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Iodine has proven to be a promising alternative to xenon as a propellant for Hall and ion thrusters. High atomic mass and favourable ionization characteristics, comparable to xenon in terms of propulsive performance, together with lower cost compared to xenon makes it an attractive option. However, its reactivity and corrosive nature raise concerns. Tests to assess material compatibility and determine whether thruster components are susceptible to corrosion are unavoidable for its safe adoption as a propellant. This paper describes the main results of an experimental campaign aimed at a qualitative assessment of the compatibility with iodine of different materials. The study included more than fifteen materials that find application in electric propulsion devices, such as cathodes, thrusters and feeding systems, including ceramics such as LaB 6 , polymers, iron and aluminum alloys, and graphite. The specimens were exposed to iodine vapor environments at temperatures reaching approximately 200 °C for extended periods (from three to over 30 h) or were directly exposed to liquid iodine. The experimental setup and results of morphological and elementary analyses are presented and discussed. The research provides some insights into the viability of using iodine as a propellant and the potential challenges associated with its corrosive properties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (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%. [ABSTRACT FROM AUTHOR]

Replacing automotive components made of iron alloys with aluminum alloys is one of the strategies to reduce vehicle weight and increase fuel efficiency in the automotive sector. Semisolid casting is a metalworking process that combines casting and forming processes. In this process, the raw material being processed is in a mixture of liquid and solid phases, and the processing method uses a casting or forming method. This research aims to study the influence of mechanical agitation models on the aluminum alloy ADC12 to microstructure and mechanical properties. By using a metal mold, gravity casting has been used as the research methodology. Mechanical stirrers (round rod stirrers, straight plate stirrers, and twist plate stirrers) have been used to mix the aluminum ADC12 slurry for 60 seconds at a speed of 300 rpm. Additionally, the ADC12 aluminum slurry has been poured into a metal mold at a temperature of 600 °C. Optical microscopy, Scanning Electron Microscopy (SEM), secondary α-Al phase dendritic arm spacing, and Si eutectic phase have been used to observe directly the microstructure features. The hardness and the tensile tests have been used to examine the mechanical properties. ADC12 aluminum alloy with mechanical characteristics of 89.7 HB, tensile strength of 249.96 MPa, and strain of 4.33 percent have been produced by using the straight plate stirrer. A lower particle size value (31.6 mm) and a Shape Factor (SF) of 0.56 corroborate this mechanical quality. More research can be done on various types of aluminum alloys, higher stirring rotation speeds, and the size, quantity, and spacing of stir blades. [ABSTRACT FROM AUTHOR]

Erosion testing was conducted on cast steel and spheroidal graphite cast iron specimens containing large amounts of manganese and several other ferrous materials in molten aluminum alloys. Based on the results, the erosion resistance of ferrous materials with a high-Mn content was quantified, and the resistance mechanism was investigated. The erosion ratios of high-Mn-containing ferrous specimens were lower than those of specimens that did not contain a high amount of Mn. An analysis of the chemical compositions in the vicinity of the contact interfaces of the high-Mn-containing specimens after testing revealed that the manganese-to-iron content ratios in the intermetallic layers were largely the same as those in the specimens and that the ratios in the melts (solidified) were greater than those in the specimens and intermetallic layers. This small-scale enrichment of manganese could be attributed to its lower diffusion rate compared to iron. In addition, the calculated isothermal phase diagrams corresponding to the testing temperature showed that the apparent saturation solubility of iron in the molten aluminum alloys decreased with the manganese content, irrespective of the silicon content in the melts. These results suggest that the local decrease in the saturation solubility of iron in the melts owing to the small-scale enrichment of manganese in the vicinity of the solid–liquid interface can improve the erosion resistance of specimens containing a high amount of manganese. [ABSTRACT FROM AUTHOR]

Mechanochemical alloying of Cu + Al and Сu + Fe + Al powders with subsequent hydrothermal treatment and calcination were used to synthesize ceramometal catalysts. In addition, CuAl + Cu foam and CuFeAl + Cu foam ceramometal catalysts reinforced with Cu foam were also synthesized. The obtained ceramometals are the metallic cores containing copper, iron and aluminum alloys, which are covered with a shell consisting of the oxides of these metals. Structural, microstructural and textural features of the synthesized composite catalysts were studied using XRD, XPS, SEM with EDX, and adsorption-desorption isotherms. It was shown that СuAl ceramometals are more active toward the low-temperature water-gas shift reaction than CuFeAl. This is related to a higher concentration of highly active sites on the surface of these ceramometals. The activity of ceramometal granules reinforced with Cu foam is much higher as compared to unreinforced ones. This is caused by the developed macropore structure and a higher permeability of granules with foam Cu, which weaken the internal diffusion limitations. The maximum activity of the CuAl + Cu foam catalyst granules exceeds that of the CuZnAl oxide catalyst by a factor of 2.5. Thermal conductivity of ceramometal catalysts was estimated to be higher for reinforced ceramometals, reaching 4.5 W/mK. So, the integration with foam Cu leads to an improvement of thermal, textural and catalytic properties of ceramometals. [Display omitted] • Porous ceramometals CuAlO/CuAl and CuFeAlO/CuFeAl are integrated with foam Cu. • Integration with foam Cu improves permeability and activity of ceramometal catalyst. • Ceramometal CuAlO/CuAl + Cu foam possesses higher activity than oxide CuZnAl one. • Active centers of CuAlO/CuAl are more active than those of CuFeAlO/CuFeAl and CuZnAl. [ABSTRACT FROM AUTHOR]

Seizure during ironing negatively affects the quality of parts and die life. To prevent seizures, lubrication has to be improved. In this study, laser-textured dies with lubricant pockets were utilized to improve seizure resistance in the ironing of aluminum alloy sheets and stainless steel cups. The effects of array patterns of micro-pockets, such as grid and crossing array patterns with circular pockets, as well as a grooved array patterns on seizure resistance, were experimentally examined by strip ironing. The sheet and die materials were the A1050-O aluminum alloy and JIS SKD11 tool steel, respectively. Moreover, the underlying physics of the lubricant flow influencing the load-carrying capacity were investigated using three-dimensional computational fluid dynamics simulations. The optimum array patterns of the micro-pockets were then utilized on a tungsten carbide-cobalt (WC-Co) die surface for ironing SUS430 stainless steel cylindrical cups. The strip ironing results showed that the grid array pattern was successful in ironing sheets with a high ironing ratio. The grid array pattern increased the load-carrying capacity of the lubricant more than the crossing pattern, as demonstrated by the simulations, thereby improving the ironing limit. The subsequent ironing of stainless steel cups revealed that when using a textured die with a grid array pattern and lubricant without the extreme pressure additive in comparison to an untextured die, the ironing limit increased by 6% and the average ironing load decreased by 35%. The seizure resistance was improved because the pockets on the surface structured by laser surface texturing improved the load-carrying capacity during ironing. [ABSTRACT FROM AUTHOR]

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.

We investigated the cross-plane thermal conductivity and boundary thermal resistance of epitaxially grown superlattice samples. These included iron vanadium aluminum alloy (Fe2VAl) and tungsten (W) or molybdenum (Mo) prepared by radio frequency magnetron sputtering. We used out-of-plane X-ray diffraction measurements to confirm the epitaxial growth of the superlattices. The superlattice with the shortest period of 1.9 nm showed satellite reflections indicating a highly ordered structure. Misfit dislocations in the 2-nm-thick Mo layer were also identified by high-resolution transmission electron microscopy. We attribute these features to the large lattice mismatch between the Fe2VAl and Mo lattices. The cross-plane thermal conductivity of the superlattice decreased as the number of interfaces increased because of thermal resistance at interlayer boundaries. A simulation of the thermal conductivity by the constant boundary resistance model reproduced the experimental data but with some deviations for samples with a smaller period (less than 20 nm). This deviation from the simulation results indicates that the phonon modes contributing to the thermal transport changed and/or the phonon scattering probability at the interfaces decreased. The superlattice of Fe2VAl/W with a period thickness greater than 20 nm had a boundary thermal resistance approximately twice as large as that of the Fe2VAl/Mo superlattice. This result provides clear evidence for the effects of the mass difference of layers on phonon scattering at an interface. [ABSTRACT FROM AUTHOR]

Metallic materials have witnessed substantial developments over the past two decades. Recent research findings suggest that certain high-entropy alloys exhibit notably improved strength-to-weight ratios, enhanced fracture resistance, superior tensile strength, and greater resistance to corrosion and oxidation compared to traditional alloy alloys [[2]]. Within the field of the newly developed metallic materials, high-entropy alloys (HEAs) stand out as an exceptionally promising group, offering a wealth of potential for future advancements in metal alloys. [Extracted from the article]

The thermodynamic properties for the full composition range of liquid Fe–Ti alloys were determined using the atom and molecule coexistence theory (AMCT). The thermodynamic model was also established to calculate the mass action concentration (activity) of the structural units in the above-mentioned binary alloy system. The temperature dependence of the activity coefficients of Ti dissolved in molten iron to form dilute solutions () relative to pure liquid, were also estimated. Simultaneously, the standard Gibbs free energy changes of dissolving Ti in the iron of liquid Fe–Ti were also studied. The excess molar mixing enthalpy , the excess molar mixing entropy , and the excess molar mixing Gibbs free energy were also studied from 1873 to 2073 K. Meanwhile, the thermodynamic properties of activities and the excess Gibbs free energy of mixing were predicted in the Fe–Al–Ti ternary melts at 1873 K under conditions of various Fe/Al ratios. [ABSTRACT FROM AUTHOR]

Secondary aluminum alloys in automotive industry have been rising in last decades; however, the iron content is still a concern whether recycled or high iron containing aluminum alloys can fulfill the mechanical requirements. As the proportion of recycled scrap increases in aluminum alloy components, the mixing and accumulation of impurities become significant issues. In this study, manganese was used to counteract the detrimental effects of iron. Accordingly, A356 alloy automobile wheels containing 0.002 wt%, 0.040 wt%, 0.069 wt%, and 0.14 wt% Mn were cast using the low-pressure die casting method, followed by T6 heat treatment. Optical microscope (OM) examinations were performed to observe intermetallics. Additionally, the mechanical properties of the produced wheels were evaluated through hardness measurements, tensile, and Charpy impact tests. After the Charpy impact test, fractured surfaces were examined using scanning electron microscopy (SEM). Micrographs from SEM and OM were quantified using digital image processing. To interpret this extensive dataset, a statistical model was developed using microstructural data as input through multiple linear regression analysis and analysis of variance. The results were discussed together with the sensitivity analysis. A weak negative linear correlation between Mn concentration and mechanical properties was found, indicating that Mn addition is not the primary factor for the observed decrease in mechanical properties. Elongation and yield strength were significantly influenced by both aspect ratio and particles/mm2, with greater sensitivity to particles/mm2. Additionally, impact energy was strongly affected by aspect ratio of particles (intermetallics and eutectic Si) and their concentration per unit area. [ABSTRACT FROM AUTHOR]

During the solidification of aluminum alloys with high iron concentrations in conjunction with electromagnetic stirring, the electromagnetic force induces movement of precipitated intermetallic grains containing iron. This force is assumed to cause macrosegregation of such compounds, although the movement process is complex due to the additional effects of melt flow on growth kinetics. The present work used in situ X-ray imaging to obtain insights into the macrosegregation process induced by electromagnetic stirring. This imaging was employed to observe the evolution of primary intermetallic α-Al(FeMn)Si grains during the solidification of an Al-10Si-2Fe-2Mn alloy in the presence of a rotating magnetic field. The α-Al(FeMn)Si grains were found to be uniformly distributed in the horizontal direction of the alloy without electromagnetic stirring but tended to congregate at the periphery of the specimen with stirring. In situ X-ray imaging confirmed that electromagnetic stirring also promoted growth of α-Al(FeMn)Si phase grains from the periphery into the center of the alloy. The α-Al(FeMn)Si phase at the sample periphery comprised a single grain, indicating that stirring led to dendrite growth. These observations together with ex situ crystallographic analyses demonstrated that macrosegregation in an Al-10Si-2Fe-2Mn alloy solidified with electromagnetic stirring resulted from grain coarsening of the α-Al(FeMn)Si phase at the sample periphery. • An X-ray imaging setup was developed to observe solidification sequences during electromagnetic stirring. • The evolution of the α-Al(FeMn)Si phase in the presence of electromagnetic stirring was observed. • The orientation of the α-Al(FeMn)Si phase was determined by the electron backscatter diffraction method. • Electromagnetic stirring promoted the grain growth of the α-Al(FeMn)Si phase. • Grain coarsening of the α-Al(FeMn)Si phase led to macrosegregation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Excessive iron in aluminum alloys forms compounds that weaken their strength and workability. Therefore, controlling the morphology of the Fe-rich phase is vital for developing strong, high-quality aluminum alloys. This research explores the controlled diffusion solidification (CDS) process, an innovative approach designed to optimize the morphology and distribution of the Fe-rich phase, thereby enhancing the alloy properties beyond what conventional methods can achieve. Specifically, the CDS process uniquely modifies the solidification behavior of the alloy, suppressing the growth of the primary Fe-rich phase and enhancing the overall properties. This demonstrating the ability of process to refine microstructural characteristics effectively. The experimental results confirm the presence of primary Si and Al 3 Fe in the CDS process samples. Consequently, the nucleation of Al 3 Fe in the precursor alloy leads to the concentration of Fe solutes reduce, impeding the nucleation and growth of the primary Fe-rich phase during the subsequent solidification process. The key factors are temperature difference between two mixed alloy and mass ratio of precursor alloys. The mass ratio influences the precipitation sequence of the precursor alloys, while the difference of temperature and concentration induces the undercooling necessary for nucleation. The study reveals that an optimal mass ratio of 4:1 in the CDS process achieves the best mechanical properties with a 73.78 % increase in ultimate tensile strength (UTS) and a 107.77 % increase in elongation (UL) compared to conventional casting. The findings provide a theoretical basis for controlling the Fe-rich phase evolution, significantly augmenting the performance of Al-Si-Fe alloys. The findings not only enhancing the optimizing fundamental reactions in the CDS process for other alloy systems but also enriching the broader field of materials science. • At a 4:1 mix ratio, the Fe-rich phase refines optimally, yielding a tensile strength of 141.7 MPa and 4.0% elongation. • In CDS, primary phases precipitate from the binary diagram; ternary eutectics form as temperature drops to the eutectic point post-blending. • During CDS mixing, subcooling regions boost nucleation, increasing nuclei and slowing grain growth. [ABSTRACT FROM AUTHOR]

Iron aluminides are iron-aluminum alloys that have excellent resistance to oxidation at high temperatures with low density, high resistance/weight ratio and a low manufacturing cost. Due to its characteristics, these alloys are presented as an option to replace stainless steels in certain applications. This works intends report the casting process and subsequent analyses involving microstructure, mechanical properties, and corrosion resistance of two Fe-Al-C alloys (Fe-11wt%Al and Fe-25wt%Al, containing 0.31-0.37%C), which were prepared in an induction furnace and poured in a permanent mold. Samples of these alloys were characterized and presented elevated hardness values of 37 HRC (alloy Fe-11wt%Al) and 49.6HRC (alloy Fe-25wt%Al) and microstructure with aluminides type Fe3Al and FeAl and also carbides type K. The Fe-11wt%Al alloy exhibited superior resistance to uniform corrosion, although both Fe-Al-C alloys exhibited significantly higher corrosion rates compared to a binary iron aluminide in 0.5M H2SO4 containing naturally dissolved oxygen. [ABSTRACT FROM AUTHOR]

Ductile iron containing Si and Mo (SiMo) is a common alloy that has been used for exhaust car manifolds due to the need for high thermal cycling and being in an oxidizing environment. Al alloying has been shown in previous studies to reduce surface degradation during high temperature exposure of SiMo ductile iron. However, it has been shown to decrease the ductility and increase cracking during thermal cycling due to graphite shape degradation. To optimize composition and casting technology of Al-alloyed SiMo ductile iron, experimental castings containing 0.0% Al (base), 1.8% Al, and 3% Al were produced using a special melting procedure and tested at high temperature. Through experimental results and analysis, it was determined that the optimal Al alloying was dependent on a balance of oxidation and thermomechanical conditions. [ABSTRACT FROM AUTHOR]

The investigation in this paper is based on the existence of carbon content and its role in the formation of Fe-Al intermetallic layer in unalloyed carbon steel C45 with a carbon content of 0.44 wt.%. Several sophisticated techniques such as PFIB SEM equipped with EDS and EBSD, GD-OES were employed for the in-depth surface analysis. The results of the metallographic examination reveal that the carbon would appear and could be well detected at the interface between the solidified aluminum and the solid iron-base steel substrate and got also incorporated in the top aluminum layer. Furthermore, due to the dissolution and outward diffusion of iron into the liquid aluminum melt during the HDA process, plus its involvement in the formation of the solid intermetallic surface layer, thus the carbon atoms gaining higher chemical affinity there will also be more likely to form carbide precipitates of different kinds like Fe3AlC and AlC inside these developing surface layers on the C45 type steel during the process of hotdip aluminizing at 700 °C. [ABSTRACT FROM AUTHOR]

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 the addition of 1.0 wt % of titanium and 0.1 wt % of zirconium to a low-carbon iron-aluminum melt containing 12–14 wt % of aluminum grinds its structure increasing tensile strength and refractory properties. Titanium and zirconium are strong carbide-forming elements. When introduced into a low-carbon iron-aluminum alloy, they form a large number of crystallization centers, thus, affecting its microstructure, allowing to get finer and more uniform granularity 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 heat-resistance, which exceeds several times the heat-resistance of famous chrome-nickel steel of Fe20Cr23Ni18 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. [ABSTRACT FROM AUTHOR]

Allowing reducing CO2 emission in automotive industry, design engineers gradually replacing steel and grey iron by aluminum alloys due to its low density. The aim of the present paper is to investigate the effect of anodic layer on friction coefficient (COF) and wear resistance of 2024A anodized aluminum alloy by using different techniques of analysis such as Tribometer and Microscratch tester. The derived laws from the friction theory shows that as the sliding speed increases are the wear resistance decreases. However, during our experiences, we have observed that this is not true for all increasing speed values. The tests are carried out at different loads conditions and at different sliding speed and hardness, wear rate and COF have been measured after and before anodizing process, metallurgical characterization was assessed using SEM microscope and XRD analysis. The results show when speed reaches the value of u=0.4m/s the wear mechanism is transformed from the severe regime to mild regime, which is considered as a significant reduction in wear rate and COF at this transition speed. [ABSTRACT FROM AUTHOR]

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Epitaxial Co2FeAl films were synthesized using the Biased Target Ion Beam Deposition technique. Post annealing yielded Co2FeAl films with an improved B2 chemical ordering. Both the magnetization and the Gilbert damping parameter were reduced with increased B2 ordering. A low damping parameter, ~0.002, was attained in B2 ordered Co2FeAl films without the presence of the L21 Heusler phase, which suggests that the B2 structure is sufficient for providing low damping in Co2FeAl. The spin polarization was ~53% and was insensitive to the chemical ordering. [ABSTRACT FROM AUTHOR]

A recently published study of high temperature nitridation of iron chromium aluminum alloys (FeCrAl) at 900°C in N2–H2 has redundantly shown the formation of locally confined corrosion pockets reaching several microns into the alloy. These nitrided pockets form underneath chromia islands laterally surrounded by the otherwise protective alumina scale. Chromia renders a nitrogen‐permeable defect under the given conditions and the presence of aluminum in the alloy. In light of these findings on FeCrAl, a focused ion beam–scanning electron microscope tomography study has been undertaken on an equally nitrided FeNiCrAl sample to characterize its nitridation corrosion features chemically and morphologically. The alloy is strengthened by a high number of chromium carbide precipitates, which are also preferential chromia formation sites. Besides the confirmation of the complete encapsulation of the corrosion pocket from the alloy by a closed and dense aluminum nitride rim, very large voids have been found in the said pockets. Furthermore, metallic particles comprising nickel and iron are deposited on top of the outer oxide scale above such void regions. [ABSTRACT FROM AUTHOR]

In solid-solution-strengthened ferritic ductile iron (SSFDI), a silicon content above 4.3 wt% leads to an abrupt decrease in ultimate tensile strength and elongation at fracture. This phenomenon has recently been proven to be attributed to the formation of iron–silicon long-range orderings that lead to an embrittlement of the material. It is assumed that the local tendency to form silicon superstructures is promoted in particular by the occurrence of silicon microsegregation. During solidification of ductile iron, silicon segregates inversely into the austenite. Thus, the highest silicon concentration is larger than the initial concentration of the melt and is located directly at the graphite nodules. As a straight consequence, the presence of silicon superstructures is expected primarily in these areas. Therefore, the focus is on homogenization of the silicon microsegregation profile in order to avoid the formation of brittle iron–silicon superstructures. For this purpose, in the present study the alloying concept of SSFDI is adapted. Thermodynamic–kinetic simulations as well as experimental investigations indicate that aluminum concentrations of approx. 1.2 wt% lead to an inversion of the silicon microsegregation. The findings provide a promising tool to shift the silicon embrittlement in SSFDI to higher silicon concentrations. This method could be used to increase the maximum strength, to improve toughness properties or to increase the process integrity against deviations in silicon content. [ABSTRACT FROM AUTHOR]

The application of an alternative laser-induced breakdown spectroscopy (LIBS) method based on transversely excited atmospheric (TEA) CO2 laser was investigated for the first time for estimating the hardness of metallic materials. The human eye-safe (TEA) CO2 laser, operating at 10.6 µm, was used for plasma generation. The LIBS spectra were recorded by employing a cost-effective CCD camera for the time-integrated and spatial resolved measurements. The cast iron and aluminum alloys samples with different hardness have been tested. The ratio between the magnesium ionic and neutral lines in LIBS spectra was applied for estimating the material hardness. In addition, the hardness of all samples included in this study was determined using the conventional method for material hardness determination, i.e. Vickers hardness test. The linear dependence of magnesium lines intensity ratio on the sample's hardness was obtained for both kinds of materials. Profilometric measurements were used to verify that the newly-introduced method is almost nondestructive for the investigated metals. The results obtained in the present work confirmed the potential of using this original LIBS system not only for the fast elemental analysis but also for the direct estimation of the hardness of metals and alloys. [ABSTRACT FROM AUTHOR]

Purpose: The 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/approach: In 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. Findings: The 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/value: This 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. [ABSTRACT FROM AUTHOR]

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents information on a study which analyzed the short-range order of iron in iron/aluminum multilayers using x-ray absorption fine structure (XAFS). Information on fluorescence XAFS experiments combined with x-ray standing waves; Scattering properties of aluminum and iron; Conclusions.

With their specific layer features and properties, surface treatments such as thermochemical treatment (nitriding, boriding) and hard coating cover a broad field of application in the wear and corrosion protection of steels. Limitations exist, however, when applying these surface treatments to softer materials, such as cast irons and aluminum alloys in terms of both their treatability and load-bearing capacity. This contribution deals with investigations into duplex surface treatments, where a pre- and post-electron beam (EB) surface treatment (e.g., hardening, remelting, alloying etc.) was combined with one of the above-mentioned treatments. Among other characteristics, the thermal EB surface treatments were characterized by high heating and cooling rates that facilitated the generation of a variety of non-equilibrium microstructures, which exhibited increased hardness and had minimal thermal effects on the surrounding base material. Furthermore, the layer thicknesses were one or two orders of magnitude higher than those generated by thermochemical treatment or hard coating. Based on the comprehensive results and using cast irons and Al alloys as examples, the study demonstrates the extent to which duplex treatments can overcome the aforementioned limitations, and how the tribological and/or corrosive load behavior is affected. The property profiles achieved after duplex surface treatment were strongly dependent on the inherent microstructural and chemical processes. These complex processes were influenced by a range of factors, such as the thermal stability of the EB surface layer generated in the first process step, the respective temperature and time period of the secondary process, etc. Hardness measurements, scratch tests, unlubricated pin-on-disc wear tests using different normal loads and potentiodynamic corrosion tests were realized to facilitate characterization of the different load behaviors of the single- and duplex-treated layers. • Classification of combination treatments for cast irons and Al alloys • Combination treatments for overcoming microstructural limitations • Electron beam surface treatment to improve the load-bearing support of thin coatings • Thermal stability of the first process layer is essential. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • DFT calculations for Fe-rich FeAl alloys with N addition are performed. • The insertion of N in FeAl alloys is more favorable than the substitution of Fe/Al atom. • 6 at.% of N stabilize the Fe 9 Al 7 and Fe 10 Al 6 alloys. • The magnetic moment increase by the ferromagnetic coupling between Fe and N, thus increasing the Fe local magnetic moment. • The total magnetic moment of Fe 9 Al 7 varies proportionally until 5 atoms of N due to the magneto-volume effect. Abstract Using the DFT calculations, the phase stability, structural deformation and magnetic moment of Fe-riche FeAl alloys in presence of different percents of nitrogen were calculated. The formation enthalpy of these Fe-Al alloys indicates that N preferred the octahedral site than the substitution one. Significant changes occur in this energy, affected by N and Fe content causing local distortions. From 25 at.% N, the phenomenon of saturation appeared and the substitution takes place. The addition of 6 at.% N stabilizes Fe 9 Al 7 and Fe 10 Al 6. The presence of N atom leading to decrease the total magnetic moment of FeAl nitride when the magnetic order is antiferromagnetic between N and Fe atom. This magnetic moment increased by the ferromagnetic coupling between Fe and N, thus increasing the Fe local magnetic moment and the magneto-volume effect. [ABSTRACT FROM AUTHOR]

To further investigate the effects of isothermal heating temperature on the interfacial reactions between the Fe-Al-Ca alloy and the Al2O3-CaO-FeO oxide, two kinds of diffusion couples with different FeO contents in the oxide were prepared and then subjected to isothermal heating at different temperatures in the range of 873 K to 1473 K for 10 h, 30 h, and 50 h. With increasing temperature of isothermal heating, in the case of 0.5 mass% FeO, fine Al2O3 particles first precipitated in the alloy near the alloy–oxide interface, and then CaO·Al2O3 branch inclusions appeared and increased in number, while for the case of 3.0 mass% FeO, Al2O3 particles were the only reaction product in the particle precipitation zone (PPZ). An improved kinetics model for predicting PPZ width was proposed and verified by experimental results. [ABSTRACT FROM AUTHOR]

Abstract The creep behavior of a fully lamellar FeAl/FeAl 2 eutectoid alloy was shown to exhibit a minimum creep rate and the absence of a pronounced steady state regime. To reveal the underlying mechanisms of creep leading to the macroscopic response described above, comprehensive TEM investigation of several crept specimens were performed. In the early stages of creep, the FeAl phase primarily carries creep deformation by dislocation motion, whereas FeAl 2 remains mostly plastically undeformed, except in certain locations near colony boundaries where the lamellar structure is disrupted/absent. Within the colonies, where the lamellae are intact, deformation is accommodated at the FeAl/FeAl 2 interface, resulting in an increase in interface dislocations. This continues to be the case at the minimum creep rate. With further progression in creep, FeAl 2 begins to participate in the process of plastic deformation in a more substantive manner through twinning and slip, while FeAl continues to plastically deform and dynamically recover. Further beyond the minimum, the lamellar structure adjacent to the colony boundaries breaks down, and these areas become the primary contributors to creep and results in a continuous loss in creep resistance. Based on these observations in the fully lamellar material, the creep response of off-eutectoid Fe-58Al and Fe-62Al as well as single-phase FeAl 2 are explained. Highlights • Creep mechanism in a lamellar FeAl/FeAl 2 alloy is examined by electron microscopy. • Initially, FeAl deforms by slip and interface dislocation content increases. • A creep rate minimum then occurs and is associated with slip and twinning in FeAl 2. • Twins nucleate at the FeAl/FeAl 2 interfaces and FeAl 2 twins on the (001) plane. • Increase in creep rate at longer time results from lamellar structure breakdown. [ABSTRACT FROM AUTHOR]

Highlights • Thin FeCrAl coatings with Mo buffer layer on Zry-4 substrate can tolerate 1200 °C steam environment. • A systematic study of the oxidation behavior of FeCrAl-Mo bi-layer coatings is presented. • The migration of FeCrAl-Mo interface and voids formation mechanisms are consistent with the Kirkendall effect. Abstract FeCrAl alloys have exhibited excellent oxidation resistance in high temperature steam environment. However, over the past few years, thin film FeCrAl on zircaloy substrate can only tolerate up to 1000 °C steam because of the fast diffusion between zirconium and iron. In this study, we introduce Mo as a buffer layer and significantly reduced the inter-diffusion of zirconium and iron. The 7-micron thick FeCrAl coatings have shown excellent oxidation resistance up to 1200 °C, which is the highest temperature of thin FeCrAl coatings reported in literature. A systematic study of the oxidation behavior of FeCrAl coatings at 1000, 1100, 1200 °C is presented in this paper. [ABSTRACT FROM AUTHOR]

Highlights • The effect of Al content on the corrosion resistance of Fe-Al alloys was revealed. • Passive film structure on Fe-25Al was evaluated by XPS. • The oxide layer effectively protected Fe-25Al against corrosion in H 2 SO 4. Abstract The influence of Al content and pre-oxidation on the corrosion behavior of binary Fe-Al alloys in 0.0126 M H 2 SO 4 was investigated. The minimum Al content for forming a passive film on binary Fe-Al at 25 °C is 15 at.% and passivation improves up to 25 at.% Al. X-ray photoelectron spectroscopy measurements show that the passive film on Fe-25Al is enriched in Al and consists of an outer layer of mixed Al and Fe hydroxides and an inner layer of Al oxide. The oxide layer generated at 1000 °C effectively protected against aqueous corrosion in H 2 SO 4. [ABSTRACT FROM AUTHOR]

This study analyzes the effects of manufacturing parameters such as the temperature and heating time on the shape and size of high-aluminum-phase precipitates produced from a 95.5 wt pct Al and 4.5 wt pct Fe powder mixture. The samples were prepared by powder metallurgy, and the changes in the heat flux during the simulation of the sintering process by differential thermal analysis were recorded to determine the temperature of the transformation. To identify the resulting structures, microscopic observations (scanning electron microscope) and chemical composition analyses were performed simultaneously. The distribution and shape of the resulting high-aluminum-phase precipitates were determined. Microhardness measurements were also performed, and Meyer's law and Kick's similarity law were applied to the results to analyze the influence of the high-aluminum phases on the reinforcement of the aluminum matrix. [ABSTRACT FROM AUTHOR]

Iron-aluminum alloys with a high (more than 10 wt.%) aluminum content are alloys with sufficiently high heat resistance and can be considered as an alternative to expensive superalloys containing nickel and chromium. A method is proposed for obtaining an equiaxial structure in cast alloys of Fe- (12-14 wt.%) Al. Alloys were smelted in an open mid-frequency induction furnace by introducing titanium-containing modifiers, which can act as crystallization centers during melt solidification when they are introduced into a liquid metal, helping to obtain an optimal grain structure of the solid metal. Several modifications were used: FeTi30, FeTi30 with the addition of metallic zirconium and the complex microcrystalline modifier "Insteel 7". All modifiers contained varying amounts of titanium. They were introduced into the melt of Fe-Al alloys 5 minutes before the metal was drained. The purpose of this study was to obtain an equiaxed grain structure of the alloys in the solid state. The desired grain shapes were achieved by introducing the FeTi30 modifier when the total titanium content in the ingot was more than 1.2% by weight. Another way to obtain the optimal structure was the introduction of FeTi30 with the addition of metallic zirconium (1.83 wt.% Ti and 0.3% Zr in the ingot). The use of the Insteel 7 modifier, consisting of Ca, Ba, Fe, Ti, Ce, and La in the form of complex silicides, is impractical because its use does not allow obtaining an equiaxial or close to equiaxial granular structure of cast Fe-Al alloys. [ABSTRACT FROM AUTHOR]

Purpose This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy.Design/methodology/approach Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation.Findings The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation.Originality/value Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts. [ABSTRACT FROM AUTHOR]

Fe‐Al alloying is a matter of interest because of its technological importance and many applications. Different growth conditions may lead to different results, ie, formation of various phases. These phases may be magnetic or nonmagnetic in nature. Cosputtering of Fe and Al with magnetron‐sputtering setup provides us with a good option of alloying and to study the various phase formations. As, yet now researchers studied the alloying through cosputtering process only in oxygen environment, so a study in nonreactive environment was inevitable and interesting. Therefore, the authors went for Fe‐Al thin‐film synthesis using the magnetron sputtering in argon environment. Hence, this paper discusses the Fe and Al alloy formation in argon environment and annealed the samples at different temperatures for different time durations so as to allow various phase formations. The samples were characterized with grazing incidence X‐ray diffraction (GIXRD), grazing incidence X‐ray reflectivity (GIXRR), magneto‐optical Kerr effect (MOKE), and atomic force microscopy (AFM) techniques so as to study structural, morphological, and magnetic properties. The results confirm that cosputtering provides better chances of alloying and also supports formation of various stable phases in comparison with other available techniques. [ABSTRACT FROM AUTHOR]

Abstract In the present work are reported the stress annealing (SA) effect on magnetic properties of Fe–Al–B alloys and the result on the piezomagnetic coefficient d 33 ⁎ = d B / d σ | H , where σ is the applied stress, B is the magnetic induction and H is the applied magnetic field. The objective is to evaluate the potential use of these alloys as smart materials of force sensors. The study comprises two alloys with compositions (Fe 0.87 Al 0.13) 98.4 B 1.6 (Al13) and (Fe 0.82 Al 0.18) 98.4 B 1.6 (Al18). The microstructure, hysteresis loops and B vs. σ | H were analyzed before and after the SA. Regarding the force sensitivity, the SA increased the piezomagnetic coefficient d 33 ⁎ due the introduction of an extrinsic anisotropy in both Fe–Al–B alloys. Moreover, the stress range, in which the piezomagnetic coefficient d 33 ⁎ is linear, is higher after the SA. Concerning the single phase (Fe 0.87 Al 0.13) 98.4 B 1.6 alloy, the force/pressure sensitivity and the linear stress range increase up to 16.8% and 47.1%, respectively. For the two phase (Fe 0.82 Al 0.18) 98.4 B 1.6 alloy, the increase was a bit higher, but the curves B vs. σ are hysteretic, spoiling the use of this material as a force sensor component. Highlights • Sensitivity of Fe–Al–B alloys for force sensor application was improved by stress annealing. • A barely linear dependence of the magnetic induction B as a function of the stress σ was obtained for small and constant magnetic field. • The single phase (Fe 0.87 Al 0.13) 98.4 B 1.6 alloy exhibits the best properties for force sensor application, since B vs. σ curves are not hysteretic. • Hysteresis on B vs. σ curves of (Fe 0.82 Al 0.18) 98.4 B 1.6 alloy is associated with a biphasic microstructure, wherein the second phase was induced by stress annealing. [ABSTRACT FROM AUTHOR]

Abstract Solid loading as a key parameter in gel casting influence both rheological behavior and stability of slurry. It also has strong impacts on microstructure and final properties of porous FeAl intermetallics. In this study, a designed non-aqueous gel casting has been developed for fabrication of porous FeAl intermetallics. The SEM analysis, bubble point method and compression test were used to investigate pore structure and properties of porous FeAl intermetallics. Results reveal that higher solid loading will improve the uniformity of pore structure and lead a decrease in maximum pore size. Gas permeability decreases but compressive strength increases with increasing solid loading. The quantitative relationship between maximum pore size (d m) and solid loading (φ) is d m = 10.52 − 0.15 φ (35 ≤ φ ≤ 50); the relationship between gas permeability (K) and solid loading (φ) is K = 13.99 − 0.22 φ (35 ≤ φ ≤ 50). Further, the distinctive phase transformation and pore formation mechanism are the main reasons for tiny volume expansion and highly open porosity of final products, respectively. Altogether, this work provides a strategy to fabricate porous FeAl intermetallics with adjustable pore structure and properties by controlling the solid loading, suggesting that the non-aqueous gel casting is a promising candidate for the preparation of porous FeAl intermetallics. Graphical abstract Unlabelled Image Highlights • Porous FeAl intermetallics were fabricated using a non-aqueous gel casting. • Higher solid loading can improve the uniformity of pore structure. • Maximum pore size and gas permeability decrease with increasing solid loading. • Compressive strength increases with increasing solid loading. • Pores are formed by removal of gel network and phase transformation. [ABSTRACT FROM AUTHOR]

Highlights • Successful incorporation of oxide particles into FeCrAl by laser beam scanning. • Dispersion of yttria and ceria strengthens the FeCrAl alloy at elevated temperature. • Ductility drops by 10–11% at 380 °C, yet does not change significantly at 500 °C. Abstract In the present work, oxide dispersion is used to improve the high-temperature strength of FeCrAl alloys, which have excellent high-temperature oxidation resistance. Laser-beam scanning is introduced as a new method for manufacturing oxide-dispersion-strengthened alloys. Various oxide powders were initially coated on the surface of the FeCrAl alloy, which was then surface-treated by a laser beam to cause the oxides to penetrate and disperse into the metal matrix. The microstructure of the dispersed oxide layer was investigated by scanning electron microscopy and energy dispersive X-ray spectroscopy to reveal the mechanisms involved in oxide dispersion during the laser-beam scanning process. The effect of the different powder materials on the strengthening of laser-beam-scanned FeCrAl was examined by tensile tests, which were carried out at room temperature, 380 °C, and 500 °C. Regardless of the powder material, the thin oxide-dispersed-strengthened specimens showed similar tensile strengths to that of untreated samples at room temperature, but showed improvements of up to 24% at elevated temperatures. The total elongation of the surface-treated samples was considerably lower than that of the untreated sample at 380 °C; however, this loss of ductility was not significant at 500 °C. [ABSTRACT FROM AUTHOR]

The postperovskite phase transition of Fe and Al-bearing MgSiO 3 bridgmanite, the most aboundant mineral in the Earth's lower mantle, is believed to be a key to understanding seismological observations in the D″ layer, e.g., the discontinuous changes in seismic wave velocities. Experimentally reported phase transition boundaries of Fe and Al-bearing bridgmanite are currently largely controversial and generally suggest wide two-phase coexistence domains. Theoretical simulations ignoring temperature effects cannot evaluate correctly two-phase coexistence domains under high-temperature. We show high-pressure and high-temperature phase transition boundaries for various compositions with geophysically relevant impurities of Fe2+SiO 3 , Fe3+Fe3+O 3 , Fe3+Al3+O 3 , and Al3+Al3+O 3 derived from the ab initio finite-temperature free energies calculated combining the internally consistent LSDA + U method and a lattice dynamics approach. We found that at ∼ 2500 K, incorporations accompanied by Fe3+ expand the two-phase coexistence domains distinctly, implying that D″ seismic discontinuities likely arise from the phase transition of Fe2+-bearing bridgmanite. [ABSTRACT FROM AUTHOR]

Abstract The nanocrystalline Fe 60 Al 35 Sn 5 alloy was produced from elemental powders in a high-energy ball mill. A full microstructural analysis and morphologic characterization of powder samples were performed by X-ray diffraction experiments and scanning electron microscopy as a function of milling time (0–60 h). The microstructure analysis of the microstructure of milled powders is focused on the evolution of the grain size, lattice strain and dislocations density. Experimental results demonstrated that a bcc-Fe (Al, Sn) solid solution with a mean crystallite size about 16 nm was achieved. In addition, the thermal behavior of the milled powders was examined by differential scanning calorimetry. Highlights • Analysis of the influence of minor Sn addition to Fe-Al nanocrystalline alloy produced by ball milling. • The single phase of bcc-Fe (Al, Sn) was totally formed after 20 h. • At low milling times the coexistence of Fe and Fe-rich solid solution was found. [ABSTRACT FROM AUTHOR]