• 한국재료학회지
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• 제11권1호
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• pp.34-38
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• 2001

Fe-28%Al($Fe_3Al$)과 Fe-28%Al-4%Cr($Fe_3Al-4Cr$) 금속간화합물을 대기중 1073, 1273, 1473k의 온도에서 최고 17일까지 장시간 산화시켰다. $Fe_3Al-4Cr$의 산화저항은 근본적으로 $Fe_3Al$과 거의 비슷하거나, 약간 우수하였다. $Fe_3Al$ 위에 형성된 산화물은 거의 순수한 ${\alpha}-AL_2O_3$로만 구성되어 있었으며, $Fe_3Al-4Cr$ 위에 형성된 산화물은 약간의 Fe와 Cr 이온이 고용된 ${\alpha}-AL_2O_3$로 구성되어 있었다. 외부산화막을 형성하기 위해 모재원소의 외부확산에 의해 산화물-모재 계면에는 Kirkendall 기공이 존재하였다. $Fe_3Al(-4Cr)$ 표면에 형성된 산화막은 1273k가지는 비교적 얇고 치밀하였으나, 1473k에서 산화막의 박리와 함께 상대적으로 큰 무게증가가 발생하였다.

• 한국분말재료학회지
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• 제12권1호
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• pp.43-50
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• 2005

Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to Al-Fe-Cr and Al-Fe-Mo powder mixture to investigate effects of Cr and Mo addition on thermal stability of Al-Fe, and thereby to enhance its thermal stability up to $500^{\circC}$. Various analytical techniques including micro-Vickers hardness test, SEM, TEM, X-ray diffractometry and corrosion test were carried out. It was found that addition of Cr and Mo to Al-Fe system played a role of grain growth inhibitor of matrix Al and some precipitates such as $Al_3Fe$ during SPS and subsequent heat treatment. The inhibition of grain growth resulted in increased Vickers hardness and thermal stability up to $500^{\circC}$ comparing to those of Al-Fe alloy system.

• 한국재료학회지
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• 제12권11호
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• pp.845-849
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• 2002

Alloys of $Fe_3$Al, $Fe_3$Al-6Cr, $Fe_3$Al-4Cr-1Mo, $Ni_3$Al, and $Ni_3$Al-2.8Cr were oxidized at $1000^{\circ}C$ in air, and the oxide scales formed were studied using XRD. SEM, EPMA, and TEM. The oxide scales that formed on $Fe_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$ containing a small amount of dissolved Fe and Cr ions, whereas those that formed on $Ni_3$Al-based alloys consisted primarily of $\alpha$-$Al_2$$O_3$, together with a small amount of $NiAl_2$$O_4$, NiO and dissolved Cr ions. For the entire alloys tested, nonadherent oxide scales formed, and voids were inevitably existed at the scale-matrix interface.

• Corrosion Science and Technology
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• 제3권3호
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• pp.98-101
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• 2004

The corrosion behavior of Al-Fe coatings was studied in the wet-seal atmosphere of molten carbonate fuel cells (MCFC). Fe-8Al, Fe-16Al, Fe-25Al, Fe-36Al, and Fe-70Al (in at.%) specimens were tested in Li/K carbonate at $650^{\circ}C$ by a single cell test and an immersion test. In general, the corrosion resistance of the Al-Fe coatings was enhanced due to the formation of a protective $LiAlO_2$ layer. However, when the Al-Fe coatings didn't have sufficient content of aluminum enough for maintaining the protective layer, the corrosion resistance of the Al-Fe coatings was severely degraded by the growth of non-protective scales like $LiAlO_2$. The test results revealed that the aluminum contents in the coatings should be higher than 25 at.% in order to form and maintain the protective $LiAlO_2$ layers.

• 한국주조공학회지
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• 제8권4호
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• pp.446-452
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• 1988

To obtain detailed information on the metastable and the equilibrium phases in rapidly solidified Al-(Fe,Ce) alloys, analysis of X-ray diffraction pattern has been carried out. It has been found that the metastable phase formed in Al-Fe alloys including up to 6wt%Fe is $Al_6Fe$ and the equilibrium phase is $Al_3Fe$. Any X-ray diffraction peak corresponding to the equilibrium phase $Al_{13}Fe_4$ has not been observed during aging. In Al-4wt%Fe alloy, which is ribbon shape with thickness less than $70\;{\mu}m$, aged at $400^{\circ}C$ for 1h after rapid solidification, unidentified phase has been found. In Al-4wt%Ce alloy, only X-ray diffraction peak corresponding to the equilibrium phase, $Al_4Ce$ has been observed. It has been found that the metastable phase Formed in Al-Fe-Ce alloys including up to 6wt% Fe and 4wt% Ce is $Al_6Fe$ and the equilibrium phases are $Al_3Fe$ and $Al_{10}CeFe_2$.

• 한국결정성장학회지
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• 제9권2호
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• pp.185-190
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• 1999

$Al_2O_3/Fe$ 복합재료 제조는 반응소결법에 의한 2단계 공정을 통해서 제조되었으며 이 공정은 장비가 간단하고 near-net-shape이 가능한 장점이 있다.$Al_2O_3/Fe$ 복합재료를 제조하기 위해서 1차로 $650^{\circ}C$에서 5시간동안 산화/환원 처리를 행하고 $1200^{\circ}C$에서 2차로 소결처리를 행하였다. 제조된 복합재료의 상분석결과 $\alpha$-Fe 와 $\alpha$-$Al_2O_3/Fe$가 주된 상이었고 소량의 $FeAl_2O_4$가 검출되었다. 이 소량의 $FeAl_2O_4$상은 Fe가 $Al_2O_4$기공을 채우는 것을 방해함으로써 소결동안 미세구조 내에 약간의 기공을 발생시킨다.

• 한국주조공학회지
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• 제19권1호
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• pp.71-76
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• 1999

Eutectic and off-eutectic Al-Fe alloys were unidirectionally solidified at the solidification rate of $1{\sim}50\;mm/min$ under the temperature gradients $75{\sim}80^{\circ}C/cm$. The investigation has been carried out for the microstructural variation, phase transition, mechanical properties by means of detailed analyses of stress-strain, micro-Vickers hardness and scanning electron micrography. The thermal stability at elevated temperature has been studied on $Al-Al_6Fe$ eutectic alloy held at $600^{\circ}C$ for $0{\sim}150$ hours. When the solidification rate was less than 10mm/min, the X-ray diffraction and EDS analysis showed the presence of $Al_3Fe$ compound. As the solidification rate more than 20 mm/min, $Al-Al_3Fe$ eutectic phase was transfered into $Al-Al_6Fe$ eutectic phase. The mechanical properties of unidirectionally solidified off-eutectic Al-Fe alloy is better than those of unidirectionally solidified eutecic Al-Fe alloy Maximum ultimate tensile strength was obtained in Al-2.25% Fe alloy which was unidirectionally solidified at the solidification rate of 20 mm/min. The metastable $Al-Al_6Fe$ phase was transferred into stable $Al-Al_3Fe$ phase at $600^{\circ}C$ held for 150 hours.

• 한국주조공학회지
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• 제33권3호
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• pp.103-112
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• 2013

Effect of Fe and Mn contents on the tensile properties of Al-4 wt%Mg-0.9 wt%Si alloy system has been studied. Common phases of Al-4 wt%Mg-0.9 wt%Si alloy system were ${\alpha}$-Al, $Mg_2Si$, ${\alpha}-Al_{12}(Fe,Mn)_3Si$ and ${\beta}-Al_5FeSi$. As Fe content of Al-4 wt%Mg-0.9 wt%Si alloy system increased from 0.15 wt% to above 0.3 wt%, ${\beta}-Al_5FeSi$ compound appeared. When Mn content of the alloy increased from 0.3 wt% to 0.5 wt%, morphology of plate shaped ${\beta}-Al_5FeSi$ compound changed to chinese script ${\alpha}-Al_{12}(Fe,Mn)_3Si$. As Fe content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Mn alloy increased from 0.15 wt% to 0.4 wt%, tensile strength of the as-cast alloy decreased from 191 MPa to 183 MPa and, elongation of the alloy also decreased from 8.0% to 6.2%. Decrease of these properties can be explained as the formation of plate shape, ${\beta}-Al_5FeSi$ phase with low Mn/Fe ratio of the alloy. However, when Mn content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Fe alloy increased from 0.3 wt% to 0.5 wt%, tensile strength of as-cast alloy increased from 181 MPa to 194 MPa and, elongation of the alloy increased from 6.8% to 7.0%. These improvements attribute to the morphology change from ${\beta}-Al_5FeSi$ phase to chinese script, ${\alpha}-Al_{15}(Fe,Mn)_3Si_2$ phase shape-modified from with high Mn/Fe ratio of the alloy.

• 한국주조공학회지
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• 제25권3호
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• pp.128-133
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• 2005

The effects of Mn and Cr on the crystallization behaviors of Fe-bearing intennetallics in A356 alloy were studied. Coarse and acicular ${\beta}-Al_{5}$FeSi phase in A356-0.20wt.%Fe alloy was modified into small ${\alpha}$-Al(Fe,Mn)Si and ${\alpha}$-Al(Fe,Cr)Si phases in response to Mn and Cr addition, respectively. Increasing of Mn addition amount elevates the crystallizing temperature of ${\alpha}$-Al(Fe,Mn)Si and the Mn/Fe ratio in the ${\alpha}$-Al(Fe,Mn)Si. Cr is more effective to modify ${\beta}-Al_{5}$FeSi in comparison with Mn. ${\alpha}$-Al(Fe,Mn)Si phase had BCC/SC dual structure.

• 대한금속재료학회지
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• 제48권11호
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• pp.981-988
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• 2010

The effects of Cr and Al contents in Fe-Al and Fe-Cr alloys on oxidation resistance, hardness, and the thermal expansion coefficient were investigated. Fe-Al and Fe-Cr alloys above 10wt.%Al and 20wt.%Cr contents have a high oxidation resistance. The hardness of the Fe-Al and Fe-Cr alloys increased with an increase in Al and Cr contents due to solid solution or formation of an intermetallic compound. The coefficients of thermal expansion of the Fe-Al alloys were higher than those of the Fe-Cr alloys because the coefficient of thermal expansion of Al was higher than that of Fe and Cr.