Fe-based Alloys Research Articles

Nanoporous structures with Fe0/FeII/FeIII co-existed as catalysts for phenol degradation

Fe-based amorphous alloy was widely concerned in the field of wastewater treatment because of its nanoporous structure, which has higher reactivity activity. However, as it is easy to get oxidative poisoning, its long-term reactivity activity is restricted. A uniform nanoporous layer has been synthesized by mechanical attrition and dealloying on the surface of Fe76Si9B10P5 amorphous alloy powders in this work. In the test of catalytic performance, due to nanoporous structure, Fe0/FeⅡ/FeⅢ are involved in the Fenton process at the same time. The Fenton reaction was further catalyzed to generate more active group · OH; therefore, the degradation rate reaches 99.8% within 60 min. This coexistence of Fe0/FeII/FeIII persisted after five cycles of the catalytic reaction, indicating the excellent catalytic stability of the catalyst. Using this tunable pretreatment method for surface activation, novel applications for metallic glasses can be developed.

Hydrogen trapping behavior at vacancies introduced by electron irradiation in B2 ordered Fe base alloys

Hydrogen trapping behavior at vacancies introduced by electron irradiation in B2 ordered Fe base alloys

Recent progress on bulk Fe-based alloys for industrial alkaline water electrolysis

Bulk Fe-based alloys have high potential for achieving green hydrogen production commercially by AWE. In this review, we systemically summarize recent development on strategies to improve their catalytic activity.

UNCONVENTIONAL METHODS OF MANUFACTURING THIN WIRES FOR APPLICATION AS INPUT MATERIAL IN ADDITIVE MANUFACTURING. PART 2: DRAWING OF Fe-BASED ALLOY WIRES

The article presents the technology of drawing thin wires made from selected iron-based alloys for use in additive manufacturing using WAAM method. The final technology of wire production was developed with the use of a drawing bench, depending on the deformed material. Steel wires with a diameter of 1 mm and mechanical properties adapted to the 3D printer were produced.

UNCONVENTIONAL METHODS OF MANUFACTURING THIN WIRES FOR APPLICATION AS INPUT MATERIAL IN ADDITIVE MANUFACTURING. PART 1: PREPARATION OF INPUT MATERIAL FOR WIRE DRAWING

Part 1 of the article presents the technological path of producing semi-finished products for wires constituting input material in additive technologies. On the basis of the developed chemical compositions of experimental Fe-based alloys, laboratory ingots with a square section of 120×120 mm / 130×130 mm were produced, which were then hot rolled into flat bars. In order to select the physical parameters of the drawing tests, numerical modelling of the process was performed. As a result of the simulations, it was found that the calculated drawing force exceeds the capabilities of the experimental drawing machine and for this reason, hydrostatic extrusion was used to produce bars intended for drawing wires. The hydrostatic extrusion method was used to make bars with a diameter of 5 mm from three tested materials, while three experimental steels showed insufficient susceptibility to extrusion at high pressure and cracked at various strain values. An analysis of possible causes of bar breakage during extrusion was carried out on the basis of the results of microstructure examination.

Magnetomechanical Properties of Fe-Si-B and Fe-Co-Si-B Metallic Glasses by Various Annealing Temperatures for Actuation Applications.

Fe-based amorphous alloys have advantages of low iron loss and high effective permeability, which are widely used in sensors and actuators. Power efficiency is one of the most important indicators among power conversion applications. We compared the magnetomechancial power conversion factors of metallic glassy ribbons FeCoSiB (Vitrovac 7600) and FeSiB (Metglas 2605SA1). We investigated the crystallization process under different annealing temperatures and tested the magnetomechancial coupling factors (k) and quality factors (Q) by using resonant and anti-resonant methods. We found that the maximum coupling factor of the annealed Vitrovac ribbons was 23% and the figure of merits k2Q was 4-7; however, the maximum coupling factor of the annealed Metglas ribbons was 73% and the maximum value of k2Q was 16. We can observe that the Metglas 2605SA1 ribbons have higher values of the magnetomechanical power efficiency than those of the Vitrovac 7600 ribbons, which means they are better to be used in subsequent research regarding acoustically driven antennas.

Phase transformations and microstructure evolutions during depressurization of hydrogenated Fe–Mn–Si–Cr alloy

Hydride formation and associated phase transformations have been extensively studied in pure Fe. However, the understanding of hydrogenation in Fe-based alloy systems is still lacking. Such an investigation is particularly important in the case of austenitic (face-centered cubic) steels given that hydrogen has been reported to alter the austenite phase stability. In the current work, we investigate the phase transformations associated with depressurization of non-hydrogenated and hydrogenated Fe–Mn–Si–Cr alloy (FMS) (Fe-28.84Mn-7.04Cr-6.14Si, in mass %) using in-situ x-ray diffraction technique. Additionally, we study the change in microstructure using electron backscatter diffraction (EBSD) and electron channeling contrast imagining (ECCI).

Enhanced thermal stability and mechanical properties of the nanocrystalline multicomponent Fe–(ZrNbMoTa)x alloys

Thermal stability and mechanical property of the multicomponent nanocrystalline Fe–ZrNbMoTa alloys were investigated. Single-phase nanocrystalline Fe–(ZrNbMoTa)x (x = 0.1, 0.2, 0.5 and 1 at. %) alloys were prepared by ball milling and followed by annealing in a set of predesigned condition. It was found that the Fe-based multicomponent alloys possess good thermal stability through 10 h annealing at 900 °C, which is attributed to the thermodynamics effect in the reduction of grain boundary energy caused by multicomponent co-segregation of Zr, Nb, Mo and Ta, and kinetics effect related to sluggish diffusion and Zener pinning of a small amount of second-phase precipitation. Additionally, nanocrystalline Fe–(ZrNbMoTa)x alloys show excellent mechanical properties. The hardness is 738.6 HV, and its yield strength and compressive strength reach up to 3100 MPa and 3600 MPa, respectively. These are attributed to the comprehensive effects of nanocrystalline, solid solution and second phase strengthening.

Effect of ultrasonic high-frequency percussion on the microstructure and corrosion resistance of Fe-based alloy coatings by high-speed laser cladding

Fe-based alloy coatings were prepared by high-speed laser cladding (HSLC) technology, and the surface was subjected to ultrasonic high-frequency percussion (UH-FP). The dendrites at the top of the coatings were smaller, and there was dendrite segregation. After UH-FP, the surface profile of the coatings was smoother, achieving the mirror effect. The roughness decreased from 2.643 μm to 0.913 μm and the residual stress of the coatings changed from 306.92 MPa to −92.18 MPa. The electrochemical corrosion behavior in a 3.5 % NaCl solution indicates that the UH-FP coatings exhibit higher corrosion resistance. Anti-corrosion mechanism was discussed based on residual stress and roughness.

Effect of Cr and Ni/Fe Ratio on the Microstructure and Mechanical Properties of γ′-Strengthened Ni–Fe-Based Alloys

Effect of Cr and Ni/Fe Ratio on the Microstructure and Mechanical Properties of γ′-Strengthened Ni–Fe-Based Alloys

Atomistic insights into stress corrosion cracking of α-Fe in supercritical water: The coupling effect of hydrogen embrittlement and intergranular corrosion

Mechanistically understanding stress corrosion cracking (SCC) of Fe-based alloy under extremely high-temperature and high-pressure conditions is a key challenge for designing and optimizing structural materials of the supercritical water (SCW) reactors. The mechanism of SCC of α-Fe in supercritical water has been investigated by reactive force-field molecular dynamics simulations, and it is obtained that SCC is caused by the coupling effect of hydrogen embrittlement and intergranular corrosion. Hydrogen atoms in metals induce vacancy formation when the loaded stress is larger than the threshold stress, resulting in forming stable vacancy-hydrogen clusters. These stable vacancies pin grain boundary (GB) and act as stress concentrators under sufficient tensile stress, leading to the generation of more vacancies. A large number of vacancies in GB promote intergranular corrosion which directly results in materials failure.

Stability and fracture mechanism of α-Fe/V6C5 interface in high vanadium Fe-based alloys by first-principles calculations

V6C5 is one kind of typical and stable vanadium carbides observed in the experiments. The α-Fe/V6C5 interface properties have an important effect on the mechanical properties of high vanadium Fe-based alloys, but the interface structure and fracture mechanism are unknown. Herein, the properties of α-Fe(001)/V6C5(001) coherent interface are studied by first-principles calculations including surface energy (σ), work of adhesion (Wad) and interfacial energy (γint). According to the results of work of adhesion and interfacial energy, MT stacking sequence of V-termination (V-MT) is the most stable interface structure. The electronic structures of α-Fe (001)/V6C5(001) interfaces reveal the formation of Fe-V, Fe-C and V-C bonds. A large amount of charge transfer between Fe and C (V) and shared electrons are in the interface, indicating that these bonds are a mixture of ionic and covalent bonds. However, during the first-principles tensile simulation, the V-terminated interface is finally destroyed due to the fracture of Fe-V bonds at the interface, while a new structure about Fe and C is formed at the C-terminated interface. The strong Fe-C bonds lead to the better tensile performance of C-terminated interface than V-terminated interface. This work provides a deeper understanding on the strengthening mechanism of high vanadium Fe-based alloys.

Parameter Study and Economic Efficiency Optimization for Laser Cladding with Wide-Band Fiber Laser

With the aim of investigating the cladding geometry characteristics by a wide-band fiber laser with coaxial rectangular nozzle, and optimizing the powder efficiency and deposition speed for economy efficiency, Fe-based alloy powder was deposited on AISI 1045 substrate by a 3000 W fiber laser in this study. Laser power (P), scan speed (V), and powder feed rate (F) were selected for a factorial design. The effects of the three process parameters on the geometry characteristics and economic efficiency of single tracks were statistically analyzed, and a linear regression model was established between the combined parameters and the relevant characteristics (including track height, ratio of track width to height, powder efficiency, and deposition speed). A process map was developed with the track shape and key economic indexes as boundaries. A flat-top feature of the track profile was found and can be utilized to achieve good cladding evenness. The process map showed that the powder efficiency and deposition speed were higher than 50% and 20 mm3/s, respectively, when selecting process parameters in the as-built operation window.

Enhanced degradation performance of Fe75B12.5Si12.5 amorphous alloys on azo dye.

The Fe75B12.5Si12.5 and Fe75B12.5C12.5 amorphous alloy ribbons were prepared by the melt spinning method. The decolorization performances of these ribbons were investigated in details. It is found that the Fe75B12.5C12.5 amorphous ribbons and Fe75B12.5Si12.5 annealed ribbons only adsorbed the azo dye molecules, with no chemical degradation process. However, the Fe75B12.5Si12.5 amorphous ribbons can reduce -N = N- to -NH2 because of their high reactivity and the local galvanic effect that occurred during the reaction to accelerate electron transfer. The reaction rate constant kobs is 0.0872min-1, 0.0474min-1, and 0.0064min-1 for Fe75B12.5Si12.5 amorphous ribbons, Fe75B12.5C12.5 amorphous ribbons, and Fe75B12.5Si12.5 annealed ribbons in the same condition, respectively. Fe75B12.5Si12.5 amorphous ribbons can effectively degrade Acid Orange II (AO II) azo dyes and achieve decolorization by breaking azo bonds in the dye in a short time, indicating the prominent capacity of Fe75B12.5Si12.5 ribbons on the degradation of AO II. Furthermore, the influence of chemical factors such as ribbons thickness, reaction temperature, initial pH, and AO II concentration of the solution on the reaction rate constant kobs of Fe75B12.5Si12.5 amorphous ribbons had also been studied. The kobs can reach 0.177min-1 under optimal conditions. In addition, all the degradation processes in this work were fitted well with the pseudo-first-order kinetic model. The results are guidance for the practical applications, and they have important implications in developing Fe-based amorphous alloys for functional application materials in the field of wastewater treatment.

Electrical discharge machining of Fe-based shape memory alloy: Parametric evaluation with microstructure analysis

In the real world, shape memory alloys (SMAs) are a great option for industrial applications including orthopedic implacers, micro tools, actuators, fitting and screening components, military appliances, aerospace components, biomedical instruments, fabricating essentials, etc. Despite their remarkable characteristics, the effective production of these alloys continues to be a problem for researchers worldwide. This paper has aimed to examine the considered machining responses, that is, material removal rate (MRR) and surface roughness (SR) in electrical discharge or spark machining (EDM) of Fe-based SMA using a Cu-electrode under varying settings of input factors namely as pulse on time (Ton), pulse off time (Toff), peak current (Ip), and gap voltage (GV). The central composite design matrix has been employed for planning the main runs. The experimental results reflect the lowest and highest for MRR as 12.49 and 73.90 mm3/min; and for SR as 5.03 and 6.65 µm, respectively. The microstructure analysis of the EDMed work samples and tool electrode surfaces has also been conducted using scanning electron microscopy. The micrographs exposed the development of debris, craters, micro-cracks, and recast layer creation on the workpiece surface and electrode tool as well. The creation of debris develops as a result of large spark energy at the work sample–tool contact as a result of a high peak current and long pulse on time. Furthermore, single and multi-objective optimization of investigated responses (i.e. MRR and SR) were tried using the desirability approach, teacher learning-based optimization (TLBO), and particle swarm optimization (PSO) techniques. The obtained optimized values for MRR and SR by using the desirability approach, TLBO, and PSO are 62.69 mm3/min and 5.56 µm; 78.85 mm3/min and 4.34 µm; and 78.91 mm3/min and 4.35 µm, correspondingly.

Development of a hardbanding material for drill pipes based on high-manganese steel reinforced with complex carbides

In the present study the new “casing-friendly” hardbanding alloy based on high-manganese steel reinforced with complex carbide particles was developed by combining thermodynamic modelling within the CALPHAD approach and first-principles calculations. The alloy, deposited by flux cored arc welding on a steel substrate, has a composite structure consisting of manganese-austenite with the ability to work hardening, fine (up to 5 µm) inclusions of the multicomponent carbide (Nb, Ti, Mo, V) and C the thin layers of (Mo,V)C at the austenite grain boundaries. The comparative wear tests carried out with commercially available hardfacing materials of the Fe-W-C and Fe-Cr-C systems showed that the proposed alloy has the best combination of properties preventing the wear of the drill casing, while its abrasion resistance as well as wear resistance in sliding friction conditions by steel counterbody is close to hypereutectic high chromium alloys. The microhardness tests performed on deformed specimen areas after the friction tests show the presence of a significant hardness gradient in the range of 800-450 HV at a distance of about 300 µm when moving perpendicularly away from the zone of friction contact. During the microscopic observation of the layer deposited with the developed alloy and the interfaces between the deposit and the base steel no cracks, pores delamination were detected indicating a strong metallurgical bonding. The hardbanding process was performed for drill pipe joints with the worn Fe-based high chromium alloy hardbanding after exploitation, which allows the drill pipe to be reused with the same durability.

A Review Article on FeMnAlNi Shape Memory Alloy

Shape memory alloys (SMAs) are the materials which remember their original shape once after the deformation has occurred. In recent days, researchers started working on Fe-based shape memory alloys as NiTi shape memory alloys has few drawbacks. Febased shape memory alloys show better advantages over NiTi SMAs. FeMnAlNi SMA has advantage of wide range of operating temperature and low stress dependence. This review article provides information on work carried out on FeMnAlNi SMA which will help the researchers to carry further research work on the alloy for various applications.

Large magnetostriction of heavy-metal-element doped Fe-based alloys

Using density functional theory calculation and rigid band model, we investigate the electronic structure and magnetostrictive properties of transition heavy-metal doped Fe-based (Fe–Al, Fe–Si, Fe–B, and Fe–Be) alloys. It is found that a small amount of addition of 4d/5d heavy-metal atoms greatly enhances the coefficient of tetragonal magnetostriction of Fe-based alloys, reaching up to about 1000 ppm in Fe87.5Al6.25Pt6.25 and Fe75Al18.75Rh6.25 alloys. The underlying mechanism is mainly ascribed to combined factors of band narrowing induced by non-bonded states in pure Fe layer, strong spin–orbit coupling effect by heavy metals, and improved mechanical properties, through analysis of the electronic density of states near Fermi level and k-mesh resolved magnetocrystalline anisotropy energy in momentum space. These results provide useful guidance for optimizing the magnetostrictive performance of Fe-based alloys for practical application.

Numerical simulation analysis of high-speed asynchronous motor based on Fe-based amorphous alloy and SMC stator

Due to its unique advantages of small size, high power density, and high efficiency, high-speed asynchronous motor (HSAM) has been widely used in aerospace, high-speed air compressor, and other advanced manufacturing equipment. Based on a developed finite element model validated by a prototype motor testing platform, the influence of stators made of different magnetic materials on the efficiency of the HSAM with a rated speed of 7500 rpm has been systematically investigated. Hereinto, the magnetic materials are silicon steel, Fe-based amorphous alloy, and SMC. Compared with silicon steel, the iron loss of HSAM can be significantly reduced by 91.1% using the stator made of Fe-based amorphous alloy in the frequency range of 0-800 Hz, while the SMC motor exhibits an advantage in lower loss when the frequency over 157.28Hz.

Effect of Ge on soft magnetic properties at elevated temperature for Si-rich Finemet-type alloy

• The effect of Ge doping on the soft magnetic properties is investigated for Si-rich Finement-type alloy. • The Curie temperature is enhanced by doping Ge in Si-rich Finemet-type alloy. • The initial permeability μ i of 540°C-annealed Fe 72 Ge 2.5 Cu 1 Nb 3 Si 17.5 B 5 alloy possesses a relatively large value of 5000 until 600°C. The results obtained by partially substituting Ge for Fe in the Fe-based nanocrystalline alloy for improving the magnetic properties at high temperatures are presented in this work. These studies were performed on the Fe 74.5- x Ge x Cu 1 Nb 2 Si 17.5 B 5 ( x =2.5, 5, 7.5) alloys. The nanocrystallization and the Curie temperature are dependent on the Ge concentration. The onset temperature of primary crystallization decreases with the increase of Ge, indicating that the dual-phase nanocrystalline structure could be formed at a relatively lower temperature compared with the Ge-free alloy . For the alloy with x =2.5at%, the Curie temperature of the amorphous alloy is enhanced to 405°C. The initial permeability μ i of 540°C-annealed alloy possesses a relatively large value of 5000 until 600°C. Such a magnetic softness at elevated temperature is superior to that of Finemet-type Fe-based nanocrystalline alloys ever reported.