Formation Of Fe2B Research Articles

Magnetic response to microstructure and phase evolution in laser thermal treated FeSiB amorphous alloy

In the current work, laser thermal treatment of the FeSiB amorphous foil with a single linear laser track was carried out. The resultant microstructure and phase evolution were examined with the aid of x-ray diffraction, differential scanning calorimetry, and site-specific transmission electron microscopy. The laser power was kept constant at 100 W, whereas, laser beam scanning speeds were varied in the range of 500–235 mm/s, generating corresponding laser fluences of 0.42–0.91 J/mm2 on the sample surface. Laser fluences of up to 0.48 J/mm2 structurally relaxed the FeSiB foil, retaining the amorphous structure. Laser fluences of higher than 0.48 J/mm2 led to partial crystallization of FeSiB amorphous foils. The crystallite sizes were in the range of 11–31 nm (laser fluence of 0.49–0.91 J/mm2). α-FeSi formed as a major phase of partial crystallization while its quantity steadily increased from 3.6 to 46 vol. % with laser fluence (laser fluence 0.49–0.91 J/mm2). Fe2B formed in recognizable quantities (≥2%) for laser fluences ≥0.53 J/mm2. Laser fluences leading to structural relaxation and evolution of predominantly α-FeSi phase exerted minimal effects on ratios of intrinsic coercivities to saturation compared to the as-cast FeSiB amorphous foil. On the contrary, formation of Fe2B in significant quantities (≥2%) led to the steady increase in intrinsic coercivities and remanence to saturation ratios as a function of laser fluence indicating a loss in soft magnetic characteristics. Nonetheless, continuous increase in fractions of α-FeSi with laser fluence led to a steady improvement in saturation magnetostriction of the FeSiB foil.

Single Fe2B Phase Particle Production by Calciothermic Reduction in Molten Salt

In this study, calciothermic single phase iron boride(Fe2B) production was investigated in a scalable molten salt system, starting from inexpensive, easily accessible oxide materials. First, the formation of Fe2B was examined in detail in the light of thermodynamic data and literature. After, effects of CaO amount (0-10 wt.%) and time (30-60 min) on particle synthesis were investigated under at constant 3.0 V cell voltage and 1273 K temperature. It was determined that the average current increased continuously with the increase in the amount of CaO, and the current efficiency increased up to 7% by weight of CaO. After the CaO ratio was determined, the effect of the electrolysis duration was examined. In durations experiments, it has been observed that, in 30 minutes’ duration, the particles are composed of Fe, Fe2B and FeB, and by increasing the experiment time to 60 min, single-phase Fe2B particles are obtained. The magnetic properties of the single-phase Fe2B particles obtained at the end of the experiment period of 60 minutes were investigated by VSM. The saturation magnetization, permanent magnetization and coercivity values of the Fe2B particles were determined as 90.718 emu/g, 33.311 Oe, 1.684 emu/g, respectively.

The Supported Boro-Additive Effect for the Selective Recovery of Dy Elements from Rare-Earth-Elements-Based Magnets.

Liquid metal extraction (LME) for recycling rare-earth elements from magnets is studied, in the present study, to examine its suitability as an environmentally friendly alternative for a circular economy. While Nd (neodymium) extraction efficiency can easily reach almost 100%, based on the high reactivity of Mg (magnesium), Dy (dysprosium) extraction has been limited because of the Dy–Fe intermetallic phase as the main extractive bottleneck. In the present paper, the boro-additive effect is designed thermodynamically and examined in the ternary and quinary systems to improve the selectivity of recovery. Based on the strong chemical affinity between B (boron) and Fe, the effect of excess boron, which is produced by the depletion of B in FeB by Mg, successfully resulted in the formation of Fe2B instead of Dy–Fe bonding. However, the growth of the Fe2B layer, which is the reason for the isolated Mg, leads to the production of other byproducts, rare-earth borides (RB4, R = Nd and Dy), as the side effect. By adjusting the ratio of FeB, the extraction efficiency of Dy over 12 h with FeB addition is improved to 80%, which is almost the same extraction efficiency of the conventional LME process over 24 h.

Plasma Arc Coatings Produced from Powder-Cored Wires with Steel Sheaths

Plasma arc coatings produced from powder-cored wires developed at the Paton Electric Welding Institute that were deposited onto a low-carbon steel substrate were characterized. Interaction between the steel sheath (constituting at least 80 wt.% of the wire) and powder cores, such as B4C, B4C + ZrO2(nano), B4C + (Cr, Fe)7C3, and B4C + (Cr, Fe)7C3 + Al, in the arc plasma spraying process was analyzed. The resultant coatings were free of defects and had low porosity (to 2.5%) and lamellar structure. The core carbide components were found to dope the coating ferritic matrix and strengthen it with carbide, carboboride, and boride precipitates. An addition of 0.5% ZrO2 nanopowder refined the coating structure and participated in the formation of Fe2B and Fe3B precipitates. An aluminum addition within 10 wt.% did not led to iron aluminides but, being easily melted, activated the interaction between components, reduced porosity, and improved adhesion strength of the coatings. The coatings reached a microhardness of 6.25–8.59 GPa, being 4 to 5.5 times higher than the microhardness of the steel wire sheath. The development and use of such powder-cored wires expanded the application of plasma arc spraying, particularly for the protection of equipment against abrasive gas wear in chemical engineering, in the production of parts for pumps, compressors, and other components, and for the recovery of worn parts.

Dry sliding wear behavior of borided hot-work tool steel at elevated temperatures

In the present study, the surface of AISI H13 hot-work tool steel was borided with EKabor II powders using powder pack-boriding method. The process was carried out at 800, 900 and 1000°C temperatures for 2, 4 and 6h periods. The wear tests were carried out using a ball-on disc tribometer at room temperature and 500°C on borided and untreated AISI H13 hot-work tool steel. Scanning electron microscope (SEM), optical microscope, 3D profilometer, X-ray diffraction analysis and micro-hardness tester were used in the evaluation of micro-structure and wear data. The increase in the boriding temperature and boriding period led to increased thickness and hardness of the boride layer. Boriding at 800°C resulted with formation of Fe2B, Mn2B, Cr5B3, phases, while FeB, Fe2B, Mn2B, and Cr5B3 boride phases occurred at 900 and 1000°C. Dominant wear mechanisms were microcrack-induced plastic deformation during high temperature wear tests; oxidation and microcrack formation during room temperature wear tests; and oxidation and severe plastic deformation for the untreated specimen.

Influence of thermal treatment on microstructure of Fe75Ni2Si8B13C2 amorphous alloy

DSC and thermomagnetic measurements of Fe75Ni2Si8B13C2 amorphous alloy investigated in 298–973K temperature range show that alloy remains amorphous up to around 773K, when it undergoes multi-step structural transformation. As thermomagnetic measurements provided more complete information, the alloy ribbon was successively annealed at temperatures chosen on the basis of these measurements and its microstructure was investigated after each annealing cycle using X-ray diffraction and SEM. XRD and microstructural analysis of the as-prepared and the annealed sample showed there is no difference between shiny and matte side of the ribbon. Two stable, α-Fe(Si) and Fe2B, and one metastable, Fe3B, crystalline phases were identified after annealing. Microstructural analysis showed that Fe3B probably acts as an intermediate in the formation of Fe2B, which formed later than the other two phases. Si and B in the alloy show a tendency to separate into different phases, exhibiting complementary fluctuations in concentration in chemical depth profile. Analysis of microstructure, combined with chemical composition, showed that after the final annealing at 973K, alloy ribbon is composed of interdispersed nanocrystals of α-Fe(Si) and Fe2B less than 90nm in size, with no observable larger domains of either phase.

Influence of thermal treatment on structure and properties of Fe75Ni2Si8B13C2 amorphous alloy

Iron-based amorphous alloys have been a focus of considerable scientific interest in recent years, both from fundamental and practical point of view. Comprehensive study of Fe75Ni2Si8B13C2 amorphous alloy investigated its thermal stability and thermally induced changes of the electrical, magnetic and mechanical properties and correlated them with microstructural changes. The alloy was investigated in 25-1000?C temperature range. Thermally induced structural transformations had been investigated using the DSC and the thermomagnetic measurements, revealing that the alloy exhibits the Curie temperature, glass transition, multi-step crystallization and recrystallization. The crystallization kinetics was determined, under non-isothermal conditions, to include three processes, corresponding to crystallization of ?-Fe, Fe3B and Fe2B phases, respectively. Microstructural analysis using the XRD and the M?ssbauer spectroscopy suggests that Fe3B acts as an intermediate in the formation of Fe2B. The microstructure was investigated on both the surface of the alloy ribbon and on the cross-section, using SEM to determine structural changes of the alloy after thermal treatment. Additionally, the XRD spectra were analyzed to determine the change in microstructural parameters of the alloy caused by the thermal treatment and the structural transformations. The M?ssbauer spectroscopy was used to determine the distribution of iron atoms between the individual crystalline phases and the amorphous matrix. The functional properties were investigated using measurements of the magnetic susceptibility, electrical resistivity and microhardness and these results were correlated with changes in the microstructural parameters (average crystalline size, microstrain) and the phase composition. The measurements were performed, where possible, both during heating cycles to observe the change of these properties with temperature, and at room temperature, after individual heating cycles to determine the change in properties caused by annealing at different temperatures.

Fabrication of TiB2-(Fe-Al) Cermets by Short Time Pulsed Current Sintering

Short time fabrication of TiB2-30mass% Fe3Al cermet was performed by pulsed current sintering method. Milled powder mixture of TiB2, Fe and Al was consolidated using a pulsed current of 0 A-1000 A with 50 % duty ratio for 50 s with 1, 10 and 100 Hz frequency. Microstructures, densities and phases present in the cermets fabricated in such a way were examined. TheTiB2-30mass% Fe3Al cermet without formation of Fe2B was successfully fabricated. Increase in the pulse frequency led to an increase in the sample density and homogeneous distribution of TiB2 particles.

Role of Fe incorporation in the self-propagating high-temperature synthesis reaction in an Al–Ti–B4C system

Effects of Fe incorporation into Al–Ti–B4C reactants on the combustion behaviors, reaction mechanism, synthesized products, and possible natural convection of fluids were investigated. The incorporation of Fe significantly promotes the self-propagating reaction and decreases the reaction dependence on the B4C particle size. The prior reaction of Fe with B4C leads to the decomposition of B4C and formation of Fe2B and free carbon. On the other hand, the reaction of Fe with Ti and Al gives rise to the emergence of Fe–Ti and Fe–Ti–Al eutectic liquids. As a result, the diffusivity and reactivity of the dissociated carbon and boron atoms are greatly facilitated and the reaction is substantially promoted, yielding a desirable product of TiC, TiB2, and FeAl phases. Moreover, the incorporation of Fe may enhance free convection of the molten phase in the reaction zone and thus contribute to the combustion synthesis process.

Study on iron purification from aluminium melt by Na2B4O7 flux

A study was carried out to investigate the effect of Na2B4O7 on the reduction of Fe concentration from commercial purity aluminium. Experiments were conducted and the double barrier layers theory was used to study the kinetics of the purification process. Results showed that the iron reduction ratio increased with the addition of Na2B4O7 and the holding time, which follows the first order exponential decay law. The addition of Na2B4O7 containing flux could reduce iron content from 0·14 wt-% to less than 0·1 wt-% and achieve an optimal ratio of 44%. Thermodynamic calculations and the XRD, SEM and EDX analyses of the molten sludge indicated that formation of Fe2B could occur spontaneously in molten aluminium with the addition of Na2B4O7 containing flux.

In-situ studies of Fe2B phase formation in MgB2 wires and tapes by means of high-energy x-ray diffraction

The phase transformations occurring in the ceramic core of Fe-sheathed MgB2 wires and tapes prepared by in-situ reaction of Mg and B precursor powders, have been studied by means of high-energy x-ray diffraction. In particular, the time evolution of the Fe2B phase, forming at the interface between the sheath and the ceramic, was studied at different sintering temperatures. The reactivity of the sheath towards Fe2B formation is strongly dependent on powder pre-treatment. In wires produced with commercial Mg and B powders without additional mechanical activation, the Fe2B phase starts forming around 650°C. In contrast, in tapes produced from a mixture of Mg and B powders subjected to high-energy ball milling, the interfacial Fe2B layer forms readily at 600°C. The increase of Fe2B volume fraction is linear to first approximation, showing that the interfacial layer does not act as a diffusion barrier against further reaction between the sheath and the ceramic core. If the ceramic core is converted to MgB2 at a temperature, which is low enough to avoid Fe2B formation, the interface is stable during further annealing at temperatures up to 700°C at least. However, too high annealing temperatures (T > 800°C), would result in formation of Fe2B, probably following the partial decomposition of MgB2.

Dispersion and reaction of TiB2in liquid iron alloys

AbstractThe degree of reaction and dispersion achieved when TiB2 powders are melted in contact with liquid iron based alloys has been assessed via a levitation dispersion test which had been developed earlier. Both Fe2B and TiC were observed to form as a result of dissolution and reaction of TiB2. The formation of TiC occurs during the reaction of commercial grade TiB2 with liquid iron alloys containing as little as 0·08 wt-%C. The reaction of high purity TiB2 with liquid iron alloys containing 0·24 wt-%C does not however lead to TiC formation. The formation of Fe2B was observed for all conditions tested, owing to the effectively zero solubility of boron in solid iron. The TiB2 remaining after dissolution and reaction was found to produce relatively good dispersions in the iron matrix and therefore additions of TiB2 to liquid iron alloys may provide a means of producing Fe–TiB2 composite materials. However, the brittle properties of Fe2B will mean that, whereas such materials may be very hard, they are li...