• 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 Powder Materials
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• v.10 no.5
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• pp.333-336
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• 2003

The purpose of this study is the fabrication of nano-sized Fe-Co alloy powders with soft magnetic properties by the slurry mixing and hydrogen reduction (SMHR) process. $FeCl_2$0 and $CoCl_2$ powders with 99.9% purities were used for synthesizing nanostructured Fe-Co alloy powder. Nano-sized Fe-Co alloy powders were successfully fabricated using SMHR, which was performed at 50$0^{\circ}C$ for 1 h in H$_2$ atmosphere. The fabricated Fe-Co alloy powders showed $\alpha$' phase (ordered body centered cubic) with the average particle size of 45 nm. The SMHR powder exhibited low coercivity force of 32.5 Oe and saturation magnetization of 214 emu/g.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.202-203
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• 2002

Ribbon type nanocrystalline alloy cores have shown excellent soft magnetic properties in the high frequency range because of small crystalline anisotropy and nearly zero magnetostriction[1]. In present, however ribbon alloys gives some limit in applications such as a large inductor and reactors of PFC circuit, which are required good DC bias property and low loss in the high frequency. Powder alloys with ultra fine grain structure can be an important way to overcome this kind of disadvantage, and to improve the high frequency soft magnetic properties in conventional metallic powder cores[2]. (omitted)

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.784-785
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• 2006

Co-based amorphous powder was produced by a new atomization process "Spinning Water Atomization Process (SWAP)", having rapid super-cooling rate. The composition of the alloys was ($(Co_{0.95}Fe_{0.05})_{1-x}Cr_x$)$_{75}Si_{15}B_{10}$ (x=0, 0.025, 0.05, 0.075). The powders became the amorphous state even if particle size was up to about $500{\mu}m$. The coercive force of powders was about 0.35 - 0.7 Oe. Furthermore, Co-based amorphous powder cores with glass binders were made by cold-pressing and sintering methods. The initial permeability of the core in the frequency range up to 100 kHz was about 110, and the core loss at 100 kHz for Bm = 0.1 T was $350kW/m^3$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.86-90
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• 2000

In this study, A equipment for measuring the initial permeability of soft-ferrite powder was developed by using a differential transformer coil, and was investigated demagnetizing factors. To measure the initial permeability of magnetic ceramic powder is cumbersome since there are not any measuring equipment and method. Magnetic powder is currently used for a magnetic fluid and microwave absorber materials, and the initial permeability of the magnetic powder is very important to be evaluated a powder for some applications.

• Journal of Powder Materials
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• v.13 no.4 s.57
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• pp.256-262
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• 2006

The amorphous $Fe_{73}Si_{16}B_7Nb_3Cu_1$ alloy strip was pulverized to get a flake-shaped powder after annealing at $425^{\circ}C$ for 90 min and subsequently ground to obtain finer flake-shaped powder by using a ball mill. The powder was mixed with polyimide-based binder of $0.5{\sim}3wt%$, and then the mixture was cold compacted to make a toroidal powder core. After crystallization treatment for 1 hour at $380{\sim}600^{\circ}C$, the powder was transformed from amorphous to nanocrystalline with the grain size of $10{\sim}15nm$. Soft magnetic characteristics of the powder core was optimized at $550{\sim}600^{\circ}C$ with the insulating binder of 3wt%. As a result, the powder core showed the outstanding magnetic properties in terms of core loss and permeability, which were originated from the optimization of the grain size and distribution of the insulating binder.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.482-483
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• 2000

• Journal of Powder Materials
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• v.3 no.1
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• pp.13-24
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• 1996

Two grades of Permalloy strips, Fe-45Ni(PB) and Fe-78Ni-4Mo-5Cu(PC) were fabricated by powder rolling process from elemental powder mixtures. The roll compacted green strips were sintered, homogenized, cold rolled with or without an intermediate annealing and finally heat treated to measure magnetic properties. For a given thickness reduction, rolling with an intermediate annealing was found more effective to achieve a full densification with no visible micropores and also to obtain better magnetic properties. Increasing the final rolling reduction also produced a marked improvement of the magnetic properties whereas the cooling rate during the final heat treatment has little effect in both grades. Addition of a small amount, 0.4% Mn slightly degraded the properties. As an overall, The PM strips produced via powder rolling yielded the similar soft magnetic properties to the corresponding commercial grades produced via wrought processing.

• Journal of Powder Materials
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• v.15 no.4
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• pp.320-330
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• 2008

On the base of experience in development of Magnetic Powder Composites, and particularly Soft Magnetic Composites, authors are trying to systematize classification and indicate possible development prospective of Magnetic Nanocomposites (MN) technology and their applications in electrical converters. Clear classification and systematization, at an early stage of any materials and technology development, are essential and lead for better understanding and communication between researchers and industry involved. This concern MN as well and it seems to be the right time to make it at present stage of their development. Presented proposal of classification distinguishes various types of MN by their magnetic properties and area of possible applications. It is not a close set of types, and can be extended due to increase of knowledge concern these nanocomposites.

• Journal of Powder Materials
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• v.14 no.5
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• pp.298-302
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• 2007

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.