Iron-aluminum Alloys Research Articles

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Analysis of Wear Resistance of Metallic-Reinforced Polyurethane Resin Composites for Sheet Metal Forming

Abstract The paper presents the results of testing the wear resistance and coefficient of friction (COF) tools made of SikaBeresin® F50 polyurethane resin intended for dies and punches for the cold sheet metal forming process. Seven sets of composite tools (rotating rings) additionally reinforced with waste metallic powders from Al and Cu alloys (5-20% by volume) from the dry cutting process of pipes and rods were tested. Wear resistance tests and determination coefficient of friction were carried out using the T-05 block-on-ring tribotester. The tests were performed for heat and corrosion resistant sheets made of nickel alloy AMS5599 (Inconel 625), iron alloy AMS5510 (321) and aluminum alloy sheets AMS4026 (6061-T4). Composite tools with the addition of 20% aluminum powder (A+B+C+20%Al) tested with a specimen of steel alloy AMS5510 and nickel alloy AMS5599 were characterized by the lowest wear resistance. In each case, the composite rotating ring without reinforcements was characterized by the lowest coefficient of friction. The use of Cu powder reinforcements in each case had a positive effect on increasing wear resistance. The best wear resistance of 0.011% was obtained for composite rotating ring with the addition of 10% copper powder paired with specimen of nickel alloy AMS5599 sheet.

Ultrathin Hematite‐Hercynite Films for Future Unassisted Solar Water Splitting

AbstractPhotoelectrochemical (PEC) water splitting requires stable, efficient, and cost‐effective photoelectrodes to enable future large‐scale solar hydrogen production. Ultrathin hematite‐hercynite photoanodes that meet all these criteria in an excellent way is presented here. Hematite‐hercynite photoelectrodes are synthesized in a self‐forming manner by thermal oxidation of iron–aluminum alloy films and characterized with regard to water splitting applications. Photoanodes fabricated from 17 wt.% Al at 493 °C for 8 h and 685 °C for 5 min exhibit, for instance, a photocurrent density of 1.24 and 1.53 mA cm−2 at 1.23 V versus RHE, respectively, as well as superior light absorption in the visible range of the solar spectrum. The PEC performance improvement in comparison to pure hematite thin film electrodes is first achieved by adjusting the aluminum concentration with an optimum range of 12–17 wt.% and second by optimizing the annealing conditions. The resulting photocurrent densities are about a factor of three higher than those obtained from electrodes synthesized from pure iron thin films using the same synthesis conditions. Finally, it is shown that ultrathin hematite‐hercynite photoelectrodes enable even unassisted solar water splitting in a NaOH (1 m) electrolyte with a maximum solar‐to‐hydrogen conversion efficiency of 0.78%.

Influence of atomic ordering and cerium doping on magnetostrictive Fe-Al alloys

Magnetostrictive iron-aluminum alloys can be a low-cost, mechanically stable alternative to iron-gallium and rare earth-iron alloys. The magnetostrictive performance of polycrystalline Fe-Al (alfenol) with 13–24 at. % Al was investigated, studying the role of compositional variation and thermal history. It was found that rapid cooling enhances the magnetostrictive response, and peak magnetostriction was found in Fe78Al22 by high temperature annealing followed by quenching. Synchrotron diffraction enabled a direct correlation of magnetostrictive behavior and the transition from short-range order to long-range ordered cluster domains in the material which can be suppressed by rapid cooling. Following recent success of doping Fe-Ga with rare earth elements, we investigated the influence of Ce doping on improving magnetostriction and found that Fe-Al shows negligible solubility for cerium, inhibiting potential magnetostriction enhancement. Our results illustrate the complex interplay between phase stability, ordering, and optimized magnetostrictive response.

Why do Fe–Al Alloys Show Good Passivation Behavior in Acids Compared to Elemental Al?

We present some general concepts and pose questions connected to the difference between the ambient temperature passive film formed on elemental aluminum in acid vs that which forms on iron-aluminum alloys containing less than about 35–40 at% Al. Data is presented which demonstrates that the non-protective oxide that forms on aluminum is not related to impurity effects, either in the matrix or in grain boundaries.We argue that the ability of aluminum to form a protective passive film in a single-phase solid solution alloy is connected to atomic-scale size effects that vanish once the aluminum concentration increases to about 60 at%.

Ближний порядок в "неупорядоченных" твердых растворах алюминия в α-железе

The atomic structure of soft magnetic iron-aluminum alloys is studied by X-ray diffraction and nuclear gamma-resonance spectroscopy. The concentration dependence of the body-centered cubic lattice constant and the short-range order (SRO) parameters in the region of a disordered solid solution is monitored. It is shown that in the concentration range from 3 to 18 at.% Al, the lattice constant increases almost linearly. Discrete decomposition of nuclear gamma resonance spectra makes it possible to determine such SRO parameters as the relative fractions of contributions from coordinations without Al atoms and with one, two, and three Al atoms in the first and second coordination shells. The deviation of the values of these fractions from the average statistical probabilities indicates the presence of a chemical order in the arrangement of atoms. The largest deviations are observed at 12 and 15 at.% Al. Conditions of preliminary heat treatment, such as quenching from the paramagnetic state and holding in the ferromagnetic state, give very similar values of the SRO parameters. The method is characterized by a high resolution in the hyperfine field, while having a rather high sensitivity for determining the intensity of individual contributions.

Short-range order in "disordered" aluminum solid solutions in α-iron

The atomic structure of soft magnetic iron-aluminum alloys is studied by X-ray diffraction and nuclear gamma-resonance spectroscopy. The concentration dependence of the body-centered cubic lattice constant and the short-range order (SRO) parameters in the region of a disordered solid solution is monitored. It is shown that in the concentration range from 3 to 18 at.% Al, the lattice constant increases almost linearly. Discrete decomposition of nuclear gamma resonance spectra makes it possible to determine such SRO parameters as the relative fractions of contributions from coordinations without Al atoms and with one, two, and three Al atoms in the first and second coordination shells. The deviation of the values of these fractions from the average statistical probabilities indicates the presence of a chemical order in the arrangement of atoms. The largest deviations are observed at 12 and 15 at.% Al. Conditions of preliminary heat treatment, such as quenching from the paramagnetic state and holding in the ferromagnetic state, give very similar values of the SRO parameters. The method is characterized by a high resolution in the hyperfine field, while having a rather high sensitivity for determining the intensity of individual contributions Keywords: soft magnetic alloys, disordered Fe-Al solid solution, local ordering, X-ray diffraction, Mossbauer effect, distribution of atoms over coordination shells.

Molecular dynamics study on friction of the iron-aluminum alloy

Iron-aluminum alloy has been widely used in aerospace, nuclear power, electronics and other fields. Taking into account the limitations of the continuum mechanics model at the microscopic scale, it is critical to use nanoscale simulation methods like molecular dynamics (MD) to have a deeper understanding of the friction and wear behavior. Through MD simulation, this thesis mainly studied the friction and wear process of iron aluminum alloy under different conditions. The main conclusions are as follows: (1) The frictional force first experiences a period of growth, and then stabilizes with some fluctuations due to the release of stress-energy caused by deformation. (2) Temperature and friction speed has no significant effect on friction force. (3) The higher the friction speed is, the more wear debris it produces, and the more severely the material is damaged. (4) The force and coefficient of friction will increase with the rise of aluminum content, and the plastic deformation of the alloy is strengthened, while the elastic deformation decreases. (5) The frictional force increases with the wear depth since the accumulation phenomenon of atoms becomes more obvious.

Effect of silicon on interfacial reaction and morphology of hot-dip aluminizing

Interfacial reaction and morphology are investigated between pure iron sheet and aluminum alloy with different silicon additions in hot-dip aluminizing (HDA) at 700 °C. The width of intermetallic reaction layer hot-dipped in a pure aluminum bath is mainly governed by the diffusion controlled growth of the η-Al5Fe2 phase. Al atoms can diffuse rapidly in a preferred [001] direction, resulting in the continuous growth of η phase with a tongue-like morphology. The addition of Si into aluminum baths reduces the growth rate of the reaction layer and eliminates the rough interface. The effect of Si inhibiting the growth of η phase can be attributed to the segregation of Si atoms at the Fe/Al interface and lead to the structural vacancy obstruction. The investigation reveals that the diffusion of Si at the interface will control the phase transformation of θ phase with a low Si content to higher Si containing τ1-Al2Fe3Si3 and τ5-Al8Fe2Si phase. The continuous τ1-Al2Fe3Si3 phase layer will be formed as the segregation concentration of the Si atoms reach 5 at.% at the interface between Al alloy and θ phase. And the continuous τ5-Al8Fe2Si layer is observed in the reaction layer of Al-6Si and Al-10Si, which will reduce the growth rate of η phase as a diffusion barrier.

Potential Al-Fe Cast Alloys for Motor Applications in Electric Vehicles: An Overview

Iron is the main component of the earth's core, the most abundant element on the earth (about 35%), and it is relatively high in the sun and other stars. Also, it is a common and cheap metal in the manufacturing industry. Recently, with the rapid development of electric vehicles, more and more automotive companies are willing to develop new lightweight material for electric motors used in electrical vehicles. The iron–containing aluminum alloys can be considered as a good candidate, due to its great strength and electricity performance. This review describes various properties of aluminum-iron alloys including mechanical properties and electrical conductivities, as well their relation to the Fe contents. Also, metallurgical aspects of aluminum-iron alloys, including phase diagrams, equilibrium and non-equilibriun solidification, microstructure development, and castability. The further research and development work are outlined in terms of developing aluminum-iron alloys for some potential and value-added automotive applications.

Anode behavior of aluminum-iron alloy AlFe2.18 doped with cerium, prazeodym and neodyme in aqueous solution of NaCl

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Thermomechanical Behavior of Brake Drums Under Extreme Braking Conditions

Braking efficiency is characterized by reduced braking time and distance, and therefore passenger safety depends on the design of the braking system. During the braking of a vehicle, the braking system must dissipate the kinetic energy by transforming it into heat energy. A too high temperature can lead to an almost total loss of braking efficiency. An excessive rise in brake temperature can also cause surface cracks extending to the outside edge of the drum friction surface. Heat transfer and temperature gradient, not to forget the vehicle's travel environment (high speed, heavy load, and steeply sloping road conditions), must thus be the essential criteria for any brake system design. The aim of the present investigation is to analyze the thermal behavior of different brake drum designs during the single emergency braking of a heavy-duty vehicle on a steeply sloping road. The calculation of the temperature field is performed in transient mode using a three-dimensional finite element model assuming a constant coefficient of friction. In this study, the influence of geometrical brake drum configurations on the thermal behavior of brake drums with two different materials in grey cast iron FG200 and aluminum alloy 356.0 reinforced with silicon carbide (SiC) particles is analyzed under extreme vehicle braking conditions. The numerical simulation results obtained using FE software ANSYS are qualitatively compared with the results already published in the literature.

Influence of titanium and zirconium on structure and heat-resistance of low-carbon iron-aluminium alloys

The paper considers the effect of introducing ferroalloys containing titanium and zirconium on the structure and heat-resistance of low-carbon ferroalloys. Theoretically and experimentally, it has been proven that addition of 1.0 mass. % of titanium and 0.1 mass. % of zirconium to a low-carbon iron-aluminum melt containing 12 – 14 mass. % of aluminum, grinds its structure increasing temporary resistance and heat-melting. Titanium and zirconium are strong carbide-forming elements. When introduced into a low-carbon iron-aluminium alloy, they form a large number of crystallization centers, thus affecting its microstructure, allowing to get shredded and more equal grain compared to an alloy without additive. This in turn increases the strength limit of processed alloy. In addition, the use of titanium as a modifying additive in a low-carbon ferroalloy allows increasing its heatresistance, which exceeds several times the heat-resistance of famous chrome-nickel steel of 20Kh23N18 grade. As a result, a new technology for obtaining titanium and zirconium was developed based on research of the effect of their modifying additives on the structure and heat-resistance of low-carbon iron-aluminum alloys.

Influence of Titanium and Zirconium on the Structure and Heat-Resistance of Low-Carbon Iron–Aluminum Alloys

Influence of Titanium and Zirconium on the Structure and Heat-Resistance of Low-Carbon Iron–Aluminum Alloys

Unexpected High Ductility of Fe40Al Alloys at Room Temperature.

Iron aluminium alloys, especially those sintered from elemental powders, suffer from low ductility. In this paper, an iron aluminium alloy (Fe40Al) produced by pressure-assisted induction sintering from elemental powders is shown and described. Samples produced by this method show an unexpectedly high ductility in the compression test that is an order of magnitude higher than the literature values. Microstructural observations show plastic behaviour with significant deformation of the grains and a lack of decohesion. At the same time, the tensile properties of these samples remain at much lower levels. An attempt to explain this phenomenon is made and described in this paper.

Fe–Al alloy for eco-friendly copper-free brake-pads

Copper (Cu) is almost an essential constituent of friction materials (FMs) since it shows multi-functionality in performance. However, it is being banned due to its adverse effects on aquatic life. In the present research work, iron-aluminum (FA25) alloy particles were explored for Cu replacement. With the help of fixed parent composition, five types of brake-pads were manufactured with variations in FA25 alloy content as 0, 5, 10, 15, and 20 wt%. One more kind of pad was developed containing Cu in 10 wt% for the sake of comparison. The brake-pads were characterized for physical, mechanical, thermal, tribological properties and noise-vibration (NV) performance. The 10 wt% alloy proved to be the optimum amount to replace the Cu with superior performance if fade resistance and counterface friendliness can be compromised slightly.

Analysis of EDM Performance, through a Thermal-Electrical Model with a Trunk-Conical Discharge Channel, Using a Steel Tool and an Aluminium Workpiece.

In this article, a finite element (FE) thermal–electrical model with a trunk-conical discharge channel is employed to simulate individual EDM discharges with a time-on of 18 μs up to 320 μs, which are subsequently compared with the experimental results to validate the model. The discharge channel is a trunk-conical electrical conductor which dissipates heat by the Joule heating effect, being the correspondent factor equal to 1. Instead of the usual copper–iron electrode combination, steel (DIN CK45) and aluminium alloys (DIN 3.4365) are the implemented materials on both the tool and the workpiece, respectively. The numerical results were measured using the melting temperature of the materials as the boundary of material removal. The results obtained with the thermal–electrical model, namely the tool wear ratio, the tool wear rate, the material removal rate, and the surface roughness, are in good agreement with experimental results, showing that the new FE model is capable of predicting accurately with different materials for the electrodes.

Combined Effects of Optimized Heat Treatment and Nickel Coating for the Improvement of Interfacial Bonding in Aluminum–Iron Alloys Hybrid Structures

The effects of nickel coating and heat treatment on the interfacial bonds of aluminum–iron (Al/Fe) alloys hybrid structures were investigated using microstructural analysis. The application of a nickel coating successfully suppressed the formation of defects such as gaps and oxide scale, improving the physical bonding of the interface. Optimizing the heat treatment conditions generated superior chemical bonding at the interface and facilitated the formation of a nickel-bearing phase in the Al matrix. Also, the types of nickel-bearing phase were influenced by solution treatment and proximity to the interface. By analyzing the isopleth phase diagram of the aluminum system for the ranges of nickel present in the Al, it was confirmed that the Ni:Cu ratio affected the precipitation characteristics of the system. However, when heated under conditions that were optimized for chemical bonding, the Al matrix decreased by approximately 40% (from 100 HV to 60 HV), due to grain growth. The effect of artificial aging increased the hardness of the Al matrix away from the interface by 35% (from 63 HV to 90 HV). On the other hand, this did not occur in the Al matrix near the interface. These results indicate that the nickel that diffused into the Al matrix interfered with the precipitation hardening effect.

Investigation on the Microstructure of ECAP-Processed Iron-Aluminium Alloys.

The present work deals with adjusting a fine-grained microstructure in iron-rich iron-aluminium alloys using the ECAP-process (Equal Channel Angular Pressing). Due to the limited formability of Fe-Al alloys with increased aluminium content, high forming temperatures and low forming speeds are required. Therefore, tool temperatures above 1100 °C are permanently needed to prevent cooling of the work pieces, which makes the design of the ECAP-process challenging. For the investigation, the Fe-Al work pieces were heated to the respective hot forming temperature in a chamber furnace and then formed in the ECAP tool at a constant punch speed of 5 mm/s. Besides the chemical composition (Fe9Al, Fe28Al and Fe38Al (at.%—Al)), the influences of a subsequent heat treatment and the holding time on the microstructure development were investigated. For this purpose, the average grain size of the microstructure was measured using the AGI (Average Grain Intercept) method and correlated with the aforementioned parameters. The results show that no significant grain refinement could be achieved with the parameters used, which is largely due to the high forming temperature significantly promoting grain growth. The holding times in the examined area do not have any influence on the grain refinement.

Professor Henein on significance of materials research in space

Speaking at the Montreal Chapter of ASM, Professor Hani Henein, FASM, University of Alberta, gave an entertaining lecture on the work of his research group in the field of micro-gravity as it related to rapid solidification of metals. He showed some interesting microstructure changes that were observed in experiments with aluminum-iron alloy and in D2 tool steel.