• Proceedings of the Korean Magnestics Society Conference
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• 2005.12a
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• pp.7-7
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• 2005

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.433-440
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• 2005

The hydrogen sorption speed of $Zr_{57}V_{36}Fe_7$ nanocrystalline and amorphous alloys was evaluated at room temperature. Nanocrystalline alloys of $Zr_{57}V_{36}Fe_7$ were prepared by planetary ball milling. The hydrogen sorption speed of nanocrystalline alloys was higher than that of the amorphous alloy. The enhanced sorption speed of nanocrystalline alloys was explained in terms of surface oxygen stability which has been known to retard the activation of amorphous alloys. The retardation can be reduced by formation of nanocrystals, which results in the observed increase in sorption properties.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.788-789
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• 2006

Microstructure and soft magnetic properties of bulk amorphous and/or nanocrystalline $Fe_{73.5}Cu_1Nb_3Si_{13.5}B_9$ alloys prepared by consolidation at 5.5GPa were investigated. The relative density of the bulk sample 1 (from amorphous powders) was 98.5% and the grain sizes were about 10.6nm. While the relative density and grain sizes of bulk sample 2 (from nanocrystalline powders) are 98% and 20.1nm, respectively. Particularly, the bulk samples exhibited a good combined magnetic property: for Sample1, $M_s=125emu/g$ and $H_c=1.5Oe;$ for Sample2, $M_s=129emu/g$ and $H_c=3.3Oe$. The success of synthesizing the nanocrystalline Fe-based bulk alloys will be encouraging for the future development of bulk nanocrystalline soft magnetic alloys.

• Journal of Surface Science and Engineering
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• v.36 no.6
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• pp.455-460
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• 2003

Microstructural and magnetic properties of nanocrystalline Fe-46 wt%Ni and Fe-36 wt%Ni alloys were investigated. Alloys were prepared by the electrodeposition process. The electrolytes were iron sulfate/nickel chloride-based and iron chloride/nickel sulfamate-based solutions. Fe-46 wt%Ni alloy was FCC structure with grain size of 10 nm, but FCC and BCC phases were found in Fe-36 wt%Ni alloy and its grain size was smaller. Effective permeability of Fe-36 wt%Ni alloy was higher than that of Fe-46 wt%Ni alloy in the high frequency range because of large electrical resistivity and small eddy current loss resulted from grain size decrease. Up to $300^{\circ}C$ of annealing temperature, grain growth of Fe-Ni alloys slowly occured. Conversely, annealing above $450^{\circ}C$ led to a drastic grain growth. In that case, effective permeability was decreased at the temperature lower than $300^{\circ}C$ but at $300^{\circ}C$ or higher effective permeability was increased. At the high frequency of 1 MHz, electrodeposited Fe-Ni alloys had higher effective permeability with an decrease in the grain size.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.491-495
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• 1995

The crystallization behaviors and magnetic properties for $Fe_{81-x}Al_{4}B_{10}Zr_{5}Cu_{x}$ (x=0, 1, 2 at%) alloys is investigated. By the addition of 1~2 Cu, the temperature range, where a single bcc phase exists, expands largely over 200 K and the grain size of bcc phase represents to less than 10 nm. For the optimally annealed Cu-added alloys, the high $\mu_{e}$ (1 kHz) above 20000 combined with the high $B_{10}$ of about 1.4 T is obtained in nanocrystalline state. The low core loss of 95.8 W/kg at 0.1 T and 100 kHz is confirmed for the nanocrystalline $Fe_{80}Al_{4}B_{10}Zr_{5}Cu_{1}$ alloy.

• Journal of Magnetics
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• v.18 no.1
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• pp.1-4
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• 2013

Structural and magnetic properties of $Fe_{50}Mn_{50}$ nanocrystalline alloys prepared by the mechanical alloying technique (using commercial Fe and Mn powders as the precursors) are studied as a function of milling time, 1 hr to 48 hrs. The nano-crystallite size and shape are examined by using scanning electron microscopy (SEM). The effect of milling time on structural characterization was investigated using X-ray diffractometer (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS). Both XRD and EXAFS studies showed that the alloying process should be completed after 36 hrs milling. Concerning the magnetic behavior, the data obtained from superconducting quantum interference devices (SQUID) exhibited both magnetic saturation ($M_s$) and coercivity ($H_c$) depend strongly on the milling time, which are related to the changes in the crystallite size and magnetic dilution.

• Journal of Magnetics
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• v.19 no.4
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• pp.327-332
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• 2014

The effect of minor element additions (Ca, Al) on microstructural change and magnetic properties of Fe-Nb-Cu-Si-B alloy has been investigated, in this paper. The Fe-Si-B-Nb-Cu(-Ca-Al) alloys were prepared by arc melting in argon gas atmosphere. The alloy ribbons were fabricated by melt-spinning, and heat-treated under a nitrogen atmosphere at $520-570^{\circ}C$ for 1 h. The soft magnetic properties of the ribbon core were analyzed using the AC B-H meter. A differential scanning calorimetry (DSC) was used to examine the crystallization behavior of the amorphous alloy ribbon. The microstructure was observed by X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The addition of Ca increased the electrical resistivity to reduce the eddy current loss. And the addition of Al decreased the intrinsic magnetocrystalline anisotropy $K_1$ resulting in the increased permeability. The reduction in the size of the ${\alpha}$-Fe precipitates was observed in the alloys containing of Ca and Al. Based on the results, it can be concluded that the additions of Ca and Al notably improved the soft magnetic properties such as permeability, coercivity and core loss in the Fe-Nb-Cu-Si-B base nanocrystalline alloys.

• Journal of Powder Materials
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• v.28 no.4
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• pp.293-300
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• 2021

We investigate the effect of phosphorous content on the microstructure and magnetic properties of Fe_83.2Si_5.33-0.33xB_10.67-0.67xP_xCu_0.8 (x = 1-4 at.%) nanocrystalline soft magnetic alloys. The simultaneous addition of Cu and P to nanocrystalline alloys reportedly decreases the nanocrystalline size significantly, to 10-20 nm. In the P-containing nanocrystalline alloy, P atoms are distributed in an amorphous residual matrix, which suppresses grain growth, increases permeability, and decreases coercivity. In this study, nanocrystalline ribbons with a composition of Fe_83.2Si_5.33-0.33xB_10.67-0.67xP_xCu_0.8 (x = 1-4 at.%) are fabricated by rapid quenching melt-spinning and thermal annealing. It is demonstrated that the addition of a small amount of P to the alloy improves the glass-forming ability and increases the resistance to undesirable Fe_x(B,P) crystallization. Among the alloys investigated in this work, an Fe_83.2Si₅B₁₀P₁Cu_0.8 nanocrystalline ribbon annealed at 460℃ exhibits excellent soft-magnetic properties including low coercivity, low core loss, and high saturation magnetization. The uniform nanocrystallization of the Fe_83.2Si₅B₁₀P₁Cu_0.8 alloy is confirmed by high-resolution transmission electron microscopy analysis.

• Journal of Magnetics
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• v.4 no.1
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• pp.1-4
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• 1999

The microstructure and magnetic properties of$ Fe_{87}Zr_7Si_4B_2$ nanocrystalline alloys were studied by magnetization measurements and M ssbauer spectrometry over a wide temperature range. Three well resolved spectral components have been found and attributed to bcc-Fe grains (with almost pure iron structure), residual amorphous matrix enriched with solute elements and interfaces formed at the grain-matrix boundaries. It has been shown that, contrary to the expectation, during crystallization the atomic segregation occurs leading to the formation of primary bcc-Fe grains and the partition of Si atoms into the residual amorphous matrix.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.82-88
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• 2019

Here, we report on nanocrystalline Si-Al-M (M = Fe, Cu, Ni, Zr) alloys for use as an anode for lithium-ion batteries, which were fabricated via a melt-spinning method. Based on the XRD and TEM analyses, it was found that the Si-Al-M alloys consist of nanocrystalline Si grains surrounded by an amorphous matrix phase. Among the Si-Al-M alloys with different metal composition, Ni-incorporated Si-Al-M alloy electrode retained the high discharge capacity of 2492 mAh/g and exhibited improved cyclability. The superior $Li^+$ storage performance of Si-Al-M alloy with Ni component is mainly responsible for the incorporated Ni, which induces the formation of ductile and conductive inactive matrix with crystalline Al phase, in addition to the grain size reduction of active Si phase.