• 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 Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.631-639
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• 2013

The removal of phosphate from surface water is becoming increasingly vital to prevent problems such as eutrophication, particularly near urban areas. Recent requirements to reduce high concentrations of phosphate rely on physicochemical methods and adsorbents that must be effective even under strict conditions. The phosphate removal efficiencies of two adsorbents, Fe-Mn-Si oxide and Fe-Mn oxide, were investigated and the data used to compare kinetics and isotherm models. The maximum adsorption capacities of the two adsorbents were 47.8 and 35.5 mg-$PO{_4}^{3-}/g$, respectively. Adsorptions in both cases were highly pH dependent; i.e., when the pH increased from 3 to 9, the average adsorption capacities of the two adsorbents decreased approximately 32.7 % and 20.3 %, respectively. The Freundlich isotherm model fitted the adsorption of Fe-Mn-Si oxide more closely than did the Langmuir model. Additionally, anionic solutions decreased adsorption because of competition with the anions in the adsorbing phosphate. Although affected by the presence of competing anions or a humic substance, Fe-Mn-Si oxide has better adsorption capacity than Fe-Mn oxide.

• 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.

• 연구논문집
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• s.29
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• pp.163-171
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• 1999

A new titanium alloy system. Ti-xFe-ySi (x,y=0-4 wt%). was designed and characterized with the point at low cost and high strength for casting applications. Fe improved room and elevated temperature mechanical properties owing to solid solution hardening and beta phase stabilization. Si yielded titanium silicides and Si addition over 1 wt% resulted in poor ductility due to coarse silicide chains at prior beta boundaries. The optimum composition was found to be Ti-4Fe-(0.5-1)Si in the viewpoint of tensile strength and ductility which are comparable to the Ti-6Al-4V. The metal-mould reaction was also examined for Ti-xFe and Ti-xSi binary alloy system. The thickness of surface reaction layer w as not affected significantly with Fe content, while it was decreased with Si content. In the Ti-4Si alloy, no reaction layer was found. The depth of surface hardening layer was about $200\mum$ regardless of the mould materials.

• Transactions of Materials Processing
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• v.28 no.3
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• pp.123-129
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• 2019

Hypereutectic Al-Si alloys have been widely utilized for wear-resistant components in the automotive industry. In order to expand the application of Hypereutectic Al-Si alloys, the addition of alloying elements forming a stable precipitate at high temperature is required. Thermally stable inter metallic compounds can be formed through the addition of transition elements such as Fe, Ni to Al alloys. However, the amount of transition element to be added to Al alloys is limited due to their low solid solubility. Also, hypereutectic Al-Si-Fe alloys form coarse primary Si phases and needle-shaped intermetallic compounds during solidification in the general casting processes. In this study, the effects of the destruction of Intermetallic compound and Si phase are investigated via hot extrusion. Both the microstructure and mechanical properties are discussed under different extrusion conditions.

• 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 Korea Foundry Society
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• v.26 no.3
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• pp.123-128
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• 2006

Mechanical and thermal properties of spray-cast hypereutectic Al-20wt.%Si-xwt.%Fe alloys (x=0, 1, 3, 5) were investigated. After the spray-casting, hot extrusion was performed at $400^{\circ}C$. Intermetallic compound (${\beta}-Al_5FeSi$) and primary Si are observed in the spray-cast aluminum alloys. The size of primary Si and intermetallic compound of the spray-aluminum alloys became finer and more uniformly distributed than that of the permanent mold cast ones. Ultimate tensile strength of the spray-cast aluminum alloys increased by increasing Fe contents, but that of the permanent mold cast aluminum alloys decreased by increasing Fe contents possibly due to increased amount of coarse intermatallic compound. The coefficient of thermal expansion (CTEs) of the aluminum alloys became lower with finer primary Si and intermetallic compound, and this is attributed to the increased amount of interfacial area between the aluminum matrix and the phases of finer Si and intermetallic compound.

• Applied Microscopy
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• v.25 no.3
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• pp.90-98
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• 1995

In the Fe-Si system, a mixture of a($Fe_{2}Si_5$) - and ${\epsilon}$(FeSi)-composition powders was sintered and heat-treated subsequently at various temperatures and time to get thermoelectric ${\beta}$-phase($FeSi_2$) compacts. The different transformational sequences depending on the heat treating temperature were found through the investigation into phase transformation and microstructural development. That is, a rapid eutectoid decomposition of ${\alpha}{\to}{\beta}+Si$ occurred together with a accompanying slow reaction between the dispersed Si formed by above decomposition and the preexisted ${\epsilon}$ phase at temperatures below $830^{\circ}C$. The unreacted Si and the micropores formed due to the density change upon the transformation coarsened as heat treating time elapsed. At temperatures above $880^{\circ}C$, however, transformation was proceeded by a peritectoid reaction of ${\alpha}+{\epsilon}{\to}{\beta}$. It took at least 200min. to achieve 90% volume fracion of transformed ${\beta}$ phase, and the growth of micro-pores was also observed in this transformational sequence with prolonged heat treating time.

• Journal of Magnetics
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• v.13 no.4
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• pp.170-172
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• 2008

Fe-6.5% Si alloys have good magnetic properties due to their high electrical resistivity, very low magneto-striction, and low crystalline anisotropy. Despite their strong potential, these alloys have seldom been used in magnetic applications because of the very poor ductility of Si-steel above 3.0 wt% Si [1-4]. It is difficult to achieve compressed Fe-6.5% Si powder cores with excellent properties because of the low density due to poor ductility. In compressed powder cores, high density is essential in order to obtain high magnetization and permeability. In this study, an attempt was made to produce Fe-3%Si powder cores because the Fe-3.0 wt% Si alloys have relatively good magnetic properties and room temperature ductility. Gas atomized Fe-3.0 wt% Si powder was compressed into toroid shape cores. By reducing the Si content to 3.0 wt%, the hysteresis loss could be greatly reduced and thus the total core loss could be minimized. The total core loss is 600 mW/$cm^3$ at 0.1 T and 50 kHz.