• Title/Summary/Keyword: CoFe alloy

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Chemical Solution Mixing and Hydrogen Reduction Method for Fabrication of Nanostructured Fe-Co Alloy Powders (화학용액 혼합과 수소환원법을 이용한 나노구조 Fe-Co 합금분말의 제조)

  • 박광현;박현우;이백희;장시영;이정근;김영도
    • Journal of Powder Materials
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    • v.11 no.2
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    • pp.137-142
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    • 2004
  • In this study, chemical solution mixing and hydrogen reduction method was used to fabricate nanostructured $Fe_xCo_{1-x}$ alloy powders. Fe-Co chloride mixture, FeCl$_2$ and COCI$_2$ with 99.9% purity, were reduced in hydrogen atmosphere. Nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated. Magnetic properties of fabricated $Fe_xCo_{1-x}$(x=0, 10, 30, 50, 70, 100) alloy powders with the same grain size were measured because size factor can affect magnetic properties. Coercivity of Fe-Co alloy powders were increased with increasing Co contents. Maximum value of coercivity in various Co contented Fe-Co alloy powders with similar grain size was 125 Oe at Fe$_{100}$. Saturation magnetization value at Fe$_{70}$Co$_{30}$ composition showed maximum value of 219 emu/g and saturation magnetization value decreased with increasing Co contents and minimum value of 155 emu/g was observed at Co$_{100}$.

Microstructure and Magnetic Properties of Nanostructured Fe-Co Alloy Powders Produced by Chemical Solution Mixing and Hydrogen Reduction Methods (화학용액혼합과 수소환원법으로 제조된 나노 구조 Fe-Co 합금분말의 미세구조 및 자성 특성)

  • 박현우;이백희;이규환;김영도
    • 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.

Microstructural Features of Multicomponent FeCoCrNiSix Alloys

  • Kong, Kyeong Ho;Kim, Kang Cheol;Kim, Won Tae;Kim, Do Hyang
    • Applied Microscopy
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    • v.45 no.1
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    • pp.32-36
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    • 2015
  • The microstructural features of FeCoCrNi, FeCoCrNiAl and FeCoCrNiSix (x=0, 5, 10, 15, 20) alloys have been investigated in the present study. The microstructure of FeCoCrNi alloy changes dramatically with equiatomic addition of Al. The fcc irregular shaped grain structure in the as-cast FeCoCrNi alloy changes into the bcc interconnected structure with phase separation of Al-Ni rich and Cr-Fe rich phases in the as-cast FeCoCrNiAl alloy. The microstructure of FeCoCrNi alloy changes with the addition of Si. With increasing the amount of Si, the fcc structure of the grains is maintained, but new phase containing higher amount of Si forms at the grain boundary. As the amount of Si increases, the fraction the Si-rich grain boundary phase increases.

Magnetic and Structural Properties of CoFeZr Alloy Films and Magnetoresistive Properties of Spin Valves Incorporating Amorphous CoFeZr Layer (CoFeZr 합금박막의 미세구조, 자기적 특성 및 비정질 CoFeZr 합금박막을 사용한 스핀밸브의 자기저항 특성에 관한 연구)

  • Ahn, Whang-Gi;Park, Dae-Won;Kim, Ki-Su;Lee, Seong-Rae
    • Journal of the Korean Magnetics Society
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    • v.18 no.6
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    • pp.227-231
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    • 2008
  • Magnetic and structural properties of CoFeZr alloy films as a function of Zr concentration and magnetoresistive properties of spin valves incorporated with amorphous CoFeZr alloy films have been studied. Magnetization and coercivity of CoFeZr alloy films decreased as the Zr content increased. A single amorphous CoFeZr phase was formed when the Zr content is about above 18 at%. Magnetoresistance ratio and exchange coupling field of spin valves with amorphous CoFeZr were reduced slightly as compared with spin valves with CoFe because the resistance of amophous CoFeZr is higher than that of crystalline CoFe. However, the ${\Delta}{\rho}$ of spin valves with amorphous CoFeZr was improved due to reduction of current shunting.

Effect of Heat-treatment in Low Thermal Expansion Coefficient Fe-Ni-Co alloy for Core Material of Increased Capacity Transmission Line (증용량 송전선 강심용 저열팽창 Fe-Ni-Co 합금에 있어서 용체화처리 영향)

  • 김봉서;유경재;김병걸;이희웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.950-952
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    • 2000
  • Considering the effective distribution coefficient of Ni in Fe-Ni-Co invar alloy containing a little amount of carbon, we investigated on the thermal expansion coefficient(${\alpha}$). Fe-Ni-Co invar alloy had a large thermal expansion coefficient in as-casted compared with solution treated. The thermal expansion coefficient of Fe-Ni-Co alloy increased with the carbon content in both state of as-casted and solution treated. The effective distribution coefficient(Ke$\^$Ni/) of Ni was smaller than unity in alloy of not containing carbon, but is way larger than unity in alloy of containing carbon. It was considered that the homogeneity of Ni in primary austenite affected thermal expansion coefficient.

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Composition and Coercivity of Fe-Co-Ni Alloy Electrodeposits (Fe-Co-Ni합금박막의 조성 및 자기적 성질)

  • 예길촌;김용웅;문근호
    • Journal of the Korean institute of surface engineering
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    • v.29 no.3
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    • pp.195-202
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    • 1996
  • The composition, the microstructure and the magnetic properties(HC and Hk) of Fe-Co-Ni alloy electrodeposits were investigated according to the electrolysis conditions using sulfate bath paddle agitated. The current efficiency of the alloys electrodeposition was considerably low in the range of 16∼50%. The Fe content(wt.%) of the alloy increased from 20% to 57% with current density, while Ni content of them decreased in the range of 70∼24% respectively, and Co content was nearly constant. As a result, Fe/Ni ratio of the alloy increased from 0.3 to 2.0 showing the anomalous codeposition. The structure of the alloy changed from fcc to the mixed one of fcc+bcc with the increase of Fe/Ni ratio. The preferred orientation of the alloy with fcc and bcc structure were (220) and (110) respectively. The alloy with Fe/Ni ratio(0.3∼l.2) had the lowest coercivity of 0.4∼0.8 Oe.

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Synthesis and Magnetic Properties of Body-centered-tetragonal Fe-Co Alloy (체심정방정 구조 Fe-Co계 합금상의 합성 및 그 자기적 특성)

  • Kim, K.M.;Kwon, H.W.;Lee, J.G.;Yu, J.H.
    • Journal of the Korean Magnetics Society
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    • v.27 no.4
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    • pp.129-134
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    • 2017
  • Bulk-type body-centered-tetragonal Fe-Co alloy was synthesised by utilising a conventional alloy preparation technologies, such as melting, solidification, and homogenising treatments, and its magnetic properties were investigated. In the $(Fe_{100-x}Co_x)_{1-y}C_y$ alloy, the composition range, from which single phase body-centered-tetragonal alloy (martensite phase) was obtained, was severely limited: Co content x = 2.5, and C content y = 0.062. Tetragonality(c/a) of the synthesised body-centered-tetragonal $(Fe_{97.5}Co_{2.5})_{0.938}C_{0.062}$ alloy was 1.05. Magnetocrystalline anisotropy constant ($K_1$) of the body-centered-tetragonal $(Fe_{97.5}Co_{2.5})_{0.938}C_{0.062}$ alloy was measured to be $9.8{\times}10^5J/m^3$), which was 3.1 time as high as the pure iron (${\alpha}-Fe$).

Thermal Properties and Microstructural Changes of Fe-Co System Valve Seat Alloy by High Densification Process (고밀도화 공정에 의한 Fe-Co 계 밸브시트 합금의 조직변화와 열적 특성)

  • Ahn, In-Shup;Park, Dong-Kyu;Ahn, Kwang-Bok;Shin, Seoung-Mok
    • Journal of Powder Materials
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    • v.26 no.2
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    • pp.112-118
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    • 2019
  • Infiltration is a popular technique used to produce valve seat rings and guides to create dense parts. In order to develop valve seat material with a good thermal conductivity and thermal expansion coefficient, Cu-infiltrated properties of sintered Fe-Co-M(M=Mo,Cr) alloy systems are studied. It is shown that the copper network that forms inside the steel alloy skeleton during infiltration enhances the thermal conductivity and thermal expansion coefficient of the steel alloy composite. The hard phase of the CoMoCr and the network precipitated FeCrC phase are distributed homogeneously as the infiltrated Cu phase increases. The increase in hardness of the alloy composite due to the increase of the Co, Ni, Cr, and Cu contents in Fe matrix by the infiltrated Cu amount increases. Using infiltration, the thermal conductivity and thermal expansion coefficient were increased to 29.5 W/mK and $15.9um/m^{\circ}C$, respectively, for tempered alloy composite.

Effect of Fcrromagnetic Layer and Magnetoresistance Behavior of Co-Evaporated Ag-CoFe Nano-Granular Alloy Films (Ag - CoFe 합금박막의 자기저항 및 강자성 상하지층의 효과)

  • 김용혁;이성래
    • Journal of the Korean Magnetics Society
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    • v.7 no.6
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    • pp.308-313
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    • 1997
  • The magnetoresistance (MR) and the saturation field behavior of the CoFe-Ag nano granular films as a function of the ferromagnetic underlayer and overlayer materials were investigated. The maximum MR ratio of 25.7 % and the saturation field of 2.1 kOe in the as-deposited 3000 $\AA$ $(Co_{92}Fe_8)_{31}Ag_{69}$ single alloy films at room temperature were obtained. The MR ratio and the saturation field of the 100 $\AA$ alloy film were 1.2 % and 5.2 kOe, respectively. Those of the sandwiched alloy films of 200 $\AA$ thick with the Fe under and overlayer of 100 $\AA$ were 11 % and 1.8 kOe respectively. The reduction of saturation field in the sandwiched alloy films is due to the exchange coupling between the ferromagnetic layers and the alloy layer. Among the Fe and FeNi, the more effective materials to reduce the saturation field of the sandwiched alloy films was Fe.

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Composition, preferred orientation and magnetic properties of Ni-Fe-Co alloy electrodeposits (Ni-Fe-Co 박막도금층의 조성, 우선배향 및 자기적 성질)

  • 예길촌;김선윤;문근호;김용웅
    • Journal of the Korean institute of surface engineering
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    • v.28 no.6
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    • pp.352-360
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    • 1995
  • The effect of electrolysis conditions on the composition, the magnetic properties and the preferred orientation of Ni-Fe-Co alloy deposits was investigated using the sulfate-chloride bath paddle agitated. Cathode current efficiency increases with the current density, showing the different tendency of the variation from that of the Ni-Fe electrodeposits. The Co content of the deposits decreases with increasing current density, while the content of Ni and Fe is shown to be minimum or maximum at 3A/$dm^2$ respectively. The Ni/Fe ratio of the alloy deposits is lower than that of Ni-Fe deposits. The coercive force($H_c$) of the deposits increases with the Co content in deposit, showing the relatively low value in the range of 1.8~5.0Wt.% Co. The anisotropy field ($H_k$) of the deposits is higher than that of Ni-Fe alloy deposits, The preferred orientation of the deposits is generally (200), but the orientation factor(R) changes with both the increase of current density and the magnetic field applied during deposition.

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