• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.419-428
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• 1994

The microvickers hardness and microstructure of Fe/Al composite fabricated by squeeze casting method were investigated. Pure Al and A356 Alloy were chosen for the matrix composition and Fe preform was fabricated with sintered Fe powder at $1000^{\circ}C$ for 30min. under hydrogen atmosphere. Experimental variables were included preheating temperature, melt temperature and applied pressure. Analysing the experimental result concerning microstructure of fabricated composites, Fe/A356 composite showed improved microstructure at $600^{\circ}C$ melt temperature and $350^{\circ}C$ preform preheating temperature in Fe distribution and Infiltrated distance. The results of EDX and XRD showed that the interfacial zones of Fe/Al composite were composed of non-equilibrium intermetallic layers[$(Al_5Fe_2)_x$, $Al_{13}Fe_4m\;Fe_3Al$, FeAl]. The microvickers hardness of Fe/Al composite showed higher value than Fe/A356 composite in interface.

• Korean Journal of Materials Research
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• v.16 no.8
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• pp.473-478
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• 2006

The coherent interface energies and misfit strain energies of Fe/XN (X=Ti, Zr, Hf) systems were calculated by first principles method. The interface energies in Fe/TiN, Fe/ZrN and Fe/HfN systems were 0.343, 0.114, and 0.030 $J/m^2$, respectively. Influence of bond energy was estimated using the discrete lattice plane/nearest neighbor broken bond(DLP/NNBB) model. It was found that the dependence of interface energy on the type of nitride was closely related to changes of the bond energies between Fe, X and N atoms before and after formation of the Fe/XN interfaces. The misfit strain energies in Fe/TiN, Fe/ZrN, and Fe/HfN systems were 0.239, 1.229, and 0.955 eV per 16 atoms(Fe; 8 atoms and XN; 8 atoms). More misfit strain energy was generated as the difference of lattice parameters between the bulk Fe and the bulk XNs increased.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.566-576
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• 2005

This paper describes an ab Initio study on interface energies, misfit strain energies, and electron structures at coherent interfaces Fe(bcc structure)/MCs(NaCl structure M=Ti, Zr, Hf). The interface energies at relaxed interfaces Fe/TiC, Fe/ZrC and Fe/HfC were 0.263, 0.153 and $0.271 J/m^2$, respectively. It was understood that the dependence of interface energy on the type of carbide was closely related to changes of the binding energies between Fe, M and C atoms before and after formation of the interfaces Fe/MCs with the help of the DLP/NNBB (Discrete Lattice Plane/ Nearest Neighbour Broken Bond) model and data of the electron structures. The misfit strain energies in Fe/TiC, Fe/ZrC and Fe/HfC systems were 0.390, 1.692 and 1.408 eV per 16 atoms(Fe: 8 atoms and MC; 8 atoms). More misfit energy was generated as difference of lattice parameters between the bulk Fe and the bulk MCs increased.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.2
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• pp.9-18
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• 1991

Among the many maunfactured processes of producing multi filamentary composites, in situ process is widely used owing tv its simplicity and easyness of mass production. In this study, the mechanical and electromagnetic properties of Cu-Fe composite materials was investigated. The tensile strength of the Cu-Fe wires increased as the Fe content and reduction ratio were increased. The Cu-30 wt%Fe composites had the best properties in terms of figure merits compared to the other Cu-Fe composites made in this study or the commercially manufactured 6/1 ACSR cables of Cu cable. The coercivity was decreased by increasing Fe content, but the squareness was increased greatly. As increasing reduction ratio, the coercivity and squareness increased up to the maximum points, and then decreased. For example, the maximum values were obtained at $0.09mm{\phi}$ for Cu-30 wt%Fe composites and at $0.066mm{\phi}$ for Cu-45 wt%Fe composites. The magnetic property of Cu-Fe wires produced by precipitation treatment was higher than that of Cu-Fe wires produced by thermomechanical treatment. By annealing Cu-Fe wires after drawing process, the coercivity, remanence and squareness were improved.

• Journal of Powder Materials
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• v.29 no.4
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• pp.325-331
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• 2022

Beta-titanium alloys are used in many industries due to their increased elongation resulting from their BCC structure and low modulus of elasticity. However, there are many limitations to their use due to the high cost of beta-stabilizer elements. In this study, biocompatible Ti-Mo-Fe beta titanium alloys are designed by replacing costly beta-stabilizer elements (e.g., Nb, Zr, or Ta) with inexpensive Mo and Fe elements. Additionally, Ti-Mo-Fe alloys designed with different Fe contents are fabricated using powder metallurgy. Fe is a strong, biocompatible beta-stabilizer element and a low-cost alloying element. The mechanical properties of the Ti-Mo-Fe metastable beta titanium alloys are analyzed in relation to the microstructural changes. When the Fe content increases, the tensile strength and elongation decrease due to brittle fracture despite a decreasing pore fraction. It is confirmed that the hardness and tensile strength of Ti-5Mo-2Fe P/M improve to more than 360 Hv and 900 MPa, respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.57-63
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• 2012

$Al_2TiO_5$ ceramics were sintered by a solid-state reaction. LAS (${\beta}$-spodumene) and $Fe_2O_3$ were added to the $Al_2TiO_5$ composition for enhancement of sintering behavior such as mechanical strength and thermal shock resistance. The sintered body was much densified by addition of LAS and $Fe_2O_3$ because LAS formed the liquid-phase and $Fe_2O_3$ suppressed the grain growth. We have systematically investigated the sintering characteristics, microstructures, mechanical properties, and thermal shock resistance according to the change of the amount of additive. When the additive of LAS (20 wt%)-$Fe_2O_3$ was added to $Al_2TiO_5$, it confirmed that superior mechanical properties of the fracture strength of over 120 MPa and the thermal shock resistance of over $1,200^{\circ}C$ were achieved.

• Journal of Magnetics
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• v.11 no.1
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• pp.25-29
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• 2006

Recent experiments have demonstrated high TMR ratios in MTJs with the MgO barrier [1,2]. The CoFeB/MgO/CoFeB junctions showed better properties than the CoFe/MgO/CoFe junctions because the MgO layer had a good crystalline structure with (001) texture and smooth and sharp interface between CoFeB/MgO [3]. The amorphous CoFeB with 20 at%B starts the crystallization at $340^{\circ}C$ [4] and this crystallization of the CoFeB helps obtaining the high TMR ratio. In this work, the compositional changes in the MgO barrier and at the interface of CoFeB/MgO/CoFeB after the CoFeB crystallization were studied in annealed MTJs. XPS depth profiles were utilized. TEM analyses showed that the MgO barrier had (100) texture on CoFeB in the junctions. B in the bottom CoFeB layer diffused into the MgO barrier and B-oxide was formed at the interface of CoFeB/MgO/CoFeB after the CoFeB crystallization.

• Clean Technology
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• v.18 no.1
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• pp.89-94
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• 2012

In this study, we investigated the activity of Pd and Pt supported on acidic Fe-ZSM5 supports for selective catalytic oxidation of ammonia ($NH_3$-SCO). Among the catalysts, Pt/Fe-ZSM5 catalyst exhibited superior $NH_3$-SCO activity to Pd/Fe-ZSM5 catalyst. We also tested Pt/Fe-ZSM5 catalysts with different Fe loading using ion-exchange method to prepare Fe-ZSM5 supports, which resulted in the increased catalytic performance with smaller Fe content: $NH_3$ was oxidized completely at low temperature ($250^{\circ}C$). The physicochemical properties of Fe-ZSM5 were investigated to figure out the relationship between the characteristics of the catalysts and the catalytic activity on $NH_3$-SCO by Inductively coupled plasma-atomic emissions spectrometer (ICP-AES), $N_2$ sorption, X-ray diffraction (XRD), temperature programmed desorption of $NH_3$ ($NH_3$-TPD) technique.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.974-977
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• 1999

PSN-PT 2성분계 압전세라믹스의 상도로부터 유전적, 압전적 특성이 양호한 MPB (Morphotropic phase boundary)부근의 조성을 선택하여 도너 도펀트인 $Nb_{2}O_{5}$와 억셉터 도펀트인 $Fe_{2}O_{3}$를 각각 $0{\sim}0.9wt%$ 첨가하여 유전 및 압전특성을 비교, 연구해보았다. 시편모두 $1250^{\circ}C$ 이상에서 이론밀도의 96%이상의 값을 얻을 수 있었고 상온, 1kHz에서 $Fe_{2}O_{3}$의 경우 0.1wt% 첨가된 시편에서 ${\varepsilon}_r$=2054의 최대 비유전율이 나타났으며, 0.7wt% 첨가된 시편에서는 $tan{\delta}$=0.49%의 최소 유전 손실값을 얻었다. $Fe_{2}O_{3}$가 0.1wt%, 0.3wt%로 첨가되었을 때 각각 $K_p$=58%, Qm=222의 값을 얻을 수 있었다.

• Journal of Magnetics
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• v.21 no.1
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.