Iron-aluminum Alloys Research Articles

Role of metal composite alloys in non-asbestos brake friction materials-A solution for copper replacement

Copper plays a vital role in the performance of brake friction materials due to its better thermal conductivity and fade resistance. But owing to the negative impact towards to the aquatic life, the usage of copper in brake material formulations is reduced considerably in developed nations. Research is being carried out globally to reduce the copper with single ingredient or combination in brake materials. Thus the present study dealt with the development of brake pads using a commercially available alloy of aluminum and iron (Mechanomade) in the formulation with other ingredients. To compare the performance, three other brake pads were also developed by replacing mechanomade with copper, aluminum, and iron in the formulation. The developed brake pads were analysed for the physical, chemical, mechanical and thermal properties as per standard industrial practice. The tribological characteristics were analysed using Chase test following SAE J661. It was evident from the test results that Iron aluminum alloy based brake pads showed good fade and recovery characteristics. To study in detail regarding the worn surface characteristics, Scanning Electron Microscope with Elemental mapping was used.

Effect of Aluminum on the Solubility of Calcium in Liquid Iron at Low Calcium and Aluminum Contents

The solubility of calcium in liquid iron as a function of aluminum content and calcium potential, at compositions relevant to production of aluminum killed steels, was studied experimentally at 1873 K. The measurements were made using a closed molybdenum chamber in which iron-aluminum alloys were held. The calcium potential was fixed using pure liquid calcium held at different temperatures. The calcium contents in the iron varied between 6 and 22 ppm by weight and the aluminum contents varied between 70 and 1900 ppm by weight. The results indicate that the effect of aluminum on the solubility of calcium in iron is very low in the composition ranges studied.

Experimental comparison of the seizure loads of gray iron journal bearing and aluminum alloy journal bearing under aligned and misaligned conditions

Materials, surface roughness of bearing and shaft, and journal misalignment affect the seizure load of journal bearing. To improve the load carrying capacity of bearing and obtain better friction pair, this paper studies experimentally the seizure loads of a gray iron journal bearing and two kinds of aluminum alloy journal bearings under both aligned and misaligned conditions. Three shafts are used to study the effects of journal surface roughness and DLC coating. The journal center locus is recorded. Results show that the combination of DLC coating and the aluminum alloy with lower hardness has the largest seizure load and inclined angle, followed by the combinations of DLC coating and gray iron, and 40Cr steel and gray iron. The surface roughness values of bearing and shaft have a considerable negative effect on seizure load, especially for aligned condition.

Theoretical calculation of elastic properties and electronic structure of B2 iron aluminides and ternary iron—aluminum alloys

The mechanical properties of FeAl and ternary Fe–X–Al (X = Cr, Mo) alloys are investigated using first-principles density functional theory (DFT), with the valence electron structures also being determined using the empirical electron theory of solids and molecules. The structural attributes of FeAl are fitted using an E–V curve, and the stable structures of the ternary alloys are systematically predicted along with their respective elastic constants and phonon frequencies. The bonding nature in FeAl is partly defined by covalence with orbital hybridization, which explains its intrinsic brittleness. The micro-mechanism by which the ductility of FeAl is improved by Cr or Mo addition is as follows: Cr or Mo addition increases the cohesive capacity of the bonds in FeAl; s, p, and d orbital electrons of the alloying element are mainly involved in the hybridization of FeAl; and the alloying elements increase the electron density of Fe and Al atomic bonding.

Removal of 4-chlorophenol from polluted water by aluminum-iron alloys.

Chlorophenols are extremely toxic to the environment and recalcitrant to biological degradation. Herein chemical degradation of 4-chlorophenol (4-CP) from aqueous solutions by zero-valent aluminum (Al), zero-valent iron (Fe), Al and Fe mixtures (Al/Fe mass ratio 90/10, labeled as Al/Fe10) and Al-Fe alloy (Al/Fe mass ratio 90/10, labeled as Al-Fe10) were investigated. No removal was found for 50 mg·L-1 4-CP under anoxic conditions at initial pH 2.5 during a period of 10 hrs while 56%, 83%, 78% and 99% of 4-CP were removed by Fe, Al, Al/Fe10 and Al-Fe10, respectively under aeration conditions. The removal of 4-CP by Al/Fe10 mixtures was primarily in the Fe mode in the beginning 4 h and then transitioned to the Al mode. The removal of 4-CP by Al-Fe10 alloy was accomplished via two intermediate products, hydroquinone (HQ) and 4-chlorocatechol (4-CC), and it was speculated that reactive oxygen species and hydroxyl radicals (·OH) play an important role in the degradation of 4-CP and that Al-Fe intermetallic compounds might catalyze the reactions. This study demonstrates that alloying Al with Fe offers a promising strategy for developing new materials for water and wastewater remediation.

Influence of iron–aluminum alloy on the tribological performance of non-asbestos brake friction materials – a solution for copper replacement

PurposeThe purpose of this study is to investigate the influence of commercially available iron–aluminum alloy compared to copper, iron and aluminum powders on the tribological performances of friction composites. The main objective is to replace copper from the friction composite formulations.Design/methodology/approachIn this study, friction composites were fabricated as of standard brake pads using commercially available iron–aluminum alloy and compared to copper powder, iron powder and aluminum powder-based without varying the other ingredients. The brake pads were developed as per the industrial procedure. The physical, mechanical and thermal properties of the developed brake pads were analyzed as per industrial standards. Tribological properties were analyzed using the chase test. Initial speed and deceleration tests in a real-time braking scenario were performed using a full-scale inertia brake dynamometer. Worn surface analysis was done using a scanning electron microscope.FindingsThe results indicate that iron–aluminum alloy (mechanomade)-based friction composites possess good physical, chemical, thermal and mechanical properties with stable fade and recovery characteristics due to its composition and flake morphology. During initial speed and deceleration braking conditions, iron–aluminum alloy also showed good tribological behavior.Originality/valueThis paper explains the influence of commercially available iron–aluminum alloy in friction composites in enhancing tribological performance by its composition and flake morphology, which could potentially replace copper in friction composites by solving subsequent problems.

Simultaneous removal of nitrate, copper and hexavalent chromium from water by aluminum-iron alloy particles

Groundwater contamination is a worldwide concern and the development of new materials for groundwater remediation has been of great interest. This study investigated removal kinetics and mechanisms of nitrate, copper ion and hexavalent chromium (20–50 mg L−1) by particles of Al-Fe alloy consisting of 20% Fe in batch reactors from a single KNO3, CuSO4, Cu(NO3)2, K2Cr2O7 and their mixed solutions. The effects of contaminant interactions and initial pH of the solution were examined and the alloy particles before and after reaction were characterized by X-ray diffraction spectrometer, scanning electron microscopy and X-ray photoelectron spectroscopy. The removal mechanisms were attributed to chemical reduction [Cu(II) to Cu, NO3− to NH3 and Cr(VI) to Cr(III)] and co-precipitation of Cr(III)-Al(III)-Fe(III) hydroxides/oxyhydroxides. Cu(II) enhanced the rates of NO3− and Cr(VI) reduction and Cr(VI) was an inhibitor for Cu(II) and NO3− reduction. This study demonstrates that Al-Fe alloy is of potential for groundwater remediation.

Enhanced alumina film adhesion of Hf/Y-doped iron–aluminum alloys during high-temperature oxidation: a new observation

The cyclic oxidation behavior of Hf/Y-doped B2 FeAl intermetallics at 1373 K was investigated. For an undoped FeAl alloy, premature spallation of the alumina film occurs due to the formation of numerous voids at the film/alloy interface and apparent shrinkage in the film. In contrast to this, doping with either Hf or Y significantly improves the interfacial adhesion between the alumina film and the alloy substrate, particularly with Hf-doping. Microstructural observation in combination with Auger electron spectroscopic analysis suggests that in addition to prohibiting interfacial void formation and alleviating film shrinkage, the addition of Hf in the FeAl alloy could consolidate the film/alloy interface by directly participating in chemical bonding across the interface as a Hf ion. This causes the spallation of alumina film from the equiaxed grains/columnar grains interface rather than the bottom of the film.

Evolution of microstructure with increasing carbon content and its effect on mechanical properties of disordered iron–aluminium alloy

Correlation of microstructure and mechanical properties of hot-rolled Fe–7 wt.% Al with varying carbon contents has been investigated in detail. The microstructures of the alloys change significantly with an increase in the carbon content. An alloy with 0.012 wt.% carbon shows a single ferrite phase, whereas with increase in carbon up to 0.65 wt.%, the microstructure evolves into a dual phase consisting of ferrite and \(\upkappa \)-pearlite. At about 1.5 wt.% carbon, the alloy exhibits only \(\upkappa \)-pearlite and with a further increase in carbon to 2.2 wt.%, an additional phase starts precipitating in the form of graphite. The room temperature tensile strength of the alloy increased significantly with an increase in the carbon content, which is in agreement with the microstructure. The yield strength and hardness of the steels with different carbon contents can be correlated well with the inter-barrier spacing in different steels.

Method of Changing the Structure of Cast Fe–Al Alloys By Inputting Titanium-containing Modifiers

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Electrodeposition of aluminium from ionic liquids on high strength steel

ABSTRACTElectroplated aluminium from ionic liquids is a promising candidate for corrosion protection of steels due to its excellent corrosion resistance. The pretreatment of the substrate is a crucial step for good adhesion of the coating and hence its performance. Conventional aqueous pretreatment of the steel substrate prior to aluminium plating does not lead to satisfactory results. In this paper, the authors systematically investigated anodic polarisation of high strength steel in Lewis acidic 1-ethyl-3-methylimidazolium chloride/AlCl3 as an electrochemical pretreatment method. The study includes cyclic voltammetry, chronoamperometric and chronopotentiometric methods as well as SEM/EDS analysis, optical microscopy, completed by roughness measurements using laser scanning profilometry and AFM. The removal of oxides and impurities from the steel surface and an increase of the surface roughness leads to excellent adhesion of the deposits. In-situ anodic polarisation and subsequently deposition results in the formation of an aluminium-iron alloy. By separation of pretreatment and deposition baths, high quality pure aluminium deposits can be achieved. It is shown that the developed pretreatment process can be successfully applied for the coating of flat substrates as well as for fasteners; the latter in a barrel plating process. The coating shows good adhesion and is evenly distributed over the substrates. Furthermore, a method for removing ionic impurities (e.g. iron) in the pre-treatment bath is suggested.

Structure and mechanical behavior of ultrafine-grained aluminum-iron alloy stabilized by nanoscaled intermetallic particles

Ultrafine-grained aluminum alloys offer interesting multifunctional properties with a combination of high strength, low electrical resistivity, and low density. However, due to thermally induced grain coarsening, they typically suffer from an intrinsic poor thermal stability. To overcome this drawback, an Al-2%Fe alloy has been selected because of the low solubility of Fe in Al and their highly positive enthalpy of mixing leading to the formation of stable intermetallic particles. The two-phase alloy has been processed by severe plastic deformation to achieve simultaneously submicrometer Al grains and a uniform distribution of nanoscaled intermetallic particles. The influence of the level of deformation on the microstructure has been investigated thanks to transmission electron microscopy and atom probe tomography and it is shown that for the highest strain a partial dissolution of the metastable Al6Fe particle occurred leading to the formation of a Fe super saturated solid solution. The thermal stability, and especially the precipitation of particles from the ultrafine-grained solid solution and the way they pin grain boundaries has been investigated both from static annealing and in-situ transmission electron microscopy experiments. The correlation between microstructural features and microhardness has been established to identify the various strengthening contributions. Finally, it is shown that ultrafine grained high purity Al with less than 0.01 at. % Fe in solid solution could preserve a grain size only 300 nm after 1 h at 250 °C.

Effects of substrate surface roughness and aluminizing agent composition on the aluminide coatings by low-temperature pack cementation

In this study, a new low-temperature aluminizing process combining surface slurry pre-coating at room temperature with pack cementation process was used to prepare the iron-aluminum alloy coating. The effects of different substrate surface roughness and aluminizing agent composition on the coating surface roughness, phase structure and the thickness of each phase in the coating were studied. The results showed that the average surface roughness of the coating with 2000# substrate and 5% AlCl3 was 2.641 μm. The aluminide coatings under different experimental parameters had the same Fe3Al, FeAl, Fe2Al5 and FeAl3 phase structure. However, the thicknesses of Fe3Al, FeAl and FeAl3 phase layers decreased with the increase of AlCl3 content. Furthermore, the aluminide coating with 2000# substrate and 5% AlCl3 had a bonding strength of 67.60 MPa and outstanding thermal shock resistance. The excellent properties of the iron-aluminum alloy coating made it possible to prepare the top coat on it.

Short-Range Order in α-FeAl Soft Magnetic Alloy

The atomic structure of iron–aluminum alloy samples containing about 7 at % of aluminum (α region of the phase diagram) was investigated by X-ray diffraction. The samples were annealed in the paramagnetic (T > TC) and ferromagnetic (T < TC) states. In the first case, the structural state was fixed by quenching from the annealing temperature in water, and, in the second case, by slow cooling. Diffraction patterns of single-crystal samples were taken on an X-ray four-circle diffractometer. It is shown that local ordering, regardless of the prehistory of a sample, is a combination of B2-phase clusters (the CsCl type structure), which were previously found in iron–silicon alloys with Si content up to 10%, and small regions with D03 short-range order. The former consist of two B2-cells having a common face, while the latter consist predominantly of one unit cell of the D03-phase. Within the accuracy of the experiment, no significant difference in the structural states in the paramagnetic and ferromagnetic phases was observed.

探究活動としてのテルミット反応を利用した 鉄-アルミニウム合金の製造について

探究活動としてのテルミット反応を利用した 鉄-アルミニウム合金の製造について

Ближний порядок в магнитомягком сплаве alpha-FeAl

AbstractThe atomic structure of iron–aluminum alloy samples containing about 7 at % of aluminum (α region of the phase diagram) was investigated by X-ray diffraction. The samples were annealed in the paramagnetic ( T &gt; ^T_ C ) and ferromagnetic ( T &lt; T _ C ) states. In the first case, the structural state was fixed by quenching from the annealing temperature in water, and, in the second case, by slow cooling. Diffraction patterns of single-crystal samples were taken on an X-ray four-circle diffractometer. It is shown that local ordering, regardless of the prehistory of a sample, is a combination of B 2-phase clusters (the CsCl type structure), which were previously found in iron–silicon alloys with Si content up to 10%, and small regions with D 0_3 short-range order. The former consist of two B 2-cells having a common face, while the latter consist predominantly of one unit cell of the D 0_3-phase. Within the accuracy of the experiment, no significant difference in the structural states in the paramagnetic and ferromagnetic phases was observed.

Rapid removal of chloroform, carbon tetrachloride and trichloroethylene in water by aluminum–iron alloy particles

ABSTRACTWater contamination with chlorinated hydrocarbons such as chloroform (CHCl3), carbon tetrachloride (CCl4) and trichloroethylene (TCE) is one of the major public health concerns. In this study, we explored the use of aluminum–iron alloys particles in millimeter scale for rapid removal of CHCl3, CCl4 and TCE from water. Three types of Al–Fe alloy particles containing 10, 20 and 58 wt% of Fe (termed as Al–Fe10, Al–Fe20 and Al–Fe58) were prepared and characterized by electrochemical polarization, X-ray diffraction and energy dispersive spectrometer. For concentrations of 30–180 μg/L CHCl3, CCl4 and TCE, a removal efficiency of 45–64% was achieved in a hydraulic contact time of less than 3 min through a column packed with 0.8–2 mm diameter of Al–Fe alloy particles. The concentration of Al and Fe ions released into water was less than 0.15 and 0.05 mg/L, respectively. Alloying Al with Fe enhances reactivity towards chlorinated hydrocarbons' degradation and the enhancement is likely the consequence of galvanic effects between different phases (Al, Fe and intermetallic Al–Fe compounds such as Al13Fe4, Fe3Al and FeAl2) and catalytic role of these intermetallic Al–Fe compounds. The results demonstrate that the use of Al–Fe alloy particles offers a viable and green option for chlorinated hydrocarbons' removal in water treatment.

A generalized mean stress correction model based on distortional strain energy

A new fatigue damage model based on the distortional strain energy is presented and discussed to account for the mean stress effects on fatigue life. The proposed model is compared to the Morrow and the SWT mean stress correction models using experimental mean stress fatigue data for Incoloy 901 superalloy, 120–90-02 ductile cast iron and 7075-T651 aluminum alloy under tensile and compressive mean stress loadings. The proposed model and the SWT model are found to show similar fatigue predictions and show good agreement for positive mean stress data and moderate negative mean stress data. The proposed model shows reasonably good agreement while the SWT model is unable to correlate mean stress data under large compressive mean stress conditions. The Morrow model provides poor correlations for all fatigue data analyzed by yielding conservative results for compressive mean stresses and non-conservative results for tensile mean stresses.

Temperature magnetism of disordered iron–aluminum alloys in a model of two intra-atomic interactions

A system of band electrons with the two constants of intra-atomic exchange interaction simulates the different local environment of magnetic atoms in alloys. Temperature behavior of the magnetic characteristics of disordered Fe-Al alloys is investigated on the basis of an improved theory of dynamic fluctuations in electron spin density. The nature of the alloys’ different properties and the unusual temperature dependence of the magnetization and magnetic susceptibility is discussed.

Chemical removal of nitrate from water by aluminum-iron alloys

Zero-valent iron has been intensively investigated in chemical reduction of nitrate in water, but the reduction requires acidic or weak acidic pH conditions and the product of the reduction is exclusively ammonium, an even more toxic substance. Zero-valent aluminum is a stronger reductant than iron, but its use for the reduction of aqueous nitrate requires considerably alkaline pH conditions. In this study, aluminum-iron alloys with an iron content of 10%, 20% and 58% (termed Al-Fe10, Al-Fe20 and Al-Fe58, respectively) were investigated for the reduction of aqueous nitrate. Al-Fe alloys were efficient to reduce nitrate in water in an entire pH range of 2–12 and the reduction proceeded in a pseudo-first order at near neutral pH conditions. The observed reaction rate constant (Kobs) of Al-Fe10 was 3 times higher than that of Fe and the Kobs of Al-Fe20 doubled that of Al-Fe10. The nitrogen selectivity of the reduction by Al-Fe10, Al-Fe20 and Al-Fe58 was 17.6%, 23.9% and 40.3%, respectively at pH 7 and the nitrogen selectivity by Al-Fe20 increased from 18.9% at pH 2–60.3% at pH 12. The enhanced selectivity and reactivity of Al-Fe alloys were likely due to the presence of an intermetallic Al-Fe compound (Al13Fe4).