• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.170-171
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• 2012

$Fe_2O_3$, Al, Cr과 Si 분말을 고 에너지 볼 밀링해서 나노분말을 제조한 후 고주파유도 가열 활성 연소합성 장치로 1분 이내의 짧은 시간에 합성 및 소결한 $Al_2O_3+4.65(Fe_{0.43}Cr_{0.17}Al_{0.323}Si_{0.077})$, $Al_2O_3$ + 5.33 ($Fe_{0.375}Cr_{0.11}Al_{0.3}Si_{0.075}$), $Al_2O_3$ + 6.15 ($Fe_{0.325}Cr_{0.155}Al_{0.448}Si_{0.072}$), $Al_2O_3$ + 3.3 ($Fe_{0.6}Cr_{0.3}Al_{0.6}$) 소결체 시편을 $700^{\circ}C$의 온도에서 100시간 동안 공기 중에서 산화 및 $N_2-H_20-H_2S$ 혼합 가스 내에서 황화 부식을 실시하였다. 그 결과 산화 및 황화 부식 후에 ${\alpha}-Al_2O_3$가 표면에 생성되어 보호 피막으로 작용하여 우수한 내식성을 보였다.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.486-492
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• 2004

We report the crystallization and magnetic properties of non-equilibrium $Al_{0.6}(Fe_{x}Cu_{1-x})_{0.4}(x=0.25, 0.50, 0.75)$ alloy powders produced by rod-milling as well as by new chemical leaching. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h or 500 h milling, only the broad peaks of nano bcc crystalline phases were detected in the XRD patterns. The crystallite size, the peak and the crystallization temperatures increased with increasing Fe. After being annealed at $600{^\circ}C$ for 1 h for as-milled alloy powders, the peaks of bcc $AlCu_{4}\;and\;Al_{13}Cu_{4}Fe_{3}\;for\;x=0.25,\;bcc\;AlCu_{4}\;and\;Al_{5}Fe_{2}\;for\;x=0.50,\;and\;Al_{5}Fe_{2},\;and\;Al_{0.5}Fe_{0.5}\;for\;x=0.75$ are observed. After being annealed at $500{^\circ}\;and\;600{^\circ}C$for 1 h for leached specimens, these non-equi-librium phases transformed into fcc Cu and $CuFe_{2}O_{4}$phases for the x=0.25 specimen, and into bcc ${\alpha}-Fe,\;fcc\;Cu,\;and\;CuFe_{2}O_{4}$ phases for both the x=0.50 and the x=0.75 specimens. The saturation magnetization decreased with increasing milling time for $Al_{0.6}(Fe_{x}Cu_{1-x})_{0.4}$ alloy powders. On cooling the leached specimens from $800{\~}850^{\circ}C$,\;the magnetization first sharply increase at about $491.4{\circ}C,\;745{\circ}C,\;and\;750.0{\circ}C$ for x=0.25, x=0.50, and x=0.75 specimens, repectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.665-668
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• 2008

Multi-layered thin films of $Fe_2O_3/Na_3AlF_6/Fe_2O_3/Cu$, Cr, Al were deposited on glass substrate by evaporation process. As high and low refractive index material, $Fe_2O_3$ and $Na_3AlF_6$ were selected and additionally Cu, Al and Cr were chosen as mid reflective layer respectively. Optical properties including reflectance were systematically studied depending on optical thickness of $Na_3AlF_6$ especially $0.25{\lambda}$ and $0.5{\lambda}$. In order to expect the experimental result, the simulation program, the Essential Macleod Program(EMP) was adopted and compared with the experimental data. Based on the results taken by spectrophotometer at viewing angle $45^{\circ}C$, the $Fe_2O_3/Na_3AlF_6/Fe_2O_3/Cu$ show the colour rage between red and orange in $0.25{\lambda}$ and green and pupple in $0.5{\lambda}$ respectively. When the Al was used as mid reflective layers in $Fe_2O_3/Na_3AlF_6/Fe_2O_3$ system, typical yellow colour and mixed colour between green and pupple were appeared in $0.25{\lambda}$ and $0.5{\lambda}$ of $Na_3AlF_6$ respectively. As compared the experimental result to simulation data, it was found out that the experimental data is relatively well matched with the EMP simulation data.

• Journal of Magnetics
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• v.10 no.3
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• pp.99-102
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• 2005

Modification in exchange bias of a NiFe/FeMn/NiFe trilayer, on introduction of a nonmagnetic Al layer at the top FeMn/NiFe interface, is investigated in multilayers prepared by rf magnetron sputtering. The introduction of Al layer leads to vanishing of bias of the top NiFe layer. But the bias for the bottom NiFe layer increases steadily with increasing Al layer thickness and attains bias (230 Oe) which is greater than that of the trilayer without the Al layer (150 Oe). When the top NiFe layer thickness is varied, exchange bias has highest value at 12 nm thickness for 1 nm thicknes of Al layer. Ion beam etching of the top NiFe layer also leads to an enhancement in bias for the bottom NiFe layer.

• Journal of Powder Materials
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• v.11 no.6 s.47
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• pp.522-527
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• 2004

Nano sized FeAl intermetallic particles were successfully synthesized by plasma arc discharge pro-cess. The synthesized powders shouted core-shell structures with the particle size of 10-20 nm. The core was metallic FeAl and shell was composed of amorphous $AI_{2}O_{3}\;and\;a\;little\;amount\;of\;metallic\;Fe_{3}O_{4}.$ Because of the difference of Fe and Al vapor pressure during synthesis, the Al contents in the nanoparticles depended on the Al contents of master alloy.

• Journal of Powder Materials
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• v.6 no.1
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• pp.56-61
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• 1999

The plastic deformation behaviors for powder extrusion of rapidly soildified Al-Si-Fe alloys at high temperature were investigated. During extrusion of Al-Si-Fe alloys, primary Si and intermetallic compound in matrix are broken finely. Additionally, during extrusion metastable $\delta$ phase($Al_4SiFe_2$) intermetallic compound disappears and the equilibrium $\beta$ phase($Al_5FeSi_2$) is formed. In gereral, it was diffcult to establish optimum process variables for extrusion condition through experimentation, because this was costly and time-consuming. In this paper, in order to overcome these problems, we compared the experimental results to the finite element analysis for extrusion behaviors of rapidly solidified Al-Si-Fe alloys. This ingormation is expected to assist in improving rapidly solidified Al-Si alloys extrusion operations.

• Journal of the Korean institute of surface engineering
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• v.38 no.6
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• pp.241-247
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• 2005

Effects of Al and Cr alloying elements on the corrosion behavior of Fe-Al-Cr alloy system was investigated using potentiodynamic and cyclic potentiodynamic polarization tests(CPPT) in the $H_2SO_4$ and HCI solutions. The corrosion morphologies in Fe-Al-Cr alloy were analysed by utilizing scanning electron microscopy(SEM) and EDX. It was found that the corrosion potential of Fe-20Cr-20Al was highest whereas the critical anodic current density and passive current density were lower than that of the other alloys in 0.1 M $H_2SO_4$ solution. The second anodic peak at 1000 mV disappeared in the case of alloys containing high Al and low Cr contents. Pitting potential increased with increasing Cr content and repassivation potential decreased with decreasing Al content in 0.1 M HCI solution. Fe-Al-Cr alloy containing high Al and Cr contents showed remarkably improved pitting resistance against $Cl^-$ attack from pit morphologies.

• Korean Journal of Metals and Materials
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• v.48 no.7
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• pp.639-643
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• 2010

Nanopowder of FeAl was synthesized by high energy ball milling. Using the pulsed current activated sintering method, a dense nanostuctured FeAl was consolidated within 2 minutes from mechanically synthesized powders of FeAl and horizontally milled powders of Fe+Al. The grain size and hardness of FeAl sintered from horizontally milled Fe+Al powders and high energy ball milled FeAl powder were 150 nm, 50 nm and $466\;kg/mm^2$, $574\;kg/mm^2$, respectively.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.92-98
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• 1996

Al-Fe alloy layers on heated steel sheet were made by Al powder spray for 30 minutes at $700^{\circ}C$, $800^{\circ}C$ and $1000^{\circ}C$, respectively. As a results, for alloy layers formed at $700^{\circ}C$ and $800^{\circ}C$, main phases were brittle phase $FeAl_3 and Fe_2Al_5$, hardnesses were very high (Hv 700~800), corrosion resistances were good and surfaces were smooth, but wear resistances were bad. For alloy layer formed at $1000^{\circ}C$, main phase was ductile phase $Fe_3Al$, hardness was low (Hv 300~400), corrosion and wear resistances were excellent, but surface was rough. Therefore, alloy layers that formed at $700^{\circ}C$ and $800^{\circ}C$ were heat treated at $1000^{\circ}C$ for 10 minutes for the purpose of smooth surface and excellent wear resistance in this study. It was investigated that brittle phase $FeAl_3 and Fe_2Al_5$ of alloy layers fromed by Al powder spray at $700^{\circ}C$ and $800^{\circ}C$ turn into ductile phase $Fe_3Al$ by heat treated at $1000^{\circ}C$ for 10 minutes without changing smooth surface. It was concluded that the alloy layers formed by Al powder spray on heated steel sheet at $700^{\circ}C$ and $800^{\circ}C$ for 30 minutes and heat treated at $1000^{\circ}C$ for 10 minutes were excellent on wear and smooth surface.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.137-143
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• 2006

The effects of Cu and Fe additions on the thermal stability, microstructure and mechanical properties of $Al_{85}-Ni_{8.5}-Mm_{6.5},\;Al_{84}-Ni_{8.5}-Mm_{6.5}Cu_1,\;Al_{84}-Ni_{8.5}-M_{m6.5}Fe_1$ alloys, manufactured by gas atomization, degassing and hot-extrusion were investigated. Gas atomization, with a wide super-cooled liquid region, allowed the alloy powders to exhibit varying microstructure depending primarily on the powder size and composition. Al hotextruded alloys consisted of homogeneously-distributed fine-grained fcc-Al matrix and intermetallic compounds. A substitution of 1 at.% Al by Cu increased the thermal stability of the amorphous phase and produced alloy microstructure with smaller fcc-Al grains. On the other hand, the same substitution of 1 at.% Al by Fe decreased the stability of the amorphous phase and produced larger fcc-Al grains. The formation of intermetallic compounds such as $Al_3Ni,\;Al_{11}Ce_3\;and\;Al_{11}La_3$ was suppressed by the addition of Cu or Fe. Among the three alloys examined, the highest Vickers hardness and compressive strength were obtained for $Al_{84}-Ni_{8.5}-M_{m6.5}Cu_1$ alloy, and related to the finest fcc-Al grain size attained from increased thermal stability with Cu addition.