Small Hc Research Articles

Single-domain configuration tune high coercive field in Co-precipitated monazite-decorated cobalt ferrite nanoparticles

Single-domain configuration is one of the important key in the applied current- technology especially information technology. In order to address this issue, a magnetic modification of cobalt ferrite nanoparticles (CFO-NPs) by decorating the monazite-natural-mineral (Ce) is presented. Monazite-decorated CFO-NPs are successfully synthesized by the co-precipitation method. The obtained nanoparticle samples are annealed at 200 °C, 300 °C, and 400 °C for 5 hours. XRD results confirms the successful decoration of the monazite sand with CFO-NPs, as demonstrated by the distinctive peaks of CFO-NPs, as well as the major peaks of the monazite-sand. The presence of monazite in the CFO-NPs sample was confirmed by the EDS results. With increasing annealing temperature, the crystallite size increases, respectively. FTIR results show that the monazite-decorated CFO-NPs outcome absorption peaks at kt ∼590/cm and ko ∼390/cm, which are the original absorptions of CFO-NPs. VSM results showed that the single-domain configuration realized owing high the HC (supported by K1 and Kσ) for samples without and annealed at 200 °C, whereas the multi-domain configuration appears to have a small HC (supported only by K1) for samples annealed at 300 °C and 400 °C. The largest HC of the monazite-decorated CFO-NPs was obtained with the annealing temperature at 200 °C, i.e., 3.02 kOe, suggesting that it be supported by both the K1 and Kσ. The magnetic properties obtained also indicate the potential for developing permanent magnets.

A closer look at the magnetic, photo-electrochemical, and optical properties of rare earth (Sm, Dy, Ho, Er, and Yb)-doped manganese ferrite for potential use as a photocatalyst

For photocatalysis technology to be applied industrially, there has been a significant increase in the need for visible-light-driven photocatalysts that possess exceptional superparamagnetic characteristics to facilitate easy separation. Hence, in this study, rare earth elements (RE) (Sm, Yb, Dy, Er, and Ho) were systematically doped into manganese ferrite (MF) using the coprecipitation method to serve two purposes, namely, reducing the photogenerated electron-hole recombination during photocatalysis and modifying the magnetic properties of MF to become superparamagnetic. The synthesised Re-doped MF was found to be visible light active, as evidenced by the transient photocurrent response and the obtained band gaps, which were in the range of 1.84–1.93 eV. From the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization plots, it was evident that different RE element dopants have different effects on improving the electrochemical properties of MF. Overall, fast electron transfer of the synthesised materials was found to decrease in the following order: Sm-MF > Dy-MF > Ho-MF > MF > Er-MF > Yb-MF. The g-factor and peak-to-peak line width were found to be in the range of (2.221–2.317) and (93.17–149.85 mT), respectively. The resonance field and hysteresis loop (Hc) were found to be in the range of (289.2–301.86 mT) and (8.24–32.61 mT), respectively. Overall, the synthesised RE-doped MF exhibits ferromagnetic properties, and the obtained small Hc values hint at these particles exhibiting superparamagnetic properties. In summary, doping MF with Sm, Dy, and Ho is more desirable as it alters the magnetic properties towards superparamagnetic and improves its electrochemical properties. Thus, this study is of importance in advancing the field of photocatalysis in water treatment and material science.

H2 impact on combustion kinetics, soot formation, and NOx emission of hydrocarbon fuel flames

Soot and carbon dioxide released from internal combustion engines became the key issues when using fossil fuels. The use of zero-carbon fuel, hydrogen, with hydrocarbon fuels can play an important role in reducing the exhaust effect on the environment and mitigating the reliance on nonrenewable energy resources. A numerical approach was executed to elucidate the H2 impact on combustion kinetics, soot formation, and NOx emission of hydrocarbon fuel under premixed and diffusion flame conditions. The results showed that hydrogen deteriorated the formations of particle number density, the volume fraction of soot, carbon monoxide, carbon dioxide and polycyclic aromatic hydrocarbons thru the reduction of small chain hydrocarbons at both premixed and diffusion flame conditions. The soot volume fraction and soot particle number density formation were prevailing in the air region of the combustion chamber at diffusion flame conditions. NO3 produced from fuel-related species such as CHO and air-related species such as NO. H2 reduced the peak molar fraction of small chain HC including CHO related species, resulting in a reduction in NO3 emissions. C3H3 species dominantly participated to reduce the CO2 and NO3 emissions, while C2H2 and C5H4CH2 were the main species to control the soot precursors formation in both HC fuel flames. Besides, NH3 emission was limited by C2H2 in DS flames.

Evaluations of structural, thermal, spectral, and magnetic properties of Li0.5Fe2.5O4 multi magnetic oxide fabricated via sol-gel auto-ignition technique

In3+ incorporated lithium ferrites have been synthesized via sol-gel auto-ignition route, and these were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Thermal analysis of pure sample shows 12% weight loss in three successive steps observed by Thermogravimetric analysis (TGA). The lattice constant, cell volume, radii (Rt and Ro), and hopping lengths exhibited decreasing behavior, while crystallite size, X-ray, and bulk densities show an increasing trend with indium substitution. The bond length of each side decreases as indium content increases. The squareness ratio (R) exhibited that synthesized ferrites are single domain. The moderate value of saturation magnetization with a small Hc and squareness ratio proposed that synthesized ferrites may be suitable for high-frequency applications.

Prenatal exposure to per- and polyfluoroalkyl substances and infancy/child growth trajectories through 2 years

BACKGROUND AND AIM: Prenatal exposure to poly- and per-fluoroalkyl substances (PFAS) has been associated with reduced birth weight, but also with excess adiposity and overweight in childhood. These mixed findings warrant investigation of relationships between prenatal PFAS exposure and dynamic offspring growth. This study aims to investigate the association between prenatal PFAS exposure and early life growth trajectories through 2 years. METHODS: In a prospective cohort of women and their children from Shanghai, China, we quantified seven PFAS congeners in pregnant women’s serum during the first trimester. Four anthropometric measures, including weight (n=1346), length/height (n=1140), weight-for-length (n=1134), and head circumference (HC, n=1082), were evaluated among children at birth (3 days), 42 days, 6 months, 12 months, and 24 months, and then standardized into z scores. Trajectory groups were identified using group-based trajectory modeling for each measure. Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for trajectory groups according to log2-transformed PFAS concentrations. RESULTS:Five trajectory groups were identified for each anthropometric measure, respectively. In each measure, the trajectory with a stable trend near the null z score was selected as the reference group. Prenatal exposure to PFAS was consistently associated with elevated odds for weight low-rising trajectory characterized by rapid increase from a low birth weight (e.g., perfluorohexane sulfonate (PFHxS): OR=1.54, 95% CI: 1.10-2.14) and length/height high-rising trajectory characterized by increase from a large value (e.g., perfluorononanoic acid (PFNA): OR=1.69, 95% CI: 1.05-2.73). Inverse associations were observed with HC high-stable trajectory characterized by large HC (e.g., perfluoroheptanoic acid (PFHpA): OR=0.75, 95% CI: 0.58-0.96) and HC low-stable trajectory characterized by small HC (e.g., PFHxS: OR=0.70, 95% CI: 0.50-1.00). No association was observed for weight-for-length trajectories. CONCLUSIONS:We observed associations between prenatal PFAS exposure and unusual growth trajectories in early life, suggesting enduring impact of prenatal PFAS exposure. KEYWORDS: PFAS, Birth outcomes, Endocrine disrupting chemicals, Multi-pollutant, Environmental epidemiology

Tuning magnetic properties based on FeCoNiSi0.4Al0.4 with dual-phase nano-crystal and nano-amorphous microstructure

The idea of adjusting the crystallinity of powders via controlling the phase composition of milling precursor (ribbons) has been used to prepare FeCoNiSi0.4Al0.4 high entropy alloy powders (HEAPs) with dual-phase nano-crystal (NC) and nano-amorphous (NA) microstructure. The crystallinity of HEAPs are related to the FCC phase proportion of milling precursor: within 60%, positive correlation; beyond 60%, negative correlation. Different phase structure for ribbons can be obtained by taking advantage of the difference in phase stability, as an extension of annealing time induces the increment of FCC phase content. The introduction of nano-scale phase separation in HEA ribbons provides a prerequisite. Multiphase NCs distribute randomly in matrix, while NCs with FCC phase are aggregated into about 50 nm regions embedded in matrix. Three kinds of phase transition are co-existed during the dry-milling process, generating the coexistence of NCs and NAs. Due to the unique microstructure, in especial NCs doped by NAs, and the skillful preparation technology, a small Hc, varying from 12.97 Oe (C0) to 28.33 Oe (C50), and a large complex permeability (μ′), varying from 2.60 (C0) to 2.30 (C50), can be obtained.

Morphology and magnetism of CoPd coverage on MoS2 flakes/SiO2

CoPd alloy nanostructures and thin films were deposited on MoS2 flakes through e-beam evaporation at a high temperature (HT) (500 K) and at room temperature (RT) (300 K). In HT growth, CoPd nanoparticles assembled at the edge of the MoS2 flake. The nanoparticles formed parallel chains at the edge of each layer in multilayered MoS2. As indicated by the quenched photoluminescence, HT deposition resulted in a flat CoPd coverage with a roughness of ≤±0.5 nm on a MoS2 terrace. By contrast, RT growth led to a relatively rough CoPd thin film on MoS2 (roughness ≤±2 nm). The film comprised a merged nanoparticle assembly. The MoS2/SiO2 step edge played a crucial role in magnetic domain pinning such that the magnetic coercivity (Hc) of Pd/Co/MoS2 was smaller than that of Pd/Co/SiO2. Similarly, RT CoPd (8 nm)/MoS2 exhibited a parallelogram-shaped hysteresis loop with a relatively small Hc value compared with that of the square hysteresis loops of RT CoPd (8 nm)/SiO2. The hydrogenation of RT CoPd (8 nm)/MoS2 resulted in reversible Hc enhancement.

Crystallization behavior and magnetic properties for the Fe73(Si0.64B0.27P0.09)23+xCu1Nb3-x (x=0, 1 and 2) alloys

In this work, with the aim of delivering the raw materials cost savings, P-containing Finemet-type Fe73(Si0.64B0.27P0.09)23+xCu1Nb3-x (x = 0, 1 and 2) amorphous alloys were fabricated by the single roller melt spinning technique to decrease Nb content. The dependence of (Si + B + P)23+x/Nb3-x ratio on crystallization behaviors and magnetic properties were investigated. The decrease of (Si + B + P)23+x/Nb3-x ratio reduced the onset temperature of ɑ-(Fe,Si) and boride phase, the interval of two onset crystallization temperatures decreases slightly, however, the crystallized alloys show a small coercivity (Hc) and moderate saturation magnetization (Ms) after annealed at the temperature higher or lower about 30 or 40 °C than the first crystallization peak temperature (Tp1-30 °C < Ta < Tp1 + 40 °C) for different anneal-holding time. For Fe73(Si0.64B0.27P0.09)24Cu1Nb2 alloy, we can attain a small Hc = 1.07 A/m, moderate Bs = 1.29 T (Ms = 140.9 emu/g) and μe = 46,600 at 1 kHz after annealed at its optimal annealing temperature about 506 °C for 40 min. In addition, it is worth noting that Fe73(Si0.64B0.27P0.09)24Cu1Nb2 nanocrystalline alloy exhibits a stable μe in a wide frequency range from 50 kHz to 200 kHz, which can open the way to new applications.

DIAGNOSTICS OF AMORPHOUS ALLOY MAGNETIC PROPERTIES AFTER THERMOMAGNETIC PROCESSING

Hysteresis magnetic properties formation and plasticity of Fe&amp;Co-based amorphous alloy tapes (brand 30KCP, the Fe–Co–Si–B system) for improvement increase in its properties and ensuring its competitive application on the control basis have been investigated. In researches magnetomeasuring installation have been used. It is intended for automatic magnetic characteristics measurement of soft magnetic materials ring samples by GOST 8.377 techniques. Defined degree of a flexural tension relaxation when annealing tapes. It was established that even at five-minute annealing at a temperature of 360 °C processes of a relaxation manage to take place almost completely. Further change in time of parameter of a relaxation is insignificant. The received dependences of magnetic characteristics on time of thermomagnetic processing at the enclosed field of 10 A/m and their comparison with usual annealing showed that coercive force changes on the same types of curves with insignificant deviations. After thermomagnetic processing in the enclosed field of 21 A/m coercive force in big fields increased approximately by 30 %, in small Hc failure observed around 5 … 15 min of processing as well as Br values increased. This observed result is very interesting in terms of magnetic reversal processes. The lack of stabilization mobile 180° domains borders, at simultaneous course stabilization 90° borders, is reflected in the form of recession of residual induction and growth of magnetic permeability. It is shown that thermomagnetic processing of amorphous alloy of brand 30KCP in not sating longitudinal field with small times of endurance 5…15 min at 360 °C leads to the drawn hysteresis loops, the lowered squareness of hysteresis loops and high values of low-field magnetic permeability 10.

Research progress and application prospect of Fe-based soft magnetic amorphous/nanocrystalline alloys

Amorphous alloy is a kind of metallic materials prepared by rapidly cooling the alloy melt through hindering crystallization in cooling process. Due to the unique structure of atomic random packing, Fe-based amorphous alloys exhibit not only structural and property isotropy, but also small structural correlation length, small magnetic anisotropic constant, and then small coercivity Hc. Like crystalline Fe-based alloys, Fe-based amorphous alloys also possess high saturation induction Bs. As a result, research on engineering applications of Fe-based amorphous alloys has been promoted by their excellent soft magnetic properties. Now Fe-based soft magnetic amorphous/nanocrystalline alloys have been produced and applied to various areas on a large scale. Here in this paper, the processes of discovery, development and application of Fe-based soft magnetic amorphous alloys are reviewed, and the effects of chemical composition, structure and preparation technology on the soft magnetic properties are introduced and discussed. The obtained theoretic results and the technological innovation show that the great contributions have been made to the development and application of Fe-based soft magnetic amorphous/crystalline alloys. Based on the progress of structure and soft magnetic property and our understanding, the development process of the fundamental research and the application progress of Fe-based soft magnetic amorphous alloys could be divided into three periods. In addition, the present challenge topics in their researches and applications are proposed.

High CO2 alters the hypoxia response of the Pacific whiteleg shrimp (Litopenaeus vannamei) transcriptome including known and novel hemocyanin isoforms

Acclimation to low O2 in many organisms involves changes at the level of the transcriptome. Here we used high-throughput RNA sequencing (RNA-Seq) to explore the global transcriptomic response and specific involvement of a suite of hemocyanin (Hc) subunits to low O2 alone and in combination with high CO2, which naturally co-occurs with low O2. Hepatopancreas mRNA of juvenile L. vannamei exposed to air-saturated water, low O2, or low O2/high CO2 for 4 or 24 h was pooled, sequenced (HiSeq 2500) and assembled (Trinity: 52,190 contigs) to create a deep strand-specific reference transcriptome. Annotation of the assembly revealed sequences encoding the previously described small Hc subunit (HcS), and three full-length isoforms of the large subunit (HcL1-3). In addition to this, a previously unidentified full-length Hc subunit was discovered. Phylogenetic analysis demonstrated the subunit to be a β-type Hc subunit (denoted HcB), making this the first report of a β-type hemocyanin subunit in the Penaeoidea. RNAs of individual shrimp were sequenced; regulated genes identified from pairwise comparisons demonstrated a distinct pattern of regulation between prolonged low O2 and low O2/high CO2 treatments by GO term enrichment analysis (Roff-Bentzen, P < 0.0001), showcasing the stabilization of energetically costly translational machinery, mobilization of energy stores, and downregulation of the ubiquitin/proteasomal degradation machinery. Exposure to hypoxia for 24 h resulted in an increase in all of the full-length hemocyanin subunits (HcS, HcL1, HcL2, HcL3, and HcB). The addition of CO2 to hypoxia muted the transcriptomic response of all the Hc subunits to low O2, except for the β-type subunit.

Isothermal electric switching of magnetization in Cr2O3/Co thin film system

We investigated the magnetoelectric properties of Cr2O3/Co all-thin-film exchange coupling system with Cr spacer layer. In this system, significantly small coercivity (Hc &amp;lt; 50 Oe) was obtained by the Cr spacer layer insertion between Cr2O3 and Co layers. Owing to the small Hc, exchange bias field, Hex, larger than Hc was achieved. It enabled us to observe magnetization switching at a zero magnetic field, when Hex was reversed by magnetoelectric effect of Cr2O3 layer. Finally, we demonstrated the isothermal magnetoelectric switching of magnetization in the Cr2O3/Cr/Co all-thin-film system. By changing the direction of the electric field during the isothermal magnetoelectric switching process, both Hex and magnetization at a zero magnetic field were reversed back and forth, i.e., isothermal magnetization switching by an electric field was achieved.

Lipid‐based nutrient supplements for pregnant women reduce newborn stunting in Bangladesh (256.6)

Maternal undernutrition and newborn stunting (birth length‐for‐age z‐score &lt; ‐2) are common in Bangladesh. In the Rang‐Din Nutrition Study, a cluster‐randomized effectiveness trial underway in northwest Bangladesh, pregnant women received either a) iron &amp; folic acid (IFA) or b) lipid‐based nutrient supplement (LNS, 20 g/d, 118 kcal) designed to enrich local diets of pregnant women with essential fatty acids, high‐quality protein and 22 micronutrients. Women (n=4011) were enrolled at 13.1 ± 3.4 wk gestation; 40% were nulliparous and 31% were underweight (BMI &lt; 18.5 kg/m2). In the full sample, there were significant reductions in newborn stunting [18.6 vs. 22.5%, adjusted relative risk (ARR)=0.83 (0.70, 0.96)] and small head circumference (HC z‐score &lt; ‐2) [20.8 vs. 24.7%, ARR=0.82 (0.71, 0.95)] in the LNS vs. IFA group; the difference in low birth weight was marginally significant (36.8 vs. 39.1%, p=0.087). LNS distribution was interrupted for 10 wk in 2012; among women who gave birth before the interruption, the rates of newborn stunting and small HC in LNS vs. IFA were 16.1 vs. 23.0% [ARR=0.66 (0.50, 0.87)] and 20.9 vs. 27.3% [ARR=0.73 (0.57, 0.91)], respectively. The effects of LNS on newborn stunting were greatest in women with household food insecurity and in those 14‐24 y of age. We conclude that LNS can improve birth outcomes in Bangladeshi women, especially those at higher risk for fetal growth restriction.Grant Funding Source: Supported by USAID through the Food and Nutrition Technical Assistance III Project (FANTA)

Formation and magnetic properties of metastable phases observed in the Fe50(HfxTa1−x)50 films by ion beam mixing

Metastable phase formation and magnetic properties of the Fe50(HfxTa1−x)50 (x=0, 0.2, …, and 1) thin films induced by ion beam mixing are studied. The results show that unique amorphous phases could be formed in all the six multilayered films. Interestingly, preferred orientations and formation of BCC-Hf phase were observed in the Fe50Hf50 multilayered films at as-deposited state and after irradiated to doses less than 6×1014Xe+/cm2. In addition, good soft magnetic properties were obtained in the formed amorphous phases. The Fe50Hf40Ta10 amorphous phase owns the maximum magnetization of 45emu/g (i.e., 1.21μB per Fe atom) at 5K, with a saturate magnetization of 7.5emu/g and a small coercivity Hc=7Oe at room temperature. The possible mechanisms responsible for the observations are discussed in terms of atomic collision theory and crystallography.

Neutron-diffraction evidence for the ferrimagnetic ground state of a molecule-based magnet with weakly coupled sublattices

The diruthenium compound [Ru2(O2CMe)4]3[Cr(CN)6] contains two weakly coupled, ferrimagnetically ordered sublattices occupying the same volume. Due to the weak, antiferromagnetic dipolar interaction Kc ≈ 5 × 10−3 meV between sublattices, a small magnetic field Hc ∼ Kc/μB ≈ 800 Oe aligns the sublattice moments. Powder neutron-diffraction measurements on a deuterated sample confirm an earlier prediction that the sublattice moments are restricted by the anisotropy of the diruthenium ‘paddle-wheels’ to the cubic diagonals. Those measurements also suggest that quantum corrections to the ground state are significant.

Co2FeAl films with perpendicular magnetic anisotropy in multilayer structure

We have fabricated Co2FeAl (CFA) films with perpendicular magnetic anisotropy (PMA) in a (Co2FeAl/Ni)6 multilayer structure. The effects of underlayer Cu thickness (tCu), Co2FeAl thickness (tCFA) and Ni thickness (tNi) on the magnetic properties have been studied. The PMA is realized with a large anisotropy energy density K = 3.7×106 ergs/cm3, a high squareness Mr/Ms = 1 and a small perpendicular coercivity Hc = 60 Oe, while tCu, tCFA and tNi are 9 nm, 0.2 nm and 0.6 nm respectively. The PMA remains after 300 °C annealing, which demonstrates better thermal stability of the (Co2FeAl/Ni)6 multilayer than that of (Co/Ni)n.

A Cross-sectional Study of the Growth Characteristics of Nigerian Infants from Birth to 2 Years of Age

Malnutrition compromises the growth of children in sub-Saharan Africa. In Nigeria, the prevalence of childhood malnutrition approaches 40%. There are few reports relating the growth characteristics of breast-fed Nigerian infants to the anthropometric properties of their mothers. A total of 100 urban and rural mother/baby pairs were recruited. The mean BMI values of the urban and rural mothers were 24.2 and 21.3 kg m(-2), respectively. The mean length, weight and head circumference of the rural infants were significantly lower than those of the urban infants. Z-scores based on World Health Organization standards showed: (i) length-for-age z-score <-2 in urban (27%) and rural (33%) children; (ii) a higher incidence of underweight and small HC in rural (33%; and 13%) versus urban children (12% and 0%); and (iii) positive correlations between all three z-scores and maternal BMI. Negative correlations were observed between infant age and z-scores for length-for-age, weight-for-age and HC-for-age.

The effect of compression ratio on exhaust emissions from a PCCI diesel engine

A description of the development of a single-cylinder test facility is presented, being based on a production 4-cylinder DI Diesel engine and designed to allow study of the emissions characteristics over a very wide range of operating conditions. The objective was to establish how engine out NO x emissions can be reduced to the estimated levels required by the next emissions target ‘Euro 6’ and thus be able to apply the findings to the original 4-cylinder engine and minimise the requirement for currently immature NO x after-treatment. It has been proposed that further reduction in compression ratio beyond current levels would be beneficial to engine out emissions and specific power, and could be facilitated by developments in cold-start technology. The results of a study using this single-cylinder facility to evaluate the effect of reducing compression ratio from 18.4 to 16.0 are presented. It was found that, although there was a small CO and HC penalty, either reducing the compression ratio or retarding the injection timing greatly reduced NO x and soot emissions when both premixed and diffusion–combustion phases were present. This effect was less significant when the combustion was solely premixed.

Microstructure and magnetism of FeCo–SiO2 nano-granular films for high frequency application

Excellent soft magnetic properties have been achieved in a wide metal volume fraction (x) range for as-deposited (Fe65Co35)x(SiO2)1−x granular films fabricated by magnetron sputtering. With the decrease in x from 0.7 to 0.5, the films exhibit small coercivity Hc not exceeding 4 Oe and high electrical resistivity ρ up to 5.48 × 103 µΩ cm. A minimum Hc value of 1.7 Oe was obtained for the sample of x = 0.57 with ρ = 2.86 × 103 µΩ cm. At a frequency lower than 1.3 GHz, the real part μ′ of complex permeability of this sample is about 170 and then decreases with frequency while the imaginary part μ″ is visible when f > 1 GHz, which may be caused by anisotropy dispersion. The FMR frequency is as high as 2.4 GHz, implying a high cut-off frequency for high frequency applications. A study of high resolution transmission electronic microscope indicates that the samples consist of Fe65Co35 particles uniformly embedded in an insulating SiO2 matrix. The excellent soft magnetic property is ascribed to exchange coupling among magnetic particles. The investigation of the Δm–H curve evidences the existence of this inter-granule interaction.

Improvement of Soft Magnetic Properties in (Fe&lt;SUB&gt;0.85&lt;/SUB&gt;B&lt;SUB&gt;0.15&lt;/SUB&gt;)&lt;SUB&gt;100&amp;minus;&lt;I&gt;x&lt;/I&gt;&lt;/SUB&gt;Cu&lt;I&gt;&lt;SUB&gt;x&lt;/SUB&gt;&lt;/I&gt; Melt-Spun Alloys

The Cu content dependence of magnetic properties in annealed (Fe0.85B0.15)100−xCux alloys fabricated by melt-spinning was discussed. The value of Hc markedly decreases with increasing x between x=1.0 and 1.5, accompanied with significant reduction of crystalline grain size. The alloy with x=1.5 showed excellent magnetic properties such as a small Hc of about 7 A/m and a high Bs of more than 1.8 T. For the present alloy system, more than 1.0% addition of Cu is effective for the formation of nano-scale grains and for the improvement of the soft magnetic properties.