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Sequential degradation measurements have been performed on passivated high performance multicrystalline silicon wafers, first at room temperature under low intensity illumination followed by a higher intensity illumination at an elevated temperature. The presence of two main degradation mechanisms, affecting the lifetime under different conditions has been demonstrated, namely, the well-studied light induced degradation caused by boron-oxygen-complexes and the less understood light and elevated temperature induced degradation. Light and elevated temperature induced degradation is the main lifetime limiting the recombination path when fully activated, but the contribution from boron-oxygen complexes is not negligible. This separation of the two degradation mechanisms might, therefore, be necessary for proper evaluation of the dominant recombination mechanism. Experiments also show regeneration of the minority carrier lifetimes caused by deactivation of both the lifetime limiting defects at comparable time scales, and under similar illumination and temperature conditions. Wafers from different heights in a high performance multicrystalline silicon ingot have been evaluated to better understand the underlying causes for the different degradation mechanisms. Effects of the iron-boron-splitting on the carrier lifetime are only visible in ungettered wafers. [ABSTRACT FROM AUTHOR]

The coercivities (Hc), saturation magnetizations (Js), and anisotropy constants K1 of (Nd1-x, Dyx)2Fe14B sintered magnets (x = 0 to 1.0) are determined using high magnetic field measurements up to about 8 MA/m. The Ha, Js, and K1 values of samples with x < 0.5 are similar to those obtained in previous studies using single crystals; the Hc values for the sintered magnets are reported here for the first time. The magnetization into the single-domain states (SDS) in Dy-substituted sintered magnets is completed in lower fields than with Dy-free magnets (for example, 0.64 MA/m in the x = 1.0 sample and 1.6 MA/m in the x = 0.25 sample). The volume fraction of magnetized SDS grains when applying fields less than the demagnetizing fields of the samples also increases with increasing Dy content, i.e., 22 vol. % for a Dy-free sample and 48 vol. % for a Nd-free sample. A characteristic magnetization behavior of large pinning-like magnetization curves appeared in samples that were initially magnetized in a direction perpendicular to the c-axis and successively magnetized in the parallel direction. The apparent pinning field increased with increasing Dy concentration and reached 2.8 MA/m for the Nd-free samples. The origin of this behavior is the tilting of the c-axis in the crystal grains of sintered magnets and the clear preference for crystal grains in Dy-substituted samples to form SDS grains. [ABSTRACT FROM AUTHOR]

Electrically detected magnetic resonance is used to identify recombination centers in a set of Czochralski-grown silicon samples processed to contain strained oxide precipitates with a wide range of densities (~1×109 cm-3 to ~7×1010 cm-3). Measurements reveal that photo-excited charge carriers recombine through Pb0 and Pb1 dangling bonds, and comparison to precipitate-free material indicates that these are present at both the sample surface and the oxide precipitates. The electronic recombination rates vary approximately linearly with precipitate density. Additional resonance lines arising from iron-boron and interstitial iron are observed and discussed. Our observations are inconsistent with bolometric heating and interpreted in terms of spin-dependent recombination. Electrically detected magnetic resonance is thus a very powerful and sensitive spectroscopic technique to selectively probe recombination centers in modern photovoltaic device materials. [ABSTRACT FROM AUTHOR]

To balance the utilization of rare earth (RE) resource and develop Ce-based permanent magnets with high performance/cost ratio, the role of La substitution in the melt-spun (Ce1−xLax)yFe14B (x = 0-0.4, and 0.5; y = 2-4) alloys has been investigated. It has been confirmed that the hard magnetic properties of Ce-based magnets can be effectively enhanced by partial substitution of La. The maximum (BH)max of (Ce,La)-Fe-B alloys can be obtained at a Ce:La atomic ratio of 7:3. The lattice parameters and Curie temperature of the hard magnetic (Ce/La)2Fe14B phase increase linearly with increasing La content. Three different alloy systems with y = 2, 2.5 and 3 show similar behavior of magnetic properties dependences on La. In the RE-rich compositions, La substitution for Ce can effectively inhibit the precipitation of the CeFe2 phase. A solid solution, Ce(La) phase with a space group of Fm-3m, appears in the (Ce0.7La0.3)yFe14B alloys with y ≥ 3.5. A good combination of magnetic properties with Hcj = 345 kA/m, J5T = 1.03 T, Jr = 0.60 T, and (BH)max= 6.3 MGOe is obtained in (Ce0.7La0.3)2.5Fe14B alloy. In addition, 30 at.% La substitution for Ce can significantly refine the grains, resulting in the enhancement of exchange coupling interaction. The present finding is beneficial for designing new and low-cost magnetic materials. [ABSTRACT FROM AUTHOR]

The effects of erosion angle and Fe 2 B orientation on cavitation erosion and interface structures of a directionally solidified (DS) Fe-B alloy in flowing liquid zinc were investigated to clarify erosion mechanism of liquid metal. The results indicate that the cavitation erosion rate of DS Fe-B alloy with Fe 2 B [001] orientation vertical to interface exhibits better erosion cavitation resistance. Erosion angle can strongly affect erosion performance that depends not only on interfacial orientation structure but also on local microturbulence. Erosion morphologies manifest that an obvious cavitation erosion occurs in strong flowing zinc disturbed and agitated zone, which results in severe cavitation pits and slip deformation of products, thus stimulating subsequent localized corrosion and pit-aggregation cracks. Cavitation erosion craters coupled with performance variations confirm that microturbulence-assisted fluid eddies and backflow are responsible for the cavitation pits. The combined effects of flow pattern and interface orientation significantly govern the epitaxial grown ζ removal/accumulation behaviors and multiphase pinning film adhesion. A model of hydraulic liquid-hammer action by cavitation-induced microjet and interface orientation interaction is proposed and discussed to account for cavitation pits and slip cracking, which reveals underlying erosion mechanism and material design of DS Fe-B alloy in flowing liquid zinc. [ABSTRACT FROM AUTHOR]

Abstract The grain boundary diffusion process (GBDP) using Dy 60 Co 40 alloy was applied to a sintered Nd-Fe-B magnet. After GBDP the temperature stability of remanence was improved greatly with the remanence temperature coefficient improving from −0.140%/°C to −0.095%/°C while the Curie temperature increased marginally. Both the coercivity and remanence were increased simultaneously at high temperatures. Microstructure and composition analysis revealed that Dy and Co enriched shells were formed on Nd 2 Fe 14 B grain boundaries after GBDP. The Dy enriched shell increased the coercivity while the Co enriched shell decreased the temperature sensitivity of remanence and then increased the remanence at high temperatures. Graphical Abstract Unlabelled Image Highlights • Dy and Co enriched shells were formed on the Nd 2 Fe 14 B grain boundaries. • Coercivity and remanence were increased simultaneously at high temperatures. • Remanence stability was improved with little change of the Curie temperature. [ABSTRACT FROM AUTHOR]

Ring-shaped (RS) polymer-bonded magnets were produced from a mixture of an isotropic nanocrystalline Nd-Fe-B powder with a nominal composition of 59.8 wt.% Fe, 29 wt.% Nd, 5 wt.% Zr, 4.8 wt.% Co and 1.4 wt.% B and a variety of epoxy resins as binders, using a compaction-molding technique. The morphology and average particle size of the powders are determined by an SEM. The magnetic properties of the magnets were measured using a permeameter. Magnetic flux on the surface of the magnets was determined by a Gauss meter. The mechanical properties of the RS specimens were determined using a tensile fracture strength (FS) test. The effects of polymer type and amount, hardener amount, applied pressing pressure and curing temperature and time on FS were investigated. The experimental results showed that at optimal conditions of 8 wt.% solid epoxy, 3.5 wt.% solid hardener, a pressing pressure of 900 MPa and a curing time of 8 h at 170 °C, a maximum tensile strength of ~ 36 MPa was achieved. Surface magnetic flux uniformity in optimal mechanical conditions was also found to be optimum at around ± 40 G, which is one of the best flux uniformities in bonded magnets. [ABSTRACT FROM AUTHOR]

Using the single-ion approximation, the weak ferromagnetic moment σ Z (Fe 2+ ) along the third-order axis of FeBO 3 crystals, which is caused by the contribution of Fe 2+ ions, has been investigated in the framework of the model Fe 2+ impurity ion –BO 3 vacancy. The extreme low-temperature behavior of the total magnetic moment due to the strong dependence of the Fe 2+ ion contribution is predicted. [ABSTRACT FROM AUTHOR]

The interfaces and erosion of oriented Fe-B alloy in flow zinc at various erosion angles were investigated. The results indicate that oriented Fe-B alloy exhibits better erosion resistance at 90° erosion. Erosion angle can strongly affect erosion resistance, which depends on not only the interfacial structure but also the epitaxial ζ accumulation. Meanwhile, cavitation erosion pits and interface spallation occur, which may be suppressed by ζ accumulation at 90° erosion, thus strengthening the adhesion of product films. [ABSTRACT FROM AUTHOR]

In this paper, effect of Ce + Gd incorporation on the structural features and properties of iron borophosphate (IBP) glasses was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetric (DSC) measurements. The results show that the solubility limit of Ce + Gd in the IBP glass with the composition of 36Fe 2 O 3 -10B 2 O 3 -54P 2 O 5 is about 8 mol%. The structural networks of the Ce + Gd containing IBP glasses consist predominantly of orthophosphate, Q 0 , groups and pyrophosphate, Q 1 , groups, along with [BO 4 ] units and a small amount of metaphosphate, Q 2 , groups. The Ce + Gd incorporation increases the density and T g but decreases thermal stability of the IBP glass. However, the thermal stability of the Ce + Gd doped IBP glasses increases with Ce + Gd until the contents of Ce + Gd nearly reach the limit solubility. Moreover, the incorporation of Ce + Gd offers depolymerizing effect on the glass networks, which increases the fraction of Q 0 and Q 1 groups, and decreases the fraction of Q 2 groups. The conclusions provide researchers with useful information to understand the roles of Ce + Gd in iron-boron-phosphate based glasses for high-level nuclear waste immobilization. [ABSTRACT FROM AUTHOR]

Iron-borosilicate magnetic composites could be applied as a soft magnetic material in high temperature and high frequency applications. In this research, the magnetic properties of soft magnetic composites with different iron particle sizes made by spark plasma sintering have been investigated. Different magnetic properties such as permeability, loss factor, and quality factor were examined up to frequencies in the order of kilohertz. The microstructural observations indicated the distribution of borosilicate on the iron grain boundaries. The results revealed that the loss factor is smaller for composites with fine particles at high frequencies. In addition, the magnetic impedance for smaller particles was greater. It was also found that the permeability and quality factor of composites with coarse particles are larger than those of fine particles. Indeed, when the particles become coarse, the density of porosities and consequently, the demagnetizing fields decrease which result in the increase of permeability. Furthermore, when the size of particles reduces, the density of grain boundaries enhances which is the main reason of lower loss factor achieved in the composites with fine particles. [ABSTRACT FROM AUTHOR]

The effects of chromium additions on three-body abrasive wear behavior of Fe-3.0 wt% B alloy have been systematically investigated using a moving wedge type of apparatus and two types of abrasives (SiC and SiO 2 grains). Features of both the worn surface and subsurface have been discussed with regard to the respective wear rates. As chromium increased, the wear rate of Fe-3.0 wt% B alloy first decreases to a minimum and then increases slightly for both abrasives. That behavior exactly reflects an opposite trend to the fracture toughness of the boride. The wear rate against SiC is evidently higher than that against SiO 2 . Mixed layers comprised of boride fragments and fatigued metallic matrix can be observed on the worn surfaces of the sample without Cr. Furthermore, the surface roughness resulting from wear first decreases and then increases using SiC; however, no obvious change takes place in the case of wear by SiO 2 . In the worn subsurface, serious fracture of the boride phase appears in 0 wt% Cr sample while nearly no such cracks can be found in the 2 wt% Cr sample. It is concluded that during three-body abrasive wear process involving both impact and indentation, the fracture toughness of the boride phases, apart from the bulk material hardness, plays a key role in the wear behavior of Fe-3.0 wt% B alloy. [ABSTRACT FROM AUTHOR]

Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the compaction pressure was led to the decrease of electrical resistivity. By increasing the frequency both real and imaginary parts of permeability decreased. The use of higher content of borosilicate resulted in the lower decreasing slop of permeability. Best combination of density, permeability and electrical resistivity was obtained in the sample with 2 wt% of borosilicate. In addition, the densification of powders with fine particles was more difficult than coarse particles due to the inter particles friction and bridging effects. Furthermore, as the particles size increases the size of open porosities before sintering where the borosilicate could aggregate enhances. This could yields to the increase in the electrical resistivity. The high ratio of surface to the volume in the powders with fine particles results in the developing the demagnetizing fields and subsequently, decreasing the permeability. The highest relative density (99.99% of theoretical density) with best distribution of borosilicate was achieved in the composites produced by spark plasma sintering (SPS). The relaxation frequency, obtained from imaginary part of permeability, was found as 340 Hz in the composites made by SPS. [ABSTRACT FROM AUTHOR]

Mischmetal-Fe-B ribbons were prepared by melt-spinning method, and industrial mischetal with low purity was selected as the raw material. By introducing La and employing nonequilibrium technology, we successfully avoid the formation of CeFe 2 phase, which decreases magnetic performance greatly. Considerable energy product and intrinsic coercivity were achieved in (MM) 2.4 Fe 14 B, which are 80.69 kJ/m 3 and 500 kA/m, respectively. Phase composition and magnetization process of all the samples were investigated. Strong pinning effect was found in all rare-earth-rich samples and was identified as a crucial factor to obtain high coercivity in ribbons compared with the sintered magnets. The Henkel plot is also measured to investigate the intergrain interaction and the results show a strong exchange coupling between grains. Based on these results, the difference in magnetic performance between nanocrystalline ribbons and sintered magnets can be explained. [ABSTRACT FROM AUTHOR]

The amorphous alloys, FeSi, FeSiB, and FeCoMoSiB, were prepared by the spinning method in pure argon. The crystallization behaviors of the three amorphous alloys were researched by in-situ X-ray diffraction (XRD), and the crystallization activation energy was calculated, based on the results of differential scanning calorimetry. The crystallization mechanism of the Fe- and Co-based alloys was analyzed, based on the experimental data. The transformation kinetics was described in terms of Johnson-Mehl-Avrami kinetics, except that the Avrami exponent of the FeSiB amorphous alloy annealed at 753 K (480 °C) was 4.12; the obtained values for the overall Avrami exponents of the other three amorphous alloys were below 1, as usually found for the Fe-Si amorphous alloys. [ABSTRACT FROM AUTHOR]

The article presents several updates on various alloy phase diagrams for binary systems. Topics discussed include the disagreement or inconsistencies among the thermodynamic models of boron-iron (B-FE) phase diagram, the thermodynamic assessment for the chromium-zirconium (Cr-Zr) phase diagram, and the phase diagram for the germanium-nickel (Ge-Ni) phase diagram.

Neodymium iron boron nanoparticles were synthesized by means of sol-gel method. Correlation between magnetic properties and structural features were evaluated. The Nd-Fe-B gel was formed in hydrogen atmosphere. The gel was subsequently annealed under vacuum condition to obtain Nd-Fe-B oxide phases. The oxides powders were reduced at different temperatures of 750, 775, 800, 825, 850, and 875 C for 3 h in a mixture of Ar and H atmosphere to prepare NdFeB nanoparticles. The role of reduction temperature on phase, morphologies, microstructure, and magnetic properties of the final powders was investigated by employing X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and vibrating sample magnetometer (VSM), respectively. The results show that NdFeB phase was formed successfully at temperatures of 750-875 C. Maximum coercivity of 1757 Oe was obtained at 875 C. The variation of coercivity was described by considering the particle size and magnetocrystalline anisotropy constant. [ABSTRACT FROM AUTHOR]

Low-temperature Fischer–Tropsch synthesis (LTFTS) is one of the green routes for liquid fuel production. We prepared nanocrystalline Fe–B catalysts with different particle sizes and microstructures by adjusting the addition sequence of the precursors. In situ carburization of the Fe–B catalysts at 423 K revealed that the addition sequence influenced the rate and degree of carburization pronouncedly. In LTFTS at 423 K, the Fe–B catalysts displayed similar, markedly high selectivity to liquid fuels, with ∼48% for C 5 –C 11 (gasoline fraction) and ∼31% for C 12 –C 20 (diesel fraction) hydrocarbons, and low selectivities to CO 2 and CH 4 , manifesting excellent carbon atom economy over the non-noble Fe–B catalysts. While the carburization degree did not affect the product distribution, the activities of the Fe–B catalysts evolved positively with the ε-Fe 2 C content. Moreover, a good linear relationship was established between the Fe–Fe coordination number and the ε-Fe 2 C content. [ABSTRACT FROM AUTHOR]

In this paper, we report on the magnetic and magnetocaloric properties in amorphous Fe BMn Zr Nb ( x = 4, 8, 12, 16 and 20) alloys. The Fe-based alloys were prepared by induction melting and melt-spinning techniques. The X-ray diffraction patterns indicate that the studied alloys are amorphous. With an increase of x from 4 to 20, the Curie temperature increases almost in a linear way from 237 to 328 K and the average saturation magnetic moment per Fe atom decreases monotonously. For a field change of 3 T, the absolute values of maximum isothermal entropy change $\left | {\Delta S_{T}^{\max }} \right |$ are found to be 2.19, 1.97, 1.63, 1.58, and 1.38 J kg K at 237, 264, 289, 318, and 330 K for x = 4, 8, 12, 16, and 20, respectively. The large magnetocaloric effect near room temperature suggests that these Fe-based amorphous alloys can be considered as magnetic refrigerants in the range of 230-330 K. The Δ S exhibits a potential law with a magnetic field exponent ∼0.72 at the Curie temperature. The similar values of n for Fe BMn Zr Nb indicate that the Δ S curves of these alloys follow a universal class. [ABSTRACT FROM AUTHOR]

Substitution is an important response for material users when faced with disruption to the availability or price of an essential material. In economic terms, substitution refers to the ability of firms to alter their patterns of material use in response to exogenous market shocks. Substitution comes in different forms which vary from situation to situation. This paper uses expert opinion to identify the specific forms of substitution that occurred in permanent magnets, specifically neodymium-iron-boron magnets, following the significant increase in rare earth prices in 2010-2011. The paper provides a framework for understanding the multifaceted nature of substitution and assesses the relative importance of five different types of substitution. Technology-for-element, grade-for-grade, and system-for-system substitution appear to have been more important than element-for-element and magnet-for-magnet substitution. Cost pass-through and absorption were also important responses. [ABSTRACT FROM AUTHOR]

A common industrially accepted method for producing magnetic alloys with fine, α-iron-free microstructure is strip casting. Small amounts of alloys can be rapidly solidified with the method called splat quenching. In both cases the quenching rate can reach 106 K/s. This work reports the results of using a method for producing small amounts of NdFeB magnetic alloys with Ce additions. The aim of the study was to determine the influence of the cooling rate on the microstructure of the cast. Implementing centrifugal casting in vacuum resulted in NdFeB alloys with the following optimal parameters: sample thickness 0.3 mm, cooling rate 105 K/s, rare earth-rich phase content about 4%, thickness of dendrites 1.1 μm, arm spacing of dendrites 0.35 μm, and oxygen content not more than 650 ppm. Theoretically, it is possible to increase the alloy thickness up to 2 mm. Decreasing the cooling speed to the critical level 4 × 103 K/s completely prevented the formation of the undesired features in the microstructure of the cast. [ABSTRACT FROM AUTHOR]

Fe–B binary alloys constitute the basis of many Fe-based metallic glasses with superior glass forming abilities and soft magnetic properties. The present work is devoted to understanding the composition rule of Fe–B binary amorphous alloys using the cluster-plus-glue-atom model and the relevant composition formula theory. According to this model, an ideal metallic glass is based on a chemical building block composed of a first-neighbor coordination polyhedral cluster plus one or three glue atoms, and the total number of valence electrons per unit formula is close to 24. For the Fe–B system, the principal cluster [B–B 2 Fe 8 ], which enters into the composition formula for metallic glasses, is derived from the eutectic phase BFe 2 (Al 2 Cu-type). This cluster, after being glued with one Fe atom, produces a cluster formula [B–B 2 Fe 8 ]Fe B 3 Fe 9 Fe 75 B 25 that presents nearly 24 valence electrons. Experimental verification was then carried out, and at the anticipated composition, the crystallization temperature and glass-forming ability indicator α was the highest, indicating the best thermal stability and glass-forming ability. The crystallization behavior and structure characteristics of Fe–B binary amorphous alloys were also discussed. [ABSTRACT FROM AUTHOR]

Calculations of the magnetocaloric effect in Fe Nb B RE (RE = Y, Gd, Tb, and Dy) upon 0.5 T magnetic field variation have been carried out. It is found that magnetic entropy change distribution of the FeNb B RE is much more uniform than that of gadolinium with a large temperature span. This feature is desirable for an Ericsson-cycle magnetic refrigerator. Therefore, it is suggested that at high working temperature, FeNb B RE samples could permit cooling applications in the automotive, aerospace, or food industries. [ABSTRACT FROM AUTHOR]

Heating of conductive materials by electric current is used in many technological processes. Application of electric pulses to metallic glasses induces their fast crystallization, which is an interesting and complex phenomenon. In this work, crystallization of the FeB amorphous alloy induced by pulses of electric current produced has been studied using X-ray diffraction and transmission electron microscopy. Ribbons of the alloy were directly subjected to single pulses of electric current 250 µs long formed by a capacitor discharge. As the value of $$\smallint I^{2} {\text{d}}t$$ was increased from 0.33 to 2.00 A s, different crystallization stages could be observed. The crystallization began through the formation of the nuclei of α-Fe. At high values of $$\smallint I^{2} {\text{d}}t$$ , α-Fe and tetragonal and orthorhombic FeB and FeB were detected in the crystallized ribbons with crystallites of about 50 nm. Thermal annealing of the ribbons at 600 °C for 2 min resulted in the formation of α-Fe and tetragonal FeB. It was concluded that pulses of electric current produced by a capacitor discharge induced transformation of the FeB amorphous phase into metastable crystalline products. [ABSTRACT FROM AUTHOR]

The behavior of iron, iron-boron (FeB) pairs, and iron-boron-phosphorus (FeB-P) complexes has been studied in B-doped Czochralski silicon with phosphorus (P) compensation and compared with that in uncompensated material. The interstitial iron concentration has been measured at temperatures from 50 to 270°C. The apparent binding energy (Eb) of FeB in compensated silicon is (0.25 ± 0.03) eV, significantly lower than the (0.53 ± 0.02) eV in uncompensated silicon. Possible reasons for this reduction in binding energy are discussed by experimental and calculation methods. The results are important for understanding and controlling the behavior of Fe in compensated silicon. [ABSTRACT FROM AUTHOR]

The magnetization and demagnetization behaviors of a commercial sintered Nd–Fe–B magnet under various post-sintering annealing conditions were investigated. Focus was placed on the various cooling rates after the two-stage post-sintering annealing process. Domain wall pinning effect was observed in the initial magnetization curves in the magnets with rapid cooling rate in the first-stage annealing, and the cooling rate of the second-stage annealing had little effect on the pinning effect. Annealing stress induced by rapid cooling is the origin of domain wall pinning. Stress-induced fringes were observed in the grain boundary region under rapid cooling conditions and the accumulated stress near the grain boundary decreases the magnetic field required to reverse domain nucleation, leading to a relatively low coercivity. [ABSTRACT FROM AUTHOR]

The erosion–corrosion properties and interface microstructure of a Fe–B alloy that contains 3.5 wt% B in flowing liquid zinc have been investigated by electron backscattered diffraction, x-ray diffraction, and scanning electron microscopy to clarify the flowing effect of liquid zinc on erosion performance using a rotating-disk technique. The Fe–B alloy erodes at a low and steady rate in flowing liquid zinc. Flowing liquid zinc can accelerate the iron and zinc mass transfer to form Fe–Zn compounds and promote the removal of loose FeZn13. Much residual corrosion-resistant Fe2B and some erosion products coexist at the erosion interface because of the chemical and micromechanical effects that are created by flowing liquid zinc. The failure of the Fe2B corrosion-resistant skeleton in flowing liquid zinc occurs because of the loss of supporting matrix and also the formation and spread of microcracks during erosion. [ABSTRACT FROM PUBLISHER]

The non-isothermal crystallization kinetics of amorphous CoFeSiB metallic glass has been studied using various thermal analytical models. The DSC curve of amorphous sample in a constant heating rate experiment showed the appearance of two crystallization events at peak temperatures 761 and 803 K, respectively. The activation energy for the secondary crystallization process was found to be lower compared to that of primary process which indicated the ease of secondary crystallization process from modified matrix due to the evolution of the primary phase. The activation energy remained constant during the primary crystallization process over the range of crystallization fraction (0.1-0.9), however, the local Avrami exponent for this crystallization process manifested complex variation with crystallized volume fraction. The validity of the JMA model for the primary crystallization process has been studied. This crystallization process was found to show autocatalytic behavior which has been given a mathematical description using a two-parameter model of Sestak-Berggren. [ABSTRACT FROM AUTHOR]

We reveal the competitive influence of two factors in the process of 'dry' milling of Nd Fe Zr B ferromagnetic alloy in hydrogen. As the rotation frequency of the mill chamber and the duration of the process increase, the range of particle sizes of the powder increases but particles become isotropic as a result of agglomeration. We indicate the possibility of application of a liquid medium (oleic acid) with an aim to prevent mechanical alloying of highly dispersed powder particles as a result of long high-energy milling. Highly dispersed anisotropic powders are obtained by milling of the alloy saturated with hydrogen in oleic acid at a rotation frequency of the mill chamber of 100-200 rpm for 12 h. [ABSTRACT FROM AUTHOR]

The thin slab casting and direct rolling process is a hot-rolled strip production method which has maintained commercial quality steel grades as a major material in many industrial applications due to its low processing cost. Few innovative products have however been developed specifically for production by thin slab direct rolling. Press hardening or hot press forming steel grades which are now widely used to produce structural automotive steel parts requiring ultra-high strength and formability may however offer an opportunity for thin slab direct rolling-specific ultra-high strength products. In this work, a newly designed press hardening steel grade developed specifically for thin slab direct rolling processing is presented. The press hardening steel has a high nitrogen content compared with press hardening steel grades produced by conventional steelmaking routes. Boron and titanium which are key alloying additions in conventional press hardening steel such as the 22MnB5 press hardening steel grade are not utilized. Cr is added in the press hardening steel to obtain the required hardenability. The properties of the new thin slab direct rolling-specific 22MnCrN5 press hardening steel grade are reviewed. The evolution of the microstructure and mechanical properties with increasing amounts of Cr additions from 0.6 to 1.4 wt pct and the effect of the cooling rate during die-quenching were studied by means of laboratory simulations. The selection of the optimum chemical composition range for the thin slab direct rolling-specific 22MnCrN5 steel in press hardening heat treatment conditions is discussed. [ABSTRACT FROM AUTHOR]

Rare earth-iron-boron permanent magnet materials exhibit large values of magnetocrystalline anisotropy. We have studied the dependence of the magnetization (moments) and the anisotropy energy on the change of the lattice parameter ratio \(c/a\) . The calculations were on the basis of the density functional theory, and were carried out with the WIEN2k code, a linearized augmented plane wave method. The spin-orbit coupling was also included to consider the relativistic effects concerning the 3d-4f interaction. [ABSTRACT FROM AUTHOR]

Direct electroless deposition, i.e., without using a sacrificial anode or substrate activation, of iron-boron (FeB) films on copper substrates is reported. Electroanalytical techniques including polarization measurements of oxidation and reduction half-reactions are employed to optimize process parameters, thereby enabling direct nucleation and sustained growth of electroless FeB films on copper. Scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction are used to characterize the film morphology, the deposition rate, the deposit composition and crystallinity. Optimized electroless FeB films have a growth rate of 0.24 μm/hr, are smooth and amorphous, and exhibit acceptable corrosion resistance. [ABSTRACT FROM AUTHOR]

The first 1,2-additions across a metal-boron double bond are reported, one a definitive chlorogallation of a Fe=B bond, the other a partial chlorogallation of a Mo=B bond that leads to a highly unusual, planar Mo-B-Ga-Cl rhombus. The two reactions occur with opposite regiochemistry, with the Ga atom bound to the Fe atom in the former and to both the Mo and B atoms in the latter. The bonding in the Mo adduct and the reasons for the differing regiochemistry of the reaction are explored computationally. [ABSTRACT FROM AUTHOR]

Lithium iron borate (LiFeBO3) has a high theoretical specific capacity (220 mAh/g), which is competitive with leading cathode candidates for next-generation lithium-ion batteries. However, a major factor making it difficult to fully access this capacity is a competing oxidative process that leads to degradation of the LiFeBO3 structure. The pristine, delithiated, and degraded phases of LiFeBO3 share a common framework with a cell volume that varies by less than 2%, making it difficult to resolve the nature of the delithiation and degradation mechanisms by conventional X-ray powder diffraction studies. A comprehensive study of the structural evolution of LiFeBO3 during (de)lithiation and degradation was therefore carried out using a wide array of bulk and local structural characterization techniques, both in situ and ex situ, with complementary electrochemical studies. Delithiation of LiFeBO3 starts with the production of LitFeBO3 (t 0.5) through a two-phase reaction, and the subsequent delithiation of this phase to form Lit-xFeBO3 (x < 0.5). However, the large overpotential needed to drive the initial two-phase delithiation reaction results in the simultaneous observation of further delithiated solid-solution products of Lit-xFeBO3 under normal conditions of electrochemical cycling. The degradation of LiFeBO3 also results in oxidation to produce a Li-deficient phase D-LidFeBO3 (d 0.5, based on the observed Fe valence of ~2.5+). However, it is shown through synchrotron X-ray diffraction, neutron diffraction, and high-resolution transmission electron microscopy studies that the degradation process results in an irreversible disordering of Fe onto the Li site, resulting in the formation of a distinct degraded phase, which cannot be electrochemically converted back to LiFeBO3 at room temperature. The Li-containing degraded phase cannot be fully delithiated, but it can reversibly cycle Li (D-Lid+yFeBO3) at a thermodynamic potential of ~1.8 V that is substantially reduced relative to the pristine phase (~2.8 V). [ABSTRACT FROM AUTHOR]

Highlights: [•] The ZnO-modified BN–FeB49 composite has been prepared though a facile route. [•] The modified sample exhibits excellent gas-sensing properties to NO x . [•] The sample’s structure provides channels for capturing and migrating of electrons. [Copyright &y& Elsevier]

The application of expansion constraint during the grain-boundary diffusion process using Nd70Cu30 eutectic alloy minimizes the remanence loss for the coercivity enhancement by optimizing the volume fraction of the Nd(Cu)-rich non-ferromagnetic intergranular layer. The diffusion-processed sample exhibits μ0 H c ∼2T, μ0 M r =1.36 T and (BH)max =358kJm−3 at room temperature. Because of the low-temperature coefficient of coercivity, the magnet showed (BH)max ∼191kJm−3 at 200°C, which is superior to that of Dy-containing high-coercivity sintered magnets. [ABSTRACT FROM AUTHOR]

Abstract: Fe–B nanochains are prepared by a modified chemical reduction method by introducing the cyclohexane–water interface for reaction. Scanning electron microscopy and transmission electron microscopy tests show that this Fe–B is composed of several wire-like nanochains. X-ray diffraction pattern reveals that the Fe–B nanochains obtained are in amorphous form. The formation of these Fe–B nanochains is discussed and attributed to the self-assembly of magnetic Fe–B nanoparticles on the cyclohexane–water interface. Compared to Fe–B nanoparticles, Fe–B nanochains exhibit much higher magnetic and electrochemical activities. [Copyright &y& Elsevier]

Abstract: In this work, a comparative evaluation has been carried out on the deposition efficiency of iron boride powder with a composition of Fe–17.9B–0.4C–1.6Si–0.3Al (wt.%) mixed with Ni powder (20 wt.%Ni) sprayed onto low carbon steel substrate by cold gas dynamic spray processes and the High Velocity Oxy-Fuel (HVOF) spraying method. The particle deformation and bonding mechanism were evaluated. Direct spraying of iron boride powders by low and high pressure cold gas spraying led to depositing a very thin single layer on the substrate, due to the intrinsic brittleness of the powder. Prior to spraying, reducing the particle size (−20μm) and increasing the internal energy of the powders by the ball milling process resulted in no appreciable improvement in deposition efficiency, implying that sprayed particles still had insufficient ductility to plastically deform and flow. Likewise, iron boride powders were spray dried and sintered with Ni particles (FeB-20wt.% Ni) to deposit layers in both low pressure and high pressure cold gas spray processes with various spray parameters. It was discovered that iron boride particles, surrounded by ductile Ni, experienced disintegration and cracking during deposition. The build up of iron boride layers was successfully obtained when spraying FeB20Ni powder by the HVOF deposition method. An abrasion wear test result of the HVOF coatings, 952 HV, was compared with HVOF sprayed WC-12Co coatings. [Copyright &y& Elsevier]

This paper presents a systematical optimal design method for powder aligning fixture during forming process and magnetizing fixture during magnetizing process for an anisotropic-bonded NdFeB magnet. Before the forming process, the mixture ratio of magnet powder and resin, molding tool temperature, and filling density are selected to improve the magnetic performance. During the forming process, a newly multiobjective optimization model is proposed to obtain the required orientation and maximum aligning field. Thus, in the magnetizing process, an anisotropic-bonded NdFeB magnet with required orientation and high residual magnetic flux density is obtained by applying a single-objective optimization process. To accurately predict the residual magnetic flux density, the transient finite element method combined with the Jiles–Atherton hysteresis model, taking the aligning field into account. [ABSTRACT FROM AUTHOR]

Highlights: [•] New phase do not appear as milling of Fe and B powders reaches 10 h and above. [•] The phases in samples contain Fe3B and α-Fe at sintering of 1173K. [•] The single bulk Fe2Bcan be fabricated at sintering temperature reaching 1273K. [•] Compared with grain size at 1173K, Fe2B at 1273K and 1373K becomes much bigger. [ABSTRACT FROM AUTHOR]

Abstract: Bulk Fe83B17 eutectic alloy rods with diameters up to 3mm were prepared by undercooling solidification combined with Cu-mold casting. The results showed that the rapid solidification led to an increase in the nucleation rate, an inhibition of the grain growth and a competition between a stable Fe2B phase and a metastable Fe3B phase. Then, pure nano-lamellar eutectic microstructures and the metastable Fe3B phase were successfully obtained in as-solidified alloys, which resulted in improved soft magnetic properties. [Copyright &y& Elsevier]

Abstract: Multilayers [(FexB1−x)/FePt)]10 were deposited on a glass substrate and formed the exchange-coupled (Fe–Pt)90(FeB)10 graded film after rapid thermal annealing at 800°C for 3min. Out-of-plane coercivity was decreased and remanent magnetization increased when the FeB was co-doped in FePt films. When Fe content was below 40% in B, the exchange-coupled FePt–FeB films showed perpendicular magnetization with the single switching field. For higher Fe concentration (x=0.5, 0.7, 1), easy magnetization of (001) textured FePt–FeB film was changed from perpendicular to mix-magnetization and finally to in-plane magnetization. Based on the microstructure, the FePtB film exhibits a granular structure, the FePt grains were isolated by nanocrystalline B or FeB cluster at the grain boundaries. The granular film was changed to interaction grain structure in the (FePt)90(Fe0.4B0.6)10 film. The hard-soft magnetic FePt–FeB grains formed the aggregated grains. [Copyright &y& Elsevier]

Abstract: The microstructure and interface characteristics of Fe–B alloy in liquid 0.25wt.% Al–Zn at various bath temperatures have been investigated. The results dominate that bath temperature can strongly affect corrosion rate and interfacial structures of Fe–B alloy in liquid 0.25wt.% Al–Zn. The phase transformation from Fe2Al5Zn x intermetallic compound to FeAl3Zn x intermetallic compound can occur at the corrosion interface when bath temperature exceeds 520°C by means of compositional self-adjustment, which is attributed to thermodynamics and kinetics of the system. Corrosion process and its interface are mainly controlled by Al and Zn inter-diffusion with the increase of bath temperature. The spalling of Fe2B generates with the increasing bath temperature owing to the presence of cracks during hot corrosion. [Copyright &y& Elsevier]

Rapidly solidified Nd9Fe73B12.6C1.4Ti4-xGax (x = 0, 0.5, 1) thick ribbons were prepared by melt spinning technique at a surface speed (vs) of 5 m/s. The influences of Gallium doping on the glass-forming ability (GFA), microstructure and magnetic properties of alloys were investigated. The coercivity of Nd-Fe-B-Ti-C nanocomposite alloy thick ribbons can be dramatically enhanced by 0.5 at. % Ga addition in a low cooling-rate regime, attributing to the weakened exchange coupling interaction and grain refinement. The results of XRD showed that the GFA of Nd-Fe-B-Ti-C alloy was enhanced by the Ga addition. Therefore, Gallium addition is effective to refine grain and improve the glass-forming ability, which provides the possibility to obtain the high performance of magnetic properties by using strip casting (SC) method. [ABSTRACT FROM AUTHOR]

Control of microstructure and texture is of critical importance in forming rare earth (RE)-iron-boron particulate suitable for anisotropic polymer-bonded permanent magnets and anisotropic sintered permanent magnets. In this study, the selected approach to controlling grain size, while maintaining texture, is through stabilization and refinement of directional growth in melt-spun ribbons. Varying concentrations of Ag were added to melt-spun ribbons of composition (Y0.55Nd0.45)2.2Fe14B1.1. Effects on microstructure and texture were observed through scanning electron microscopy (SEM) and x-ray diffraction (XRD). It was determined that Ag stabilized columnar growth (compared to alloys with no Ag added) with additions as small as 0.3 at. %, but the Ag also produced a unique texture in the ribbons. In RE-Fe-B ribbons without Ag, strong <00l> texture is observed at the free surface and a mechanism has been established. In all Ag-containing ribbons, the observed texture is canted to both the c- and a-axes, but the mechanism remains unclear. [ABSTRACT FROM AUTHOR]

We have investigated the effects of Hf, Ti and Ta addition on crystallization behavior, microstructure and magnetic properties of melt-spun Fe90Nd5B3.5M1.5 (M = Hf, Ti and Ta) alloy ribbons. Optimization of processing conditions lead to the development of nano-composite magnets, made from high Bs soft magnetic bcc α-Fe (grain size ∼20 nm) and tetragonal Nd2Fe14B (grain size ∼18 nm) hard magnetic phases. Hf is most effective in restraining the growth of α-Fe and Nd2Fe14B phases during annealing. The Fe90Nd5B3.5Hf1.5 ribbon annealed at 1003 K for 600 s exhibits very high maximum energy product (BH)max ∼127 kJ/m3 and reduced remanence ∼1.34 T. Strong exchange coupling among the nano-sized soft and hard magnetic phases is shown to be responsible for the excellent magnetic properties. Among low Nd-containing NdFeB nano-composite magnets, the present alloy seems to have highest (BH)max. [ABSTRACT FROM AUTHOR]

A large coercivity and anisotropy enhancement in perpendicular NdDyFeB (120 nm)/Dy (tDy) films has been realized by a Dy grain-boundary diffusion process. The coercivity HC and the ratio Mr/Ms reach their maxima at tDy = 50 nm, and the magnetic domain sizes increase with increasing tDy. The HC and Mr/Ms increasing with tDy is due to the enhancement of the anisotropy of (Nd,Dy)2Fe14B grains by Dy substitution for Nd. The coercivity mechanism is a nucleation-type mechanism. Dy and Nd elements coexist at grain boundaries, forming a (Nd,Dy)-rich phase, which may promote the nucleation of reversal domains. [ABSTRACT FROM AUTHOR]

Thin films of Nd/sub 2/Fe/sub 14/B (/spl sim/30-60 nm) were grown with c-axis texture by means of molecular beam epitaxy. A two-phase structure is observed in both the X-ray diffraction and the hysteresis loops, due to an interfacial reaction during the initial growth. Coercivities are 1-2 T at 20 K, and the anisotropy fields are bulk-like. Microstructural analysis by atomic and magnetic force microscopies reveal lateral grain sizes of /spl sim/200 nm, which could explain the hard magnetic properties. [ABSTRACT FROM PUBLISHER]