Fe-Ni Alloys Research Articles

FeNi steel alloys under effect of molten lead liquid at high temperature 750℃: A molecular dynamics simulation study

Materials that have superior properties are indispensable for technological applications. Steel that has strong, heat- resistant, corrosion-resistant properties is indispensable for application in the design of liquid lead metal-cooled nuclear reactors. One of the steels that need to be studied for superior properties is FeNi alloy steel. In this study, the influence of FeNi steel composition was studied using computational methods of simulating molecular dynamics. The exact composition of FeNi steel to be able to work in liquid lead reactor coolant was analyzed using the CNA (common neighbor analysis) method. Molecular dynamics simulation uses the MOLDY program while the calculation of CNA values uses the OVITO program. From the simulation results, it can be known the effectiveness of variations in Fe and Ni composition that are able to produce the most stable FeNi alloy steel from the influence of liquid lead metal corrosion.

CTAB-Assisted Synthesis of FeNi Alloy Nanoparticles: Effective and Stable Electrocatalysts for Urea Oxidation Reactions.

Development of highly efficient electrocatalysts for treating urea-rich wastewater is an important problem in environmental management and energy production. In this work, an iron-nickel alloy (Fe-Ni alloy) was synthesized via soft-template cetyltrimethylammonium bromide (CTAB)-assisted precipitation using low-temperature calcination. The as-synthesized nanoalloy was characterized by X-ray diffraction (XRD), which revealed the formation of a face-centered cubic (FCC) structure of the Fe-Ni alloy; field emission-scanning electron microscopic (FE-SEM) analysis revealed the spherical shape of the Fe-Ni alloy; high-resolution transmission electron microscopy (HR-TEM) revealed the average size to be ∼33.09 nm; and X-ray photoelectron spectroscopy (XPS) showed the presence of Fe, Ni, C, and O components and their chemical composition and valence states in the Fe-Ni alloy. The electrochemical urea oxidation reaction (UOR) was investigated by conducting linear sweep voltammetry (LSV) tests on the synthesized electrocatalysts with different Ni/Fe ratios in alkaline electrolytes with urea. The potential required to reach a current density of 10 mA cm-2 is 1.27 V vs RHE, which demonstrates the higher electrochemical activity of the Fe-Ni alloy compared to other individual compounds. This could be due to CTAB which improved the structural stability and synergetic and electronic effects in the nanoscale. This study will further contribute to renewable energy generation technology with long-term energy sustainability and also opens up great potential for reducing water pollution.

Highly-dispersed Ni3Fe alloy nanoparticles anchored on MgAl-LDO for efficient catalytic amination of KA-oil to cyclohexylamine

The partial oxidation of cyclohexylamine to cyclohexanone oxime provides the new approach for preparation of caprolactam, which is vital important monomer of nylon-6 fibers and resins. In this work, a simple and efficient reductive amination of KA-oil to cyclohexylamine was developed over hydrotalcite-derived 9 %Ni-3 %Fe/MgAl-LDO catalyst. The results showed that the 9 %Ni-3 %Fe/MgAl-LDO catalyst exhibited the excellent catalytic performance, 97 % of cyclohexanol conversion and 99 % of cyclohexanone conversion were achieved with 98 % of selectivity to cyclohexylamine over 100 h at 170 °C. The highly-dispersed Ni3Fe alloy nanoparticles anchored on MgAl-LDO are responsible for the excellent catalytic performance and stability of catalyst. Moreover, the Ni sites of Ni3Fe alloy (111) facet as dominant catalytic active sites were identified by DFT calculation. The present work provides a new approach for green preparation of cyclohexylamine from reductive amination of KA-oil over hydrotalcite-derived 9 %Ni-3 %Fe/MgAl-LDO catalyst, and has important industrial application prospects.

High-Pressure Die Casting of Al–Ce–La–Ni–Fe Alloys

The effects on phase equilibria of La and Fe additions to the Al–Ce–Ni-based alloy system are explored under high-pressure die casting conditions. The addition of La to Al–Ce–Ni-based alloy system only reacts with Ce synergistically to promote the formation of the Al11(Ce,La)3 intermetallic phase as predicted by CALculation of PHAse Diagrams (CALPHAD) and verified experimentally. High Fe additions react with Ni to form the Al9FeNi intermetallic phase, which is an additional eutectic former. The targeted co-precipitation type eutectic morphology is achieved in the alloys studied. Additional coarse particles of Al11(Ce,La)3, present in the alloys studied and not predicted by CALPHAD, are attributed to possible inclusions of Ce and La oxide, present in the mischmetal feedstock used. Both alloys exhibit exceptional mechanical stability after 10 hours at 400 °C due to the stability of the phases formed during solidification. The alloy with high Fe additions possessed better mechanical properties after heat treatment based on the higher eutectic content and more substantial improvement to the morphology of secondary phases after treatment.

Automatic center identification of electron diffraction with multi-scale transformer networks

Selected area electron diffraction (SAED) is a widely used technique for characterizing the structure and measuring lattice parameters of materials. An autonomous analytic method has become an urgent demand for the large-scale SAED data produced from in-situ experiments. In this work, we realize the automatic processing for center identification with a proposed deep segmentation model named the multi-scale Transformer (MS-Trans) network. This algorithm enables robust segmentation of the central spots by combining a novel gated axial-attention module and multi-scale feature fusion. The proposed MS-Trans model shows high precision and robustness, enabling autonomous processing of SAED patterns without any prior knowledge. The application on in-situ SAED data of the oxidation process of FeNi alloy demonstrates its capability of implementing autonomous quantitative processing.© 2017 Elsevier Inc. All rights reserved.

Promoted Overall Water Splitting Catalytic Activity and Durability of Ni3Fe Alloy by Designing N-Doped Carbon Encapsulation.

Combining an electrochemically stable material onto the surface of a catalyst can improve the durability of a transition metal catalyst, and enable the catalyst to operate stably at high current density. Herein, the contribution of the N-doped carbon shell (NCS) to the electrochemical properties is evaluated by comparing the characteristics of the Ni3Fe@NCS catalyst with the N-doped carbon shell, and the Ni3Fe catalyst. The synthesized Ni3Fe@NCS catalyst has a distinct overpotential difference from the Ni3Fe catalyst (ηOER = 468.8mV, ηHER = 462.2mV) at (200 and -200)mAcm-2 in 1m KOH. In stability test at (10 and -10)mAcm-2, the Ni3Fe@NCS catalyst showed a stability of (95.47 and 99.6)%, while the Ni3Fe catalyst showed a stability of (72.4 and 95.9)%, respectively. In addition, the in situ X-ray Absorption Near Edge Spectroscopy (XANES) results show that redox reaction appeared in the Ni3Fe catalyst by applying voltages of (1.7 and -0.48)V. The decomposition of nickel and iron due to the redox reaction is detected as a high ppm concentration in the Ni3Fe catalyst through Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis. This work presents the strategy and design of a next-generation electrochemical catalyst to improve the electrocatalytic properties and stability.

NiCoCrFeY High Entropy Alloy Nanopowders and Their Soft Magnetic Properties.

High entropy alloy nanopowders were successfully prepared by liquid-phase reduction methods and their applications were preliminarily discussed. The prepared high entropy alloy nanopowders consisted of FeNi alloy spherical powders and NiFeCoCrY alloy spherical powders with a particle size of about 100 nm. The powders have soft magnetic properties, the saturation magnetization field strength were up to 5000 Qe and the saturation magnetization strength Ms was about 17.3 emu/g. The powders have the excellent property of low high-frequency loss in the frequency range of 0.3-8.5 GHz. When the thickness of the powders coating was 5 mm, the powders showed excellent absorption performance in the Ku band; and when the thickness of the powders coating was 10 mm; the powders showed good wave-absorbing performance in the X band. The powders have good moulding, and the powders have large specific surface area, so that the magnetic powder core composites could be prepared under low pressure and without coating insulators, and the magnetic powder cores showed excellent frequency-constant magnetization and magnetic field-constant magnetization characteristics. In the frequency range of 1~100 KHz; the μm of the magnetic powder core heat-treated at 800 °C reached 359, the μe was about 4.6 and the change rate of μe with frequency was less than 1%, meanwhile; the magnetic powder core still maintains constant μe value under the action of the external magnetic field from 0 to 12,000 A/m. The high entropy alloy nanopowders have a broad application prospect in soft magnetic composites.

Design and preparation of an epoxy resin matrix composite structure with broadband wave-absorbing properties

Aiming at the poor effect of broadband wave-absorbing, the structural wave-absorbing composites structure were designed and prepared by choosing FeNi alloy powder/epoxy nanocomposites as the wave-absorbing interlayer, and carbon fibers/epoxy composites as the structural materials. Firstly, “80 wt% Fe50Ni50 alloy powder/epoxy resin nanocomposites” were successfully prepared, with a density of about 2.4 g/cm3, which can be applied as wave-absorbing interlayer. Then, electromagnetic parameters and loss mechanisms of the wave-absorbing sandwich in the frequency band of 1–18 GHz were studied in detail. Finally, the radar wave absorption characteristics of the structural wave-absorbing composites were optimized. The study shows that the electromagnetic loss mechanism of wave-absorbing sandwich is dominated by conductive loss and eddy current loss in the frequency range of 1–6 GHz, and eddy current loss, resonant loss and relaxation polarization in the frequency range of 6–18 GHz. In the frequency band of 2.5–8 GHz, the angular tangent of the magnetic loss of the interlayer is tanδm ≥ 0.5, and, the attenuation constant is stabilized in the range of 160–180 in the frequency band of 5.2–13.2 GHz, which shows that the interlayer has a good capacity of electromagnetic wave absorption. Different wave-absorbing properties can be designed by changing the thickness of the wave-absorbing interlayer. And the “fiberglass/interlayer/carbon fiber” composite board with a thickness of 2.0 mm interlayer and 3.0 mm-thick “fiberglass/ epoxy” has excellent broadband wave-absorbing properties. The sandwich composites have wave-absorbing peaks of |RL|≥10 dB in the frequency bands of 4.93–8.79 GHz and 14.96–18.0 GHz, with the peak width of 6.90 GHz, and the absorption peak of |RL|≥54 dB.

The Microstructure and Magnetic Properties of a Soft Magnetic Fe-12Al Alloy Additively Manufactured via Laser Powder Bed Fusion (L-PBF)

Soft magnetic Fe-Al alloys have been a subject of research in the past. However, they never saw the same reception in technical applications as the Fe-Si or Fe-Ni alloys, which is, to some extent, due to a low ductility level and difficulties in manufacturing. Additive manufacturing (AM) technology could be a way to avoid issues in conventional manufacturing and produce soft magnetic components from these alloys, as has already been shown with similarly brittle Fe-Si alloys. While AM has already been applied to certain Fe-Al alloys, no magnetic properties of AM Fe-Al alloys have been reported in the literature so far. Therefore, in this work, a Fe-12Al alloy was additively manufactured through laser powder bed fusion (L-PBF) and characterized regarding its microstructure and magnetic properties. A comparison was made with the materials produced by casting and rolling, prepared from melts with an identical chemical composition. In order to improve the magnetic properties, a heat treatment at a higher temperature (1300 °C) than typically applied for conventionally manufactured materials (850–1150 °C) is proposed for the AM material. The specially heat-treated AM material reached values (HC: 11.3 A/m; µmax: 13.1 × 103) that were close to the heat-treated cast material (HC: 12.4 A/m; µmax: 20.3 × 103). While the DC magnetic values of hot- and cold-rolled materials (HC: 3.2 to 4.1 A/m; µmax: 36.6 to 40.4 × 103) were not met, the AM material actually showed fewer losses than the rolled material under AC conditions. One explanation for this effect can be domain refinement effects. This study shows that it is possible to additively manufacture Fe-Al alloys with good soft magnetic behavior. With optimized manufacturing and post-processing, further improvements of the magnetic properties of AM L-PBF Fe-12Al may still be possible.

Accessible Ni‐Fe‐Oxalate Framework for Electrochemical Urea Oxidation with Radically Enhanced Kinetics

AbstractUrea oxidation reaction (UOR) has been utilized to substitute the oxygen evolution reaction (OER), to escalate the energy conversion efficiency in electrochemical hydrogen generation processes with denitrification of widespread urea in wastewater. This study reports breakthroughs in Ni‐based UOR electrocatalysts, particularly with NiFe oxalate (O‐NFF), derived from Ni3Fe alloy foam with prismatic nanostructures and elevated surface area. The O‐NFF achieves cutting‐edge performances, representing 500 mA cm−2 of current density at 1.47 V RHE and exceptionally low Tafel slope of 12.1 mV dec−1 (in 1 m KOH with 0.33 m urea). X‐ray photoelectron/absorption spectroscopy (XPS/XAS) coupled with density functional theory calculations unveil that oxalate ligands induce charge deficient Ni center, promoting stable urea‐O adsorption. Furthermore, Fe dopants enhance oxalate‐O charge density and H‐bond strength, facilitating C‐N cleavage for N2 and NO2− formation. The extraordinary UOR kinetics by the tandem effects of oxalate and Fe prevent Ni over‐oxidation, corroborated by operando XAS, minimizing OER interference. It agrees with an adaptive reconstruction to Fe‐doped β‐NiOOH on top surface in extended urea electrolysis with marginal loss in UOR kinetics. This findings shed light to bimetal‐organic‐framework as (pre)catalysts to improve industrial electrolytic H2 production.

Phase field study on phase stability at high temperatures in nanograined Fe–Ni alloy prepared by plastic deformation

The phase stability at high temperatures in nanograined Fe–Ni alloy prepared by surface mechanical attrition treatment (SMAT) and ball milling (BM) modes are drastically different. For example, the onset temperature (As) of reverse martensitic transformation (RMT) of nanocrystal prepared by SMAT is higher than that of coarse crystal, while BM exhibits the opposite result. The elastoplastic phase field model for RMT was first proposed to investigate the correlation between RMT and its forward martensitic transformation (FMT), in turn, the above experimental phenomena were revealed in this paper. The prepared nanocrystals with the same diameter (15 nm) by SMAT and BM mode were taken as representative examples. The simulation results indicated that the strain energy is relaxed by the applied strain during FMT in nanocrystalline prepared by smaller plastic deformation mode (e.g. SMAT), but it is enhanced by larger plastic deformation mode (e.g. BM). The stored strain energy in BM mode is much larger than that in SMAT mode, and hence the driving force provided for subsequent RMT is also larger in BM mode. Therefore, the phase stability of the martensitic nanocrystals prepared by BM mode at high temperatures is much lower than the counterpart by SMAT mode, which agrees well with the experimental measurements.

Fe-Ni-based alloys as highly active and low-cost oxygen evolution reaction catalyst in alkaline media.

NiFe-based oxo-hydroxides are highly active for the oxygen evolution reaction but require complex synthesis and are poorly durable when deposited on foreign supports. Herein we demonstrate that easily processable, Earth-abundant and cheap Fe-Ni alloys spontaneously develop a highly active NiFe oxo-hydroxide surface, exsolved upon electrochemical activation. While the manufacturing process and the initial surface state of the alloys do not impact the oxygen evolution reaction performance, the growth/composition of the NiFe oxo-hydroxide surface layer depends on the alloying elements and initial atomic Fe/Ni ratio, hence driving oxygen evolution reaction activity. Whatever the initial Fe/Ni ratio of the Fe-Ni alloy (varying between 0.004 and 7.4), the best oxygen evolution reaction performance (beyond that of commercial IrO2) and durability was obtained for a surface Fe/Ni ratio between 0.2 and 0.4 and includes numerous active sites (high NiIII/NiII capacitive response) and high efficiency (high Fe/Ni ratio). This knowledge paves the way to active and durable Fe-Ni alloy oxygen-evolving electrodes for alkaline water electrolysers.

Melt infiltration for the preparation of finely dispersed Ni-FeOx nanoparticles on SBA-15 for the hydrodeoxygenation of m-cresol

The polymer-assisted melting infiltration method was used to finely disperse Ni, Fe and bimetallic Ni-Fe precursors in ordered mesoporous SBA-15 support. This approach allowed to obtain small Ni nanoparticles, in the order of 2 nm in size, with finely dispersed iron oxide surrounding metallic Ni, without evidence of Ni-Fe alloy formation. The catalysts were used in the HDO reaction of m-cresol at 300 °C and atmospheric pressure. The conversion of m-cresol was found to be dependent on Ni content, with the total reaction rate decreasing when Ni is partially replaced by iron. Toluene was the main product obtained for both, mono Ni and bimetallic Ni-Fe catalysts, thus suggesting that nickel nanoparticles when in the form of small sized particles, are the active sites for deoxygenation, independent on the presence of oxophilic iron site in their proximity. Such findings will serve for the further design of effective catalysts for the upgrading of lignin-derived bio-oil.

Novel graphene-like layer-by-layer stacked carbon nanotube-supported Fe-Ni alloy for oxygen evolution and oxygen reduction reactions

In this study, we prepared a novel graphene-like stacked carbon nanotube-supported Fe-Ni alloy nanometer composite material. The cubic structure of nickel dimethylglyoxime was synthesized as the base material. Under hydrothermal condition, FePc was adsorbed on the surface of the nickel dimethylglyoxime cube. In addition, hydrogen peroxide not only decomposes FePc into Pc and Fe2+, but also reduces Fe2+ to Fe. On the other hand, hydrogen peroxide was first found could decompose and peel the cube of nickel dimethylglyoxime into a novel type of nanotubes with graphene-like nanosheet stacking structure. After the final calcination, the Fe2+ and Ni2+ were converted to FeNi alloy, and the dimethylglyoxime carrier with its loaded Pc was converted to carbon material. The novel structure has a large BET, which is conducive to electron transport, product transport and provides a large active site for Fe-Ni3 alloy. The composite has high electro-catalysis performance for OER and ORR, which provides a new idea for the study of new energy reserves, energy conversion and reserve materials. This study provides a new idea for preparing novel carbon nanotube-loaded transition metal composites in the field of electrocatalysis.

Effects of cerium oxide on the activity of Fe-Ni/Al2O3 catalyst in the decomposition of methane

The Fe-Ni/γ-Al2O3 catalyst promoted with cerium oxide was investigated in the decomposition of methane. Using X-ray diffraction analysis (XRD) and temperature-programmed reduction analysis (TPR-H2), it was established that the introduction of cerium oxide into composition of Fe-Ni/γ-Al2O3 promotes the formation of Ni-Fe alloys, because as well as an increase in the mobility and amount of active oxygen of the Fe-Ni/Al2O3 catalyst with the introduction of cerium. The results also showed that the addition of cerium oxide to Fe-Ni/γ-Al2O3 improved the catalytic stability by increasing the carbon diffusion rate and preventing the formation of encapsulated carbon. Analysis of spent catalysts using scanning (SEM), transmission electron microscopy (TEM), and Raman spectroscopy showed that carbon in the form of graphene is formed on Fe-Ni/γ-Al2O3, the introduction of cerium oxide contributes to the dispersion of the active phases of the Fe-Ni/γ-Al2O3 catalyst, thereby creating conditions for the nucleation and growth of free carbon in the form of nanotubes.

Self-Assembly Dual Active Site Nanocomposite Anode Ce0.6Mn0.3Fe0.1O2-δ/NiFe/MnOx for Electrooxidative Dehydrogenation of Ethane to Ethylene.

As the demand for ethylene grows continuously in industry, conversion of ethane to ethylene has become more and more important; however, it still faces fundamental challenges of low ethane conversion, low ethylene selectivity, overoxidation, and instability of catalysts. Electrooxidative dehydrogenation of ethane (EODHE) in a solid oxide electrolysis cell (SOEC) is an alternative process. Here, a multiphase oxide Ce0.6Mn0.3Fe0.1O2-δ-NiFe-MnOx has been fabricated by a self-assembly process and utilized as the SOEC anode material for EODHE. The highest ethane conversions reached 52.23% with 94.11% ethylene selectivity at the anode side and CO with 10.9 mL min-1 cm-2 at the cathode side, at 1.8 V at 700 °C. The remarkable electrooxidative performance of CMF-NiFe-MnOx is ascribed to the NiFe alloy and MnOx nanoparticles and improvement of the concentration of oxygen vacancies within the fluorite substrate, generating dual active sites for C2H6 adsorption, dehydrogenation, and selective transformation of hydrogen without overoxidizing the ethylene generated. Such a tailored strategy achieves no significant degradation observed after 120 h of operation and constitutes a promising basis for EODHE.

Pressure-dependent magnetic properties of FeNi alloy: Theoretical study

The influence of external pressures on the structural and magnetic properties of the FeNi alloy is elucidated using density functional theory (DFT) and Monte Carlo simulation. Utilizing a range of pressures, the study showcases compressive behavior in lattice constants, with both a and c exhibiting reductions. A sharp decline in magnetic moments is recorded at a critical pressure of 54 GPa. Indicating a magnetic phase transition from ferro to paramagnetic phase. Beyond this critical pressure, dynamical instability becomes evident, attributable to the aforementioned magnetic phase transition. Further examination of exchange interaction parameters reveals that while Fe–Fe interactions exhibited a consistent decrease with pressure, the FeNi and NiNi interactions remained relatively stable across the examined pressure range. At pressures close to 0 GPa, the Curie temperature (TC) was found to be around 838 K. As the external pressure is applied, a consequential decline in TC is witnessed, suggesting a significant sensitivity of the magnetic phase transition to external pressures. In particular, this study indicates that the FeNi alloy is sensitive to external pressures, emphasizing some relation between structural and magnetic properties.

FeNi decorated nitrogen-doped hollow carbon spheres as ultra-stable bifunctional oxygen electrocatalyst for rechargeable zinc-air battery with 2.7% decay after 300 hours cycling.

Research on non-noble metal bifunctional electrocatalysts with high efficiency and long-lasting stability is crucial for many energy storage devices such as zinc-air batteries. In this report, nitrogen-doped porous hollow carbon spheres with a size of about 300 nm were fabricated using a modified Stöber method and decorated with an FeNi alloy through a pyrolytic reduction process, resulting in a promising bifunctional electrocatalyst for both the oxygen evolution reaction and oxygen reduction reaction. The as-prepared FeNi@NHCS electrocatalyst exhibits excellent bifunctional activity in KOH electrolyte, attributed to its mesoporous structure, large specific surface area, and the strong coupling between the FeNi nanoalloy and nitrogen-doped carbon carriers. The electrocatalyst demonstrates excellent ORR performance with E1/2 = 0.828 V and OER activity with Ej=10 mA = 1.51 V. A zinc-air battery using FeNi@NHCS as the air electrode achieves an open-circuit voltage of 1.432 V and a maximum power density of 181.8 mW cm-2. After 300 h of galvanostatic charge-discharge cycles, the charge-discharge voltage gap (ΔU) of the battery had only decayed by 2.7%, demonstrating superior cycling stability.

High-temperature deformation behaviour and processing map of near eutectic Al–Co–Cr–Fe–Ni alloy

The high-temperature deformation behaviour of near-eutectic high entropy alloy was studied at 800–1100 °C and 0.01–10 s−1. The microstructure of the as-cast alloy depicted a proeutectic L12 phase and epitaxially grown eutectic colonies of lamellar L12 and B2. Deformation temperature and strain rate played vital roles in defining the precipitation and deformation behaviour of the alloy. The lower-temperature deformed samples were characterized by extensive deformation twinning and strain accumulation. In contrast, high-temperature deformation led to uniform deformation with dynamic recrystallization, recovery, B2 lamellar fragmentation and B2 precipitation. The microstructure of the deformed samples corresponded well with the processing maps developed via dynamic materials model. The processing zones for the alloy were identified to be 800–950 °C and 10−2 – 10−1.25 s−1 as well as 925–1100 °C and 10−2 – 10−0.5 s−1. The critical material flow parameters displayed a complex relationship with temperature, strain rate and strain. In the studied temperature and strain rate regime, the critical strain rate was determined to be 0.1s−1. At strain rates above and below this value, the critical strain for recrystallization was higher. Within the studied temperature and strain rate regime, the near eutectic alloy displayed superior compressive strength and wider thermos-mechanical processing region than its eutectic counterpart.

Multi-functional perovskite oxide Pr0.6Sr0.4Mn0.2Fe0.7Ni0.1O3−δ as an efficient quasi-symmetric electrode for solid oxide fuel/electrolysis cells

Pr0.6Sr0.4Mn0.2Fe0.7Ni0.1O3−δ (PSMFN) is developed as a quasi-symmetric electrode catalyst for SOCs, which undergoes in situ exsolution of Fe–Ni alloy nanoparticles with a phase transition to a Ruddlesden–Popper structure under fuel conditions.