• 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.

• 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.

• 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.

• 한국표면공학회지
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• 제45권2호
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• pp.61-69
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• 2012

Alloys of Fe-(5, 10, 15)Al and Fe-(10, 20, 30, 40)Cr were corroded at 700 and $800^{\circ}C$ for 70 hr in either atmospheric air or 1 atm of Ar+$1%SO_2$ gases. In these atmospheres, Fe-5Al and Fe-10Cr alloys displayed poor corrosion resistance. In atmospheric air, Fe-5Al alloys formed oxide nodules, while Fe-10Cr alloys formed thick scales and internal oxides. In Ar+$1%SO_2$ gases, Fe-5Al and Fe-10Cr alloys formed thick, nonadherent bi-layered scales, which grew primarily by the outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions. By contrast, in atmospheric air and Ar+$1%SO_2$ gases, Fe-(10, 15)Al and Fe-(20, 30, 40)Cr alloys displayed good corrosion resistance by forming $Al_2O_3$ and $Cr_2O_3$ layers on the surface, respectively.

• 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.

• 한국표면공학회지
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• 제38권6호
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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.

• 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.

• 한국주조공학회지
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• 제23권2호
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• pp.77-85
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• 2003

Some alloying elements such as Cr, B, Ti and Si were added individually or as a mixture to Fe-30 at.%Al alloys. The alloys were melted using an arc furnace and then heat-treated for homogenization at 1000$^{\circ}C$ for 7 days and followed by rolling at 1000$^{\circ}C$. The alloying elements on rolling characteristics were investigated by the microstructures and fracture mode before and after rolling. The microstructures before rolling showed that all of the alloys had equiaxed grains. On the other hand, the microstructures of rolling plane as well as its perpendicular plane became elongated after rolling. The alloys such as Fe-30Al, Fe-30Al-3Ti, Fe-30Al-0.5B, Fe-30Al-5Cr and Fe-30Al-3Ti-0.5B revealed better rolling behaviour from the point that intergranular and cleavage fractures were not fundamentally occurred. But the addition of 5Ti or 3Si to Fe-Al alloys had detrimental effects. The Ti-added alloy system such as Fe-30Al-5Ti, Fe-30Al-5Ti-5Cr, Fe-30Al-3Ti-5Cr and Fe-30Al-5Ti-0.5B were cracked through grain and showed cleavage fracture. The Si-added alloy system such as Fe-30Al-5Si, Fe-27Al-3Si and Fe-27Al-5Cr-3Si were cracked along the grain boundary and showed intergranular fracture. $DO_3{\leftrightarrow}B_2$ transition temperature of Fe-30at.%Al alloy was 520$^{\circ}C$, whereas the addition of 3Ti and 3Ti+0.5B comparably increased the temperature to 797 and 773$^{\circ}C$, respectively.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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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.

• 한국자기학회지
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• 제8권6호
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• pp.362-368
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• 1998

반강자성 Cr86Al14계 스핀밸브막의 자기특성과 내열 내식성에 대해 연구하엿다. Cr86Al14스핀밸브막의 자기적성질은 강자성층, 자성층 및 비자성층두께에 의존하였으며, glass/Cr86Al14(600$\AA$)/Ni81Fe19(50$\AA$)/Cu(40$\AA$)/Ni81Fe19(40$\AA$)구조에서의 교환결합자장(Hex)은 20 Oe, 자기저항비(MR ratio (%))는 2%를 나타내었다. Cr96Al14 및 Fe50Mn50 스핀밸브막은 annealing온도가 증가함에 따라 모두 Hex 및 MR비가 감소하는 경향을 나타내엇으나 FeMn막에 비해 CrAl막이 우수하여, FeMn막은 15$0^{\circ}C$, CrAl막은 25$0^{\circ}C$에서 Hex 및 MR비값을 상실하였다. 또한 가혹한 환경에서의 스핀밸브막의 부식저항성을 평가하고자 35$^{\circ}C$,90% 습도상태의 챔버내에서 Hex와 MR비값의 변화를 관찰한 결과 CrAl막의 경우에는 Hex 및 MR비 값이 시간이 경과해는 변화지 않았으나, FeMn막은 15일정도 경과하자 거의 상실하는 결과를 나타냈다. SEM관찰결과 FeMn막은 pitting이 나타났으며 15일정도 경과후에는 박리가 발생하였다.