particle sizes is also evaluated.

Cl K-edge XANES spectra of atmospheric rust on Fe, Fe-Cr and Fe-Ni alloys exposed to saline environment

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2004-01-01

Cl K-edge XANES measurements of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys in chloride pollution have been performed using synchrotron radiation in order to clarify roles of anticorrosive alloying elements and of Cl in the corrosion resistance of weathering steel. The spectra of binary alloys show a shoulder structure near the absorption edge. The intensity of the shoulder peak depends on the kind and amount of the alloying element, whereas the energy position is invariant. This indicates that Cl is not combined directly with alloying elements in the rust. (author)

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Surface crack nucleation and propagation in electrodeposited nanocrystalline Ni-P alloy during high cycle fatigue

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Shigeaki; Kamata, Akiyuki [Department of Mechanical Engineering, Faculty of Engineering, Ashikaga Institute of Technology, 268-1 Omae, Ashikaga, Tochigi 326-8558 (Japan); Watanabe, Tadao, E-mail: skoba@ashitech.ac.j [Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang, 110004 (China)

2010-07-01

The morphology of specimen surface after fatigue fracture was evaluated in connection with grain orientation distribution and grain boundary microstructure to reveal a mechanism of fatigue fracture in nanocrystalline materials. The electrodeposited and sharply {l_brace}001{r_brace} textured Ni -2.0 mass% P alloy with the average grain size of ca. 45 nm and high fractions of low-angle and {Sigma}3 boundaries showed 2 times higher fatigue limit than electrodeposited microcrystalline Ni polycrystal. The surface features of fatigued specimen were classified into two different types of morphologies characterized as brittle fracture at the central area and as ductile fracture at the surrounding area.

The effect of alloying elements on the vacancy defect evolution in electron-irradiated austenitic Fe-Ni alloys studied by positron annihilation

Energy Technology Data Exchange (ETDEWEB)

Druzhkov, A.P. [Institute of Metal Physics, Ural Branch RAS, 18 Kovalevskaya St., 620041 Ekaterinburg (Russian Federation)], E-mail: druzhkov@imp.uran.ru; Perminov, D.A.; Davletshin, A.E. [Institute of Metal Physics, Ural Branch RAS, 18 Kovalevskaya St., 620041 Ekaterinburg (Russian Federation)

2009-01-31

The vacancy defect evolution under electron irradiation in austenitic Fe-34.2 wt% Ni alloys containing oversized (aluminum) and undersized (silicon) alloying elements was investigated by positron annihilation spectroscopy at temperatures between 300 and 573 K. It is found that the accumulation of vacancy defects is considerably suppressed in the silicon-doped alloy. This effect is observed at all the irradiation temperatures. The obtained results provide evidence that the silicon-doped alloy forms stable low-mobility clusters involving several Si and interstitial atoms, which are centers of the enhanced recombination of migrating vacancies. The clusters of Si-interstitial atoms also modify the annealing of vacancy defects in the Fe-Ni-Si alloy. The interaction between small vacancy agglomerates and solute Al atoms is observed in the Fe-Ni-Al alloy under irradiation at 300-423 K.

Influence of Ti addition and sintering method on microstructure and mechanical behavior of a medium-entropy Al0.6CoNiFe alloy

International Nuclear Information System (INIS)

Fu, Zhiqiang; Chen, Weiping; Chen, Zhen; Wen, Haiming; Lavernia, Enrique J.

2014-01-01

The influence of Ti addition and sintering method on the microstructure and mechanical behavior of a medium-entropy alloy, Al 0.6 CoNiFe alloy, was studied in detail. Alloying behavior, microstructure, phase evolution and mechanical properties of Al 0.6 CoNiFe and Ti 0.4 Al 0.6 CoNiFe alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by mechanical testing. During the mechanical alloying (MA) process, a supersaturated solid solution consisting of both BCC and FCC phases was formed in the Al 0.6 CoNiFe alloy. With Ti addition, the Ti 0.4 Al 0.6 CoNiFe alloy exhibited a supersaturated solid solution with a single FCC phase. Following hot pressing (HP), the HP sintered (HP’ed) Al 0.6 CoNiFe bulk alloy was composed of a major BCC phase and a minor FCC phase. The HP’ed Ti 0.4 Al 0.6 CoNiFe alloy exhibited a FCC phase, two BCC phases and a trace unidentified phase. Nanoscale twins were present in the HP’ed Ti 0.4 Al 0.6 CoNiFe alloy, where deformation twins were observed in the FCC phase. Our results suggest that the addition of Ti facilitated the formation of nanoscale twins. The compressive strength and Vickers hardness of HP’ed Ti 0.4 Al 0.6 CoNiFe alloy were slightly lower than the corresponding values of the HP’ed Al 0.6 CoNiFe alloy. In contrast with HP’ed Al 0.6 CoNiFe alloy, spark plasma sintered (SPS’ed) Al 0.6 CoNiFe alloy exhibited a major FCC phase and a minor BCC phase. Moreover, the SPS’ed Al 0.6 CoNiFe alloy exhibited a lower compressive strength and Vickers hardness, but singificantly higher plasticity, as compared to those of the HP’ed counterpart material

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.

Microemulsion synthesis and magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Beygi, H., E-mail: hossein.beygi@stu-mail.um.ac.ir; Babakhani, A.

2017-01-01

This paper investigates synthesis of Fe{sub x}Ni{sub (1−x)} bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. Fe{sub x}Ni{sub (1−x)} nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl{sub 2}·6H{sub 2}O to FeCl{sub 2}·4H{sub 2}O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties. - Highlights: • Fe{sub x}Ni{sub (1−x)} alloy NPs synthesized by simultaneous metal ions reduction in microemulsion. • Finer NPs synthesized at lower amount of oil and water and higher amount of CTAB. • Chain-like Fe{sub x}Ni{sub (1−x)} NPs are ferromagnetic; higher aspect ratio, more magnetization. • Spherical Fe{sub x}Ni({sub 1−x)} NPs with smaller size (7 nm) are superparamagnetic. • Spherical Fe{sub x}Ni{sub (1−x)} nanoparticles with higher x had increased magnetic properties.

Electrochemical passivation behaviour of nanocrystalline Fe 80 Si ...

Indian Academy of Sciences (India)

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

Effects of environment on the release of Ni, Cr, Fe, and Co from new and recast Ni-Cr alloy.

Science.gov (United States)

Oyar, Perihan; Can, Gülşen; Atakol, Orhan

2014-07-01

The addition of previously cast alloy to new alloy for economic reasons may increase the release of elements. The purpose of this study was to analyze the effects of the immersion period, immersion media, and addition of previously cast alloy to new alloy on the release of elements. Disk-shaped specimens were prepared from a Ni-Cr alloy (Ni: 61 wt%, Cr: 26 wt%, Mo: 11 wt%, Si: 1.5 wt%, Fe, Ce, Al, and Co alloy (group N) and 50% new/50% recast alloy (group R). After the immersion of the specimens in both NaCl (pH 4) and artificial saliva (pH 6.7) for 3, 7, 14, 30, and 60 days, the release of ions was determined by using atomic absorption spectrometry. Data were analyzed with a 3-way ANOVA (α=.001). The release of Ni was significantly affected by the immersion period, of Ni and Cr by the alloy and media (Palloy (Palloy in artificial saliva was 109.71 for Ni, 6.49 for Cr, 223.22 for Fe, and 29.90 μg/L for Co. The release of Co in NaCl was below the detection limit in both groups. The release of Ni in NaCl and artificial saliva increased with the length of the immersion period in both groups. The release of Cr and Fe was higher in artificial saliva than in NaCl in group R, regardless of the immersion period. The release of Co in NaCl was below the detection limit in both groups. Copyright © 2014 The Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Kinetic study of the annealing reactions in Cu-Ni-Fe alloys; Estudio cinetico de las reacciones de recocido en aleaciones de Cu-Ni-Fe

Energy Technology Data Exchange (ETDEWEB)

Donoso, E.

2014-07-01

The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC) and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi{sub 3} phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi{sub 3} phase. (Author)

Austenitic alloys Fe-Ni-Cr dominating

International Nuclear Information System (INIS)

Gibson, R.C.; Korenko, M.K.

1980-01-01

Austenitic alloy essentially comprising 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminium, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06% zirconium, the balance being iron. The characteristic of this alloy is a conventional elasticity limit to within 2% of at least 450 MPa, with a maximum tensile strength of at least 500 MPa at a test temperature of 650 0 C after immersion annealing at 1038 0 C and 30% hardening. To this effect the invention concerns Ni-Cr-Fe high temperature alloys possessing excellent mechanical strength characteristics, that can be obtained with lower levels of nickel and chromium than those used in alloys of this kind in the present state of the technique, a higher amount of niobium than in the previous alloys and with the addition of 0.5 to 1.5% vanadium [fr

Features of Pd-Ni-Fe solder system for vacuum brazing of low alloy steels

International Nuclear Information System (INIS)

Radzievskij, V.N.; Kurochko, R.S.; Lotsmanov, S.N.; Rymar', V.I.

1975-01-01

The brazing solder of the Pd-Ni-Fe alloyed with copper and lithium, in order to decrease the melting point and provide for a better spreading, when soldered in vacuum ensures a uniform strength of soldered joints with the base metal of low-alloyed steels of 34KHNIM-type. The properties of low-alloyed steel joints brazed with the Pd-Ni-Fe-system solder little depend on the changes in the soldering parameters. The soldered joint keeps a homogeneous structure after all the stages of heat treatment (annealing, quenching and tempering)

Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

Science.gov (United States)

Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

2013-10-01

We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

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.

Physical and Mechanical Properties of LoVAR: A New Lightweight Particle-Reinforced Fe-36Ni Alloy

Science.gov (United States)

Stephenson, Timothy; Tricker, David; Tarrant, Andrew; Michel, Robert; Clune, Jason

2015-01-01

Fe-36Ni is an alloy of choice for low thermal expansion coefficient (CTE) for optical, instrument and electrical applications in particular where dimensional stability is critical. This paper outlines the development of a particle-reinforced Fe-36Ni alloy that offers reduced density and lower CTE compared to the matrix alloy. A summary of processing capability will be given relating the composition and microstructure to mechanical and physical properties.

Fe-based nanocrystalline powder cores with ultra-low core loss

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiangyue, E-mail: wangxiangyue1986@163.com [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Lu, Zhichao; Lu, Caowei; Li, Deren [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

2013-12-15

Melt-spun amorphous Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloy strip was crushed to make flake-shaped fine powders. The passivated powders by phosphoric acid were mixed with organic and inorganic binder, followed by cold compaction to form toroid-shaped bonded powder-metallurgical magnets. The powder cores were heat-treated to crystallize the amorphous structure and to control the nano-grain structure. Well-coated phosphate-oxide insulation layer on the powder surface decreased the the core loss with the insulation of each powder. FeCuNbSiB nanocrystalline alloy powder core prepared from the powder having phosphate-oxide layer exhibits a stable permeability up to high frequency range over 2 MHz. Especially, the core loss could be reduced remarkably. At the other hand, the softened inorganic binder in the annealing process could effectively improve the intensity of powder cores. - Highlights: • Fe-based nanocrystalline powder cores were prepared with low core loss. • Well-coated phosphate-oxide insulation layer on the powder surface decreased the core loss. • Fe-based nanocrystalline powder cores exhibited a stable permeability up to high frequency range over 2 MHz. • The softened inorganic binder in the annealing process could effectively improve the intensity of powder cores.

Fabrication of metallic alloy powder (Ni{sub 3}Fe) from Fe–77Ni scrap

Energy Technology Data Exchange (ETDEWEB)

Seo, Inseok [ES Materials Research Center, Research Institute of Industrial Science and Technology, Incheon 406-840 (Korea, Republic of); Shin, Shun-Myung [Extractive Metallurgy Department, Korea Institute of Geoscience and Mineral Resources, Deajeon 305-350 (Korea, Republic of); Ha, Sang-An [Department of Environmental Engineering, Silla University, Busan 46958 (Korea, Republic of); Wang, Jei-Pil, E-mail: jpwang@pknu.ac.kr [Department of Metallurgical Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of)

2016-06-15

The oxidation behavior of Fe–77Ni alloy scrap was investigated at an oxygen partial pressure of 0.2 atm and temperatures ranging from 400 °C to 900 °C. The corresponding oxidation rate increased with increasing temperature and obeyed the parabolic rate law, as evidenced by its linear proportionality to the temperature. In addition, surface morphologies, cross-sectional views, compositions, structural properties were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Diffusion through either the spinel structure or the NiO layer, which were both present in the alloy during oxidation at elevated temperatures, was deemed the rate-limiting step of the reaction. The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap was obtained using ball-milling and sieving processes. In fact, 15 h of milling yielded a recovery ratio of 97%. Using hydrogen gas, the oxide powder was successfully reduced to an alloy powder of Ni{sub 3}Fe and reduction rates of ∼97% were achieved after 3 h at 1000 °C. - Highlights: • The oxidation behavior of Fe–77Ni alloy scrap was investigated. • The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap. • Using hydrogen gas, the oxide powder was successfully reclaimed. • Reduction rates of ∼97% were achieved after 3 h at 1000 °C.

Study of self-diffusion of Fe in nanocrystalline FeNZr alloys using nuclear resonance reflectivity from isotopic multilayers

International Nuclear Information System (INIS)

Gupta, Ajay; Chakravarty, Sajoy; Gupta, Mukul; Horisberger, M.; Rueffer, Rudolf; Wille, Hans-Christian; Leupold, Olaf

2005-01-01

It is demonstrated that nuclear resonance reflectivity from isotopic multilayers can be used to do accurate measurements of self diffusion of iron in thin film samples. Diffusion lengths down to ∼ 1A 0 can be measured. The technique has been used to measure the self-diffusion of iron in FeNZr nanocrystalline alloys. The activation energy for self-diffusion of iron is found to be 0.8% ± 0.01 eV while the pre-exponential factor is 3.54 x 10 13 m 2 /s. (author)

Structural investigations on nanocrystalline Ni-W alloy films by transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Klimenkov, M. [Institut fuer Materialforschung, Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany); Haseeb, A.S.M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Bade, K., E-mail: klaus.bade@imt.fzk.d [Institut fuer Mikrostrukturtechnik, Forschungszentrum Karlsruhe, 76021 Karlsruhe (Germany)

2009-10-30

Electrodeposited Ni-W alloys have been investigated in the as-deposited state by transmission electron microscopy in order to investigate the microstructural features in dependence of the tungsten content. Within the tungsten content range from 7 at.% up to 12 at.%, the microstructure is nanocrystalline characterized by a bimodal grain size distribution, consisting out of 20 to 200 nm sized grains and also larger grains with several 100 nm characteristic dimension. No clear trend in microstructure formation is visible with W content or deposition conditions in the investigated W content range. Only solid solution phase characteristics were observed. The lattice constant is 0.360 nm for 12 at.% W as derived from electron diffraction for the solid solution face centered cubic structure. Larger grains show twinning and stacking faults. Voids with diameter of a few nm were detected along with some multiple twinned particles, indicating high stress level during growth. About 2 at.% difference in the alloy composition from grain to grain was measured.

Nanocrystallization in amorphous Fe40Ni40(Si+B)19Mo1-2 ribbons

International Nuclear Information System (INIS)

Saiseng, S.; Winotai, P.; Nilpairuch, S.; Limsuwan, P.; Tang, I.M.

2004-01-01

Cut Fe 40 Ni 40 (Si+B) 19 Mo 1-2 ribbons were annealed for 2 h at various temperatures between 350 deg. C and 600 deg. C. XRD and Mossbauer effect spectroscopy (ME) measurements were then performed on all of the ribbons. The magnetic properties of several ribbons were measured using a vibrating sample magnetometer (VSM). A differential thermal analysis scan (over the range 20-800 deg. C) of the as-cast ribbon showed two phase transitions; the first at 454 deg. C and the second at 525 deg. C. Both the XRD and ME spectra of the as cast, the 350 deg. C and 400 deg. C annealed ribbons showed that they were amorphous. The ME spectra of the 450 deg. C, 475 deg. C and 500 deg. C annealed ribbons showed that these ribbons contained α-Fe, α-Fe(Si) and t-Fe 2 B nanocrystallites. For the ribbons annealed above 550 deg. C, crystallites of t-Fe 2 B, t-Fe 3 B, t-Fe 5 SiB 2 and FCC-FeNi appeared, with the α-Fe and α-Fe(Si) crystallites disappearing. The sextets of all of the Fe compounds appeared in the ME spectra of the 525 deg. C annealed ribbon. The VSM measurements supported the picture of a two-stage phase transitions; amorphous phase→a nanocrystalline phase (Fe-containing nanocrystallites in an amorphous matrix) at 454 deg. C and then a second transition, the nanocrystalline phase→a disordered alloy containing Fe-B and Fe-Ni crystallites at 525 deg. C

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

Science.gov (United States)

Hadef, Fatma

2016-12-01

The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe-Al-X systems, in order to improve mainly Fe-Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems.

Synthesis and Characterization of High-Entropy Alloy AlFeCoNiCuCr by Laser Cladding

Directory of Open Access Journals (Sweden)

Xiaoyang Ye

2011-01-01

Full Text Available High-entropy alloys have been recently found to have novel microstructures and unique properties. In this study, a novel AlFeCoNiCuCr high-entropy alloy was prepared by laser cladding. The microstructure, chemical composition, and constituent phases of the synthesized alloy were characterized by SEM, EDS, XRD, and TEM, respectively. High-temperature hardness was also evaluated. Experimental results demonstrate that the AlFeCoNiCuCr clad layer is composed of only BCC and FCC phases. The clad layers exhibit higher hardness at higher Al atomic content. The AlFeCoNiCuCr clad layer exhibits increased hardness at temperature between 400–700°C.

Preparation of nanocrystalline Ce{sub 1−x}Sm{sub x}(Fe,Co){sub 11}Ti by melt spinning and mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Wuest, H., E-mail: holger.wuest@de.bosch.com [Robert Bosch GmbH, Postfach 10 60 50, 70049 Stuttgart (Germany); Bommer, L., E-mail: lars.bommer@de.bosch.com [Robert Bosch GmbH, Postfach 10 60 50, 70049 Stuttgart (Germany); Huber, A.M., E-mail: arne.huber@de.bosch.com [Robert Bosch GmbH, Postfach 10 60 50, 70049 Stuttgart (Germany); Goll, D., E-mail: dagmar.goll@htw-aalen.de [Aalen University, Materials Research Institute, Beethovenstr. 1, 73430 Aalen (Germany); Weissgaerber, T., E-mail: thomas.weissgaerber@ifam-dd.fraunhofer.de [Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), Branch Lab Dresden, Winterbergstraße 28, 01277 Dresden (Germany); Kieback, B., E-mail: bernd.kieback@ifam-dd.fraunhofer.de [Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), Branch Lab Dresden, Winterbergstraße 28, 01277 Dresden (Germany); Technische Universität Dresden, Institute for Materials Science, Helmholtzstraße 7, 01069 Dresden (Germany)

2017-04-15

Permanent magnetic materials based on Ce(Fe, Co){sub 12−x}Ti{sub x} with the ThMn{sub 12} structure are promising candidates for replacing NdFeB magnets. Its intrinsic magnetic properties are not far below the values of Nd{sub 2}Fe{sub 14}B, 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 Ce{sub 1−x}Sm{sub x}Fe{sub 11−y}Co{sub y}Ti (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 H{sub c,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. - Highlights: • CeFe{sub 11}Ti nanocrystalline samples demonstrate values of H{sub c,J} up to 77 kA/m. • SmFe{sub 11}Ti nanocrystalline samples demonstrate values of H{sub c,J} up to 392 kA/m. • Dependence of H{sub c,J} on x in Ce{sub 1−x}Sm{sub x(}Fe, Co){sub 11}Ti obeys non-linear dependence. • Optimum annealing shifts to from 800 °C for CeFe{sub 11}Ti to 900 °C for SmFe{sub 11}Ti.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-15

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

Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

Science.gov (United States)

Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

2018-05-01

High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

Anti-corrosive and anti-microbial properties of nanocrystalline Ni-Ag coatings

Energy Technology Data Exchange (ETDEWEB)

Raghupathy, Y.; Natarajan, K.A.; Srivastava, Chandan, E-mail: csrivastava@materials.iisc.ernet.in

2016-04-15

Graphical abstract: - Highlights: • Electrodeposition yielded phase-segregated, nanocrystalline Ni-Ag coatings. • Ni-Ag alloys exhibited smaller Ni crystals compared to pure Ni. • Ultra fine Ni grains of size 12–14 nm favoured Ni-Ag solid solution. • Nanocrystalline Ag resisted bio-fouling by Sulphate Reducing bacteria. • Ni-Ag outperformed pure Ni in corrosion and bio-corrosion tests. - Abstract: Anti-corrosive and anti-bacterial properties of electrodeposited nanocrystalline Ni-Ag coatings are illustrated. Pure Ni, Ni-7 at.% Ag, & Ni-14 at.% Ag coatings were electrodeposited on Cu substrate. Coating consisted of Ni-rich and Ag-rich solid solution phases. With increase in the Ag content, the corrosion resistance of the Ni-Ag coating initially increased and then decreased. The initial increase was due to the Ni-Ag solid solution. The subsequent decrease was due to the increased galvanic coupling between the Ag-rich and Ni-rich phases. For all Ag contents, the corrosion resistance of the Ni-Ag coating was higher than the pure Ni coating. Exposure to Sulphate Reducing Bacteria (SRB) revealed that the extent of bio-fouling decreased with increase in the Ag content. After 2 month exposure to SRB, the Ni-Ag coatings demonstrated less loss in corrosion resistance (58% for Ni-7 at.% Ag and 20% for Ni-14 at.% Ag) when compared pure Ni coating (115%).

X-ray peak broadening analysis of Fe50Ni50 nanocrystalline alloys ...

Indian Academy of Sciences (India)

Administrator

for milling operation is the one in which a balance state is created between fracturing and ... In this work, Fe50Ni50 nanocrystals were prepared by high- energy ball milling ..... Addison–Wesley Publishing Company Inc). Djekoun A, Bouzabata ...

Cavitation erosion of Ti-Ni shape memory alloy deposited coatings and Fe base shape memory alloy solid

International Nuclear Information System (INIS)

Hattori, Shuji; Fujisawa, Seiji; Owa, Tomonobu

2007-01-01

In this study, cavitation erosion tests were carried out by using thermal spraying and deposition of Ti-Ni shape memory alloy for the surface coating. The results show the test speciment of Ti-Ni thermal spraying has many initial defects, so that the erosion resistance is very low. The erosion resistance of Ti-Ni deposit is about 5-10 times higher than that of SUS 304, thus erosion resistance of Ti-Ni deposit is better than that of Ti-Ni thermal spraying. The cavitation erosion tests were carried out by using Fe-Mn-Si with shape memory and gunmetal with low elastic modulus. The erosion resistance of Fe-Mn-Si shape memory alloy solid is about 9 times higher than that of SUS 304. The erosion resistance of gunmetal is almost the same as SUS 304, because the test specimen of gunmetal has many small defects on the original surface. (author)

The Microstructures and Electrical Resistivity of (Al, Cr, TiFeCoNiOx High-Entropy Alloy Oxide Thin Films

Directory of Open Access Journals (Sweden)

Chun-Huei Tsau

2015-01-01

Full Text Available The (Al, Cr, TiFeCoNi alloy thin films were deposited by PVD and using the equimolar targets with same compositions from the concept of high-entropy alloys. The thin films became metal oxide films after annealing at vacuum furnace for a period; and the resistivity of these thin films decreased sharply. After optimum annealing treatment, the lowest resistivity of the FeCoNiOx, CrFeCoNiOx, AlFeCoNiOx, and TiFeCoNiOx films was 22, 42, 18, and 35 μΩ-cm, respectively. This value is close to that of most of the metallic alloys. This phenomenon was caused by delaminating of the alloy oxide thin films because the oxidation was from the surfaces of the thin films. The low resistivity of these oxide films was contributed to the nonfully oxidized elements in the bottom layers and also vanishing of the defects during annealing.

A study on the electrodeposition of NiFe alloy thin films using chronocoulometry and electrochemical quartz crystal microgravimetry

CERN Document Server

Myung, N S

2001-01-01

Ni, Fe and NiFe alloy thin films were electrodeposited at a polycrystalline Au surface using a range of electrolytes and potentials. Coulometry and EQCM were used for real-time monitoring of electroplating efficiency of the Ni and Fe. The plating efficiency of NiFe alloy thin films was computed with the aid of ICP spectrometry. In general, plating efficiency increased to a steady value with deposition time. Plating efficiency of Fe was lower than that of Ni at -0.85 and -1.0 V but the efficiency approached to the similar plateau value to that of Ni at more negative potentials. The films with higher content of Fe showed different stripping behavior from the ones with higher content of Ni. Finally, compositional data and real-time plating efficiency are presented for films electrodeposited using a range of electrolytes and potentials.

Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2015-10-25

Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

Directory of Open Access Journals (Sweden)

Alvaro A. Rodriguez

2018-01-01

Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

Magnetic Mineralogy of Troilite-Inclusions and their Fe-Ni Host Alloys in IAB Iron Meteorites

Science.gov (United States)

Kontny, A. M.; Kramar, U.; Luecke, W.

2011-12-01

Iron-nickel meteorites often contain isolated, mostly rounded troilite nodules enclosed in a bulk of Fe-Ni alloy. As sulfur has a low solubility in metal, it is excluded from the crystallization of metal during cooling. Therefore troilite nodules are interpreted to be trapped droplets of residual sulfur-enriched melts. Microscopic examinations of the interface (mm-range) between troilite inclusions and Fe-Ni alloy yield clear mineralogical differences compared to the troilite inclusion. Such rims around troilite nodules seem to occur exclusively in Fe-Ni meteorites with slow cooling rates, and therefore might provide interesting clues on segregation, fractional crystallization and reequilibration processes between the Fe-Ni alloy and the sulfide phases. These interfaces however are also highly sensitive to terrestrial weathering. We present microscopic observations in combination with temperature-dependent magnetic susceptibility (k-T curves) in order to identify the magnetic mineralogy of the Morasko (Poland) and Coahuila (Mexico) meteorites, which both geochemically belong to the non-magmatic IAB or IIICD group. In the k-T curves both, rim and troilite nodule are characterized by Curie temperatures (TC) that can be related to magnetite, daubreelite (FeCr2O4), Fe-hydroxide and sometimes cohenite. Therefore the interface seems to be geochemically more similar to the troilite nodule than the Fe-Ni alloy. Optical microscopy in combination with the ferrofluid method revealed complex microstructures of intergrown magnetic (TC = 780-785 °C) and non-magnetic phases in the Fe-Ni alloy, which differ in their Ni-concentration. Towards the rim of the troilite nodule the concentration of magnetic cohenite ((Fe,Ni)3C) and especially schreibersite ((Fe,Ni)3P), which are both intergrown with the metal, increases. Cohenite is easily identified microscopically by a very characteristic stripe-like magnetic domain structure and it shows a TC at about 200 °C. The carbon-rich, dark

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-08-01

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

Development of Fe-Ni and Ni-base alloys without {gamma}' strengthening for advanced USC boilers

Energy Technology Data Exchange (ETDEWEB)

Semba, Hiroyuki; Okada, Hirokazu; Igarashi, Masaaki; Hirata, Hiroyuki [Sumitomo Metal Industries, Ltd., Amagasaki, Hyogo (Japan). Corporate Research and Development Labs.; Yoshizawa, Mitsuru [Sumitomo Metal Industries Ltd., Amagasaki, Hyogo (Japan). Steel Tube Works

2010-07-01

An Fe-Ni base alloy, 23Cr-45Ni-7W alloy (HR6W) strengthened by Fe{sub 2}W-type Laves phase is one of the candidate materials for the piping application. Stability of long-term creep strength and superior creep rupture ductility have been proved by creep rupture tests up to 60000h at 650-800 C. The 10{sup 5}h extrapolated creep rupture strength at 700 C approved by TUV is 85MPa. It has also been confirmed that HR6W has excellent microstructural stability by means of microstructural observations after term creep tests and aging. A thick wall pipe of HR6W, which is 457mm in diameter and 60mm in wall thickness, has successfully been manufactured by the Erhart Push Bench press method. This trial production has shown that hot workability of HR6W is sufficient for manufacturing thick wall piping for A-USC plants. A new Ni-base alloy, 30r-50Ni-4W alloy (HR35) has been proposed for piping application having comparable creep rupture strength with Alloy 617 at 700 C. This alloy is not strengthened by {gamma}' phase but mainly by {alpha}-Cr phase. The 10{sup 5}h extrapolated creep rupture strength is estimated to be 114 MPa at 700 C. It has sufficient creep rupture ductility compared with Alloy 617. A thick wall pipe of HR35 has also been successfully manufactured. Capability of HR6W and HR35 as structural materials for A-USC plants has been examined in detail. They have high resistance to relaxation cracking after welding. It is, therefore, concluded that both the alloys are promising candidates especially for thick wall piping in A-USC power plants. (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

High-temperature oxidation of advanced FeCrNi alloy in steam environments

Science.gov (United States)

Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Rumaiz, Abdul K.; Bai, Jianming; Ghose, Sanjit; Rebak, Raul B.; Ecker, Lynne E.

2017-12-01

Alloys of iron-chromium-nickel are being explored as alternative cladding materials to improve safety margins under severe accident conditions. Our research focuses on non-destructively investigating the oxidation behavior of the FeCrNi alloy "Alloy 33" using synchrotron-based methods. The evolution and structure of oxide layer formed in steam environments were characterized using X-ray diffraction, hard X-ray photoelectron spectroscopy, X-ray fluorescence methods and scanning electron microscopy. Our results demonstrate that a compact and continuous oxide scale was formed consisting of two layers, chromium oxide and spinel phase (FeCr2O4) oxides, wherein the concentration of the FeCr2O4 phase decreased from the surface to the bulk-oxide interface.

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.

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.

Pulse electrodeposition of Fe-Ni-Cr alloys

International Nuclear Information System (INIS)

Adelkhani, H.

2000-01-01

Pulse Electroplating is a relativity new technique in electrodeposition of pure metals and alloys which has resulted in a number of improvement over the traditional direct current method. Among these are a better composition control, lower porosity, reduction of internal stresses and hydrogen content as well as other impurities. In this work Pulse plating of Fe-Ni-Cr alloys has been investigated by using a series of planned experiments. A domain of Pulse parameters, such a pulse frequency, pulse duration, current density and batch condition such as Ph, temperature and has been defined where the coating quality is optimal. The result obtained were Compared with those of D C electroplating and finally a number of recommendations are made for future works towards a semi-industrial process

Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

Science.gov (United States)

Muralidharan, Govindarajan

2017-09-05

An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

Nanocrystalline FeSiBNbCu alloys: Differences between mechanical and thermal crystallization process in amorphous precursors

International Nuclear Information System (INIS)

Lopez, M.; Marin, P.; Agudo, P.; Carabias, I.; Venta, J. de la; Hernando, A.

2007-01-01

Nanocrystalline magnetic particles obtained by high energy ball milling of FeSiBNbCu alloy were prepared from rapidly quenched ribbons as a starting material. Structural characterization was made by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and Moessbauer spectroscopy. The structural changes observed in this amorphous material suggest that nanocrystallization process takes place in a different way from the one induced by thermal treatments. Our different studies reveals that after short grinding times (up to 40 h) the material is composed by a two phase system of very fine nanocrystals embedded in a residual amorphous phase, while for largest periods of milling (from 140 h) the sample consists of a very fine nanocrystalline phase with a large fraction of grain boundary

Structural, microstructural and Mössbauer studies of nanocrystalline Fe100-x Alx powders elaborated by mechanical alloying

Directory of Open Access Journals (Sweden)

Akkouche K.

2012-06-01

Full Text Available Nanocrystalline Fe100-xAlx powders (x= 25, 30, 34 and 40 at % were prepared by the mechanical alloying process using a vario-planetary high-energy ball mill for a milling time of 35 h. The formation and physical properties of the alloys were investigated as a function of Al content by means of X-ray diffraction, scanning electron microscopy (SEM, energy dispersive X-ray and Mössbauer spectroscopy. For all Fe100-xAlx samples, the complete formation of bcc phase was observed after 35 h of milling. As Al content increases, the lattice parameter increases, whereas the grain size decreases from 106 to 12 nm. The powder particle morphology for different compositions was observed by SEM. The Mössbauer spectra were adjusted with a singlet line and a sextet containing two components. The singlet was attributed to the formation of paramagnetic A2 disordered structure rich with Al. About the sextet, the first component indicated the formation of Fe clusters/ Fe-rich phases; however, the second component is characteristic of disordered ferromagnetic phase.

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

Energy Technology Data Exchange (ETDEWEB)

Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

2017-02-28

Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

New amorphous and nanocrystalline alloys based on the Ni-Si-B system

Energy Technology Data Exchange (ETDEWEB)

Battezzati, L.; Rizzi, P.; Romussi, S. [Turin Univ. (Italy). Dipt. di Chimica

1998-08-01

The glass formation and crystallization of a Ni{sub 36}Fe{sub 32}Ta{sub 7}Si{sub 8}B{sub 17} alloy is reported. In its equilibrium state it has a complex constitution made of at least four phases. It starts melting at 1227 K and displays a liquidus at 1460 K, but it shows a tendency to undercool even on cooling at 10 K/min in a HTDSC cell. Amorphous ribbons were produced by melt spinning. In DSC experiments the crystallization of the amorphous alloy occurs with a primary reaction giving a peak skewed on the high temperature side with onset at 836 K using an heating rate of 40 K/min. XRD analysis and TEM observations demonstrate that crystals with size below 10 nm and lattice parameter close to that of Ni are formed during this transformation. The mechanism of crystallization is very sensitive to changes in composition. In fact, nanocrystals are not found in alloys easily amorphized as the present one but containing a different ratio of metallic elements. (orig.) 16 refs.

Peculiarities of phase transformation in Ni3Fe powder alloy

International Nuclear Information System (INIS)

Nuzhdin, A.A.

1990-01-01

Ordering process in sintered powder alloy Ni 3 Fe by normal and high temperatures was studied. Thermal stresses connected with porosity level of material effect on transformation peculiarities. The changes of electric conductivity, thermal expansion coefficient, bulk modulus during transformation were studied. The analysis of this changes was made

Reactive Stresses in Ni49Fe18Ga27Co6 Shape-Memory-Alloy Single Crystals

Science.gov (United States)

Averkin, A. I.; Krymov, V. M.; Guzilova, L. I.; Timashov, R. B.; Soldatov, A. V.; Nikolaev, V. I.

2018-03-01

The reactive stresses induced in Ni49Fe18Ga27Co6-alloy single crystals during martensitic transformations with a limited possibility of shape-memory-strain recovery have been experimentally studied. The data on these crystals are compared with the results obtained previously for Cu-Al-Ni, Ni-Ti, and Ni‒Fe-Ga crystals. The potential of application of the Ni49Fe18Ga27Co6 single crystals in designing drives and power motors is demonstrated.

Fluorescence x-ray absorption fine structure studies of Fe-Ni-S and Fe-Ni-Si melts to 1600 K

Science.gov (United States)

Manghnani, M. H.; Hong, X.; Balogh, J.; Amulele, G.; Sekar, M.; Newville, M.

2008-04-01

We report NiK -edge fluorescence x-ray absorption fine structure spectra (XAFS) for Fe0.75Ni0.05S0.20 and Fe0.75Ni0.05Si0.20 ternary alloys from room temperature up to 1600 K. A high-temperature furnace designed for these studies incorporates two x-ray transparent windows and enables both a vertical orientation of the molten sample and a wide opening angle, so that XAFS can be measured in the fluorescence mode with a detector at 90° with respect to the incident x-ray beam. An analysis of the Ni XAFS data for these two alloys indicates different local structural environments for Ni in Fe0.75Ni0.05S0.20 and Fe0.75Ni0.05Si0.20 melts, with more Ni-Si coordination than Ni-S coordination persisting from room temperature through melting. These results suggest that light elements such as S and Si may impact the structural and chemical properties of Fe-Ni alloys with a composition similar to the earth’s core.

Synthesis and Characterization of Nanocrystalline Ni50Al50-xMox (X=0-5 Intermetallic Compound During Mechanical Alloying Process

Directory of Open Access Journals (Sweden)

A. Khajesarvi

2015-07-01

Full Text Available In the present study, nanocrystalline Ni50Al50-xMox (X = 0, 0.5, 1, 2.5, 5 intermetallic compound was produced through mechanical alloying of nickel, aluminum, and molybdenum powders. AlNi compounds with good and attractive properties such as high melting point, high strength to weight ratio and high corrosion resistance especially at high temperatures have attracted the attention of many researchers. Powders produced from milling were analyzed using scanning electron microscopy (SEM and X-ray diffractometry (XRD. The results showed that intermetallic compound of NiAl formed at different stage of milling operation. It was concluded that at first disordered solid solution of (Ni,Al was formed then it converted into ordered intermetallic compound of NiAl. With increasing the atomic percent of molybdenum, average grain size decreased from 3 to 0.5 μm. Parameter lattice and lattice strain increased with increasing the atomic percent of molybdenum, while the crystal structure became finer up to 10 nm. Also, maximum microhardness was obtained for NiAl49Mo1 alloy.

High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

International Nuclear Information System (INIS)

Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

2008-01-01

We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

Industrialization of nanocrystalline Fe–Si–B–P–Cu alloys for high magnetic flux density cores

International Nuclear Information System (INIS)

Takenaka, Kana; Setyawan, Albertus D.; Sharma, Parmanand; Nishiyama, Nobuyuki; Makino, Akihiro

2016-01-01

Nanocrystalline Fe–Si–B–P–Cu alloys exhibit high saturation magnetic flux density (B s ) and extremely low magnetic core loss (W), simultaneously. Low amorphous-forming ability of these alloys hinders their application potential in power transformers and motors. Here we report a solution to this problem. Minor addition of C is found to be effective in increasing the amorphous-forming ability of Fe–Si–B–P–Cu alloys. It allows fabrication of 120 mm wide ribbons (which was limited to less than 40 mm) without noticeable degradation in magnetic properties. The nanocrystalline (Fe 85.7 Si 0.5 B 9.5 P 3.5 Cu 0.8 ) 99 C 1 ribbons exhibit low coercivity (H c )~4.5 A/m, high B s ~1.83 T and low W~0.27 W/kg (@ 1.5 T and 50 Hz). Success in fabrication of long (60–100 m) and wide (~120 mm) ribbons, which are made up of low cost elements is promising for mass production of energy efficient high power transformers and motors - Highlights: • Minor addition of C in FeSiBPCu alloy increases amorphous-forming ability. • The FeSiBPCuC alloy exhibits B s close to Si-steel and Core loss lower than it. • Excellent soft magnetic properties were obtained for 120 mm wide ribbons. • Nanocrystalline FeSiBPCuC alloy can be produced at industrial scale with low cost. • The alloy is suitable for making low energy loss power transformers and motors.

Soft magnetic properties of hybrid ferromagnetic films with CoFe, NiFe, and NiFeCuMo layers

Energy Technology Data Exchange (ETDEWEB)

Choi, Jong-Gu [Eastern-western Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Hwang, Do-Guwn [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Rhee, Jang-Roh [Dept. of Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Lee, Sang-Suk, E-mail: sslee@sangji.ac.kr [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of)

2011-09-30

Two-layered ferromagnetic alloy films (NiFe and CoFe) with intermediate NiFeCuMo soft magnetic layers of different thicknesses were investigated to understand the relationship between coercivity and magnetization process by taking into account the strength of hard-axis saturation field. The thickness dependence of H{sub EC} (easy-axis coercivity), H{sub HS} (hard-axis saturation field), and {chi} (susceptibility) of the NiFeCuMo thin films in glass/Ta(5 nm)/[CoFe or NiFe(5 nm-t/2)]/NiFeCuMo(t = 0, 4, 6, 8, 10 nm)/[CoFe or NiFe(5 nm-t/2)]/Ta(5 nm) films prepared using the ion beam deposition method was determined. The magnetic properties (H{sub EC}, H{sub HS}, and {chi}) of the ferromagnetic CoFe, NiFe three-layers with an intermediate NiFeCuMo super-soft magnetic layer were strongly dependent on the thickness of the NiFeCuMo layer.

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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-01

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

Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

International Nuclear Information System (INIS)

Qiu, X.W.; Zhang, Y.P.; Liu, C.G.

2014-01-01

Highlights: • Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. • Al 2 CrFeNiCoCuTi x coatings show excellent corrosion resistance and wear resistance. • Al 2 CrFeNiCoCuTi x coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials

Magnetic characterization of nanocrystalline Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) alloys during milling and subsequent annealing

Energy Technology Data Exchange (ETDEWEB)

Rastabi, Reza Amini; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid; Sodaee, Tahmineh

2016-10-15

Magnetic characterization of nanocrystalline Fe–Cr–Co alloys during milling and annealing process was the goal of this study. To formation of Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) solid solution, different powder mixtures of Fe, Cr and Co elements were mechanically milled in a planetary ball mill. The annealing process was done in as-milled samples at different temperature in the range of 500–640 °C for 2 h. The produced samples were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. Performed mechanical alloying in different powder mixtures lead to the formation of Fe–Cr–Co α-phase solid solution with average crystallite sizes of about 10 nm. The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The coercivity of produced alloys after annealing process decreased and reached to about 40–150 Oe. The highest value of coercivity in as-milled and annealed samples was achieved in alloys with higher Cr contents. - Highlights: • Hc and Ms of produced alloys obtained in the range of 110–200 Oe and 150–220 emu/g. • The highest value of Hc in milled and annealed samples was achieved in Fe{sub 45}Cr{sub 35}Co{sub 20}. • Hc of produced alloys after spinodal decomposition decreased to about 40–150 Oe. • The effect of crystalline defects and residual strain on magnetic fields pinning in milled samples is higher than spinodal decomposition in annealed samples. • The highest value of Hc in as-milled and annealed samples was achieved in Fe{sub 45}Cr{sub 35}Co{sub 20}. The coercivity of produced alloys after annealing process decreased and reach to about 40–150 Oe. • The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu

FeNi{sub 3} alloy nanocrystals grown on graphene: Controllable synthesis, in-depth characterization and enhanced electromagnetic performance

Energy Technology Data Exchange (ETDEWEB)

Ma, Teng; Yuan, Mengwei [Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University, Beijing 100875 (China); Islam, Saiful M. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Li, Huifeng [Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University, Beijing 100875 (China); Ma, Shulan, E-mail: mashulan@bnu.edu.cn [Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University, Beijing 100875 (China); Sun, Genban, E-mail: gbsun@bnu.edu.cn [Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University, Beijing 100875 (China); Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Xiaojing [Beijing Key Laboratory of Energy Conversion and Storage Materials and College of Chemistry, Beijing Normal University, Beijing 100875 (China)

2016-09-05

FeNi{sub 3} nanocrystals as an ideal candidate for EM-wave-absorption material have a great advantage due to their excellent magnetic properties. However, its large permittivity and poor chemical stability confine its application. A strategy to improve electromagnetic performance of FeNi{sub 3}via phase-controlled synthesis of FeNi{sub 3} nanostructures grown on graphene networks has been employed in this work. The phases, structures, sizes and morphologies of FeNi{sub 3} nanocomposites were in-depth characterized by using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), and Raman spectroscopy. The results of electromagnetic performance tests for the as-synthesized FeNi{sub 3} nanocomposites showed excellent microwave absorbability in comparison with the corresponding FeNi{sub 3} nanocrystals, especially in the low (2–6 GHz) and middle (6–12 GHz) frequencies. The one-pot method we utilized is simple and effective, and because of its versatility, it may be extended to prepare some magnetic metal or alloy materials via this route. - Highlights: • Monodispersed FeNi{sub 3} alloy nanocrystals have been successfully assembled on 2D graphene via a one-pot strategy. • The process ensures different crystal phase and controlled morphology and size in the monodispersed particles. • The nanocomposites exhibit excellent microwave absorbability, which is stronger than the corresponding alloy monomer.

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

Mechanism of swelling suppression in phosphorous-modified Fe-Ni-Cr alloys

International Nuclear Information System (INIS)

Lee, E.H.; Mansur, L.K.

1986-01-01

Five simple alloys were ion irradiated at 948 0 K in an experiment designed to investigate the mechanism of swelling suppression associated with phosphorous additions. One of the alloys was the simple ternary Fe-15Ni-13Cr, another had 0.05% P added and the other three had further additions of the phosphide precipitate-forming elements Ti and/or Si. Ion irradiations were carried out with heavy ions only (Ni or Fe) or with heavy ions followed by dual heavy ions and helium. The ternary with and without P swelled readily early in dose with or without helium. The other three alloys only showed swelling in the presence of helium and exhibited a long delay in dose prior to the onset of swelling. These displayed fine distributions of Fe 2 P type phosphide precipitates enhanced by irradiation. The phosphide particles gave rise to very high concentrations of stable helium filled cavities at the precipitate matrix interfaces. The results were analyzed in terms of the theory of cavity swelling. The accumulation of the critical number of gas atoms in an individual cavity is required in the theory for point defect driven swelling to begin. It is concluded that the primary mechanism leading to swelling suppression is therefore the dilution of injected helium over a very large number of cavities. It is suggested that this mechanism may offer a key for alloy design for swelling resistance in high helium environments

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)

Stacking fault energy measurements in solid solution strengthened Ni-Cr-Fe alloys using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Unfried-Silgado, Jimy [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Universidade Estadual de Campinas UNICAMP, Faculdade de Engenharia Mecanica FEM, Campinas (Brazil); Universidad Autonoma del Caribe, Grupo IMTEF, Ingenieria Mecanica, Barranquilla (Colombia); Wu, Leonardo [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Furlan Ferreira, Fabio [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (CCNH), Sao Paulo (Brazil); Mario Garzon, Carlos [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Ramirez, Antonio J, E-mail: antonio.ramirez@lnnano.org.br [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil)

2012-12-15

The stacking fault energy (SFE) in a set of experimental Ni-Cr-Fe alloys was determined using line profile analysis on synchrotron X-ray diffraction measurements. The methodology used here is supported by the Warren-Averbach calculations and the relationships among the stacking fault probability ({alpha}) and the mean-square microstrain (<{epsilon}{sup 2}{sub L}>). These parameters were obtained experimentally from cold-worked and annealed specimens extracted from the set of studied Ni-alloys. The obtained results show that the SFE in these alloys is strongly influenced by the kind and quantity of addition elements. Different effects due to the action of carbide-forming elements and the solid solution hardening elements on the SFE are discussed here. The simultaneous addition of Nb, Hf, and, Mo, in the studied Ni-Cr-Fe alloys have generated the stronger decreasing of the SFE. The relationships between SFE and the contributions on electronic structure from each element of additions were established.

On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

Directory of Open Access Journals (Sweden)

Anna M. Manzoni

2016-03-01

Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

Properties of ternary NiFeW alloy coating by jet electrodeposition

Indian Academy of Sciences (India)

In this paper, ternary NiFeW alloy coatings were prepared by jet electrodeposition, and the effects of lord salt concentration, jet speed, current density and temperature on the properties of the coatings, including the composition, microhardness, surface morphology, structure and corrosion resistance, were investigated.

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

Microstructure, Texture, and Mechanical Behavior of As-cast Ni-Fe-W Matrix Alloy

Science.gov (United States)

Rao, A. Sambasiva; Manda, Premkumar; Mohan, M. K.; Nandy, T. K.; Singh, A. K.

2018-04-01

This article describes the tensile properties, flow, and work-hardening behavior of an experimental alloy 53Ni-29Fe-18W in as-cast condition. The microstructure of the alloy 53Ni-29Fe-18W displays single phase (fcc) in as-cast condition along with typical dendritic features. The bulk texture of the as-cast alloy reveals the triclinic sample symmetry and characteristic nature of coarse-grained materials. The alloy exhibits maximum strength ( σ YS and σ UTS) values along the transverse direction. The elongation values are maximum and minimum along the transverse and longitudinal directions, respectively. Tensile fracture surfaces of both the longitudinal and transverse samples display complete ductile fracture features. Two types of slip lines, namely, planar and intersecting, are observed in deformed specimens and the density of slip lines increases with increasing the amount of deformation. The alloy displays moderate in-plane anisotropy ( A IP) and reasonably low anisotropic index ( δ) values, respectively. The instantaneous or work-hardening rate curves portray three typical stages (I through III) along both the longitudinal and transverse directions. The alloy exhibits dislocation-controlled strain hardening during tensile testing, and slip is the predominant deformation mechanism.

The thermodynamic stability induced by solute co-segregation in nanocrystalline ternary alloys

Energy Technology Data Exchange (ETDEWEB)

Liang, Tao; Chen, Zheng; Zhang, Jinyong; Zhang, Ping [China Univ. of Mining and Technology, Xuzhou (China). School of Mateial Science and Engineering; Yang, Xiaoqin [China Univ. of Mining and Technology, Xuzhou (China). School of Chemical Engineering and Technology

2017-06-15

The grain growth and thermodynamic stability induced by solute co-segregation in ternary alloys are presented. Grain growth behavior of the single-phase supersaturated grains prepared in Ni-Fe-Pb alloy melt at different undercoolings was investigated by performing isothermal annealings at T = 400 C-800 C. Combining the multicomponent Gibbs adsorption equation and Guttmann's grain boundary segregation model, an empirical relation for isothermal grain growth was derived. By application of the model to grain growth in Ni-Fe-Pb, Fe-Cr-Zr and Fe-Ni-Zr alloys, it was predicted that driving grain boundary energy to zero is possible in alloys due to the co-segregation induced by the interactive effect between the solutes Fe/Pb, Zr/Ni and Zr/Cr. A non-linear relationship rather than a simple linear relation between 1/D* (D* the metastable equilibrium grain size) and ln(T) was predicted due to the interactive effect.

A CEMS study of surface oxidation of Fe-Ni alloys

International Nuclear Information System (INIS)

Cruz, B.; Tabares, J.A.; Bohorquez, A.; Perez Alcazar, G.A.

1997-01-01

A study by conversion electron Moessbauer spectroscopy (CEMS) carried out by using a parallel plate avalanche counter with samples of Fe-Ni alloys (50 and 65 at.% Fe) is reported. Each sample was analyzed without oxidation and after heating it under an oxygen atmosphere at 200 C. All CEMS measurements were carried out at room temperature. In both samples (50 and 65 at.% Fe), without oxidation and after oxidation, the Moessbauer spectra showed a six line magnetic spectrum according to their ferromagnetic character, with a broad hyperfine field distribution (HFD), according to the disordered character of the alloys. The obtained mean hyperfine field (MHF) for the sample 50 at.% Fe was 30.9 T, meanwhile for the invar composition (65 at.% Fe) was 25.5 T, which is close to values previously reported by transmission Moessbauer spectroscopy (TMS). Results from the treated samples (with oxidation at 200 C) showed a difference in the surface composition as a result of this process. In the 50 at.% Fe sample, additionally appeared a double that could be assigned to an oxihydroxide of Fe 3+ . Otherwise, the 65 at.% Fe sample (invar) presented ferromagnetic oxides (α-Fe 2 O 3 and Fe 3 O 4 ) with a large relative area (82.5%). (orig.)

Vacancies supersaturation induced by fast neutron irradiation in FeNi alloys

International Nuclear Information System (INIS)

Lucki, G.; Chambron, W.; Watanabe, S.; Verdone, J.

1975-01-01

The void formation in metals and alloys during irradiation with high-energy particles is a problem of interest in physics and of paramount importance in nuclear technology. Voids are formed as a consequence of vacancy supersaturation and result in swelling as well as in changes of mechanical, electrical and magnetic properties of materials used in power reactors. Isothermal annealings were performed between 400 and 500 0 C with and without fast-neutron (1 MeV) irradiation. Pure Fe--Ni (50--50 at. percent) was irradiated in the Melousine reactor in Grenoble, and Fe--Ni(Mo) (50--50 at. percent + 50 ppM), in the IEAR-1 reactor at the Instituto de Energia Atomica in Sao Paulo. The toroidal-shaped specimens were fabricated from Johnson Mathey zone-refined ingots, and were initially annealed at 800 0 C during 1 h in hydrogen atmosphere and then slowly cooled (4 h) inside the furnace. Magnetic After Effect measurements (MAE) permitted the evaluation of activation energies during fast-neutron irradiation (1.54 eV) and without irradiation (3.14 eV) for pure Fe--Ni and respectively (1.36 eV) and (2.32 eV) for Fe--Ni(Mo). Since the time constants of the relaxation process are inversely proportional to the vacancy concentration, a quantitative evaluation of vacancy supersaturation was made; it decreases from the value 700 at 410 0 C to the value 40 at 490 0 C for pure Fe--Ni and from 765 to 121 for Fe--Ni(Mo) in the same temperature range. 3 figures, 5 tables

Si effects on radiation induced segregation in high purity Fe-18Cr-14Ni alloys irradiated by Ni ions

International Nuclear Information System (INIS)

Ohta, Joji; Kako, Kenji; Mayuzumi, Masami; Kusanagi, Hideo; Suzuki, Takayoshi

1999-01-01

To illustrate the effects of the element Si on radiation induced segregation, which causes irradiation assisted stress corrosion cracking (IASCC), we investigated grain boundary chemistry of high purity Fe-18Cr-14Ni-Si alloys irradiated by Ni ions using FE-TEM. The addition of Si up to 1% does not affect the Cr depletion at grain boundaries, while it slightly enhances the depletion of Fe and the segregation of Ni and Si. The addition of 2% Si causes the depletion of Cr and Fe and the segregation of Ni and Si at grain boundaries. Thus, the Si content should be as low as possible. In order to reduce the depletion of Cr at grain boundaries, which is one of the major causes of IASCC, Si content should be less than 1%. (author)

Stability of an Electrodeposited Nanocrystalline Ni-Based Alloy Coating in Oil and Gas Wells with the Coexistence of H₂S and CO₂.

Science.gov (United States)

Sui, Yiyong; Sun, Chong; Sun, Jianbo; Pu, Baolin; Ren, Wei; Zhao, Weimin

2017-06-09

The stability of an electrodeposited nanocrystalline Ni-based alloy coating in a H₂S/CO₂ environment was investigated by electrochemical measurements, weight loss method, and surface characterization. The results showed that both the cathodic and anodic processes of the Ni-based alloy coating were simultaneously suppressed, displaying a dramatic decrease of the corrosion current density. The corrosion of the Ni-based alloy coating was controlled by H₂S corrosion and showed general corrosion morphology under the test temperatures. The corrosion products, mainly consisting of Ni₃S₂, NiS, or Ni₃S₄, had excellent stability in acid solution. The corrosion rate decreased with the rise of temperature, while the adhesive force of the corrosion scale increased. With the rise of temperature, the deposited morphology and composition of corrosion products changed, the NiS content in the corrosion scale increased, and the stability and adhesive strength of the corrosion scale improved. The corrosion scale of the Ni-based alloy coating was stable, compact, had strong adhesion, and caused low weight loss, so the corrosion rates calculated by the weight loss method cannot reveal the actual oxidation rate of the coating. As the corrosion time was prolonged, the Ni-based coating was thinned while the corrosion scale thickened. The corrosion scale was closely combined with the coating, but cannot fully prevent the corrosive reactants from reaching the substrate.

Influence of Weak External Magnetic Field on Amorphous and Nanocrystalline Fe-based Alloys

Science.gov (United States)

Degmová, J.; Sitek, J.

2010-07-01

Nanoperm, Hitperm and Finamet amorphous and nanocrystalline alloys were measured by Mössbauer spectrometry in a weak external magnetic field of 0.5 T. It was shown that the most sensitive parameters of Mössbauer spectra are the intensities of the 2nd and the 5th lines. Rather small changes were observed also in the case of internal magnetic field values. The spectrum of nanocrystalline Nanoperm showed the increase in A23 parameter (ratio of line intensities) from 2.4 to 3.7 and decrease of internal magnetic field from 20 to 19 T for amorphous subspectrum under the influence of magnetic field. Spectrum of nanocrystalline Finemet shown decrease in A23 parameter from 3.5 to 2.6 almost without a change in the internal magnetic field value. In the case of amorphous Nanoperm and Finemet samples, the changes are almost negligible. Hitperm alloy showed the highest sensitivity to the weak magnetic field, when the A23 parameter increased from 0.4 to 2.5 in the external magnetic fields. The A23 parameter of crystalline subspectrum increased from 2.7 to 3.8 and the value of internal magnetic field corresponding to amorphous subspectrum increased from 22 to 24 T. The behavior of nanocrystalline alloys under weak external magnetic field was analyzed within the three-level relaxation model of magnetic dynamics in an assembly of single-domain particles.

ANOMALOUS ELECTRODEPOSITION OF Fe-Ni ALLOY COATING FROM SIMPLE AND COMPLEX BATHS AND ITS MAGNETIC PROPERTY

Directory of Open Access Journals (Sweden)

M A Islam

2010-03-01

Full Text Available Electrodeposition of Fe-Ni thin films has been carried on copper substrate under various electrodeposition conditions from two simple and six complex baths. Sulfate baths composing of NiSO4. 7H2O, FeSO4.7H2O, H3BO3 and Na2SO4KEYWORDS: Anomalous Electrodeposition, Fe-Ni Coating, Complexing agent, Current Density, Magnetic Property. 1. INTRODUCTION Alloy electrodeposition technologies can extend tremendously the potential of electrochemical deposition processes to provide coatings that require unique mechanical, chemical and physical properties [1]. There has been a great research interest in the development and characterization of iron-nickel (Fe-Ni thin films due to their operational capacity, economic interest, magnetic and other properties [2]. Due to their unique low coefficient of thermal expansion (CTE and soft magnetic properties, Fe-Ni alloys have been used in industrial applications for over 100 years [3]. Typical examples of applications that are based on the low CTE of Fe-Ni alloys include: thermostatic bimetals, glass sealing, integrated circuit packaging, cathode ray tube, shadow masks, membranes for liquid natural gas tankers; applications based on the soft magnetic properties include: read-write heads for magnetic storage, magnetic actuators, magnetic shielding, high performance transformer cores. comprise the simple baths whereas complex baths were prepared by adding ascorbic acid, saccharin and citric acid in simple baths. The effect of bath composition, pH and applied current density on coating appearance, composition, morphology and magnetic property were studied. Wet chemical analysis technique was used to analyze the coating composition whereas SEM and VSM were used to study the deposit morphology and magnetic property respectively. Addition of complexing agents in plating baths suppressed the anomalous nature of Fe-Ni alloy electrodeposition. Coatings obtained from simple baths were characterized by coarse grained non

Thermal Expansion Properties of Fe-42Ni-Si Alloy Strips Fabricated by Melt Drag Casting Process

International Nuclear Information System (INIS)

Kim, Moo Kyum; Ahn, Yong Sik; Namkung, Jeong; Kim, Moon Chul; Kim, Yong Chan

2007-01-01

Thermal expansion property was investigated on Fe-42% Ni alloy strip added by alloying element of Si of 0∼1.5wt.%. The strip was fabricated by a melt drag casting process. Addition of Si enlarged the solid-liquid region and reduced the melting point which leads to the increase of the formability of a strip. The alloy containing 0.6 wt.% Si showed the lowest thermal expansion ratio in the temperature range between 20 to 350 .deg. C. The grain size was increased with reduction ratio and annealing temperature, which resulted in the decrease of the thermal expansion coefficient of strip. Because of grain refining by precipitation of Ni 3 Fe, the alloy strip containing 1.5 wt.% Si showed higher thermal expansion ratio compared with the alloy containing 0.6 wt.% Si

Alloying Behavior and Properties of FeSiBAlNiCo x High Entropy Alloys Fabricated by Mechanical Alloying and Spark Plasma Sintering

Science.gov (United States)

Wang, Wen; Li, Boyu; Zhai, Sicheng; Xu, Juan; Niu, Zuozhe; Xu, Jing; Wang, Yan

2018-02-01

In this paper, FeSiBAlNiCo x (x = 0.2, 0.8) high-entropy alloy (HEA) powders were fabricated by mechanical alloying process, and the powders milled for 140 h were sintered by spark plasma sintering (SPS) technique. The microstructures and properties of as-milled powders and as-sintered samples were investigated. The results reveal that the final milling products (140 h) of both sample powders present the fully amorphous structure. The increased Co contents obviously enhance the glass forming ability and thermal stability of amorphous HEA powders, which are reflected by the shorter formation time of fully amorphous phase and the higher onset crystallization temperature, respectively. According to coercivity, the as-milled FeSiBAlNiCo x (x = 0.2, 0.8) powders (140 h) are the semi-hard magnetic materials. FeSiBAlNiCo0.8 HEA powders possess the highest saturation magnetization and largest remanence ratio. The SPS-ed products of both bulk HEAs are composed of body-centered cubic solid solution, and FeSi and FeB intermetallic phases. They possess the high relative density above 97% and excellent microhardness exceeding 1150 HV. The as-sintered bulks undergo the remarkable increase in saturation magnetization compared with the as-milled state. The SPS-ed FeSiBAlNiCo0.8 HEA exhibits the soft magnetic properties. The electrochemical corrosion test is carried out in 3.5% NaCl solution. The SPS-ed FeSiBAlNiCo0.2 HEA reveals the better passivity with low passive current density, and the higher pitting resistance with wide passive region.

Certain structural properties of the phase-binder of the alloys in W-Ni-Fe system

International Nuclear Information System (INIS)

Minakova, R.V.; Storchak, N.A.; Verkhovodov, P.A.; Bazhenova, L.G.; Poltoratskaya, V.L.

1980-01-01

The paper is concerned with effect of cooling conditions and subsequent heat treatment on grain size, lattice parameter and distribution of composing elements in the phase-binder of the W-Ni-Fe-alloy. The X-ray diffraction analysis was used to determine that the phase-binder structure depends on the heat treatment after liquid-phase sintering and consists of coarse grains with a diameter 3-8 mm for the annealed W-Ni-Fe-alloy decreasing to 40-100 μm at slow cooling. The determined change in solubility and of grain interface enrichment with tungsten in the phase-binder

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

Science.gov (United States)

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

2013-08-01

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

Evaluation of mechanical properties of nanocrystalline Ti-Mo-Fe-Sn alloys system; Avaliacao de propriedades mecanicas de ligas nanocristalinas do sistema Ti-Mo-Fe-Sn

Energy Technology Data Exchange (ETDEWEB)

Rocha, M.O.A; Vidilli, A.L.; Afonso, C.R.M., E-mail: andre.vidilli@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

2014-07-01

The Ti-6Al-4V, widely used in biomaterials, exhibits elastic modulus (E) of approximately 110GPa, which is significantly higher than the one of human bone (E = 10 to 30 GPa). In this project, a process of rapid solidification was utilized in 4 different alloys of Ti-Mo-Fe-Sn, in order to produce ultrafine nanocrystalline eutectic alloys, which present high strength (1800-2500 MPa), low elastic modulus (50-110 GPa) and good corrosion resistance. The alloys Ti{sub 62}Fe{sub 30}Mo{sub 8}, Ti{sub 56}Fe{sub 30}Mo{sub 8}Sn{sub 6}, Ti{sub 63}Fe{sub 23}Mo{sub 8}Sn{sub 6}, Ti{sub 60}Fe{sub 23}Mo{sub 8}Sn{sub 9} show Vickers microhardness de, respectively, 745 (1mm), 733 (1mm), 609 (1mm) e 651(1mm) HV. The characterization was performed using scanning electron microscopy (SEM) and X- ray diffraction (XRD). The results indicated the presence of a β-Ti (bcc) matrix and the intermetallic TiFe and Ti{sub 3}Sn phases, and the microstructure were formed by dendrites, and eutectic constituents, which were present in the compositions Ti{sub 62}Fe{sub 30}Mo{sub 8}, Ti{sub 56}Fe{sub 30}Mo{sub 8}Sn{sub 6}, Ti{sub 63}Fe{sub 23}Mo{sub 8}Sn{sub 6}, Ti{sub 60}Fe{sub 23}Mo{sub 8}Sn{sub 9}. (author)

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

Science.gov (United States)

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

2018-06-01

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

The effect of solution pH on the electrochemical performance of nanocrystalline metal ferrites MFe2O4 (M=Cu, Zn, and Ni) thin films

Science.gov (United States)

Elsayed, E. M.; Rashad, M. M.; Khalil, H. F. Y.; Ibrahim, I. A.; Hussein, M. R.; El-Sabbah, M. M. B.

2016-04-01

Nanocrystalline metal ferrite MFe2O4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe2 alloy films were annealed in air at 400 °C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe2O4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe2O4 films at pH values of 1 and 12 compared with that of NiFe2O4 and CuFe2O4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.

Stress-induced Curie temperature increase in the Fe{sub 64}Ni{sub 36} invar alloy

Energy Technology Data Exchange (ETDEWEB)

Gorria, Pedro; Martinez-Blanco, David; Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo (Spain); Boada, Roberto; Chaboy, Jesus [ICMA and Departamento de Fisica de la Materia Condensada, CSIC - Universidad de Zaragoza (Spain); Fernandez-Martinez, Alejandro [LGIT, University of Grenoble and CNRS, Maison des Geosciences, Grenoble (France); Institut Laue-Langevin, Grenoble (France); Garbarino, Gaston; Castro, German R.; Mezouar, Mohamed [European Synchrotron Radiation Facility (ESRF), Grenoble (France); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon (United Kingdom); Alonso, J.I.G. [Department of Physical and Analytical Chemistry, University of Oviedo (Spain); Hernando, Antonio [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Madrid (Spain)

2009-05-15

Structural and magnetic changes on invar Fe{sub 64}Ni{sub 36} alloy (T{sub C}=500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X-ray diffraction under high pressures and X-ray absorption at both Fe and Ni K-edges. We argue that the strain induced in the Fe{sub 64}Ni{sub 36} material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature ({delta}T{sub C}=70 K). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Interaction between solute atoms and radiation defects in Fe-Ni-Si and Fe-Mn-Si alloys under irradiation with proton ions at low-temperature

Energy Technology Data Exchange (ETDEWEB)

Murakami, Kenta, E-mail: murakami@tokai.t.u-tokyo.ac.jp [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Ibaraki, 319-1188 (Japan); Iwai, Takeo, E-mail: iwai@med.id.yamagata-u.ac.jp [Faculty of Medicine, Yamagata University, 2-2-2 Iida-Nishi, Yamagata, Yamagata-shi, 990-9585 (Japan); Abe, Hiroaki [Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Ibaraki, 319-1188 (Japan); Sekimura, Naoto, E-mail: sekimura@n.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1, Tokyo, Hongo, Bunkyo, 113-8656 (Japan)

2016-12-15

Isochronal annealing followed by residual resistivity measurements at 12 K was performed in Fe-0.6Ni-0.6Si and Fe-1.5Mn-0.6Si alloys irradiated with 1 MeV proton ions below 70 K, and recovery stages were compared with those of Fe–0.6Ni and Fe–1.5Mn. The effects of silicon addition in the Fe-Ni alloy was observed as the appearance of a new recovery stage at 282–372 K, presumably corresponding to clustering of solute atoms in matrix, and as a change in mixed dumbbell migration at 122–142 K. Silicon addition mitigated the manganese effect in Fe–Mn alloy that is obstructing the recovery of radiation defects. Reduction of resistivity in Fe-Mn-Si alloy also suggested formation of small solute atom clusters.

Phase fields of nickel silicides obtained by mechanical alloying in the nanocrystalline state

Science.gov (United States)

Datta, M. K.; Pabi, S. K.; Murty, B. S.

2000-06-01

Solid state reactions induced by mechanical alloying (MA) of elemental blends of Ni and Si have been studied over the entire composition range of the Ni-Si system. A monotonous increase of the lattice parameter of the Ni rich solid solution, Ni(Si), is observed with refinement of crystallite size. Nanocrystalline phase/phase mixtures of Ni(Si), Ni(Si)+Ni31Si12, Ni31Si12+Ni2Si, Ni2Si+NiSi and NiSi+Si, have been obtained during MA, over the composition ranges of 0-10, 10-28, 28-33, 33-50, and >50 at. % Si, respectively. The results clearly suggest that only congruent melting phases, Ni31Si12, Ni2Si, and NiSi form, while the formation of noncongruent melting phases, Ni3Si, Ni3Si2, and NiSi2, is bypassed in the nanocrystalline state. The phase formation during MA has been discussed based on thermodynamic arguments. The predicted phase fields obtained from effective free energy calculations are quite consistent with those obtained during MA.

Note: Erosion of W-Ni-Fe and W-Cu alloy electrodes in repetitive spark gaps.

Science.gov (United States)

Wu, Jiawei; Han, Ruoyu; Ding, Weidong; Qiu, Aici; Tang, Junping

2018-02-01

A pair of W-Ni-Fe and W-Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W-Cu electrode surface to polygons while the W-Ni-Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W-Ni-Fe electrodes increased to ∼3 μm while that of W-Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W-Ni-Fe alloy has a better erosion resistance and potential to be further applied in spark gaps.

Composition pathway in Fe-Cu-Ni alloy during coarsening

Science.gov (United States)

Mukherjee, Rajdip; Choudhury, Abhik; Nestler, Britta

2013-10-01

In this work the microstructure evolution for a two phase Fe-Cu-Ni ternary alloy is studied in order to understand the kinetic composition paths during coarsening of precipitates. We have employed a quantitative phase-field model utilizing the CALPHAD database to simulate the temporal evolution of a multi-particle system in a two-dimensional domain. The paths for the far-field matrix and for precipitate average compositions obtained from simulation are found to be rectilinear. The trends are compared with the corresponding sharp interface theory, in the context of an additional degree of freedom for determining the interface compositions due to the Gibbs-Thomson effect in a ternary alloy.

Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

Energy Technology Data Exchange (ETDEWEB)

Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

2011-06-15

Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

Low Temperature Diffusion Transformations in Fe-Ni-Ti Alloys During Deformation and Irradiation

Science.gov (United States)

Sagaradze, Victor; Shabashov, Valery; Kataeva, Natalya; Kozlov, Kirill; Arbuzov, Vadim; Danilov, Sergey; Ustyugov, Yury

2018-03-01

The deformation-induced dissolution of Ni3Ti intermetallics in the matrix of austenitic alloys of Fe-36Ni-3Ti type was revealed in the course of their cascade-forming neutron irradiation and cold deformation at low temperatures via employment of Mössbauer method. The anomalous deformation-related dissolution of the intermetallics has been explained by the migration of deformation-induced interstitial atoms from the particles into a matrix in the stress field of moving dislocations. When rising the deformation temperature, this process is substituted for by the intermetallics precipitation accelerated by point defects. A calculation of diffusion processes has shown the possibility of the realization of the low-temperature diffusion of interstitial atoms in configurations of the crowdions and dumbbell pairs at 77-173 K. The existence of interstitial atoms in the Fe-36Ni alloy irradiated by electrons or deformed at 77 K was substantiated in the experiments of the electrical resistivity measurements.

Modification of amorphous metal alloys and nanocrystals by radiation

International Nuclear Information System (INIS)

Holkova, D.; Sitek, J.

2017-01-01

The paper deals with radiation damage and modification of amorphous metal alloys by neutron irradiation and electrons. Initial experiments were focused on electron irradiation, with various amorphous precursors as well as nanocrystalline alloys: Fe_8_1Nb_7B_1_2, (Fe_3Ni_1)_8_1Nb_7B_1_2, (Fe_3Ni_1)_8_1Nb_7B_1_2 and NANOMET Fe_8_1_._6B_9_._6Si_4_._8P_3Cu_1 being selected for the irradiated objects. The experimental part summarizes the previous results obtained by Moessbauer spectroscopy as well as XRD. (authors)

Creation of submicrocrystalline structure and enhancing of functional properties of Ti-Ni-Fe alloys with the shape-memory effect using equichannel-angular pressing (ECAP)

International Nuclear Information System (INIS)

Prokoshkin, S.D.; Belousov, M.N.; Abramov, V.Ya.

2007-01-01

Methods of X-ray diffraction analysis, transmission electron microscopy, mechanical and thermomechanical tests are used to study structure, mechanical and service properties of Ti-Ni-Fe system shape memory alloys (Ti-47.6 % Ni-2.4 % Fe; Ti-47 % Ni-3 % Fe; Ti-46.6 % Ni-3.4 % Fe). The alloys are subjected to hardening, high temperature thermomechanical treatment (HTMT) and equal-channel angular pressing (EChAP). Thermomechanical connecting pieces of given alloys are tested for carrying capacity and low temperature stability. It is established that the use of EChAP and post-deformation annealing at pressing temperature provides more high properties of the alloys in comparison with hardening and HTMT [ru

Deformation behavior of multilayered NiFe with bimodal grain size distribution at room and elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Fiebig, Jochen, E-mail: jmfiebig@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); Jian, Jie [Department of Electrical and Computer Engineering, Texas A& M University, College Station, TX 77843-3128 (United States); Kurmanaeva, Lilia [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); McCrea, Jon [Integran Technologies Inc., Toronto (Canada); Wang, Haiyan [Department of Electrical and Computer Engineering, Texas A& M University, College Station, TX 77843-3128 (United States); Lavernia, Enrique [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697 (United States); Mukherjee, Amiya [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95817 (United States)

2016-02-22

We describe a study of the temperature dependent deformation behavior of a multilayered NiFe-60 wt%Fe alloy with a layer thickness of 5 μm fabricated by electrodeposition. The structure of adjacent layers alternates between a nanocrystalline and a coarse grained. Uniaxial tensile tests at temperature between 20 °C and 400 °C and strain rate of 10{sup −4}–10{sup −2} were used to determine the mechanical behavior. Microstructure observations via transmission electron microscopy and fractography were performed to provide insight into the underlying deformation mechanism. The mechanical behavior is discussed in the context of the bimodal microstructure of multilayered samples and the contribution of each sub-layer to strength and ductility. The results reveal that even at higher temperatures the nanocrystalline layer determines the mechanical performance of multilayered materials.

Microstructural characterisation of high-entropy alloy AlCoCrFeNi fabricated by laser engineered net shaping

Energy Technology Data Exchange (ETDEWEB)

Kunce, I., E-mail: ikunce@wat.edu.pl [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Polanski, M.; Karczewski, K. [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Plocinski, T.; Kurzydlowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw (Poland)

2015-11-05

Laser engineered net shaping (LENS) was used to produce thin-walled samples of the high-entropy alloy AlCoCrFeNi from a prealloyed powder. To determine the effect of the cooling rate during solidification on the microstructure of the alloy, different laser scanning rates were used. A microstructural study of the surfaces of the sample walls was performed using X-ray diffraction analysis and optical and scanning/transmission electron microscopy. The crystal structure of the alloy was determined to be a body-centred cubic (bcc)-derivative B2-ordered type. The microstructure of the alloy produced by LENS was dendritic. Further, it was found that with an increase in the laser scanning rate from 2.5 to 40 mm s{sup −1}, the average grain size decreased from 108.3 ± 32.4 μm to 30.6 ± 9.2 μm. The maximum cooling rate achieved during the laser cladding of the alloy was 44 × 10{sup 3} K s{sup −1}. The electron microscopy study of the alloy showed the presence of precipitates. The morphology of the disordered bcc (Fe, Cr)-rich precipitates in the ordered B2 (Al, Ni)-rich matrix changed in the dendritic and interdendritic regions from fine and spherical (with a diameter of less 100 nm) to spinodal (with the thickness being less than 100 nm). The LENS- produced AlCoCrFeNi alloy exhibited an average microhardness of approximately 543 HV0.5; this was approximately 13% higher than the hardness in the as-cast state and can be attributed to the grain refinemet in the LENS- produced alloy. Moreover, it was found that increasing the cooling rate during laser cladding increasess the microhardness of the alloy. - Highlights: • Laser-engineered net shaping is used to produce samples of AlCoCrFeNi alloy. • The alloy has a body-centred cubic (bcc)-derivative B2-ordered crystal structure. • Electron microscopy images of the alloy show the presence of precipitates. • The microhardness of the laser-clad alloy is higher than that of the as-cast alloy. • The cooling rate

Production and characterization of stainless steel based Fe-Cr-Ni-Mn-Si(-Co) shape memory alloys

International Nuclear Information System (INIS)

Otubo, J.

1995-01-01

It is well known that the Fe based alloys can exhibit shape memory effect due to the γ to ε martensitic transformation. The effect may not be as striking as observed in the NiTi alloy but it might become attractive from the practical point of view. In this work, two compositions of Fe-Cr-Ni-Mn-Si(-Co) stainless steel based shape memory alloy, prepared by the VIM technique, will be presented. The results are good with shape recovery of 95% for a pre-strain of 4% after some training cycles. In terms of workability the alloys produced are worse than the usual AISI304. However, adjusting the thermo-mechanical processing, it is perfectly possible to produce wire as thin as 1,20mm in dia. or down. (orig.)

On the nature of the variation of martensitic transformation hysteresis and SME characteristics in Fe-Ni-base alloys

International Nuclear Information System (INIS)

Koval, Yu.N.; Monastyrsky, G.E.

1995-01-01

The purpose of this paper is to summarize the various investigations, both by the authors and other works, concerning with the martensitic transformation and SME in Fe-Ni-base alloys. The thermal hysteresis dependence on the alloying elements and thermal treatments are surveyed. The contribution and effect on SME characteristics of widely used alloying elements such as Ti, Nb, Ni, Al, Co, Ta and peculiarities of thermal treatment are discussed. It is noted the main goal of these treatments is to reduce the symmetry of transformation by the ordering or precipitation of a fine coherent phase. The physical principles of transformation hysteresis manipulation in Fe-base alloys is discussed and it concluded that the thermal cycling behavior of Fe-base alloys is very complex and is not clearly understood at present. On the other hand, it is pointed out that thermal cycling is an effective method for control and improvement of SME in these alloys. It is concluded that Fe-base alloys are highly evolved shape memory materials-having a wide working range, good workability and are relatively cheap. In addition, the properties are easily controlled by suitably alloying, aging and thermal cycling. (orig.)

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-09-01

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

Stress Corrosion Cracking of Ni-Fe-Cr Alloys Relevant to Nuclear Power Plants

Science.gov (United States)

Persaud, Suraj

Stress corrosion cracking (SCC) of Ni-Fe-Cr alloys and weld metals was investigated in simulated environments representative of high temperature water used in the primary and secondary circuits of nuclear power plants. The mechanism of primary water SCC (PWSCC) was studied in Alloys 600, 690, 800 and Alloy 82 dissimilar metal welds using the internal oxidation model as a guide. Initial experiments were carried out in a 480°C hydrogenated steam environment considered to simulate high temperature reducing primary water. Ni alloys underwent classical internal oxidation intragranularly resulting in the expulsion of the solvent metal, Ni, to the surface. Selective intergranular oxidation of Cr in Alloy 600 resulted in embrittlement, while other alloys were resistant owing to their increased Cr contents. Atom probe tomography was used to determine the short-circuit diffusion path used for Ni expulsion at a sub-nanometer scale, which was concluded to be oxide-metal interfaces. Further exposures of Alloys 600 and 800 were done in 315°C simulated primary water and intergranular oxidation tendency was comparable to 480°C hydrogenated steam. Secondary side work involved SCC experiments and electrochemical measurements, which were done at 315°C in acid sulfate solutions. Alloy 800 C-rings were found to undergo acid sulfate SCC (AcSCC) to a depth of up to 300 microm in 0.55 M sulfate solution at pH 4.3. A focused-ion beam was used to extract a crack tip from a C-ring and high resolution analytical electron microscopy revealed a duplex oxide structure and the presence of sulfur. Electrochemical measurements were taken on Ni alloys to complement crack tip analysis; sulfate was concluded to be the aggressive anion in mixed sulfate and chloride systems. Results from electrochemical measurements and crack tip analysis suggested a slip dissolution-type mechanism to explain AcSCC in Ni alloys.

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.

Microstructure and Tribological Properties of AlCoCrFeNiTi0.5 High-Entropy Alloy in Hydrogen Peroxide Solution

Science.gov (United States)

Yu, Y.; Liu, W. M.; Zhang, T. B.; Li, J. S.; Wang, J.; Kou, H. C.; Li, J.

2014-01-01

Microstructure and tribological properties of an AlCoCrFeNiTi0.5 high-entropy alloy in high-concentration hydrogen peroxide solution were investigated in this work. The results show that the sigma phase precipitates and the content of bcc2 decrease during the annealing process. Meanwhile, the complex construction of the interdendrite region changes into simple isolated-island shape, and much more spherical precipitates are formed. Those changes of microstructure during the annealing process lead to the increase of hardness of this alloy. In the testing conditions, the AlCoCrFeNiTi0.5 alloy shows smoother worn surfaces and steadier coefficient of friction curves than does the 1Cr18Ni9Ti stainless steel, and SiC ceramic preserves better wear resistance than ZrO2 ceramic. After annealing, the wear resistance of the AlCoCrFeNiTi0.5 alloy increases coupled with SiC counterface but decreases with ZrO2 counterface.

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

Directory of Open Access Journals (Sweden)

N. Cayetano-Castro

2015-01-01

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

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Moessbauer and XRD study of pulse plated Fe-P and Fe-Ni thin layers

International Nuclear Information System (INIS)

Miko, Annamaria; Kuzmann, Erno; Lakatos-Varsanyi, Magda; Kakay, Attila; Nagy, Ferenc; Varga, Lajos Karoly

2005-01-01

57 Fe conversion electron Moessbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and 57 Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t on = 2 ms), with short relaxation time (t off = 9 ms) and low current density (I p = 0.05 Acm -2 ) or at short deposition time (t on = 1 ms) with long relaxation time (t off = 250 ms) and high current density (I p = 1.0 Acm -2 ). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5-8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid

International Nuclear Information System (INIS)

Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W.; Shih, H.C.

2008-01-01

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al x CrFe 1.5 MnNi 0.5 (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm 2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm 2 ). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H 2 SO 4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al 0.3 CrFe 1.5 MnNi 0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe 1.5 MnNi 0.5 and Al 0.3 CrFe 1.5 MnNi 0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al x CrFe 1.5 MnNi 0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion

Phase transformation and grain growth behavior of a nanocrystalline 18/8 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Kotan, Hasan, E-mail: hasankotan@gmail.com [Konya Necmettin Erbakan University, Department of Metallurgical & Materials Engineering, Konya 42090 (Turkey); Darling, Kris A. [US Army Research Laboratory, Weapons and Materials Research Directorate, RDRL-WMM-F, Aberdeen Proving Ground, MD 21005-5069 (United States)

2017-02-16

Fe-18Cr-8Ni and Fe-18Cr-8Ni-1Y (at%) stainless steel powders were nanostructured by mechanical alloying from elemental powders and subjected to 90 min annealing treatments at various temperatures. The microstructural evolutions as a function of alloy compositions and temperatures were investigated by in-situ and ex-situ x-ray diffraction experiments, transmission electron microscopy and focused ion beam microscopy. The dependence of hardness on the microstructure was utilized to study the mechanical changes. It was found that the resulting microstructures by mechanical alloying were bcc solid solution, the so-called α’-martensite structure. The high temperature in-situ x-ray diffraction experiments showed that the martensite-to-austenite reverse phase transformation was completed above 800 and 900 °C for Fe-18Cr-8Ni and Fe-18Cr-8Ni-1Y steels, respectively. A partial or complete retransformation to martensite was observed upon cooling to room temperature. Annealing of nanocrystalline Fe-18Cr-8Ni steel yielded grain growth reaching to micron sizes at 1100 °C while addition of 1 at% yttrium stabilized the microstructure around 160 nm grain size and 6 GPa hardness after 90 min annealing at 1200 °C.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-06-15

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

Nanoindentation and micro-mechanical fracture toughness of electrodeposited nanocrystalline Ni–W alloy films

International Nuclear Information System (INIS)

Armstrong, D.E.J.; Haseeb, A.S.M.A.; Roberts, S.G.; Wilkinson, A.J.; Bade, K.

2012-01-01

Nanocrystalline nickel–tungsten alloys have great potential in the fabrication of components for microelectromechanical systems. Here the fracture toughness of Ni–12.7 at.%W alloy micro-cantilever beams was investigated. Micro-cantilevers were fabricated by UV lithography and electrodeposition and notched by focused ion beam machining. Load was applied using a nanoindenter and fracture toughness was calculated from the fracture load. Fracture toughness of the Ni–12.7 at.%W was in the range of 1.49–5.14 MPa √m. This is higher than the fracture toughness of Si (another important microelectromechanical systems material), but considerably lower than that of electrodeposited nickel and other nickel based alloys. - Highlights: ► Micro-scale cantilevers manufactured by electro-deposition and focused ion beam machining. ► Nanoindenter used to perform micro-scale fracture test on Ni-13at%W micro-cantilevers. ► Calculation of fracture toughness of electrodeposited Ni-13at%W thin films. ► Fracture toughness values lower than that of nanocrystalline nickel.

Alloying behavior and deformation twinning in a CoNiFeCrAl0.6Ti0.4 high entropy alloy processed by spark plasma sintering

International Nuclear Information System (INIS)

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

2013-01-01

Highlights: ► CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been synthesized via MA and SPS. ► Deformation twinning possibly occurred during MA or SPS. ► This alloy exhibits excellent mechanical properties. ► The fracture mechanism of this alloy is intergranular fracture and plastic fracture. -- Abstract: Inequi-atomic CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been designed and fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Alloying behavior, microstructure, phase evolution and mechanical properties of CoNiFeCrAl 0.6 Ti 0.4 alloy were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM), as well as by an Instron testing system. During MA, a supersaturated solid solution consisting of a FCC phase and a metastable BCC phase was formed. Two FCC phases (named FCC1 and FCC2) and a new BCC phase were observed after SPS. During SPS, the metastable BCC phase transformed into the FCC2 phase and the new BCC phase. Meanwhile, the FCC1 phase was the initial FCC phase which was formed during MA. Moreover, nanoscale twins obviously presented only in partial FCC1 phase after SPS. Deformation twinning may be occurred during MA or SPS. The sintered alloy with a high relative density of 98.83% exhibits excellent comprehensive mechanical properties. The yield stress, compressive strength, compression ratio and Vickers hardness of the alloy are 2.08, 2.52 GPa, 11.5% and 573 H V , respectively. The fracture mechanism of CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy is mainly performed at intergranular fracture and plastic fracture mode

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

Improvement of antiscuff properties and thermal stability of alloys of the Fe-Cr-Ni-Si system used for building-up of fittings

International Nuclear Information System (INIS)

Luzhanskij, I.B.; Runov, A.E.; Gel'man, A.S.; Stepin, V.S.

1978-01-01

Studied was the influence of the system and the degree of alloying of alloys of the Fe-Cr-Ni-Si system on their operational characteristics in the operation mode of the energy armature of superhigh parameters. The TsN18 alloy has been developed (containing 0.1 to 0.2% C; 3.5 to 6.0% Si; 0.5 to 3.0% Mn; 16 to 17% Cr; 10.5 to 12% Ni; 1.5 to 3% Mo; the balance being Fe), bombining a high resistance to scuffing with a fairly high heat resistance; the alloy lending itself to building up and to machining. The dependence of the wear resistance of the alloys of the Fe-Cr-Ni-Si system on two factors has been established; namely, - the antifriction characteristics of the film of secondary structures, and physico-mechanical properties of the alloy

Study of the microstructure and of microhardness variation of a Ni-Fe-Cr austenitic alloy by niobium

International Nuclear Information System (INIS)

Carvalho e Camargo, M.U. de; Lucki, G.

1979-01-01

The mechanisms of hardening and corrosion resistance increase in Ni-Fe-Cr austenitic stainless steels by Nb additions are of interest to nuclear technology Niobium additions to a 321 type stainless steel were made in order to study the microhardness, electrical resistivity and metallography. Experimental measurements results are shown. The effect of Nb additions as a micro-alloying element and the thermal and mechanical processes (cold working in particular) in the microstructure and microhardness properties of the 11% Ni - 70%Fe - 17% Cr austenitic alloys were studied. (Author) [pt

Thermal evolution of nanocrystalline co-sputtered Ni–Zr alloy films: Structural, magnetic and MD simulation studies

International Nuclear Information System (INIS)

Bhattacharya, Debarati; Rao, T.V. Chandrasekhar; Bhushan, K.G.; Ali, Kawsar; Debnath, A.; Singh, S.; Arya, A.; Bhattacharya, S.; Basu, S.

2015-01-01

Monophasic and homogeneous Ni 10 Zr 7 nanocrystalline alloy films were successfully grown at room temperature by co-sputtering in an indigenously developed three-gun DC/RF magnetron sputtering unit. The films could be produced with long-range crystallographic and chemical order in the alloy, thus overcoming the widely acknowledged inherent proclivity of the glass forming Ni–Zr couple towards amorphization. Crystallinity of these alloys is a desirable feature with regard to improved efficacy in applications such as hydrogen storage, catalytic activity and nuclear reactor engineering, to name a few. Thermal stability of this crystalline phase, being vital for transition to viable applications, was investigated through systematic annealing of the alloy films at 473 K, 673 K and 923 K for various durations. While the films were stable at 473 K, the effect of annealing at 673 K was to create segregation into nanocrystalline Ni (superparamagnetic) and amorphous Ni + Zr (non-magnetic) phases. Detailed analyses of the physical and magnetic structures before and after annealing were performed through several techniques effectual in analyzing stratified configurations and the findings were all consistent with each other. Polarized neutron and X-ray reflectometry, grazing incidence x-ray diffraction, time-of-flight secondary ion mass spectroscopy and X-ray photoelectron spectroscopy were used to gauge phase separation at nanometer length scales. SQUID based magnetometry was used to investigate macroscopic magnetic properties. Simulated annealing performed on this system using molecular dynamic calculations corroborated well with the experimental results. This study provides a thorough understanding of the creation and thermal evolution of a crystalline Ni–Zr alloy. - Highlights: • Nanocrystalline Ni 10 Zr 7 alloy thin films deposited successfully by co-sputtering. • Creation of a crystalline alloy in a binary system with a tendency to amorphize. • Quantitative

Thermal evolution of nanocrystalline co-sputtered Ni–Zr alloy films: Structural, magnetic and MD simulation studies

Energy Technology Data Exchange (ETDEWEB)

Bhattacharya, Debarati, E-mail: debarati@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Rao, T.V. Chandrasekhar; Bhushan, K.G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ali, Kawsar [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Debnath, A. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Arya, A. [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Bhattacharya, S. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Basu, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2015-11-15

Monophasic and homogeneous Ni{sub 10}Zr{sub 7} nanocrystalline alloy films were successfully grown at room temperature by co-sputtering in an indigenously developed three-gun DC/RF magnetron sputtering unit. The films could be produced with long-range crystallographic and chemical order in the alloy, thus overcoming the widely acknowledged inherent proclivity of the glass forming Ni–Zr couple towards amorphization. Crystallinity of these alloys is a desirable feature with regard to improved efficacy in applications such as hydrogen storage, catalytic activity and nuclear reactor engineering, to name a few. Thermal stability of this crystalline phase, being vital for transition to viable applications, was investigated through systematic annealing of the alloy films at 473 K, 673 K and 923 K for various durations. While the films were stable at 473 K, the effect of annealing at 673 K was to create segregation into nanocrystalline Ni (superparamagnetic) and amorphous Ni + Zr (non-magnetic) phases. Detailed analyses of the physical and magnetic structures before and after annealing were performed through several techniques effectual in analyzing stratified configurations and the findings were all consistent with each other. Polarized neutron and X-ray reflectometry, grazing incidence x-ray diffraction, time-of-flight secondary ion mass spectroscopy and X-ray photoelectron spectroscopy were used to gauge phase separation at nanometer length scales. SQUID based magnetometry was used to investigate macroscopic magnetic properties. Simulated annealing performed on this system using molecular dynamic calculations corroborated well with the experimental results. This study provides a thorough understanding of the creation and thermal evolution of a crystalline Ni–Zr alloy. - Highlights: • Nanocrystalline Ni{sub 10}Zr{sub 7} alloy thin films deposited successfully by co-sputtering. • Creation of a crystalline alloy in a binary system with a tendency to amorphize. �

Martensite shear phase reversion-induced nanograined/ultrafine-grained Fe-16Cr-10Ni alloy: The effect of interstitial alloying elements and degree of austenite stability on phase reversion

Energy Technology Data Exchange (ETDEWEB)

Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Zhang, Z.; Venkatasurya, P.K.C. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, Oulu 90014 (Finland)

2010-11-15

Research highlights: {yields} Development of a novel process involving phase-reversion annealing process. {yields} Austensite stability strongly influences development of nanograined structure. {yields} Interstitial elements influence microstructural evolution during annealing. - Abstract: We describe here an electron microscopy study of microstructural evolution associated with martensitic shear phase reversion-induced nanograined/ultrafine-grained (NG/UFG) structure in an experimental Fe-16Cr-10Ni alloy with very low interstitial content. The primary objective is to understand and obtain fundamental insights on the influence of degree of austenite stability (Fe-16Cr-10Ni, 301LN, and 301 have different austenite stability index) and interstitial elements (carbon and nitrogen) in terms of phase reversion process, microstructural evolution during reversion annealing, and temperature-time annealing sequence. A relative comparison of Fe-16Cr-10Ni alloy with 301LN and 301 austenitic stainless steels indicated that phase reversion in Fe-16Cr-10Ni occurred by shear mechanism, which is similar to that observed for 301, but is different from the diffusional mechanism in 301LN steel. While the phase reversion in the experimental Fe-16Cr-10Ni alloy and 301 austenitic stainless steel occurred by shear mechanism, there were fundamental differences between these two alloys. The reversed strain-free austenite grains in Fe-16Cr-10Ni alloy were characterized by nearly same crystallographic orientation, where as in 301 steel there was evidence of break-up of martensite laths during reversion annealing resulting in several regions of misoriented austenite grains in 301 steel. Furthermore, a higher phase reversion annealing temperature range (800-900 deg. C) was required to obtain a fully NG/UFG structure of grain size 200-600 nm. The difference in the phase reversion and the temperature-time sequence in the three stages is explained in terms of Gibbs free energy change that

Tensile properties and bend ductility of (Fe,Ni)3V long-range-ordered alloys after irradiation in HFIR

International Nuclear Information System (INIS)

Braski, D.N.

1984-01-01

The objective of this work was to determine the effect of neutron irradiation on the tensile properties and bend ductility of (Fe,Ni) 3 V long-range-ordered (LRO) alloys. Several (Fe,Ni) 3 V LRO alloys were irradiated in HFIR-CTR-42 and -43 at 400 to 600 0 C, to approximately 10 dpa and approximately 1000 at. ppm He. Additions of cerium or carbon and the use of cold-worked microstructures did not improve the embrittlement resistance of the LRO alloys. The LRO-37-5RS alloy, with a microstructure produced by rapid solidification, exhibited the highest ductilities, and further study of the RS microstructure is warranted. The correlation between bend ductility and tensile ductility was poor

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

Hydrogen storage performances of LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) alloys prepared by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Wang, Haitao [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Zhai, Tingting; Yang, Tai; Yuan, Zeming; Zhao, Dongliang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China)

2015-10-05

Highlights: • Amorphous and nanostructured alloys were prepared by mechanical milling. • The maximum discharge capacity of ball milled alloys reaches to 1053.5 mA h/g. • The addition of Ni significantly increases the discharge capacity. • Increasing milling time reduces the kinetic performances of ball milled alloys. - Abstract: In order to improve the hydrogen storage performances of Mg-based materials, LaMg{sub 11}Ni alloy was prepared by vacuum induction melting. Then the nanocrystalline/amorphous LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) hydrogen storage alloys were synthesized by ball milling technology. The structure characterizations of the alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage characteristics were tested by using programmed control battery testing system. The electrochemical impedance spectra (EIS), potentiodynamic polarization curves and potential-step curves were also plotted by an electrochemical workstation (PARSTAT 2273). The results indicate that the as-milled alloys exhibit a nanocrystalline and amorphous structure, and the amorphization degree of the alloys visibly increases with extending milling time. Prolonging the milling duration markedly enhances the electrochemical discharge capacity and cyclic stability of the alloys. The electrochemical kinetics, including high rate discharge ability (HRD), charge transfer rate, limiting current density (I{sub L}), hydrogen diffusion coefficient (D), monotonously decrease with milling time prolonging.

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

Directory of Open Access Journals (Sweden)

Yan Zhang

2013-06-01

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

Annealing effects on structure and mechanical properties of CoCrFeNiTiAlx high-entropy alloys

International Nuclear Information System (INIS)

Zhang, K B; Fu, Z Y; Zhang, J Y; Wang, W M; Lee, S W; Niihara, K

2011-01-01

Novel CoCrFeNiTiAl x (x:molar ratio, other elements are equimolar) high-entropy alloys were prepared by vacuum arc melting and these alloys were subsequently annealed at 1000 deg. C for 2 h. The annealing effects on structure and mechanical properties were investigated. Compared with the as-cast alloys, there are many complex intermetallic phases precipitated from the solid solution matrix in the as-annealed alloys with Al content lower than Al 1.0 . Only simple BCC solid solution structure appears in the as-annealed Al 1.5 and Al 2.0 alloys. This kind of alloys exhibit high resistance to anneal softening. Most as-annealed alloys possess even higher Visker hardness than the as-cast ones. The as-annealed Al 0.5 alloys shows the highest compressive strength while the Al 0 alloy exhibits the best ductility, which is about 2.6 GPa and 13%, respectively. The CoCrFeNiTiAl x high-entropy alloys possess integrated high temperature mechanical property as well.

The scale constituents and spalling characteristics of Ni-Fe(O-60%) alloys oxidized in air at 800-12000C

International Nuclear Information System (INIS)

Tomlinson, W.J.; Gardner, M.J.; Kowalski, R.J.

1977-01-01

The spalling behaviour of scales on Ni-Fe alloys containing 0, 2, 10, 20, 30, 40, 50 and 60% Fe oxidized in air at 900, 1000, 1100 and 1200 0 C for periods up to 165 h have been investigated. The phases present and their relative amounts in the scales formed at 1200 0 C have been determined. Spalling was most severe in the Ni-30% Fe alloy, which had a scale consisting of 30% Nisub(x)Fesub(3-x)O 4 and 70% Nisub(1-x)Fesub(x)O. (author)

Stability of an Electrodeposited Nanocrystalline Ni-Based Alloy Coating in Oil and Gas Wells with the Coexistence of H2S and CO2

Directory of Open Access Journals (Sweden)

Yiyong Sui

2017-06-01

Full Text Available The stability of an electrodeposited nanocrystalline Ni-based alloy coating in a H2S/CO2 environment was investigated by electrochemical measurements, weight loss method, and surface characterization. The results showed that both the cathodic and anodic processes of the Ni-based alloy coating were simultaneously suppressed, displaying a dramatic decrease of the corrosion current density. The corrosion of the Ni-based alloy coating was controlled by H2S corrosion and showed general corrosion morphology under the test temperatures. The corrosion products, mainly consisting of Ni3S2, NiS, or Ni3S4, had excellent stability in acid solution. The corrosion rate decreased with the rise of temperature, while the adhesive force of the corrosion scale increased. With the rise of temperature, the deposited morphology and composition of corrosion products changed, the NiS content in the corrosion scale increased, and the stability and adhesive strength of the corrosion scale improved. The corrosion scale of the Ni-based alloy coating was stable, compact, had strong adhesion, and caused low weight loss, so the corrosion rates calculated by the weight loss method cannot reveal the actual oxidation rate of the coating. As the corrosion time was prolonged, the Ni-based coating was thinned while the corrosion scale thickened. The corrosion scale was closely combined with the coating, but cannot fully prevent the corrosive reactants from reaching the substrate.

MFM of nanocrystalline NdFeB: a study of the effect of processing route on the micromagnetic structure

Science.gov (United States)

Al-Khafaji, M. A.; Marashi, S. P. H.; Rainforth, W. M.; Gibbs, M. R. J.; Davies, H. A.; Bishop, J. E. L.; Heydon, G.

1998-12-01

The magnetic domain structure of near stoichiometric (Nd 11.8Fe 82.3B 5.9) nanocrystalline alloy ribbon has been examined using magnetic force microscopy (MFM) as a function of processing conditions. Amorphous structured ribbons of Nd 2Fe 14B with an average thickness of 25 μm were produced by chill block melt-spinning. Subsequently, samples were heat treated at 600°C for 4 min to produce a nanocrystalline structure consisting of Nd 2Fe 14B grains of average size ˜35 nm. These were compared to ribbons of the same composition, but melt spun directly to the nanocrystalline state, also with an average grain size of ˜35 nm. MFM imaging was undertaken using CoCr, NiFe and Fe/SiO 2 coated pyramidal Si tips. The as-cast amorphous ribbons exhibited weak magnetic contrast with a correlation length of 130±20 nm, but with a small elongation in one direction, as shown by Fourier transforms of the MFM images. Nanocrystalline samples produced by devitrification exhibited longer correlation lengths of 1000±50 nm and with a stronger angular component to the Fourier transform. The application of a 5 T field to the nanophase sample in a direction normal to the sample plane resulted in a reduction of the correlation length to 600±50 nm and a reduction in the directionality of the magnetic contrast. However, the application of a 5 T field in the plane of the ribbon resulted in an elongation of the contrast in a direction parallel to the applied field, irrespective of the in-plane field direction. In contrast, ribbon melt spun directly to a nanocrystalline structure exhibited a uniform Fourier transform both in the as-cast and remanent states. The length scale of dominant magnetic structure was 350±30 nm for the as-cast and 620±30 nm for the remanent state. Within the dominant magnetic structure, a finer structure was apparent, of a scale comparable to the grain size.

Helium accumulation and bubble formation in FeCoNiCr alloy under high fluence He+ implantation

Science.gov (United States)

Chen, Da; Tong, Y.; Li, H.; Wang, J.; Zhao, Y. L.; Hu, Alice; Kai, J. J.

2018-04-01

Face-centered cubic (FCC) high-entropy alloys (HEA), as emerging alloys with equal-molar or near equal-molar constituents, show a promising radiation damage resistance under heavy ion bombardment, making them potential for structural material application in next-generation nuclear reactors, but the accumulation of light helium ions, a product of nuclear fission reaction, has not been studied. The present work experimentally studied the helium accumulation and bubble formation at implantation temperatures of 523 K, 573 K and 673 K in a homogenized FCC FeCoNiCr HEA, a HEA showing excellent radiation damage resistance under heavy ion irradiation. The size and population density of helium bubbles in FeCoNiCr samples were quantitatively analyzed through transmission electron microscopy (TEM), and the helium content existing in bubbles were estimated from a high-pressure Equation of State (EOS). We found that the helium diffusion in such condition was dominated by the self-interstitial/He replacement mechanism, and the corresponding activation energy in FeCoNiCr is comparable with the vacancy migration energy in Ni and austenitic stainless steel but only 14.3%, 31.4% and 51.4% of the accumulated helium precipitated into helium bubbles at 523 K, 573 K and 673 K, respectively, smaller than the pure Ni case. Importantly, the small bubble size suggested that FeCoNiCr HEA has a high resistance of helium bubble formation compared with Ni and steels.

Nuclear Magnetic Resonance (NMR) study of the nanocrystalline alloy Fe73.5 Cu1 Nb3 Si13.5 B9

International Nuclear Information System (INIS)

Aliaga-Guerra, D.; Iannarella, L.; Fontes, M.B.; Guimaraes, A.P.; Skorvanek, I.

1994-05-01

Nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloys were studied with spin echo NMR at 4.2 K, from 15 to 100 MHz. Several lines are observed, with signals from domains and domain walls. Signals at 50-90 MHz appear to arise from 93 Nb nuclei in the amorphous matrix and in the interface of the crystallites. (author). 5 refs, 3 figs

Phase and magnetic studies of the high-energy alloyed Ni-Fe

Czech Academy of Sciences Publication Activity Database

Jirásková, Yvonna; Buršík, Jiří; Turek, Ilja; Hapla, Miroslav; Titov, A.; Životský, O.

2014-01-01

Roč. 594, May (2014), s. 133-140 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/1350 Grant - others:VŠB(CZ) CZ.1.07/2.3.00/20.0074 Institutional support: RVO:68081723 Keywords : Ni-Fe * mechanical alloying * magnetic properties * microstructure * particle interactions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

Neutronic irradiation effect in FeNi alloys, observed by magnetic measurements

International Nuclear Information System (INIS)

Sciani, V.; Lucki, G.

1986-01-01

In this work some aspects of radiation damage are analysed through the influence of neutron irradiation on magnetic properties of FeNi alloys. The main points emphasized are: radiation enhanced diffusion, determination of the activation energy for diffusion process and vacancies supersaturation, which is an important parameter from technological point of view and a necessary condition for the void formation. (Author) [pt

Moessbauer and XRD study of pulse plated Fe-P and Fe-Ni thin layers

Energy Technology Data Exchange (ETDEWEB)

Miko, Annamaria [Bay Zoltan Institute for Material Science (Hungary); Kuzmann, Erno, E-mail: kuzmann@para.chem.elte.hu [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Lakatos-Varsanyi, Magda [Bay Zoltan Institute for Material Science (Hungary); Kakay, Attila [Research Institute for Solid State Physics and Optics (Hungary); Nagy, Ferenc [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Varga, Lajos Karoly [Research Institute for Solid State Physics and Optics (Hungary)

2005-09-15

{sup 57}Fe conversion electron Moessbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and {sup 57}Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t{sub on} = 2 ms), with short relaxation time (t{sub off} = 9 ms) and low current density (I{sub p} = 0.05 Acm{sup -2}) or at short deposition time (t{sub on} = 1 ms) with long relaxation time (t{sub off} = 250 ms) and high current density (I{sub p} = 1.0 Acm{sup -2}). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5-8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

Effect of mechanical alloying on FeCrC reinforced Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, S. Osman [Univ. of Namik Kemal, Tekirdag (Turkey); Teker, Tanju [Adiyaman Univ. (Turkey). Dept. of Metallurgical and Materials Engineering; Demir, Fatih [Batman Univ. (Turkey)

2016-05-01

Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing and rewelding of powder particles in a high-energy ball mill. In the present study, the intermetallic matrix composites (IMCs) of Ni-Al reinforced by M{sub 7}C{sub 3} were produced by powder metallurgical routes via solid state reaction of Ni, Al and M{sub 7}C{sub 3} particulates by mechanical alloying processes. Ni, Al and M{sub 7}C{sub 3} powders having 100 μm were mixed, mechanical alloyed and the compacts were combusted in a furnace. The mechanically alloyed (MAed) powders were investigated by X-ray diffraction (XRD), microhardness measurement, optic microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The presence of the carbides depressed the formation of unwanted NiAl intermetallic phases. The mechanical alloyed M{sub 7}C{sub 3} particles were unstable and decomposed partially within the matrix during alloying and sintering, and the morphology of the composites changed with the dissolution ratio of M{sub 7}C{sub 3} and sintering temperature.

Effect of 1.0% Ni on high-temperature impression creep and hardness of recycled aluminium alloy with high Fe content

Science.gov (United States)

Faisal, M.; Mazni, Noor; Prasada Rao, A. K.

2018-03-01

Reported work focusses on the effect of 1.0% Ni addition on the microstructure, high- temperature impression creep and thereby the hardness of recycled Al-alloy containing >2wt% Fe, obtained from automotive scrap. Present studies have shown that the addition of 1.0% Ni have supress the formation of α-phase (Al5FeSi) by supressing the peritectic transformation of β-phase (Al8Fe2Si). Such suppression is found to improve the hardness and high-temperature impression creep of the recycled aluminium alloy.

Surface of Ti-Ni alloys after their preparation

International Nuclear Information System (INIS)

Saldan, I.; Frenzel, J.; Shekhah, O.; Chelmowski, R.; Birkner, A.; Woell, Ch.

2009-01-01

The Ti 3.87 Ni 1.73 Fe 0.7 O 0.3, Ti 3.87 Ni 1.73 Fe 0.4 N 0.3 and Ti 3.87 Ni 1.73 Fe 0.4 C 0.3 alloys were investigated regarding their surface characteristics. The scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used for phase characterization. The X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical composition of alloy surface. The atomic force microscopy (AFM) to observe alloy surface topography after cutting and electrochemical polishing separately has been done. The transmission electron microscopy (TEM) with X-ray diffraction was carried out to get a high contrast images and the diffraction pattern from alloy surface. The results clearly shown, that all alloys were multiphase, and their surface was totally oxidized with no pure metals

Radiation damage buildup and dislocation evolution in Ni and equiatomic multicomponent Ni-based alloys

Energy Technology Data Exchange (ETDEWEB)

Levo, E. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Granberg, F., E-mail: fredric.granberg@helsinki.fi [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Fridlund, C.; Nordlund, K. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Djurabekova, F. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland)

2017-07-15

Single-phase multicomponent alloys of equal atomic concentrations (“equiatomic”) have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied materials. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, the NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

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

Photocatalytic behaviors and structural characterization of nanocrystalline Fe-doped TiO2 synthesized by mechanical alloying

International Nuclear Information System (INIS)

Kim, Dong Hyun; Hong, Hyun Seon; Kim, Sun Jae; Song, Jae Sung; Lee, Kyung Sub

2004-01-01

Nanocrystalline Fe-doped TiO 2 powders were synthesized by mechanical alloying (MA) with varying Fe contents from 0 up to 4.8 wt.% to shift the absorption threshold into the visible light region. The photocatalytic feasibility of the Fe-doped TiO 2 powder was evaluated by quantifying the visible light absorption capacity using ultraviolet and visible (UV-Vis) spectroscopy and photoluminescence spectroscopy. Effects of Fe additions on the crystal structures and the morphologies of the Fe-doped powders were also investigated as a function of the doping content using transmission electron microscopy-electron diffraction pattern (TEM-EDP), X-ray diffraction (XRD) and energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS). The UV-Vis study showed that the UV absorption for the Fe-doped powder moved to a longer wavelength (red shift) and the photoefficiency was enhanced. Based on the analysis of the photoluminescence spectra, the red shift was believed to be induced by localizing the dopant level near the valence band of TiO 2 . The UV-Vis absorption depended on the Fe concentration. TEM-EDP and XRD investigations showed that the Fe-doped powder had a rutile phase in which the added Fe atoms were dissolved. The rutile phase was composed of spherical particles and chestnut bur shaped particles, resulting in a larger surface area than the spherical P-25 powder

Structure characterization of nanocrystalline Ni–W alloys obtained by electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Indyka, P., E-mail: paulina.indyka@uj.edu.pl [Jagiellonian University, Faculty of Chemistry, 3 Ingardena St., 30-059 Krakow (Poland); Beltowska-Lehman, E.; Tarkowski, L.; Bigos, A. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow (Poland); García-Lecina, E. [Surface Finishing Department, CIDETEC-IK4 – Centre for Electrochemical Technologies, P° Miramón 196, 20009 Donostia-San Sebastián (Spain)

2014-03-25

Highlights: • Ni–W alloy coatings were electrodeposited from an aqueous electrolyte solutions. • The microstructure was studied with respect to electrodeposition process parameters. • We report optimal plating conditions for crack-free, nanocrystalline Ni–W coatings. • Crystalline Ni–W coatings exhibited the phase structure of an α-Ni(W) solid solution. • Coatings revealed tensile residual stresses and weakly pronounced 〈1 1 0〉 fiber texture. -- Abstract: Ni–W coatings of different tungsten content (2–50 wt%) were electrodeposited on a steel substrates from an aqueous complex sulfate–citrate galvanic baths, under controlled hydrodynamic conditions in a Rotating Disk Electrode (RDE) system. The optimum conditions for the electrodeposition of crack-free, homogeneous nanocrystalline Ni–W coatings were determined on the basis of the microstructure investigation results. The XRD structural characterizations of Ni–W alloy coatings obtained under different experimental conditions were complemented by SEM and TEM analysis. Results of the study revealed that the main factor influencing the microstructure formation of the Ni–W coatings is the chemical composition of an electrolyte solution. X-ray and electron diffraction patterns of all nanocrystalline Ni–W coatings revealed mainly the fcc phase structure of an α-Ni(W) solid solution with a lattice parameter increased along with tungsten content. The use of additives in the plating bath resulted in the formation of equiaxial/quasifibrous, nanocrystalline Ni–W grains of an average size of about 10 nm. The coatings were characterized by relatively high tensile residual stresses (500–1000 MPa), depending on the electrodeposition conditions. Ni–W coatings exhibited weakly pronounced fiber type 〈1 1 0〉 crystallographic texture, consistent with the symmetry of the plating process. Coatings of the highest tungsten content 50 wt% were found to be amorphous.

Magnetic Behavior of Ni-Fe Core-Shell and Alloy Nanowires

Science.gov (United States)

Tripathy, Jagnyaseni; Vargas, Jose; Spinu, Leonard; Wiley, John

2013-03-01

Template assisted synthesis was used to fabricate a series of Ni-Fe core-shell and alloy nanowires. By controlling reaction conditions as well as pore structure, both systems could be targeted and magnetic properties followed as a function of architectures. In the core-shell structure coercivity increases with decrease in shell thickness while for the alloys, coercivity squareness improve with increase pore diameter. Details on the systematic studies of these materials will be presented in terms of hysteretic measurements, including first order reversal curves (FORC), and FMR data. Magnetic variation as a function of structure and nanowire aspect ratios will be presented and the origins of these behaviors discussed. Advanced Material Research Institute

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

Science.gov (United States)

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

2013-12-01

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

Stress corrosion cracking of Ni-Fe-Cr alloys in acid sulfate environments relevant to CANDU steam generators

Energy Technology Data Exchange (ETDEWEB)

Persaud, S.Y.; Carcea, A.G., E-mail: suraj.persaud@mail.utoronto.ca [Univ. of Toronto, Toronto, ON (Canada); Huang, J.; Korinek, A.; Botton, G.A. [McMaster Univ., Hamilton, ON (Canada); Newman, R.C. [Univ. of Toronto, Toronto, ON (Canada)

2014-07-01

Ni-Fe-Cr alloys used in nuclear plants have been found susceptible to stress corrosion cracking (SCC) in acid sulfate environments. Electrochemical measurements and SCC tests were done using Ni, Alloy 600, and Alloy 800 in acid sulfate solutions at 315 {sup o}C. Electrochemical measurements suggested that sulfate is a particularly aggressive anion in mixed chloride systems. Cracks with lengths in excess of 300 μm were present on stressed Alloy 800 samples after 60 hours. High resolution analytical electron microscopy was used to extract a crack tip from an Alloy 800 sample and draw final conclusions with respect to the mechanism of SCC. (author)

Multiferroic properties of nanocrystalline BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0.0–0.15) perovskite ceramics

Energy Technology Data Exchange (ETDEWEB)

Chaudhari, Yogesh [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India); Department of Physics, Shri. Pancham Khemaraj Mahavidyalaya, Sawantwadi 416510, Maharastra (India); Mahajan, Chandrashekhar M. [Department of Engineering Sciences and Humanities (DESH), Vishwakarma Institute of Technology, Pune 411 016, Maharastra (India); Singh, Amrita [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Jagtap, Prashant [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India); Chatterjee, Ratnamala [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Bendre, Subhash, E-mail: bendrest@gmail.com [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India)

2015-12-01

Ni doped BiFeO{sub 3} (x=0, 0.05, 0.1 and 0.15) nanocrystalline ceramics were synthesized by the solution combustion method (SCM) to obtain optimal multiferroic properties. The effect of Ni doping on structural, morphological, ferroelectric, magnetic and dielectric properties of BiFeO{sub 3} was studied. The structural investigations by using X-ray diffraction (XRD) pattern confirmed that BiFe{sub 1−x}Ni{sub x}O{sub 3} ceramics have rhombhohedral perovskite structure. The ferroelectric hysteresis measurements for BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0, 0.05, 0.1, 0.15) compound at room temperature found to exhibit unsaturated behavior and presents partial reversal of polarization. The magnetic measurements demonstrated an enhancement of ferromagnetic property due to Ni doping in BiFeO{sub 3} when compared with undoped BiFeO{sub 3}. The variation of dielectric constant with temperature in BiFe{sub 0.9}Ni{sub 0.1}O{sub 3} and BiFe{sub 0.85}Ni{sub 0.15}O{sub 3} samples evidenced an apparent dielectric anomaly around 350 °C and 300 °C which corresponds to antiferromagnetic to paramagnetic phase transition of (T{sub N}) of BiFeO{sub 3}. The dependence of room temperature dielectric properties on frequency signifies that both dielectric constant (ε) and dielectric loss (tan δ) are the strong function of frequency. The results show that solution combustion method leads to synthesis of an excellent and reproducible BiFe{sub 1−x}Ni{sub x}O{sub 3} multiferroic ceramics. - Highlights: • Synthesis of BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0, 0.05, 0.1 and 0.15) multiferroic ceramics. • Solution Combustion Method (SCM). • Ferroelectric and dielectric properties of undoped and Ni doped BiFeO{sub 3} ceramics. • High temperature synthesis of BiFe{sub 1−x}Ni{sub x}O{sub 3} multiferroic ceramics. • First detailed report about SCM synthesized the BiFe{sub 1−x}Ni{sub x}O{sub 3} ceramics.

Effects of annealing on the microstructure and magnetic property of the mechanically alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaoxia; Zhou, Xuan; Yu, Shuaishuai; Wei, Congcong; Xu, Jing; Wang, Yan, E-mail: mse_wangy@ujn.edu.cn

2017-05-15

The effects of annealing treatment on the microstructure, thermal stability, and magnetic properties of the mechanical alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys (HEAs) have been investigated in this project. The simple crystallization products in FeSiBAlNi amorphous HEAs with Co and Ag addition reveal the high phase stability during heating process. At high annealing treatment, the crystallized HEAs possess the good semi-hard magnetic property. It can conclude that crystallization products containing proper FeSi-rich and FeB-rich phases are beneficial to improve the magnetic property. Annealing near the exothermic peak temperature presents the best enhancing effect on the semi-hard magnetic property of FeSiBAlNiCo. It performs both large saturated magnetization and remanence ratio of 13.0 emu/g and near 45%, which exhibit 465% and 105% enhancement compared with as-milled state, respectively. - Highlights: • Co, Cu, Ag additions affect crystallization behavior of FeSiBAlNi amorphous HEAs. • Crystallization products in FeSiBAlNi Co/Ag reveal high phase stability. • Proper FeSi-rich and FeB-rich phases are beneficial to improve magnetic property. • Annealing treatment improves semi-hard magnetic property compared to as-milled state. • Annealing near exothermic peak temperature shows best enhancing effect on magnetism.

The effects of Ni substitution on the magnetic properties of as-cast and annealed Fe-Co amorphous alloy wires

International Nuclear Information System (INIS)

Pinitsoontorn, S.; Badini Confalonieri, G.A..; Davies, H.A.; Gibbs, M.R.J.

2005-01-01

Amorphous alloy wires of composition (Co x Fe y Ni z ) 72.5 Si 12.5 B 15 , with Ni substituted for both Co and Fe, were prepared by the rotating water bath chill cast technique. The maximum Ni content that can be substituted in order to cast amorphous wire is reported. The effects of Ni addition on the hysteresis loop parameters and the major magnetic properties of the as-cast wire are reported

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.)

Linear arrangement of nano-scale magnetic particles formed in Cu-Fe-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Kang, Sung, E-mail: k3201s@hotmail.co [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeda, Mahoto [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeguchi, Masaki [Advanced Electron Microscopy Group, National Institute for Materials Science (NIMS), Sakura 3-13, Tsukuba, 305-0047 (Japan); Bae, Dong-Sik [School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam, 641-773 (Korea, Republic of)

2010-04-30

The structural evolution of nano-scale magnetic particles formed in Cu-Fe-Ni alloys on isothermal annealing at 878 K has been investigated by means of transmission electron microscopy (TEM), electron dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS) and field-emission scanning electron microscopy (FE-SEM). Phase decomposition of Cu-Fe-Ni occurred after an as-quenched specimen received a short anneal, and nano-scale magnetic particles were formed randomly in the Cu-rich matrix. A striking feature that two or more nano-scale particles with a cubic shape were aligned linearly along <1,0,0> directions was observed, and the trend was more pronounced at later stages of the precipitation. Large numbers of <1,0,0> linear chains of precipitates extended in three dimensions in late stages of annealing.

Synthesis, crystallization behavior and surface modification of Ni-Cr-Si-Fe amorphous alloy

International Nuclear Information System (INIS)

Iqbal, M.; Akhter, J.I.; Rajput, M.U.; Mahmood, K.; Hussain, Z.; Hussain, S.; Rafiq, M.

2011-01-01

A quaternary Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ amorphous alloy was synthesized by melt spinning technique. Surface modification was done by electron beam melting (EBM), neutron irradiation and gamma-rays. Microstructure of as cast, annealed and modified samples was examined by scanning electron microscope. Crystallization behavior was studied by annealing the samples in vacuum at different temperatures in the range 773-1073 K. Techniques of X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for characterization. Differential scanning calorimetry (DSC) was conducted at various heating rates in the range 10-40 K/min. Thermal parameters like glass transition temperature T/sub g/, crystallization temperature T/sub x/, supercooled liquid region delta T/sub x/ and reduced glass transition temperature T/sub rg/ were measured. The Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ alloy exhibits wide supercooled liquid region of 60 K indicating good thermal stability. The activation energy was calculated to be 160 +- 4 kJ/mol using Kissinger and Ozawa equations respectively which indicates high resistance against crystallization. The XRD results of the samples annealed at 773 K, 923 K, 973 K and 1073 K/20 min show nucleation of Ni/sub 2/Cr/sub 3/ and NiCrFe crystalline phases. Vickers microhardness of the as cast ribbon was measured to be 680. About 30-50 % increase in hardness was achieved by applying EBM technique. (author)

Phase Evolution and Mechanical Properties of AlCoCrFeNiSi x High-Entropy Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering

Science.gov (United States)

Kumar, Anil; Swarnakar, Akhilesh Kumar; Chopkar, Manoj

2018-05-01

In the current investigation, AlCoCrFeNiSi x (x = 0, 0.3, 0.6 and 0.9 in atomic ratio) high-entropy alloy systems are prepared by mechanical alloying and subsequently consolidated by spark plasma sintering. The microstructural and mechanical properties were analyzed to understand the effect of Si addition in AlCoCrFeNi alloy. The x-ray diffraction analysis reveals the supersaturated solid solution of the body-centered cubic structure after 20 h of ball milling. However, the consolidation promotes the transformation of body-centered phases partially into the face-centered cubic structure and sigma phases. A recently proposed geometric model based on the atomic stress theory has been extended for the first time to classify single phase and multi-phases on the high-entropy alloys prepared by mechanical alloying and spark plasma sintering process. Improved microhardness and better wear resistance were achieved as the Si content increased from 0 to 0.9 in the present high-entropy alloy.

Recoil-free Fraction in Amorphous and Nanocrystalline Aluminium Based Alloys

Science.gov (United States)

Sitek, Jozef

2008-10-01

Aluminium based rapidly quenched alloys of nominal composition Al90Fe7Nb3 and Al94Fe2V4 were studied by Mössbauer spectroscopy. We have measured the recoil-free fraction and thermal shift at room and liquid nitrogen temperature. The frequency modes of atomic vibrations were determined and consequently the characteristic Debye temperature was derived. Characteristic temperature calculated from f-factor was lower than those fitted from second order Doppler shift. This indicates the presence of different frequency modes for amorphous and nanocrystalline states.

Explosive device of conduit using Ti Ni alloy

Directory of Open Access Journals (Sweden)

A. Yu. Kolobov

2014-01-01

Full Text Available Presently, materials have been developed which are capable at changing temperate to return significant inelastic deformations, exhibit rubber-like elasticity, convert heat into mechanical work, etc. The aggregate of these effects is usually called the shape memory effect.At present a great number of compounds and alloys with a shape memory effect has been known.These are alloys based on titanium nickelide (TiNi, copper-based alloys (Cu-Al, Cu-Sn, Cu-Al-Ni, Cu-Zn-Si, etc., gold and silver (Ag-Cd, Au-Ag-Cd, Au-Cd-Cu, Au-Zn-Cu, etc., manganese (Mn-Cr, Fe-Cu, Mn-Cu-Ni, Mn-Cu-Zr, Mn-Ni, etc., iron (Fe-Mn, Fe-Ni, Fe-Al, etc., and other compounds.The alloys based on titanium nickelide (nitinol are the most widely used.Alloys with shape memory effect find various applications in engineering and medicine, namely connecting devices, actuators, transformable design, multipurpose medical implants, etc.There is a task of breaking fuel conduit during separating the spacecraft from the rocket in space technology.The paper examines the procedure for design calculation of the separating device of conduit with the use of Ti-Ni alloy. This device can be used instead of the pyro-knives.The device contains two semi-rings from Ti-Ni alloy. In the place of break on the conduit an annular radius groove is made.At a temperature of martensite passage the semi-rings undergo deformation and in the strained state are set in the device. With heating to the temperature of the austenitic passage of bushing macro-deformation the energy stored by the nitinol bushing is great enough to break the conduit on the neck.The procedures of design calculation and response time of device are given.

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)

Structural Investigation of Rapidly Quenched FeCoPtB Alloys

International Nuclear Information System (INIS)

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

2011-01-01

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

Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

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....

Phase evolution, mechanical and corrosion behavior of Fe(100-x) Ni(x) alloys synthesized by powder metallurgy

Science.gov (United States)

Singh, Neera; Parkash, Om; Kumar, Devendra

2018-03-01

In the present investigation, Fe(100-x) Ni(x) alloys (x = 10, 20, 30, 40 and 50 wt%) were synthesized through the evolution of γ-taenite and α-kamacite phases by powder metallurgy route using commercially available Fe and Ni powders. Mechanically mixed powders of Fe and Ni were compacted at room temperature and sintered at three different temperatures 1000, 1200 and 1250 °C for 1 h. Both Ni concentration and sintering temperature have shown a strong impact on the phase formation, tribological and electrochemical behavior. Micro structural study has shown the formation of taenite (γ-Fe,Ni) and kamacite (α-Fe,Ni) phases in the sintered specimens. An increase in Ni fraction resulted in formation of more taenite which reduces hardness and wear resistance of specimens. Increasing the sintering temperature decreased the defect concentration with enhanced taenite formation, aiding to higher densification. Taenite formed completely in Fe50Ni50 after sintering at 1250 °C. Tribological test revealed the maximum wear resistance for Fe70Ni30 specimen due to the presence of both kamacite and taenite in significant proportions. The formation of taenite as well as the decrease in defect concentration improves the corrosion resistance of the specimens significantly in 1M HCl solution. A maximum corrosion protection efficiency of around ∼87% was achieved in acidic medium for Fe50Ni50, sintered at 1250 °C.

Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

Science.gov (United States)

Guo, Zhengqi; Pan, Jian; Zhu, Deqing; Zhang, Feng

2018-02-01

In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

Magnetic nanowires (Fe, Fe-Co, Fe-Ni – magnetic moment reorientation in respect of wires composition

Directory of Open Access Journals (Sweden)

Kalska-Szostko Beata

2015-03-01

Full Text Available Magnetic nanowires of Fe, Fe-Co, and Fe-Ni alloy and layered structure were prepared by electrochemical alternating current (AC deposition method. The morphology of the nanowires in and without the matrix was studied by energy dispersive X-ray spectroscopy (EDX, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. The wires either show strong dependence on the combination of elements deposition (alloy or layered or chemical composition (Co or Ni. The magnetic properties of the nanostructures were determined on the basis of Mössbauer spectroscopy (MS.

Long-term creep rupture strength of weldment of Fe-Ni based alloy as candidate tube and pipe for advanced USC boilers

Energy Technology Data Exchange (ETDEWEB)

Bao, Gang; Sato, Takashi [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Research Laboratory; Marumoto, Yoshihide [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Div.

2010-07-01

A lot of works have been going to develop 700C USC power plant in Europe and Japan. High strength Ni based alloys such as Alloy 617, Alloy 740 and Alloy 263 were the candidates for boiler tube and pipe in Europe, and Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is also a candidate for tube and pipe in Japan. One of the Key issues to achieve 700 C boilers is the welding process of these alloys. Authors investigated the weldability and the long-term creep rupture strength of HR6W tube. The weldments were investigated metallurgically to find proper welding procedure and creep rupture tests are ongoing exceed 38,000 hours. The long-term creep rupture strengths of the HST weld joints are similar to those of parent metals and integrity of the weldments was confirmed based on with other mechanical testing results. (orig.)

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.)

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.%.

Magnetic ageing study of high and medium permeability nanocrystalline FeSiCuNbB alloys

Energy Technology Data Exchange (ETDEWEB)

Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

2017-04-15

increasing the energy efficiency is one of the most important issues in modern power electronic systems. In aircraft applications, the energy efficiency must be associated with a maximum reduction of mass and volume, so a high components compactness. A consequence from this compactness is the increase of operating temperature. Thus, the magnetic materials used in these applications, have to work at high temperature. It raises the question of the thermal ageing problem. The reliability of these components operating at this condition becomes a real problem which deserves serious interest. Our work takes part in this context by studying the magnetic material thermal ageing. The nanocrystalline materials are getting more and more used in power electronic applications. Main advantages of nanocrystalline materials compared to ferrite are: high saturation flux density of almost 1.25 T and low dynamic losses for low and medium frequencies. The nanocrystalline Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloys have been chosen in our aging study. This study is based on monitoring the magnetic characteristics for several continuous thermal ageing (100, 150, 200 and 240 °C). An important experimental work of magnetic characterization is being done following a specific monitoring protocol. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The magnetic ageing of the nanocrystalline materials is related to their annealing. • The degradations with ageing are not related to a change of the grain size diameter. • The amount of anisotropies introduced with ageing depends just on ageing conditions.

Nanocrystalline spinel ferrite (MFe2O4, M = Ni, Co, Mn, Mg, Zn) powders prepared by a simple aloe vera plant-extracted solution hydrothermal route

International Nuclear Information System (INIS)

Phumying, Santi; Labuayai, Sarawuth; Swatsitang, Ekaphan; Amornkitbamrung, Vittaya; Maensiri, Santi

2013-01-01

Graphical abstract: This figure shows the specific magnetization curves of the as-prepared MFe 2 O 4 (M = Ni, Co, Mn, Mg, Zn) powders obtained from room temperature VSM measurement. These curves are typical for a soft magnetic material and indicate hysteresis ferromagnetism in the field ranges of ±500 Oe, ±1000 Oe, and ±2000 Oe for the CoFe 2 O 4 , MgFe 2 O 4 and MnFe 2 O 4 respectively, whereas the samples of NiFe 2 O 4 and ZnFe 2 O 4 show a superparamagnetic behavior. Highlights: ► Nanocrystalline MFe 2 O 4 powders were synthesized by a novel hydrothermal method. ► Metal acetylacetonates and aloe vera plant-extracted solution are used. ► This biosynthetic route is very simple and provides high-yield oxide nanomaterials. ► XRD and TEM results indicate that the prepared samples have only spinel structure. ► The maximum M s of 68.9 emu/g at 10 kOe were observed for the samples of MnFe 2 O 4 . - Abstract: Nanocrystalline spinel ferrite MFe 2 O 4 (M = Ni, Co, Mn, Mg, Zn) powders were synthesized by a novel hydrothermal method using Fe(acac) 3 , M(acac) 3 (M = Ni, Co, Mn, Mg, Zn) and aloe vera plant extracted solution. The X-ray diffraction and selected-area electron diffraction results indicate that the synthesized nanocrystalline have only spinel structure without the presence of other phase impurities. The crystal structure and morphology of the spinel ferrite powders, as revealed by TEM, show that the NiFe 2 O 4 and CoFe 2 O 4 samples contain nanoparticles, whereas the MnFe 2 O 4 and MgFe 2 O 4 samples consist of many nanoplatelets and nanoparticles. Interestingly, the ZnFe 2 O 4 sample contains plate-like structure of networked nanocrystalline particles. Room temperature magnetization results show a ferromagnetic behavior of the CoFe 2 O 4 , MnFe 2 O 4 and MgFe 2 O 4 samples, whereas the samples of NiFe 2 O 4 and ZnFe 2 O 4 exhibit a superparamagnetic behavior

Shape memory and pseudoelastic properties of Fe-Mn-Si and Ti-Ni based alloys

International Nuclear Information System (INIS)

Guenin, G.

1997-01-01

The aim of this presentation is to analyse and discuss some recent advances in shape memory and pseudoelastic properties of different alloys. Experimental work in connection with theoretical ones will be reviewed. The first part is devoted to the microstructural origin of shape memory properties of Fe-Mn-Si based alloys (γ-ε transformation); the second part is a synthetic analysis of the effects of thermomechanical treatments on shape memory and pseudoelastic effects in Ti-Ni alloys, with some focus on the behaviour of the R phase introduced. (orig.)

Effect of alloying elements on the stability of Ni2M in Alloy690 based upon thermodynamic calculation

International Nuclear Information System (INIS)

Horiuchi, Toshiaki; Kuwano, Kazuhiro; Satoh, Naohiro

2012-01-01

Some researchers recently point out that Ni based alloys used in nuclear power plants have the ordering tendency, which is a potential to decrease mechanical properties within the expected lifetime of the plants. In the present study, authors evaluated the effect of 8 alloying elements on the ordering tendency in Alloy690 based upon thermodynamic calculation by Thermo-Calc. It is clarified that the additive amount of Fe, Cr, Ti and Si, particularly Fe and Cr, was influential for the stability of Ni 2 M, while that of Mn, Cu, B and C had almost no effect for that. Authors therefore designed the Ni 2 M stabilized alloy by no addition of Fe in Alloy690. Ni 2 M is estimated to be stable even at 773 K in the Ni 2 M stabilized alloy. The influence by long range ordering or precipitating of Ni 2 M in Alloy690 for mechanical properties or SCC susceptibility is expected to be clarified by the sample obtained in the present study. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2005-10-15

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

Vibrational thermodynamics of Fe90Zr7B3 nanocrystalline alloy from nuclear inelastic scattering

DEFF Research Database (Denmark)

Stankov, S.; Miglierini, M.; Chumakov, A. I.

2010-01-01

Recently we determined the iron-partial density of vibrational states (DOS) of nanocrystalline Fe(90)Zr(7)B(3) (Nanoperm), synthesized by crystallization of an amorphous precursor, for various stages of nanocrystallization separating the DOS of the nanograins from that of the interfaces [S. Stank......, vibrational entropy, and lattice specific heat as the material transforms from amorphous, through nanocrystalline, to fully crystallized state. The reported results shed new light on the previously observed anomalies in the vibrational thermodynamics of nanocrystalline materials....

Some aspects of thermally induced martensite in Fe-30% Ni-5% Cu alloy

International Nuclear Information System (INIS)

Guener, M.; Gueler, E.; Yasar, E.; Aktas, H.

2007-01-01

Kinetical, morphological, crystallographical and several thermal properties of thermally induced martensite in the austenite phase of Fe-30% Ni-5% Cu alloy were investigated. Scanning electron microscope (SEM), transmission electron microscope (TEM) and differential scanning calorimetry (DSC) techniques were used during study. Kinetics of the transformation was found to be as athermal type. SEM and TEM observations revealed α' (BCC) martensite formation in the austenite phase of alloy by thermal effect. These thermally induced α' martensites exhibited a thin plate-like morphology with twinnings

The effect of small 4th element alloying additions on the calculated phase stability in the Fe-Cr-Ni system

International Nuclear Information System (INIS)

Watkin, J.S.

1979-01-01

Recent studies into the void swelling of Fe-Cr-Ni alloys have revealed that the magnitude of swelling depends upon alloy constitution and this together with the fact that minor element additions also play a major role in swelling necessitate a detailed knowledge of the influence of small 4th element additions on phase stability. In this paper the effects of additions of Nb, Ti, Al, Mo, Co and C to the Fe-Cr-Ni ternary are assessed by calculation. They confirm the ferritising tendencies of Nb, Ti and Al and the strong austenitising effect of C. Confirmation is also found for the scaling factors in the equivalent Ni and Cr equations in common usage and the paper presents Fe-Cr-Ni ternary sections at 400, 550 and 700 0 C modified for 1 at.% addition of each of the above elements. (orig.) [de

Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

Directory of Open Access Journals (Sweden)

Hao-Hsiang Huang

2011-01-01

Full Text Available The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100 silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of 1m. The single-layer Ni-alloy and CrN coatings deposited at 350∘C were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the corr and corr values ranged from –0.64 to –0.33 V and 1.42×10−5 to 1.14×10−6 A/cm2, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

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

Science.gov (United States)

Geng, Yunlong

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

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.)

Tensile ductility of an AlCoCrFeNi multi-phase high-entropy alloy through hot isostatic pressing (HIP) and homogenization

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhi, E-mail: Zhi.Tang@alcoa.com [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061 (United States); Senkov, Oleg N. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH 45433 (United States); Parish, Chad M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhang, Chuan; Zhang, Fan [CompuTherm LLC, 437 S. Yellowstone Dr., Suite 217, Madison, WI 53719 (United States); Santodonato, Louis J. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wang, Gongyao [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Zhao, Guangfeng; Yang, Fuqian [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Liaw, Peter K., E-mail: pliaw@utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

2015-10-28

The microstructure and phase composition of an AlCoCrFeNi high-entropy alloy (HEA) were studied in as-cast (AlCoCrFeNi-AC, AC represents as-cast) and homogenized (AlCoCrFeNi-HP, HP signifies hot isostatic pressed and homogenized) conditions. The AlCoCrFeNi-AC ally has a dendritric structure in the consisting primarily of a nano-lamellar mixture of A2 (disordered body-centered-cubic (BCC)) and B2 (ordered BCC) phases, formed by an eutectic reaction. The homogenization heat treatment, consisting of hot isostatic pressed for 1 h at 1100 °C, 207 MPa and annealing at 1150 °C for 50 h, resulted in an increase in the volume fraction of the A1 phase and formation of a Sigma (σ) phase. Tensile properties in as-cast and homogenized conditions are reported at 700 °C. The ultimate tensile strength was virtually unaffected by heat treatment, and was 396±4 MPa at 700 °C. However, homogenization produced a noticeable increase in ductility. The AlCoCrFeNi-AC alloy showed a tensile elongation of only 1.0%, while after the heat-treatment, the elongation of AlCoCrFeNi-HP was 11.7%. Thermodynamic modeling of non-equilibrium and equilibrium phase diagrams for the AlCoCrFeNi HEA gave good agreement with the experimental observations of the phase contents in the AlCoCrFeNi-AC and AlCoCrFeNi-HP. The reasons for the improvement of ductility after the heat treatment and the crack initiation subjected to tensile loading were discussed.

Comparison of the two relaxation peaks in the Ti50Ni48Fe2 alloy

International Nuclear Information System (INIS)

Fan Genlian; Zhou Yumei; Otsuka, Kazuhiro; Ren Xiaobing; Suzuki, Tetsuro; Yin Fuxing

2009-01-01

The internal friction (tan δ) and storage modulus of Ti 50 Ni 48 Fe 2 alloy were studied by dynamic mechanical analysis (DMA). On cooling, a broad relaxation peak with tan δ value as high as 0.2 was detected in R-phase. On heating, another relaxation peak with tan δ value of 0.06 was found in B19' martensite. Both relaxation peaks disappeared when the alloy was dehydrogenated in a dynamic vacuum furnace. Thus, the origin of both relaxation peaks was attributed to the interaction between twin boundaries and hydrogen atoms, as recently proved in Ti-Ni-Cu alloy. The direct comparison of these two relaxation peaks in the same sample indicates that the height of relaxation peaks increases with the decreasing of twinning shear.

Magnetic and calorimetric investigations of ferromagnetic shape memory alloy Ni54Fe19Ga27

International Nuclear Information System (INIS)

Sharma, V K; Chattopadhyay, M K; Kumar, Ravi; Ganguli, Tapas; Kaul, Rakesh; Majumdar, S; Roy, S B

2007-01-01

We report results of magnetization and differential scanning calorimetry measurements in the ferromagnetic shape memory alloy Ni 54 Fe 19 Ga 27 . This alloy undergoes an austenite-martensite phase transition in its ferromagnetic state. The nature of the ferromagnetic state, both in the austenite and the martensite phase, is studied in detail. The ferromagnetic state in the martensite phase is found to have higher anisotropy energy as compared with the austenite phase. The estimated anisotropy constant is comparable to that of a well-studied ferromagnetic shape memory alloy system NiMnGa. Further, the present study highlights various interesting features accompanying the martensitic transition (MT). These features suggest the possibility of either a premartensitic transition and/or an inter-MT in this system

Thermodynamic and experimental study on phase stability in nanocrystalline alloys

International Nuclear Information System (INIS)

Xu Wenwu; Song Xiaoyan; Lu Nianduan; Huang Chuan

2010-01-01

Nanocrystalline alloys exhibit apparently different phase transformation characteristics in comparison to the conventional polycrystalline alloys. The special phase stability and phase transformation behavior, as well as the essential mechanisms of the nanocrystalline alloys, were described quantitatively in a nanothermodynamic point of view. By introducing the relationship between the excess volume at the grain boundary and the nanograin size, the Gibbs free energy was determined distinctly as a function of temperature and the nanograin size. Accordingly, the grain-size-dependence of the phase stability and phase transformation characteristics of the nanocrystalline alloy were calculated systematically, and the correlations between the phase constitution, the phase transformation temperature and the critical nanograin size were predicted. A series of experiments was performed to investigate the phase transformations at room temperature and high temperatures using the nanocrystalline Sm 2 Co 17 alloy as an example. The phase constitution and phase transformation sequence found in nanocrystalline Sm 2 Co 17 alloys with various grain-size levels agree well with the calculations by the nanothermodynamic model.

Ab initio and Atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

Science.gov (United States)

Piochaud, J. B.; Becquart, C. S.; Domain, C.

2014-06-01

Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multiscale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe70Cr20Ni10). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT calculations. The point defect properties in the Fe70Cr20Ni10, and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed.

An investigation on hydrogen storage kinetics of nanocrystalline and amorphous Mg2Ni1-xCox (x = 0-0.4) alloy prepared by melt spinning

International Nuclear Information System (INIS)

Zhang Yanghuan; Li Baowei; Ren Huipin; Ding Xiaoxia; Liu Xiaogang; Chen Lele

2011-01-01

Research highlights: → The investigation of the structures of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys indicates that a nanocrystalline and amorphous structure can be obtained in the experiment alloys by melt spinning technology. The substitution of Co for Ni facilitates the glass formation in the Mg 2 Ni-type alloy. And the amorphization degree of the alloys visibly increases with increasing Co content. → Both the melt spinning and Co substitution significantly improve the hydrogen storage kinetics of the alloys. The hydrogen absorption saturation ratio (R t a ) and hydrogen desorption ratio (R t d ) as well as the high rate discharge ability (HRD) increase with rising spinning rate and Co content. The hydrogen diffusion coefficient (D), the Tafel polarization curves and the electrochemical impedance spectra (EIS) measurements show that the electrochemical kinetics notably increases with rising spinning rate and Co content. → Furthermore, all the as-spun alloys, when the spinning rate reaches to 30 m/s, have nearly same hydrogen absorption kinetics, indicating that the hydrogen absorption kinetics of the as-spun alloy is predominately controlled by diffusion ability of hydrogen atoms. - Abstract: In order to improve the hydrogen storage kinetics of the Mg 2 Ni-type alloys, Ni in the alloy was partially substituted by element Co, and melt-spinning technology was used for the preparation of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys. The structures of the as-cast and spun alloys are characterized by XRD, SEM and TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys is tested by an automatic galvanostatic system. The hydrogen diffusion coefficients in the alloys are calculated by virtue of potential-step method. The electrochemical impedance spectrums (EIS) and the Tafel

Negative and positive magnetocaloric effect in Ni-Fe-Mn-Ga alloy

International Nuclear Information System (INIS)

Duan Jingfang; Huang Peng; Zhang Hu; Long Yi; Wu Guangheng; Rongchang Ye; Chang Yongqin; Farong Wan

2007-01-01

The phase transition process and magnetic entropy change ΔS of Ni 54.5 FeMn 20 Ga 24.5 alloy were studied. Substitution of Fe for Ni increases the Curie temperature and decreases the temperature of martensitic phase transition. The transition from ferromagnetic martensitic to ferrormagnetic austenitic state leads to an abrupt increase of magnetization below 0.5T and an abrupt decrease of magnetization above 0.5T. The sign of ΔS changes from positive to negative with increasing the applied field from 0.5 to 2T. The maximal value of the positive magnetic entropy change ΔS is about 3.1J/kgK for the applied field from 0 to 0.5T. The increase of applied field from 1.5T results in a negative ΔS. The peak of negative ΔS is -2.1J/kgK for a field change of 2T

Evaluation of structural, morphological and magnetic properties of CuZnNi (Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4) nanocrystalline ferrites for core, switching and MLCI’s applications

International Nuclear Information System (INIS)

Akhtar, Majid Niaz; Khan, Muhammad Azhar; Ahmad, Mukhtar; Nazir, M.S.; Imran, M.; Ali, A.; Sattar, A.; Murtaza, G.

2017-01-01

The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4 ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics. - Highlights: • Cu substituted

Nanostructured Fe-Cr Alloys for Advanced Nuclear Energy Applications

Energy Technology Data Exchange (ETDEWEB)

Scattergood, Ronald O. [North Carolina State Univ., Raleigh, NC (United States)

2016-04-26

We have completed research on the grain-size stabilization of model nanostructured Fe14Cr base alloys at high temperatures by the addition of non-equilibrium solutes. Fe14Cr base alloys are representative for nuclear reactor applications. The neutron flux in a nuclear reactor will generate He atoms that coalesce to form He bubbles. These can lead to premature failure of the reactor components, limiting their lifetime and increasing the cost and capacity for power generation. In order to mitigate such failures, Fe14Cr base alloys have been processed to contain very small nano-size oxide particles (less than 10 nm in size) that trap He atoms and reduce bubble formation. Theoretical and experimental results indicate that the grain boundaries can also be very effective traps for He atoms and bubble formation. An optimum grain size will be less than 100 nm, ie., nanocrystalline alloys must be used. Powder metallurgy methods based on high-energy ball milling can produce Fe-Cr base nanocrystalline alloys that are suitable for nuclear energy applications. The problem with nanocrystalline alloys is that excess grain-boundary energy will cause grains to grow at higher temperatures and their propensity for He trapping will be lost. The nano-size oxide particles in current generation nuclear alloys provide some grain size stabilization by reducing grain-boundary mobility (Zener pinning – a kinetic effect). However the current mitigation strategy minimizing bubble formation is based primarily on He trapping by nano-size oxide particles. An alternate approach to nanoscale grain size stabilization has been proposed. This is based on the addition of small amounts of atoms that are large compared to the base alloy. At higher temperatures these will diffuse to the grain boundaries and will produce an equilibrium state for the grain size at higher temperatures (thermodynamic stabilization – an equilibrium effect). This would be preferred compared to a kinetic effect, which is not

Effect of iron content on the structure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25} and (AlTi){sub 60-x}Ni{sub 20}Cu{sub 20}Fe{sub x} (x=15, 20) high-entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Fazakas, É., E-mail: eva.fazakas@bayzoltan.hu [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525, P.O.B. 49 (Hungary); Bay Zoltán Nonprofit Ltd., For Applied Research H-1116 Budapest, Fehérvári út 130 (Hungary); Zadorozhnyy, V. [National University of Science and Technology «MISIS», Leninsky prosp., 4, Moscow 119049 (Russian Federation); Louzguine-Luzgin, D.V. [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2015-12-15

Highlights: • Three new refractory alloys namely: Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20}, were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}C{sub u25} Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys are relatively hard and ductile. Being heat treated at 973 K the Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

Strength and low temperature toughness of Fe-13%Ni-Mo alloys

International Nuclear Information System (INIS)

Ishikawa, Keisuke; Maruyama, Norio; Tsuya, Kazuo

1978-01-01

Mechanical tests were made on newly developed Fe-13%Ni-Mo alloys for eryogenic service. The effects of the additional elements were investigated from the viewpoint of the strength and the low temperature toughness. The alloys added by Al, Ti or V have the better balance of these properties. They did not show low temperature brittleness induced by cleavage fracture in Charpy impact test at 77 K. The microfractography showed the utterly dimple rupture patterns on the broken surface of all specimens. It would be supposed that the cleavage fracture stress is considerably higher than the flow stress. These alloys are superior to some commercial structural materials for low temperature use in the balance between the strength at 300 K and the toughness at 77 K. Additionally, it is noted that these experimental alloys have a good advantage in getting high strength and high toughness by the rather simple heat treatment. (auth.)

Effect of cathode vibration and heat treatment on electromagnetic properties of flake-shaped diatomite coated with Ni-Fe alloy by electroplating

Science.gov (United States)

Lan, Mingming; Li, Huiqin; Huang, Weihua; Xu, Guangyin; Li, Yan

2015-03-01

In this paper, flake-shaped diatomite particles were used as forming templates for the fabrication of the ferromagnetic functional fillers by way of electroplating Ni-Fe alloy method. The effects of cathode vibration frequency on the content of Ni-Fe alloy in the coating and the surface morphologies of the coatings were evaluated. The electromagnetic properties of the coated diatomite particles before and after heat treatment were also investigated in detail. The results show that the core-shell flake-shaped diatomite particles with high content of Ni-Fe alloy and good surface qualities of the coatings can be obtained by adjusting cathode vibration frequency. The coated diatomite particles with heat treatment filled paraffin wax composites exhibit a superior microwave absorbing and electromagnetic properties compared to the non-heat treated samples. Additionally, the peaks of reflection loss are found to be able to shift to lower frequency by the heat treatment process, which indicates the heat treatment can adjust microwave absorbing frequency band.

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.)

X-ray fluorescence analysis of Fe - Ni - Mo systems

International Nuclear Information System (INIS)

Belyaev, E.E.; Ershov, A.V.; Mashin, A.I.; Mashin, N.I.; Rudnevskij, N.K.

1998-01-01

Procedures for the X-ray fluorescence determination of the composition and thickness of Fe - Ni - Mo thin films and the concentration of elements in thick films of the Fe - Ni - Mo alloy are developed [ru

Ordering of equiatomic Fe-Ni alloy under irradiation

International Nuclear Information System (INIS)

Penisson, J.M.; Bourret, A.

1975-01-01

The interpretations of many kinetic studies on the ordering of alloys by heat treatments use models based on chemical kinetic equations or statistical models. In these models it is assumed that ordering takes place by a hole process. When ordering occurs under irradiation a strong supersaturation in interstitials and holes exists and the question is to know what defects take part in the ordering process. Thus in the order-disorder transformation in Fe-Ni demonstrated after neutron irradiation it is assumed that only the holes participate in the ordering. To check this hypothesis the above transformation was observed during electron irradiation in an electron microscope at 1MeV. Owing to the strong flux available the ordering takes place fairly quickly ( [fr

Site occupancy of Fe in ternary Ni 75-x

Indian Academy of Sciences (India)

The results of a detailed structural and magnetic study clearly indicate that regardless of the thermal history of the samples, Fe has a strong preference for the Ni sites in Ni-poor (non-stoichiometric) Ni75Al25 alloys. Fe substitution has a profound effect on the nature of magnetism in Ni75Al25.

Structural and magnetic properties of Ni0.8M0.2Fe2O4 (M = Cu, Co) nano-crystalline ferrites

Science.gov (United States)

Vijaya Babu, K.; Satyanarayana, G.; Sailaja, B.; Santosh Kumar, G. V.; Jalaiah, K.; Ravi, M.

2018-06-01

Nano-crystalline nickel ferrites are interesting materials due to their large physical and magnetic properties. In the present work, two kinds of spinel ferrites Ni0.8M0.2Fe2O4 (M = Cu, Co) are synthesized by using sol-gel auto-combustion method and the results are compared with NiFe2O4. The structural properties of synthesized ferrites are determined by using X-ray powder diffraction; scanning electron microscope and Fourier transform infrared spectroscopy. The cation distribution obtained from X-ray diffraction show that cobalt/copper occupies only tetrahedral site in spinel lattice. The lattice constant increases with the substitution of cobalt/copper. The structural parameters like bond lengths, tetrahedral and octahedral edges have been varied with the substitution. The microstructural study is carried out by using SEM technique and the average grain size is increased with nickel ferrite. The initial permeability (μi) is improving with the substitution. The observed g-value from ESR is approximately equal to standard value.

Enhancing pitting corrosion resistance of Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} high-entropy alloys by anodic treatment in sulfuric acid

Energy Technology Data Exchange (ETDEWEB)

Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Shih, H.C. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan (China)], E-mail: hcshih@mx.nthu.edu.tw

2008-12-01

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 {omega}cm{sup 2} as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 {omega}cm{sup 2}). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H{sub 2}SO{sub 4} solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe{sub 1.5}MnNi{sub 0.5} and Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} alloys optimized their surface structures and minimized their susceptibility to pitting corrosion.

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

Energy Technology Data Exchange (ETDEWEB)

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

2014-07-01

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

Novel synthesis of Ni-ferrite (NiFe2O4) electrode material for supercapacitor applications

International Nuclear Information System (INIS)

Venkatachalam, V.; Jayavel, R.

2015-01-01

Novel nanocrystalline NiFe 2 O 4 has been synthesized through combustion route using citric acid as a fuel. Phase of the synthesized material was analyzed using powder X-ray diffraction. The XRD study revealed the formation of spinel phase cubic NiFe 2 O 4 with high crystallinity. The average crystallite size of NiFe 2 O 4 nanomaterial was calculated from scherrer equation. The electrochemical properties were realized by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. The electrode material shows a maximum specific capacitance of 454 F/g with pseudocapacitive behavior. High capacitance retention of electrode material over 1000 continuous charging-discharging cycles suggests its excellent electrochemical stability. The results revealed that the nickel ferrite electrode is a potential candidate for energy storage applications in supercapacitor

Effect of conventional and subzero treating on the mechanical properties of aged martensitic Fe-12 wt.% Ni-X wt.% Mn alloys

International Nuclear Information System (INIS)

Nedjad, S. Hossein; Nili-Ahmadabadi, M.; Mahmudi, R.; Farhangi, H.

2003-01-01

Fe-Ni-Mn maraging alloys are suffering from sever embrittlement after aging. Mechanism of the embrittelement has not been well understood yet. Segregation of Mn atoms or formation of Austenite particles at prior Austenite grain boundaries (PAGBs) have been reported as embrittelement mechanisms while it remains controversial now. For better understanding of embrittelement behavior, effect of subzero treating after aging, double aging and modification of alloy composition on the mechanical properties and fracture behavior were investigated. Alloys of chemical compositions Fe-11.9 wt.% Ni-6.3 wt.% Mn and Fe-10.5 wt.% Ni-5.8 wt.% Mo-3 wt.% Mn were studied. Double solution annealing was performed at 1223 and 1093 K for 3.6 ks followed by water quenching. After aging at 723 K for 0.9 ks (under aging) and 172.8 ks (over aging), tensile properties of specimens heat treated conventionally and cryogenically were measured. Double aging was done at 623 K for 3.6 ks followed by a step aging at 753, 783 and 803 K. Aging behavior and tensile properties of Fe-10.5 wt.% Ni-5.8 wt.% Mo-3 wt.% Mn were investigated after aging at 773 K. Results showed that alloy modification yields reasonable tensile properties while subzero treatment and double aging couldn't improve tensile properties. An insight toward more investigation of the embrittelement mechanism was made on the basis of this study

The chemical composition and parameters of production processes influence on structure and properties of W-Ni-Fe alloys

International Nuclear Information System (INIS)

Majewski, T.; Przetakiewicz, W.

2000-01-01

Tungsten heavy alloys, i.e. tungsten based metal-matrix composites are characterized by unique properties, because except their high hardness, strength and density, they also possess excellent ductility, impact strength, machinability and corrosion resistance. This combination of properties makes these alloys suitable for wide range of engineering applications, e.g. in the mechanical engineering, in the mining, sport and medicine and also in the armament and aviation. Production process of these materials consists of many phases and it is very difficult to accomplish, because properties of heavy alloys are extremely sensitive to processing history. In this article dependence of chemical composition of mixture of powders on structure and mechanical properties of W-Ni-Fe alloys was determined. It was found that increase of tungsten contents and Ni/Fe ratio causes reduction of ductility and increase of growth rate of tungsten particle. There is the maximum ultimate tensile strength of W-Ni-Fe alloys with content of tungsten 93%. The study also presents relationship between these properties and succeeding parameters of production process: composition of sintering atmosphere, time and temperature following heat treatment and plastic working. Using a wet hydrogen atmosphere (with high dew point) causes reduction of porosity and improvement of mechanical properties. With sintering temperature above 1500 o C these parameters decrease. If the sintering time is elongated above 1 h also density and mechanical properties of heavy alloys decrease. Tungsten heavy alloys are also used for production of kinetic energy penetrators and so properties for different range of strain rates were compared. It was found that yield and failure strengths increase with increasing strain rate, failure strain decreases with increasing strain rate. This information can help in optimization the production process of such composites. (author)

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

Martensite. gamma. -->. cap alpha. transformations in various purity Fe-Ni-Mo alloys

Energy Technology Data Exchange (ETDEWEB)

Nikitina, I.I.; Rozhkova, A.S. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))

1982-06-01

Kinetics of isothermal and athermal ..gamma.. ..-->.. ..cap alpha.. martensitic transitions in the Fe-25.5% Ni-4.5% Mo alloys with different degree of purity is studied. The determinant role of dislocation blocking by interstitials in stabilization of isothermal martensitic transformation is displayed. Presented are the data permitting to consider that the character of martensitic transition kinetics is determined by the ratio of the process moving force and resistance to microplastic deformation.

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

International Nuclear Information System (INIS)

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

1993-01-01

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

Effect of current density and pH in obtaining the Ni-Fe alloy by electrodeposition; Efeito da densidade de corrente e pH na obtencao da liga Ni-Fe por eletrodeposicao

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Jose Anderson Machado; Raulino, Anamelia de Medeiros Dantas; Raulino, Jose Leonardo Costa; Campos, Ana Regina Nascimento; Prasad, Shiva; Santana, Renato Alexandre Costa de, E-mail: jmo.anderson@gmail.com, E-mail: anameliadantas@yahoo.com.br, E-mail: leonardo.jcr@hotmail.com, E-mail: arncampos@yahoo.com.br, E-mail: prasad@deq.ufcg.edu.br, E-mail: renatoacs@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Lab. de Eletroquimica e Corrosao

2017-01-15

Metallic coatings can be applied for different purposes, for example to improve the mechanical, catalytic, anti corrosive properties or simply to improve the decorative appearance. In the work the Fe-Ni alloys have been obtained by electrodeposition process using a simple electrolytic bath containing the reagents, nickel sulfate, iron sulfate and sodium tartrate. A complete experimental design 2{sup 2} , associated with the response surface methodology (RSM) technique was used as optimization tool. Chemical composition, current efficiency, surface morphology and electrochemical corrosion measures were performed. It was observed that a decrease in the pH favored an increase in iron and decrease in nickel contents in the alloy. The iron content influenced the alloy morphology. The best experiment showed an average corrosion resistance 5471.5 Ω.cm² and a corrosion current density 4.814x10{sup -6} A/cm². This experiment presented a composition of 70 wt% Ni and 30 wt% Fe in the alloy and an average deposition current efficiency of 58.7%. (author)

Nanophase intermetallic FeAl obtained by sintering after mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

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

2009-08-26

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

Ab initio and atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

International Nuclear Information System (INIS)

Piochaud, J.B.; Becquart, C.S.; Domain, C.

2013-01-01

Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multi-scale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe 70 Cr 20 Ni 10 ). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT (Density Functional Theory) calculations. The point defect properties in the Fe 70 Cr 20 Ni 10 , and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation (TNES) and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed. Preliminary results show that it is the solute- grain boundaries interactions which drive TNES

The use of nitrogen to improve the corrosion resistance of FeCrNiMo alloys for the chemical process industries

Energy Technology Data Exchange (ETDEWEB)

Kearns, J.R.; Deverell, H.E.

1987-06-01

The addition of 0.1 to 0.25 wt% nitrogen to austenitic alloys has been shown to enhance resistance to localized corrosion in oxidizing chloride and reducing acid solutions. Further tests of FeCrNiMo alloys assess the effects of nitrogen additions on: mechanical properties, chloride and caustic stress corrosion cracking resistance, passivation characteristics, and general corrosion rates in various acid, alkali, and salt solutions pertinent to the chemical process industries. The precipitation of chromium-rich secondary phases was retarded by solid solution additions of 0.1 to 0.25 wt% nitrogen. The corrosion resistance of FeCrNiMoN alloys in the welded condition was improved by using shield-gas mixtures of argon and 2.5 to 5.0 wt% nitrogen.

Bimodal microstructure and deformation of cryomilled bulk nanocrystalline Al-7.5Mg alloy

International Nuclear Information System (INIS)

Lee, Z.; Witkin, D.B.; Radmilovic, V.; Lavernia, E.J.; Nutt, S.R.

2005-01-01

The microstructure, mechanical properties and deformation response of bimodal structured nanocrystalline Al-7.5Mg alloy were investigated. Grain refinement was achieved by cryomilling of atomized Al-7.5Mg powders, and then cryomilled nanocrystalline powders blended with 15 and 30% unmilled coarse-grained powders were consolidated by hot isostatic pressing followed by extrusion to produce bulk nanocrystalline alloys. Bimodal bulk nanocrystalline Al-7.5Mg alloys, which were comprised of nanocrystalline grains separated by coarse-grain regions, show balanced mechanical properties of enhanced yield and ultimate strength and reasonable ductility and toughness compared to comparable conventional alloys and nanocrystalline metals. The investigation of tensile and hardness test suggests unusual deformation mechanisms and interactions between ductile coarse-grain bands and nanocrystalline regions

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)

The effect of thermomechanical processing on the microstructure and mechanical properties of the nanocrystalline TiNiCo shape memory alloy

International Nuclear Information System (INIS)

Mohammad Sharifi, E.; Kermanpur, A.; Karimzadeh, F.

2014-01-01

The effect of thermomechanical processing comprising cold rolling followed by annealing on the microstructural evolution and mechanical behavior of the Ti 50 Ni 48 Co 2 shape memory alloy was investigated. The annealed specimens were subjected to cold rolling at room temperature with various thickness reductions up to 70%. Transmission electron microscopy revealed that the initial deformation mechanism of Ti 50 Ni 48 Co 2 alloy during cold rolling was stress-induced martensitic transformation followed by plastic deformation of martensite via dislocation slip and subsequent martensite to austenite transformation via the reverse transformation after unloading. Microstructural investigations showed that by increasing the cold deformation, a high density of dislocations is accumulated, leading gradually to nanocrystallization and amorphization. After annealing at 400 °C for 1 h, the amorphous phase formed in the cold rolled specimens was completely crystallized and an entirely nanocrystalline structure was achieved. Results showed that the stress–strain curves of the cold rolled specimens exhibited plastic deformation of austenite without the stress plateau region. However, the stress plateau appeared in the stress–strain curves of the annealed specimens, whose stress level and length were increased with increasing thickness reduction

Magnetic properties of the CrMnFeCoNi high-entropy alloy

International Nuclear Information System (INIS)

Schneeweiss, Oldřich; Friák, Martin; Masaryk University, Brno; Dudová, Marie; Holec, David

2017-01-01

In this paper, we present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ± 0.001 emu T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μ B ), while the local moments of Ni atoms effectively vanish. Finally, these results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

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.

Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

International Nuclear Information System (INIS)

Baldenebro-Lopez, F.J.; Herrera-Ramírez, J.M.; Arredondo-Rea, S.P.; Gómez-Esparza, C.D.; Martínez-Sánchez, R.

2015-01-01

Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying

Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

Energy Technology Data Exchange (ETDEWEB)

Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

2015-09-15

Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

International Nuclear Information System (INIS)

Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

1998-01-01

The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

The role of Zr and Nb in oxidation/sulfidation behavior of Fe-Cr-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Natesan, K. (Argonne National Lab., IL (USA)); Baxter, D.J. (Argonne National Lab., IL (USA) INCO Alloy Ltd., Hereford, England (UK))

1990-11-01

05Structural Fe-Cr-Ni alloys may undergo rapid degradation at elevated temperatures unless protective surface oxide scales are formed and maintained. The ability of alloys to resist rapid degradation strongly depends on their Cr content and the chemistry of the exposure environment. Normally, 20 wt % Cr is required for service at temperatures up to 1000{degree}C; the presence of sulfur, however, inhibits formation of a protective surface oxide scale. The oxidation and sulfidation behavior of Fe-Cr-Ni alloys is examined over a wide temperature range (650 to 1000{degree}C), with particular emphasis on the effects of alloy Cr content and the radiation of reactive elements such as Nb and Zr. Both Nb and Zr are shown to promote protective oxidation behavior on the 12 wt % Cr alloy in oxidizing environments and to suppress sulfidation in mixed oxygen/sulfur environments. Additions of Nb and Zr at 3 wt % level resulted in stabilization of Cr{sub 2}O{sub 3} scale and led to a barrier layer of Nb- or Zr-rich oxide at the scale/metal interface, which acted to minimize the transport of base metal cations across the scale. Oxide scales were preformed in sulfur-free environments and subsequently exposed to oxygen/sulfur mixed-gas atmospheres. Preformed scales were found to delay the onset of breakaway corrosion. Corrosions test results obtained under isothermal and thermal cycling conditions are presented. 58 refs., 55 figs., 8 tabs.

High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

Energy Technology Data Exchange (ETDEWEB)

Tracy, Cameron L.; Park, Sulgiye; Rittman, Dylan R.; Zinkle, Steven J.; Bei, Hongbin; Lang, Maik; Ewing, Rodney C.; Mao, Wendy L.

2017-05-25

High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.

Analysis of Microstructure and Sliding Wear Behavior of Co1.5CrFeNi1.5Ti0.5 High-Entropy Alloy

Science.gov (United States)

Lentzaris, K.; Poulia, A.; Georgatis, E.; Lekatou, A. G.; Karantzalis, A. E.

2018-04-01

Α Co1.5CrFeNi1.5Ti0.5 high-entropy alloy (HEA) of the well-known family of CoCrFeNiTi has been designed using empirical parameters. The aim of this design was the production of a HEA with fcc structure that gives ductile behavior and also high strength because of the solid solution effect. The VEC calculations (8.1) supported the fcc structure while the δ factor calculations (4.97) not being out of the limit values, advised a significant lattice distortion. From the other hand, the ΔΗ mix calculations (- 9.64 kJ/mol) gave strong indications that no intermetallic would be formed. In order to investigate its potential application, the Co1.5CrFeNi1.5Ti0.5 HEA was prepared by vacuum arc melting and a primary assessment of its surface degradation response was conducted by means of sliding wear testing using different counterbody systems for a total sliding distance of 1000 m. An effort to correlate the alloy's wear response with the microstructural characteristics was attempted. Finally, the wear behavior of the Co1.5CrFeNi1.5Ti0.5 HEA was compared with that of two commercially used wear-resistant alloys. The results obtained provided some first signs of the high-entropy alloys' better wear performance when tested under sliding conditions against a steel ball.

Radiation damage studies of the FeNi alloys, pure and with impurities, by measuring magnetic properties

International Nuclear Information System (INIS)

Sciani, Valdir

1978-01-01

Radiation damage studies are interesting from various points of view, but they have two main aspects, fundamental and technological. The void formations in metals and alloys during irradiation with high energy particles is a problem of interest in Nuclear Technology. The supersaturation of vacancies is one condition for a void formation, which results in swelling as well as in changes of mechanical, electrical and magnetic properties of materials used in power reactor. Isothermal and linear annealings have been performed before, during and after irradiation with neutrons from the IEAR-1 reactor, between 400 and 500 deg C in argon atmosphere. The samples used have a following nominal compositions: Fe Ni (50 - 50% at); FeNiMo ( 50 - 50% at + 50 ppm); FeNiCr ( 49,95 - 49,95 - 0,1% at); FeNiCr (49,75 - 49,75 - 0,5% at). The initial permeability disaccommodation has been followed by Magnetic After Effect (MAE) Method, which permitted the determination of the time constants, activation energies and Curie points. From these parameters it was possible to evaluate the super saturation of vacancies, showing that the MAE can be used as practical method for the election of nuclear materials without attaining high fluences. Some observations have been performed for the sample FeNiCr (49,75 - 49,75 - 0,5% at), which showed pronounced anomalies in the initial permeability during linear annealing.(author)

Superelasticity, corrosion resistance and biocompatibility of the Ti–19Zr–10Nb–1Fe alloy

Energy Technology Data Exchange (ETDEWEB)

Xue, Pengfei [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Yan, E-mail: liyan@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Li, Kangming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University, Beijing 100191 (China); Zhang, Deyuan [Life Tech Scientific Corporation, Shenzhen 518057 (China); Zhou, Chungen [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2015-05-01

Microstructure, mechanical properties, superelasticity and biocompatibility of a Ti–19Zr–10Nb–1Fe alloy are investigated. X-ray diffraction spectroscopy and transmission electron microscopy observations show that the as-cast Ti–19Zr–10Nb–1Fe alloy is composed of α′ and β phases, but only the β phase exists in the as-rolled and as-quenched alloys. The tensile stress–strain tests indicate that the as-quenched alloy exhibits a good combination of mechanical properties with a large elongation of 25%, a low Young's modulus of 59 GPa and a high ultimate tensile stress of 723 MPa. Superelastic recovery behavior is found in the as-quenched alloy during tensile tests, and the corresponding maximum of superelastic strain is 4.7% at the pre-strain of 6%. A superelastic recovery of 4% with high stability is achieved after 10 cyclic loading–unloading training processes. Potentiodynamic polarization and ion release measurements indicate that the as-quenched alloy shows a lower corrosion rate in Hank's solution and a much less ion release rate in 0.9% NaCl solution than those of the NiTi alloys. Cell culture results indicate that the osteoblasts' adhesion and proliferation are similar on both the Ti–19Zr–10Nb–1Fe and NiTi alloys. A better hemocompatibility is confirmed for the as-quenched Ti–19Zr–10Nb–1Fe alloy, attributed to more stable platelet adhesion and small activation degree, and a much lower hemolysis rate compared with the NiTi alloy. - Highlights: • A stable superelastic strain of 4.0% is achieved for the Ti–19Zr–10Nb–1Fe alloy. • The ion release rates of Ti–19Zr–10Nb–1Fe are much lower than that of Ni in NiTi. • Ti–19Zr–10Nb–1Fe has a similar cytocompatibility compared with the NiTi alloy. • Ti–19Zr–10Nb–1Fe exhibits a better hemocompatibility than the NiTi alloy.

Structural and transport properties of nanocrystalline MnFe/sub 2/O/sub 4/ synthesized by co-precipitation method

International Nuclear Information System (INIS)

Akhtar, M.J.; Younas, M.

2012-01-01

The nanocrystalline ferrites with spinel structures have been the focus of scientific investigation and received continuous interest in recent decades. The structural and electrical properties of these materials have become an important area of research and are attracting considerable interest due to broad range of applications. Spinel ferrites have been shown to exhibit interesting dielectric properties in the nanocrystalline form in comparison to the corresponding bulk materials. Structural and electrical properties of nanocrystalline MnFe/sub 2/O/sub 4/ were investigated. X-ray diffraction and X-ray absorption fine structure spectroscopy results showed that nanocrystalline MnFe/sub 2/O/sub 4/ had cubic symmetry with 80% inversion. shows the X-ray absorption near edge structure (XANES) spectra of MnFe/sub 2/O/sub 4/ and Zn/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/, used as model compounds. The electrical transport properties were investigated by employing impedance spectroscopy. It was observed that the dielectric constant decreased with the increase in frequency. The effects of frequency on dielectric properties were more prominent in the low frequency region, where dielectric constant increased as temperature was increased. (Orig./A.B.)

Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe-Ni, and Co-Ni doped tungsten oxide

International Nuclear Information System (INIS)

Wang Shiliang; He Yuehui; Zou Jou; Wang Yong; Huang Han

2009-01-01

Numbers of W whiskers were obtained by reducing Ni, Ni-Fe, and Ni-Co doped tungsten oxide in a mixed atmosphere of humid H 2 and N 2 . The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni-W, Fe-Ni, or Co-Ni-W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe-Ni, or Co-Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO 2 (OH) 2 .

Comparison of the irradiation effects on swelling and microstructure in commercial alloy A-286 and a simple Fe--25 Ni--15Cr gamma prime hardened alloy