• Korean Journal of Materials Research
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• v.8 no.3
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• pp.252-255
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• 1998

In this paper, we investigate the magneto-impedance(M1) effect of the FeCoSiB amorphous magnktic films. The amorphous magnetic film having near zero magnetostriction is fabricated by using the sputtering method, and then annealed in magnetic field. When the external magnetic field is directly applied to the fabricated film, the voltage amplitude between both side of the magnetic film varies about 76.2% at 120[MHzl and the impedance varies about 2.1%/0e. Thus, we find that the fabricated magnetic film has the characteristics of good sensor element.

• Korean Journal of Materials Research
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• v.11 no.6
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• pp.477-482
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• 2001

The velocity changes of magneto surface acoustic wave (MSAW) have been investigated in the MSAW devices composed of wedge type transducer and as-sputtered ($Fe_{1-x}$ $Co_{x}$ )$_{89}$ $Zr_{ 11}$ (x=0~1.0)amorphous films on glass substrates. The velocity changes of devices depended sensistively on exciting frequency of MSAW, applying the DC bias magnetic field. film thickness and film composition. Particularly. it was conformed that velocity changes increased with the increase of the exciting frequency of MSAW and the thickness of magnetic films. A device deposited x= 0.8 film along the MSAW propagation direction among the devices exhibited a large velocity change of 0.062% at 8.7 MHz for the applied field of 70 Oe.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.1-7
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• 2010

Experiments have demonstrated that the addition of a moderate amount of V to $Fe_{52}Co_{(20-x)}B_{20}Si_4Nb_4V_x$ amorphous alloy enhances the plasticity of the alloy. In particular, $Fe_{52}Co_{17.5}B_{20}Si_4Nb_4V_{2.5}$ alloy withstood a maximum of 8.3% strain prior to fracture along with a strength exceeding 4.7 GPa. Energy dispersive x-ray spectroscopy conducted on the $Fe_{52}Co_{17.5}B_{20}Si_4Nb_4V_{2.5}$ alloy exhibited evidence of compositional modulation, indicating that nm-scale phase separation had occurred at local regions. In this study, the role played by nm-scale phase separation on the plasticity was investigated in terms of structural disordering and shear localization in order to better understand the structural origin of the enhanced plasticity shown by the developed alloy.

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1539-1542
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• 2022

Artificial intelligence operated with machine learning was performed to optimize the amount of metalloid elements (Si, B, and P) subjected to be added to a Fe-based amorphous alloy for enhancement of soft magnetic properties. The effect of metalloid elements on magnetic properties was investigated through correlation analysis. Si and P were investigated as elements that affect saturation magnetization while B was investigated as an element that affect coercivity. The coefficient of determination R²(coefficient of determination) obtained from regression analysis by learning with the Random Forest Algorithm (RFR) was 0.95 In particular, the R² value measured after including phase information of the Fe-Si-B-P ribbon increased to 0.98. The optimal range of metalloid addition was predicted through correlation analysis method and machine learning.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.225-234
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• 1996

Needle-like $\alpha-Fe_{2}O_{3}$ particles as precursor for magnetic recording media were prepared directly from amorphous ferric hydroxide in the aqueous solution by hydrothermal reaction. Ellipsoidal or rectangular $\alpha-Fe_{2}O_{3}$ particles were formed in the range of pH 10.75~11.75. The length and acicularity of $\alpha-Fe_{2}O_{3}$ particles were decreased gradually with increasing of citric acid concentration. The formation of needle-like $\alpha-Fe_{2}O_{3}$ particles was inhibited above citric acid concentration of $1.5{\times}10^{-4}\;mol$. We can synthesize $\alpha-Fe_{2}O_{3}$ particles with the most superior acicularity at $140^{\circ}C$ and can not expect a good needle-like particles above $220^{\circ}C$.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.709-714
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• 2000

SAW 소자에 응용 가능한 자성박막재의 개발을 목적으로 RF 스퍼터링법으로 증착한 (Fe(sub)0.6Co(sub)0.4)(sub)89Zr(sub)11/Fe(sub)1-xCo(sub)x)Zr(sub)11(x=0, 0.6, 0.9)<원문잠조> 비정질 다층박막의 자기특성을 조사하였다. 수직자기장중열처리를 행하였을 때 상온에서 비자성 Fe(sub)89Zr(sub)11 층의 삽입에서만 다층박막화의 효과가 나타났다. 일 예로 (Fe(sub)0.6Co(sub)0.4)(sub)89Zr(sub)11(30${\AA}$)/Fe(sub)89-Zr(sub)11(40${\AA}$)<원문참조> 박막시편에 1kHz, 50 mOe의 여기자기장으로 평가된 최대 미분투자율${\mu}$(sub)d.max는 단층막의 750에서 1650으로 2배 이상 증가, 구동 바이어스자기장 Hw는 20 Oe에서 6Oe로 3배 이하로 감소하는 양호한 특성이 얻어졌다. 그러나 다른 중용 특성인 자왜는 34% 정도 감소하는 것으로 추정되었다.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.91-92
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• 2004

• Journal of Magnetics
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• v.19 no.3
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• pp.291-294
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• 2014

In this paper, we examine the electrical and magnetic properties of three different types of shield materials used for wireless power transfer systems: namely, FeSiAl-composite, NiZn-ferrite, and FeSi-amorphous types. The power transfer efficiency and resistance of an RX coil are measured, while varying the shield thickness. For all three types, a thicker shield provides better power transfer efficiency. Analysis of the measurements shows that the FeSiAl-composite type is suitable for systems with size limitation. In terms of magnetic properties, the FeSi-amorphous type shows the best features, and is suited to high power applications. This work can be used as a guideline to select suitable shielding material in various wireless power transfer systems.

• Journal of Surface Science and Engineering
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• v.32 no.1
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• pp.43-48
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• 1999

Oxidation behavior of 304 and 316 stainless steels was studied. After solution heat treatment, specimens were polished up to 1$mu \textrm{m}$ using $Al_2O_3$ powder and then subjected to oxidation between $300^{\circ}C$ and 50$0^{\circ}C$ in dry air. TEM and EDS were used for analyzing the components and structure of oxide film. TEM analysis of oxide film revealed that thin amorphous Fe oxide ($Fe_2O_3$) was formed on the top of surface while polycrystalline (Cr, $Fe_2O_3$ was formed below the amorphous Fe oxide layer. The specimens oxidized at $500^{\circ}C$ showed that 316 stainless steel had higher oxidation resistance than 304 stainless steel. These results suggest that Mo component of 316 stainless steel suppresses the formation of Cr carbide which may result in a local Cr depleted area.

• Journal of Magnetics
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• v.18 no.3
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• pp.240-244
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• 2013

The influences of Gallium doping on the magnetic microstructures and corrosion behaviors of Nd-Fe-B-Ti-C alloys are investigated. The cooling rate for obtaining fully amorphous structure is raised, and the glassforming ability is improved by the Ga addition. The High Resolution Transmission Electron Microscopy image shows that the ${\alpha}$-Fe and $Fe_3B$ soft magnetic phases become granular surrounded by the $Nd_2Fe_{14}B$ hard magnetic phase. The rms and $({\Delta}{\varphi})_{rms}$ value of Nd-Fe-B-Ti-C nanocomposite alloy thick ribbons in the typical topographic and magnetic force images detected by Magnetic Force Microscopy(MFM) decreases with 0.5 at% Ga addition. The corrosion resistances of $Nd_9Fe_{73}B_{12.6}C_{1.4}Ti_{4-x}Ga_x$ (x = 0, 0.5, 1) alloys are enhanced by the Ga addition. It can be attributed to the formation of more amorphous phases in the Ga doped samples.