Ni3Fe Phase Research Articles

Studies of electrical resistivity and magnetic properties of CuFe and CuNiFe films prepared by magnetron sputtering

The Cu-Fe binary alloys exhibit severe elemental segregation, resulting in an inhomogeneous microstructure, which leads to differences in microregion magnetic properties, thus affecting their application. Employing magnetron sputtering to produce films is advantageous for achieving a consistent dispersion of Fe within the Cu matrix. Furthermore, the addition of Ni will result in a more uniform distribution of Fe and facilitate the formation of the ferromagnetic Ni3Fe phase. In this study, Cu100−xFex and Cu100−x(Ni3/4Fe1/4)x series films were prepared by magnetron sputtering technique. The magnetic properties of films are closely related to their ferromagnetic element content. An increase in the content of ferromagnetic elements leads to an improvement in the saturation magnetization (MS) strength and a decrease in the coercivity (HC). The formation of Fe-Fe pairs is more favorable for magnetic properties compared to Ni-Fe pairs. Meanwhile, by comparing with bulk alloys, the distribution of the magnetic elements severely affects the magnetic properties. Moreover, the resistivity of Cu100−xFex films (20.3–96.7 μΩ cm) is much higher than that of Cu100−x(Ni3/4Fe1/4)x films (15.6–60.6 μΩ cm), which depends on the magnetic properties. This study systematically analyzes the effect of the content and distribution of magnetic elements on magnetic and electrical properties.

Effect of heat treatment on microstructure and properties of CrMnFeCoNiMo high entropy alloy coating

In this paper, CrMnFeCoNiMo high entropy alloy coating was prepared on 304 stainless steel by plasma cladding technology. The effects of different heat treatment processes on the microstructure, hardness, wear resistance and corrosion resistance of high entropy alloy coatings were studied. The XRD and SEM images of the coating show that the phase structure is mainly Ni–Cr–Co–Mo phase. The impurity phase-[CrFe] solid solution and Ni3Fe phase will be formed between 950 °C and 1050 °C. The homogenization effect of the coating composition is more excellent under the heat treatment conditions of 950 °C and more than 1 h holding time. The hardness of the coating is relatively high at 850 °C heat treatment temperature and holding for 1 h, which is 670 HV0.2. When the temperature rises to 950 °C and 1050 °C, the hardness of the coating decreases. The coating has relatively high wear resistance at 950 °C heat treatment temperature and holding for 1 h, and the friction coefficient is about 0.27. Moreover, under this heat treatment condition, the surface composition of the coating is uniform and the corrosion resistance is good. The self-corrosion current is 1.325 × 10−7 A and the self-corrosion potential is −0.202 V.

Influence of Powder Mass Flow Rates on Wear Resistance and Impact Toughness of Inconel 718 Surface Coatings

Optimum laser cladding processing parameters were obtained based on the study of various powder mass flow rates for the repair of 27SiMn steel parts using Inconel 718 powder. In this study, fusion coating process parameters were set according to the influence of powder mass flow rates on fusion coating properties. The cross-sectional microstructure, X-ray diffraction patterns, micro-hardness distribution, friction, wear properties, impact properties, and fracture morphology of the clad layers were investigated for the various process parameters. The results indicate that the volume fraction for the Ni3Fe phase increases and then decreases as the powder mass flow rate increases. The micro-hardness, friction properties, and impact properties of the samples followed the same trend as those of Ni3Fe. At powder mass flow rates up to 20 g/min, microstructures in the cladding layer tended to be uniform with microstructures with fine grains, and micro-hardness and impact toughness reached maximum values of 328.2 HV0.5 and 45.4 J/cm2, respectively, which show better mechanical properties and wear resistance.

Temperature influence on NiFeMo nanoparticles magnetic properties and their viability in biomedical applications.

NiFeMo alloy nanoparticles were synthesized by co-precipitation in the presence of organic additives. Nanoparticles thermal evolution shows that there is a significant increase in the average size (from 28 to 60 nm), consolidating a crystalline structure of the same type as the Ni3 Fe phase but with lattice parameter a=0.362 nm. Measurements of magnetic properties follow this morphological and structural evolution increasing saturation magnetization (Ms) by 578% and reducing remanence magnetization (Mr) by 29%. Cell viability assays on as-synthesized revealed that nanoparticles (NPs) are not cytotoxic up to a concentration of 0.4μg/mL for both non-tumorigenic (fibroblasts and macrophages) and tumor cells (melanoma).

Ni-Fe-Al LDH derived Ni[sbnd]Fe nanosheet for green diesel production from lipid hydrotreatment

In order to deal with the deficiency of active sites in Ni catalyst, NiFe nanosheet (Ni-Fe/Al2O3-NS) catalyst was synthesized by using Ni-Fe-Al LDH as the precursor. The catalyst was further utilized in the lipid hydrotreatment for green diesel production. With a lamellar structure and large Ni loading (more than 60%), the Ni-Fe/Al2O3-NS catalyst possessed abundant Ni sties with high dispersion, large surface area, and strong acidity. Moreover, in Ni-Fe/Al2O3-NS the highly active Ni3Fe phase was formed, which promoted the decarbonylation route in hydrotreatment. The Ni-Fe/Al2O3-NS catalyst achieved 98.7% conversion with 98.1% alkane yield in oleic acid hydrotreatment under very mild conditions (220 °C, 2 MPa of hydrogen pressure, 3 h). The catalytic performance of Ni-Fe/Al2O3-NS was much higher than traditional Ni-Fe/Al2O3 and other catalysts reported in current related studies.

Effect of laser powers on the mechanical properties 27SiMn steel with Inconel 718 cladding coatings

In order to know the influence of laser power on the steel (27SiMn) used for repairing the column with Inconel 718 powder materials, and to obtain the optimal laser power parameters with the best mechanical properties of cladding layer, the microstructure, tensile properties and fracture morphology of the Inconel 718 alloy under three laser powers (1800 W, 2100 W and 2400 W) were investigated by using the single-factor variable method, keeping the scanning speed, powder feeding amount and spot diameter unchanged. The results show that with increase of laser power the mechanical properties of the Inconel 718 alloy coating prepared on the surface for the column steel gradually decreased, and the mechanical properties were the best when the laser power is 1800 W. The yield strength of Inconel 718 alloy coating prepared at 1800 W was 61.7% higher than that of the substrate, and its value is 970 MPa. The elongation is reduced by 50% compared with the substrate, and its value is 7%. The microstructure of 27SiMn steel with cladding coating is (Ni, Fe, Cr) phase and Ni3Fe phase, and the microstructure of the coating is mainly composed of uniform cellular crystals. This study provides a valuable reference for the additive manufacturing of industrial materials of 27SiMn steel with laser-cladding coating.

Optimization of electrodeposition nanocrytalline Ni-Fe alloy coatings for the replacement of Ni coatings

Fabricating nanocrystalline Ni-Fe alloy coatings with excellent brightness and corrosion resistance could reduce the use of Ni and benefit economically. Nanocrystalline Ni-Fe alloy coatings were electrodeposited on steel substrates and the coatings with 34.55% Fe content were achieved at the optimized conditions with the current efficiency high up to 80.30%. The electrodeposition behavior of Ni-Fe coatings was investigated by cyclic voltammetry (CV), chronopotentiometry and chronoamperometry. CV tests illustrate that Ni2+ and Fe2+ are co-electrodeposited to form single phase and the deposition of Ni is inhibited by the presence of Fe2+ while the deposition of Fe is boosted by the Ni2+ according to chronopotentiometry. The nucleation and growth of nanocrystalline Ni-Fe alloy coatings is 3D diffusion-controlled instantaneous nucleation process. Intermetallic compound, namely Ni3Fe phase, was formed according to XRD analysis and TEM analysis, while the mean grain size is 4.79 nm. SEM and AFM images demonstrate that nanocrystalline and compact surface were fabricated and the roughness is lower than 5 nm, better than pure Ni coating. Due to the nanocrystalline and compact surface, the icorr and Rct of nanocrystalline Ni-Fe alloy coating are 0.7544 μA cm−2 and 8560 Ω respectively, indicating that Ni-Fe alloy coating is of good corrosion resistance.

Microstructure Evolution and Mossbauer Spectroscopy Research of Nanostructured Ni3 Fe Intermetallic

Nanocrystalline Ni75Fe25 (Ni3Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni3Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni3Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni3Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni3Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.

A comparative study of Ni75Fe25 microcomponents fabricated by microelectroforming and micromolding

Abstract NiFe alloy microcomponents are widely used in electromagnetic devices and microelectromechanical systems due to high saturation magnetization and low coercivity. In this paper, freestanding Ni75Fe25 microcomponents are fabricated by both microelectroforming and micromolding. The microstructure, microhardness, and magnetic property of Ni75Fe25 microcomponents fabricated by the two methods are systematically investigated. The microstructure is characterized by X-ray diffraction, transmission electron microscopy, and electron backscatter diffraction. The magnetic property is examined by a vibrating sample magnetometer. The formability of those two methods is evaluated by the minimum feature size and maximum aspect ratio that can be achieved. The results show that nanocrystalline and microcrystalline Ni75Fe25 microcomponents with a FCC Ni3Fe phase are fabricated by microelectroforming and micromolding, respectively. Compared with micromolded Ni75Fe25 microcomponents, microelectroformed ones have higher dimensional precision, lower surface roughness, greater microhardness, and higher saturation magnetization because of the nanosized grains, whereas micromolded Ni75Fe25 microcomponents have smaller feature size, larger aspect ratio, and lower coercivity.

Efficient Polysulfide Redox Enabled by Lattice-Distorted Ni3Fe Intermetallic Electrocatalyst-Modified Separator for Lithium-Sulfur Batteries.

Exploring efficient electrocatalysts for lithium-sulfur (Li-S) batteries is of great significance for the sulfur/polysulfide/sulfide multiphase conversion. Herein, we report nickel-iron intermetallic (Ni3Fe) as a novel electrocatalyst to trigger the highly efficient polysulfide-involving surface reactions. The incorporation of iron into the cubic nickel phase can induce strong electronic interaction and lattice distortion, thereby activating the inferior Ni phase to catalytically active Ni3Fe phase. Kinetics investigations reveal that the Ni3Fe phase promotes the redox kinetics of the multiphase conversion of Li-S electrochemistry. As a result, the Li-S cells assembled with a 70 wt % sulfur cathode and a Ni3Fe-modified separator deliver initial capacities of 1310.3 mA h g-1 at 0.1 C and 598 mA h g-1 at 4 C with excellent rate capability and a long cycle life of 1000 cycles at 1 C with a low capacity fading rate of ∼0.034 per cycle. More impressively, the Ni3Fe-catalyzed cells exhibit outstanding performance even at harsh working conditions, such as high sulfur loading (7.7 mg cm-2) or lean electrolyte/sulfur ratio (∼6 μL mg-1). This work provides a new concept on exploring advanced intermetallic catalysts for high-rate and long-life Li-S batteries.

Fishnet-like Ni–Fe–N co-modified graphene aerogel catalyst for highly efficient oxygen reduction reaction in an alkaline medium

The bimetallic nanoparticles of Ni and Fe co-modified reduced graphene oxide (rGO) aerogel were prepared by a fishnet-like one-step hydrothermal method, and the nitrogen atoms were successfully doped to the carbon layers with heat treatment of ammonia. By SEM and TEM, it could be observed that the rGO aerogel is a porous structure with particles of metal uniformly distributed on carbon sheets, and the sizes of nanoparticles were approximately 20–100 nm. The Raman results indicated that the GO was successfully reduced by ethylene glycol in the hydrothermal process. XPS results showed that nitrogen was introduced to rGO nanosheets, and Ni–Fe–NrGO possessed the higher contents of pyridinic N and graphitic N. XRD results suggested the Ni3Fe phase exists in the Ni–Fe–NrGO, which was consistent with EDX results. The electro-catalyzed oxygen reduction reaction (ORR) properties were evaluated by a rotating disk electrode (RDE). The Ni–Fe–NrGO sample showed synergistic effect with a relatively higher onset potential and diffusion-limiting current density of approximately 4.01 mA cm−2, with an electron transfer number close to 4, and exhibited an excellent ORR performance compared with the commercial Pt/C electro-catalyst.

STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF THIN LAYERS OF BINARY Ni–Fe ALLOYS ELECTRODEPOSITED BY TWO DIFFERENT BATHS: ACID AND IONIC LIQUID

The deposition of Ni–Fe thin layers in boric acid and ionic liquid ([BuMePyr][Tf2N]) baths were successfully prepared. The obtained materials have been characterized by X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX) and SEM. Meanwhile, these materials were carried out by chronoamperometry or chronopotentiometry by varying the intensity of the current and the deposition potential. The results indicate that the coatings of Ni–Fe alloys were successfully obtained by electroplating on the copper substrates, and the alloys composition shows irregular behavior with polarization. The nickel content in the samples is in the range of 55–90%, but the iron content ranges from 10–30%, when potential deposits were varied from [Formula: see text]2[Formula: see text]V to [Formula: see text]4[Formula: see text]V vs Ni electrode. The results also showed that the thin layers are monophased; they contain the Ni3Fe phase. Further, SEM images of Ni–Fe alloys show the different shapes of particles.

Structural modifications of thin magnetic Permalloy films induced by ion implantation and thermal annealing: A comparison

We report the structural properties of thin magnetic Permalloy films treated by two different methods: broad beam Ga+ ion implantation at an energy of 30keV as well as annealing at different temperatures under ultrahigh vacuum. Transmission electron microscopy imaging and X-ray diffraction measurements have demonstrated that both ion implantation and annealing (above 300°C) lead to further material crystallization and crystallite growth. Whereas annealing (above 400°C) leads to a strain-free state with an almost constant lattice parameter and to a further enhancement of the initial (111) texture, ion beam implantation boosts the growth of small, arbitrarily oriented crystallites and leads to an linear increase in the lattice parameter, introducing microstrain into the sample. The observed decrease in the saturation magnetization for the implanted samples is mainly attributed to the presence of the non-magnetic Ga atoms incorporated in the Permalloy film itself. The increase in the saturation magnetization for the samples annealed at temperatures above 500°C is explained by an arising dewetting effect since no ordered Ni3Fe phase was detected with anomalous X-ray diffraction.

Exchange bias magnetism in films of NiFe/(Ni,Fe)O nanocrystallite dispersions

Ni3Fe/(Ni,Fe)O thin films having a nanocrystallite dispersion morphology were prepared by a reactive ion beam-assisted deposition technique. The crystallite sizes of these dispersion-based films were observed to decrease from 8.4 ± 0.3 nm to 3.4 ± 0.3 nm as the deposition flow-rate increased from 2.78% to 7.89% O2/Ar. Thin film composition was determined using selective area electron diffraction images and Multislice simulations. Through a detailed analysis of high resolution transmission electron microscopy images, the nanocrystallites were determined to be Ni3Fe (a ferromagnet), NiO, and FeO (both antiferromagnets). It was determined that the interfacial molar Ni3Fe ratio in the nanocrystallite dispersions increased slightly at first, then decreased as the oxygen content was increased; at 7.89% O2/Ar, the interfacial molar ratio was essentially zero (only NiO and FeO remained). For nanocrystallite dispersion films grown with O2/Ar flow-rate greater than 7.89%, no interfacial (intermixed) Ni3Fe phase was detected, which resulted in no measurable exchange bias. Comparing the exchange bias field between the nanocrystallite dispersion films at 5 K, we observed a decrease in the magnitude of the exchange bias field as the nanocrystallite size decreased. The exchange bias coupling for all samples measured set in at essentially the same temperature (i.e., the exchange bias blocking temperature). Since the ferromagnetic/anti-ferromagnetic (FM/AFM) contact area in the nanocrystallite dispersion films increased as the nanocrystallite size decreased, the increase in the magnitude of the exchange bias could be attributed to larger regions of defects (vacancies and bond distortions) which occupied a significant portion of the FM/AFM interfaces in the nanocrystallite dispersion films.

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

A report on the systematic study of the changes in the phase composition, morphology, and magnetic properties of the Fe–Ni alloy is presented. Structure studies based on the X-ray diffraction and transmission electron microscopy reveal that the step-wise alloying by high energy ball milling for time up to 6000min proceeds in three stages: (i) solid state diffusion of Ni into bcc-Fe, (ii) the ongoing diffusion of Ni into bcc-Fe and simultaneous diffusion of Fe into fcc-Ni, and (iii) structural transformation of bcc-FeNi into fcc-NiFe and final formation of the Ni3Fe phase. Except for ferromagnetic phases, a small contribution of the paramagnetic component is detected by Mössbauer spectrometry. The alloying process is accompanied by an initial rapid decrease in crystallite size followed by a sluggish decrease down to the mean final size of 12nm. The changes in the grain size and phase compositions are reflected in magnetic characteristics. The results yielded from the Henkel graphs confirm a dominance of the negative particle interactions.

A Mössbauer investigation of the formation of the Ni3Fe phase by high energy ball milling and subsequent annealing

Ni–Fe alloys obtained by high energy ball milling of pure Ni and Fe powders were investigated by 57Fe Mössbauer spectrometry. The Mössbauer spectra of the as-milled powders were fitted with two magnetic contributions, corresponding to the α-Fe and Ni–Fe phases. As the milling time increases, the relative intensity of the α-Fe contribution decreases while that of the Ni–Fe phase increases. After about 10 h of milling, a Ni–Fe phase with a composition close to Ni3Fe is obtained and no more α-Fe phase is present in the powder. The contribution of the Ni–Fe phase is carefully investigated, and the value of the hyperfine field shows that Ni3Fe is formed in a disordered state. The influence of an annealing treatment at 330 °C is discussed and compared to the results of both X-ray diffraction analysis and magnetic measurements previously obtained.

Phase and Microstructural Analysis of Hot Rolled FeNi42 Sheet, its Response in Magnetic and Mechanical Properties

AbstractInclusions unavoidably existing in steels and consequently also in final products obtained by e.g. rolling markedly affects the physical properties. This paper is devoted to investigation of FeNi42 steel hot rolled into a sheet form. The structural and phase analysis is done by scanning electron microscopy, X‐ray diffraction, and Mössbauer spectroscopy completed by magnetic and hardness measurements. The results yield an inhomogeneous nickel distribution in the sheet resulting in a formation of the intermetallic Ni3Fe phase. A depletion of sheet surface by nickel leads to an intensive surface oxidation; its thickness increases in the direction of sheet edges. The non‐metallic oxide inclusions are concentrated predominantly at grain boundaries, which contribute to an easier cracking. The formation of Ni3Fe affects a small increase in saturation magnetization. The oxides and consequently cracks formation cause magnetic hardening as can be seen on an increase of the structurally sensitive remnant magnetization. The hard oxide inclusions evoke also the hardening of material, rise brittleness and crack liability.

Ni<sub>3</sub>Fe Mechanically Alloyed: “Shock Mode” versus “Friction Mode”

Ni3Fe powder has been obtained by high energy ball milling from elemental powders. We used two extreme conditions for milling: “friction mode” – friction between powder and ball/vial– and “shock mode” – direct impact of ball to powders. The influence of milling mode - friction and shock – was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the Ni3Fe grain size obtained by “friction mode” after 30 hours of milling was around 10 nm. For “shock mode” milling the average grain sizes was around 17 nm after 20 hours. The grain size was calculated using Williamson-Hall formula for both, “shock mode” and “friction mode” of milled powders and Scherrer formula for annealed powders. The powders were subjected to an annealing (30 min. at 350 °C) in order to eliminate the internal stress accumulated to the milling process and to finish the Ni3Fe phase formation.

Influence of wet milling conditions on the structural and magnetic properties of Ni 3Fe nanocrystalline intermetallic compound

Nanocrystalline Ni 3Fe compound is obtained by dry and wet milling under argon atmosphere, using benzene as surfactant. X-ray diffraction patterns show that the Ni 3Fe phase is formed after 2 h of milling followed by annealing (350 °C for 4 h). The mean size of the crystallites is 12 ± 2 nm for 40 h of wet milling. Iron and chromium contamination was evidenced by X-ray microanalysis. The increase in benzene quantity shifts the powder particle size distribution towards smaller particle size ranges. DSC analysis revealed the presence of benzene in the wet milled powders. Spontaneous magnetization decreases with increasing milling time and benzene quantity. Annealing at 350 °C for 4 h leads to a substantial increase of the spontaneous magnetization.

Direct and alternating current magnetic properties of FeNi particles coated with SiO2

FeNi particles coated with SiO2 have been prepared by a rapid and simple chemical synthesis. The precursor compound has been reduced in hydrogen gas at different temperature and its structure and magnetic properties were studied. The experimental results showed that the Ni3Fe and NiFe2O4 (or Ni1.43Fe1.7O4) phases co-existed when treated at 500°C and only the Ni3Fe phase existed when treated above 600°C. The particles exhibited a dependence of the magnetization on the H2 reduction temperature and the SiO2/FeNi weight ratio. The specific magnetization σS increased and the coercive force HC decreased with increasing reduction temperature. This result can be explained by an incomplete conversion of the precursor compound to Ni3Fe during the reduction procedure. There was a decrease in σS and increase in HC with the increase of SiO2/FeNi ratio. The coated materials have lower permeability than the uncoated materials and the μ′ of the sample 10% SiO2/FeNi is frequency-independent.