• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1102-1107
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• 1999

FeAl matrix composite was fabricated successfully by hot-pressing. The mechanical properties of FeAl alloys have been widely studies, but their behaviors of surface hardening effect by plasma nitriding has not yet been studied. This study was to analysis the relationship between microstructure of the sintered composite by hot-pressing and surface hardening at plasma nitriding treatment. Surface hardening of FeAl base alloys was improved by plasma nitriding with increasing plasma treatment time. Excellent surface hardness in the FeAl alloys could be obtained by plasma nitriding($\textrm{H}_{\textrm{v}}$ 100gf, diffusion layer: 1100~1450kg/$\textrm{mm}^2$, matrix : 330~360kg/$\textrm{mm}^2$). Diffusion layer size increased with increasing plasma nitriding times and decreased with increasing Sic, content.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.34-39
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• 2018

Steel crucible used for molten Al has a problem of very limited lifetime because of the interaction between Fe and molten Al. This study was performed to improve the lifetime of steel crucible for molten Al by coating metallic Al and by further anodizing treatment to form thick and uniform anodic oxide films. The lifetime of the steel crucible was improved slightly by Al coating from 30 to 40 hours by metallic Al coating and largely to 120 hours by coating the surface with anodic oxide film. The improved lifetime was attributed to blocking of the reaction between Fe and molten Al with the help of anodic oxide layer with more than 20 um thickness on the crucible surface. The failure of the steel crucible arises from the formation of intermetallic compounds and pores at the steel/Al interface.

• Corrosion Science and Technology
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• v.11 no.1
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• pp.9-14
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• 2012

The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at $800^{\circ}C$ for 60 s in $N_{2}$-10% $H_{2}$ atmosphere with a dew point of $-30^{\circ}C$, and were then galvanized in a bath containing 0.2 %Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only $Fe_{2}Al_{5}$ intermetallic phase was formed. No orientation relationship between the $Fe_{2}Al_{5}$ phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from $Al^{3+}$ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of $Fe_{2}Al_{5}$ and $Al_{2}O_{3}$. TEM/EDS analysis verifies the existence of $Al_{2}O_{3}$ in the boundaries of $Fe_{2}Al_{5}$ grains. The nucleation of $Fe_{2}Al_{5}$ and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of $Fe_{2}Al_{5}$.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.240-245
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• 1998

In the view point of the environmental conservation and the energy reduction, the recycling of metal scrap is coming as one of the global subjects in the world. In this study, the movement of intermetallics with electromagnetic force in a melt of a scrap of Al-Si-Cu alloy (JIS ADC12), which was widely used in diecasting process, was investigated in order to eliminate the Fe element, which was usually accumulated in a scrap. In this study, we applied electromagnetic method to eliminate Fe element in ADC12 aluminum alloy scrap which contains 1.64wt.% Fe and the effects of electromagnetic force on the particle movement was visualized and confirmed by water modeling and experiment. As a result, the Fe intermetallic compounds are moved to the direction opposite to that of the electromagnetic force as the force applies, thus eliminated from the bulk metal. Therefore, the content of Fe in matrix decreased from 1.64wt.% to 0.45wt.%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.180-183
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• 1999

It is well known that Fe3Al intermetallic compound shows an anomalous peak of the yield strength at about 50$0^{\circ}C$ and then decrease at higher temperatures The dislocation structure was examined by transmission electron microscopy and high temperatures. The dislocation structure was examined by transmission electron microscopy and high temperature mechanical properties were examined by tensile and load relaxation tests. The flow stress curves obtained from load relaxation tests were then analyzed in terms of internal variable deformation theory. it was found that the flow curves consisted of three micro-deformation mechanisms -i. e inelastic deformation mode plastic deformation mode and dislocation creep deformation mode depending on both dislocation structure and deformation temperature. The flow curves could be well described by the constitutive equations of these three micro-deformation mechanisms based on the internal variable deformation theory.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.216-216
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• 2015

용융아연 도금 공정에서 강판이 도금욕에 침적되는 동안 강판으로부터 용출되는 Fe는 도금욕 내 Al, Zn와 반응하여 다양한 형태의 드로스를 형성시키는 원인이 된다. 이들 드로스는 강판 표면에 다양한 형태의 결함을 야기하므로, 실제 도금 공정에서 도금욕 내 발생하는 드로스의 생성거동에 관한 이해는 필수적이다. 따라서 본 연구에서는 도금욕 내 $Fe_xAl_yZn_z$계 드로스 생성에 미치는 도금욕 내 Al 및 Fe 함량의 영향에 대해 고찰하였으며, in-situ sampling 기법 및 finger rotating method를 이용하였다.

• Journal of Korea Foundry Society
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• v.21 no.1
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• pp.24-32
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• 2001

Recently, iron aluminides based on Fe3Al and FeAl are ordered intermetallic alloys that offer good oxidation resistance, excellent sulfidation resistance, and potentially lower cost than many high-temperature structural materials. They have better strength, elasticity to weight ratio and high temperature strength, therefore, they can be cosidered as candidate heat resistance structural materials for automobiles, ships, airplanes and spaceships applications. The changes in the mechanical properties and fracture behavior were investigated for Fe-30at.%Al-5at.%Cr alloys when Ti, Hf and Zr were added respectively. For mechanical properties such as Rockwell hardness and yield strength at room temperature, those were decreased in the case of Fe-30at.%Al-5at.%Cr alloy then increased in the case of 5at.% and 10at.% addition of Ti alone. However, Rockwell hardness and yield strength decreased again at 15%Ti then increased dramatically due to the precipitation hardening of the second phase on the specimen at 20%Ti. For fracture modes, cleavage fracture showed in the case of Fe-30at.%Al and Fe-30at.%Al-5at.%Cr alloys. As the amount of Ti addition changed cleavage to transgranular fracture and to quasi-cleavage fracture at 20%Ti. When Hf, Zr and Hf+Zr were added respectively, transgranular, cleavage and quasi-cleavage fracture were coexisted.

• Journal of Korea Foundry Society
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• v.29 no.4
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• pp.169-175
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• 2009

Effect of iron and manganese contents on die soldering reaction has been studied in Al-9wt.%Si-0.3wt.%Mg alloy. Ternary ${\alpha}_{hcp}-Al_8Fe_2Si$ and ${\alpha}_{bcc}-Al_8Fe_2Si$ intermetallic compounds formed by interaction diffusion between Al-Si-Mg system alloy melt and SKD61 die steel surface. Thickness of soldering reaction layer in die steel surface decreased as Fe and Mn contents of the melts increased : When Fe content of Al-9wt.%Si-0.3wt.%Mg melts at constant 0.5wt%Mn content was 0.15wt.%, 0.45wt.% and 0.6wt.%, thickness of soldered layer of each alloy was $64.5{\mu}m,\;57.3{\mu}m$ and $46.9{\mu}m$ respectively. For Mn content of the alloy melts at constant 0.45wt.%Fe content was 0.30wt.%, 0.50wt.% and 0.70wt.%, thickness of soldered layer of each alloy was $66.1{\mu}m,\;57.3{\mu}m$ and $48.3{\mu}m$ respectively.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.61-68
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• 2005

Dissimilar joining of Al 6013-T4 alloys and austenite stainless steel was carried out using friction stir welding technique. Microstructures near the weld zone and mechanical properties of the joint have been investigated. Microstructures in the stainless steel side were composed of the heat affected zone and the plastically deformed zone, while those in the Al alloy side were composed of the recrystallized zone including stainless steel particles, the thermo-mechanically affected zone and the heat affected zone. TEM micrographs revealed that the interface region was composed of the mixed layers of elongated stainless steel and ultra-fine grained Al alloy with lamella structure and intermetallic compound layer. Thickness of the intermetallic layer was approximately 300nm and was identified as the A14Fe with hexagonal close packed structure. Mechanical properties, such as tensile and fatigue strengths were lower than those of 6013 Al alloy base metal, because tool inserting location was deviated to Al alloy from the butt line, which resulted in the lack of the stirring.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4062-4071
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• 2022

Long-term aluminum (Al) corrosion tests were designed to investigate the condition that would generate severe Al corrosion and precipitation. Buffer agents of sodium tetraborate (NaTB), trisodium phosphate (TSP) and sodium hydroxide (NaOH) were adopted. The insulation materials, fiberglass and calcium silicate (Ca-sil), were examined to explore their effects on Al corrosion. The results show that significant precipitates were formed in both NaTB/TSP-buffered solutions at high pH. The precipitates formed in NaTB solution raise more concerns on chemical effects in GSI-191. A passivation layer formed on the surfaces of coupon in solution with the presence of insulations could effectively mitigate Al corrosion. The Fe-enriched intermetallic particles (IPs) embedded in coupon appeared to serve as seeds to readily induce precipitation via providing extra area for heterogeneous Al hydroxide precipitation. X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses indicate that the precipitates are mainly boehmite (γ-AlOOH) and no direct evidence confirms the presence of sodium aluminum silicate or calcium phosphate.