• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1500-1502
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• 2001

Plate-type ${\beta}-FeSi_2$ single crystals were grown using $FeSi_2$, Fe, and Si as starting materials by the chemical transport reaction method. The ${\beta}-FeSi_2$ single crystal was an orthorhombic structure. The direct optical energy gap was found to be 0.87eV at 300K. Hall effect shows a n-type conductivity in the ${\beta}-FeSi_2$ single crystal. The electrical resistivity values was 1.608$\Omega$cm and electron mobility was $3{\times}10^{-1}cm^2/V{\cdot}sec$ at room temperature.

• Korean Journal of Materials Research
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• v.1 no.3
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• pp.145-150
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• 1991

Crystallization and embrittlement of $Fe_{78}B_{13}Si_{9}$ amorphous alloy was investigated by differential scanning calorimetry, X-ray diffraction and transmission electron microscopy. The crystallization comprizes two exothermic processes. In the first crystallization stage, $\alpha$-(Fe, Si) dendrites are formed from the amorphous state, and in the second crystallization, $Fe_2B$ compounds are formed. An abrupt decrease of the fracture strain of the ribbon started from amorphous started annealed at about $340^{\circ}C$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.5-7
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• 1988

Effect of isothermal aging on the crystallization of $Fe_{78}B_{13}Si_{9}$ metallic glass has been investigated by electrical resistivity, X-ray measurements, bending test, thermal analysis and transmission electron microscopy. Amorphous $Fe_{78}B_{13}Si_{9}$ alloy was annealed isothermally for 5 to 1200 mon. between 300 C and 540 C. It has been found that close relation between relative resistivity and X-ray diffraction pattern showed. The crystalline peak of $\alpha$-(Fe, Si) and Fe$_2$B are detected by X-ray experiment. The crystalline phases observed by TEM show $\alpha$-(Fe, Si) and Fe$_3$B with dendritic and cylindrical morphology, respectively. It has been also found that the embrittleness of aged samples rapidly increased with the crystallization and was shown before the crystallization.th the crystallization and was shown before the crystallization.

• Journal of the Korean Magnetics Society
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• v.10 no.6
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• pp.269-273
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• 2000

Fe-l7Cr-2M(M=Si, Nb, Mo) alloy powder was prepared by plasma electrode rotating atomizer and than the alloy powder was formed and sintered. The particle shape of the Fe-l7Cr-2M(M=Si, Nb, Mo) alloy power is spherical. The saturation magnetization of the sintered Fe-17Cr-2Mo and Fe-l7Cr-2Nb alloy are 155 emu/g. The saturation magnetization of the sintered Fe-l7Cr-2Si alloy is less than that of the sintered Fe-l7Cr-2Mo and Fe-l7Cr-2Nb alloy. The amplitude relative permeability of the sintered Fe-l7Cr-2M(M=Si, Nb, Mo) alloy has the maximum value in the range of 3∼5 Oe applied field at forming pressure 12 ton/cm$^2$, sintering temperature 1200$^{\circ}C$, and frequency 1 kHz. Power loss of the sintered Fe-l7Cr-2Nb alloy is 40 mW/cc at applied field, H$\sub$a/=5 Oe, and frequency, f=1 kHz. The power loss of the sintered Fe-l7Cr-2Nb alloy is a half of that of the sintered Fe-l7Cr-2Si and Fe-l7Cr-2Mo alloy.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.153-158
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• 1998

현재 변압기 철심 재료는 주로 방향성 전기 강판이 사용되고 있으며, 우수한 자기유도 특성과 낮은 철손이 중요한 요건이다. 방향성 전기강판은 약 3%Si을 함유하며 2차 재결정에 의해 {100}<001> Gross texture로 배향된다. 극박 3%Si-Fe의 2차 재결정에 미치는 냉간 압연율의 효과에 대한 연구결과 보고는 거의 없다. 본 연구의 목적은 다단 냉간압연에 의해 제조되는 박판 3%Si-Fe strip의 자기유도에 미치는 최종 냉간 압연율의 효과를 밝히는 것이다. (중략)

• Korean Journal of Materials Research
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• v.6 no.11
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• pp.1061-1066
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• 1996

RF magnetron reactive sputtering법으로 Fe75.5Zr8.3N16.2/SiO2(250$\AA$) 다층 박막을 FeZrN의 두께를 변화시키면서 제조하고, 제조된 박막을 진공 열처리하여 열처리 온도에 따른 포화자화, 보자력, 고주파에서의 투자율 그리고 열적 안정성을 조사하였다. Fe75.5Zr8.3N16.2/SiO2(250$\AA$) 다층박막은 FeZrN의 두께가 800$\AA$이상일 때 좋은 연자성을 나타내었다. Fe75.5Zr8.3N16.2/SiO2(250$\AA$)다층 박막을 45$0^{\circ}C$로 열처리 했을 때 포화자속밀도(1.08 T), 보자력 0.41 Oe, 1 MHz에서의 실효 투자율은 3000이상의 연자성을 나타내었다. 그 이유는 X-선 회절 분석 결과 열처리에 의해서 ZrN 미결정이 석출하여 $\alpha$-Fe 결정 성장이 억제되어 우수한 연자기적 성질이 나타난다고 판단된다. 이때 $\alpha$-Fe 입자 크기는 40-50$\AA$, ZrN의 입자 크기는 10-15$\AA$이다. 그리고 실효 투자율의 주파수 의존성에서 단층막에서는 5 MHz 이상에서 실효 투자율이 급격히 감소하는 경향을 보였으나, 다층막에서는 40MHz까지 실효 투자율이 1600이 되어 고주파에서의 연자성이 개선되었다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.168-168
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• 1999

Recently, Fe/Si multilayered films (MLF) have been a focus of interest due to the strong antiferromagnetic (AF) coupling observed in such kind of MLF originates from the same nature as in the metal/metal MLF. In particular, a question of whether the spacer layer in the Fe/Si MLF is metallic or semiconducting is of interest. In spite of various experimental techniques envolved in the study, the chemical composition and the properties of the interfacial regions in the MLF exhibiting the AF coupling is still questionable. The nature of the AF coupling and the interfacial properties of Fe/Si MLF are investigated in this study. A series of Fe/Si MLF with a fixed nominal thickness of Fe(3nm) and a variable thickness of Sk(1.0-2.2nm) were deposited by RF-sputtering onto glass substrates at room temperature. The atomic structures and the actual sublayer thicknesses of the Fe/Si MLF are investigated by using x-ray diffraction. The magnetic-field dependence of the equatorial Kerr effect clearly shows an appearance of the AF coupling between Fe sublayers at tsi = 1.5 - 1.8 nm. the drastic discrepancies between the experimental magnetooptical (MO) and optical properties, and based on the assumption of sharp interfaces between Fe and Si sublayers leads to a conclusion that pure si is absent in the AF-coupled Fe/Si MLF. Introducing in the model nonmagnetic semiconducting FeSi alloy layers between Fe and Si sublayers or as spacer between pure Fe sublayers only slightly improves the agreement between model and experiment. A reasonable agreement between experimental and simulated MO spectra was reached with using the fitted optical properties for the spacer with a typical metallic type of behavior. The results of the magnetic properties measured by vibrating sample magnetometer and magnetic circular dichroism are also analyzed in connection with the MO and optical properties.

• Advanced Composite Materials
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• v.18 no.4
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• pp.351-364
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• 2009

The thermal stability and elevated temperature mechanical properties of $SiC_P$/Al-11.7Fe-1.3V-1.7Si (Al-11.7Fe-1.3V-1.7Si reinforced with SiC particulates) composites sheets prepared by spray deposition (SD) $\rightarrow$ hot pressing $\rightarrow$ rolling process were investigated. The experimental results showed that the composite possessed high ${\sigma}_b$ (elevated temperature tensile strength), for instance, ${\sigma}_b$ was 315.8 MPa, which was tested at $315^{\circ}C$, meanwhile the figure was 232.6 MPa tested at $400^{\circ}C$, and the elongations were 2.5% and 1.4%, respectively. Furthermore, the composite sheets exhibited excellent thermal stability: the hardness showed no significant decline after annealing at $550^{\circ}C$ for 200 h or at $600^{\circ}C$ for 10 h. The good elevated temperature mechanical properties and excellent thermal stability should mainly be attributed to the formation of spherical ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase particulates in the aluminum matrix. Furthermore, the addition of SiC particles into the alloy is another important factor, which the following properties are responsible for. The resultant Si of the reaction between Al matrix and SiC particles diffused into Al matrix can stabilize ${\alpha}-Al_{12}(Fe,\;V)_3Si$ dispersed phase; in addition, the interface (Si layer) improved the wettability of Al/$SiC_P$, hence, elevated the bonding between them. Furthermore, the fine $Al_4C_3$ phase also strengthened the matrix as a dispersion-strengthened phase. Meanwhile, load is transferred from Al matrix to SiC particles, which increased the cooling rate of the melt droplets and improved the solution strengthening and dispersion strengthening.

• Korean Journal of Crystallography
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• v.15 no.2
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• pp.104-109
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• 2004

The mechanical synthesis of thermoelectric material $FeSi_2$ by planetary ball mill has been investigated. The homogeneous and amorphous mixture of Fe-Si has been obtained by mechanical alloying for 850 rpm-40 min. The $\beta-FeSi_2$ powder could be synthesized by 1123 K-3 hr annealing heat treatment after mechanical alloying for 850 rpm-10, 20, and 40 min. The ceramic samples doped with the maximum content up to $10\;at.\;\%$ Co have exhibited semiconduction phenomena and maximum thermoelectric powder at 440K.

• Journal of the Korean Magnetics Society
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• v.18 no.5
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• pp.195-199
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• 2008

Composites of $Fe_{93.5}Si_{6.5}$ powder and epoxy were prepared using a thermal curing process. Scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and network analyzer were used to analyze the structure, electromagnetic properties and microwave absorption of the composites. Results show that the saturation magnetization depends on the fraction of the $Fe_{93.5}Si_{6.5}$ powder in the composite, which affects initial permeability. It is believed that the eddy current loss is a dominant factor over 1 GHz and that the resonance frequency of the composite decreases with increasing fractions of $Fe_{93.5}Si_{6.5}$ powder. Finally, reflection loss was calculated from the permeability and permittivity of these composites. Composite with 50 wt.% $Fe_{93.5}Si_{6.5}$ powder fractions and 5 mm thickness showed reflection loss below -20 dB from 3.66 GHz to 4.16 GHz. Therefore, it is believed that thin Fe-Si/epoxy composites may be a good candidate for microwave absorption application.