• 제목/요약/키워드: Fe-FeS alloys

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Fe-(8.5~36.9) wt% Cr합금의 600~800℃, (N2,H2S,수증기)-혼합 가스분위기에서의 부식 (Corrosion of Fe-(8.5~36.9) wt% Cr Alloys at 600~800℃ in (N2, H2S, H2O)-Mixed Gases)

  • 김민정;이동복
    • 대한금속재료학회지
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    • 제50권3호
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    • pp.218-223
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    • 2012
  • Fe-(8.5, 18.5, 28.3, 36.9) wt% Cr alloys were corroded between 600 and $800^{\circ}C$ for up to 70 h in a 1 atm gas mixture that consisted of 0.0242 atm of $H_2S$, 0.031 atm of water vapor, and 0.9448 atm of nitrogen gas. Their corrosion resistance increased with an increment in the Cr content. The Fe-8.5%Cr alloy corroded fast, forming thick, fragile, nonadherent scales that consisted primarily of an outer FeS layer and an inner (Fe, Cr, O, S)-mixed layer. The outer FeS layer grew into the air by the outward diffusion of $Fe^{2+}$ ions, whereas the inner mixed layer grew by the inward diffusion of oxygen and sulfur ions. At the interface of the outer and inner scales, voids developed and cracking occurred. The Fe-(18.5, 28.3, 36.9)% Cr alloys displayed much better corrosion resistance than the Fe-8.5Cr alloy, because thin $Cr_2O_3$ or $Cr_2S_3$ scales formed.

Fe-XAl-0.3Y 합금의 고온 황화환경(Ps2=10-3Pa)에서의 부식거동 (Corrosion Behaviour of Fe-XAl-0.3Y Alloys at High Temperature Sulfidation Environment(Ps2=10-3Pa))

  • 이병우;박화순
    • 한국재료학회지
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    • 제14권8호
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    • pp.547-551
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    • 2004
  • The sulfidation behaviour of Fe-XAl-0.3Y(X=5, 10, 14, 25 $wt.\%$) alloys was investigated at 1123 K in $H_2/H_{2}S$ gas atmosphere for $1\sim24$ hrs using SEM/EDX, XRD and EPMA. The weight changes of Fe-XAl-0.3Y alloys followed the parabolic rate law, Sulfidation rates of iron aluminide alloys with high Al content were one-twentieth lower than that of 5Al alloys. This is due to the formation of protective $Al_{2}O_3$ oxides on the surface of 10Al, 14Al and 25Al alloys. By calculating partial pressure of impurity oxygen contained $H_2/H_{2}S$ gas, the $Al_{2}O_3$ oxides formation could be explained using Fe-Al-S-O thermodynamic stability diagram. The sulfidation product scales of the 5Al alloy showed that thick iron sulfide scale(FeS) containing porosities formed during early stages of sulfidation. With continued sulfidation, aluminum sulfide was formed at the alloy/scale interface.

Fe가 첨가된 과공정 Al-Si-Fe합금 압출재의 기계적특성 및 미세조직에 관한 연구 (Effect of Fe Addition on Mechanical Properties and Microstructure of As-Extruded Hypereutectic Al-Si-Fe Alloy)

  • 이세동;김덕현;백아름;임수근
    • 소성∙가공
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    • 제28권3호
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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.

The Annealing Effect on Magnetocaloric Properties of Fe91-xYxZr9 Alloys

  • Kim, K.S.;Min, S.G.;Zidanic, J.;Yu, S.C.
    • Journal of Magnetics
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    • 제12권4호
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    • pp.133-136
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    • 2007
  • We have carried out the study of magnetocaloric effect for as-quenched and annealed $Fe_{91-x}Y_xZr_9$ alloys. Samples were prepared by arc melting the high-purity elemental constituents under argon gas atmosphere and by single roller melt spinning. These alloys were annealed one hour at 773 K in vacuum chamber. The magnetization behaviours of the samples were measured by vibrating sample magnetometer. The Curie temperature increases with increasing Y concentration (x=0 to 8). Temperature dependence of the entropy variation ${\Delta}S_M$ was found to appear in the vicinity of the Curie temperature. The results show that annealed $Fe_{86}Y_5Zr_9$ and $Fe_{83}Y_8Zr_9$ alloys a bigger magnetocaloric effect than that those in as-quenched alloys. The value is 1.23 J/kg K for annealed $Fe_{86}Y_5Zr_9$ alloy and 0.89 J/kg K for as-quenched alloy, respectively. In addition, the values of ${\Delta}S_M$ for $Fe_{83}Y_8Zr_9$ alloy is 0.72 J/Kg K for as-quenched and 1.09 J/Kg K for annealed alloy, respectively.

Fe-Mn 합금의 γ→ε 마르텐사이트변태에 필요한 구동력 (Driving Forces for γ→ε Martensitic Transformation of Fe-Mn Alloys)

  • 이영국;최종술
    • 열처리공학회지
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    • 제9권4호
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    • pp.243-251
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    • 1996
  • Dilatometric experiment and thermodynamic calculation have been performed to determine $M_s$, $A_s$ and driving forces for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation of Fe-Mn alloys. The transformation temperatures($M_s$, $A_s$, $T_o) were decreased with increasing manganese content and were newly formulated as a function of manganese content. Driving force for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation was increased from -75J/mole to -105J/mole with increasing manganese content from 15wt.% to 25wt.%. Transformation temperature hysteresis($A_s-M_s$) was also increased from 50K to 80K with increasing mangenese content from 15wt.% to 25wt.%. The small driving force(-75J/mole~-105J/mole) and small ${\Delta}T$(50K~80K) for ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation indicated that Fe-Mn alloys behave like thermoelastic martensitic alloys : We would like to call them semi-thermoelastic martensitic alloys.

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Spontaneous Hall Effect in Amorphous Tb-Fe and Sm-Fe Thin films

  • Kim, T. W.;S. H. Lim;R. J. Gambino
    • 한국자기학회:학술대회 개요집
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    • 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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    • pp.337-345
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    • 2000
  • The spontaneous Hall effect in amorphous Tb-Fe and Sm-Fe thin films, which possess excellent magnetic softness, is investigated in this work to seek a possibility of practical applications of these thin films as sensors. The resistivity of Tb-Fe thin films ranges from 180 to 250 Ωcm as the Tb content varies from 35 to 46 at. %. Tb-Fe thin films show negative Hall resistivity ranging from - 7.3 to - 5.0 Ωcm in the same composition range, giving the normalized resistivity ratio in the range of -4.1 to -2.0 %. On the other hand, the resistivity of Sm-Fe thin films ranges from 150 to 166 Ωcm as the Sm content varies from 22 to 31 at. %. Sm-Fe thin films show positive Hall resistivity which varies from 7.1 to 2.8 Ωcm in the same composition range, giving the normalized resistivity ratio in the range of 4.8 to 1.7 %. These values are significantly high compared with the values of other R-T alloys, Tb-Co alloys for example, where the highest reported value is 2.5 %. Between the two different sets of samples, Tb-Fe thin films with perpendicular anisotropy are considered to be more suitable for practical applications, since saturation is reached at a los magnetic field, approximately 2 kOe in a Tb$\sub$35.1/ Fe$\sub$64.9/ thin film, for example.

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Fe-Cr-Mn-X계 합금의 감쇠능 및 플라즈마 이온 질화특성에 미치는 합금원소의 영향 [II플라즈마 이온 질화특성] (The Effect of Alloy Elements on the Damping Capacity and Plasma Ion Nitriding Characteristic of Fe-Cr-Mn-X Alloys. [II Plasma Ion Nitriding Characteristic])

  • 손동욱;이해후;성장현;박규섭;김창규;강창룡
    • 동력기계공학회지
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    • 제9권1호
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    • pp.76-81
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    • 2005
  • The effect of micro-pulse plasma nitriding temperature and time on the case thickness, hardness and nitride formation in the surface of Fe-12Cr-22Mn-X alloy with 3% Co and 1% Ti alloys elements investigated. External compound layer and internal diffusion layer was constituted in plasma nitride case of Fe-12Cr-22Mn-X alloys and formed nitride phase such as ${\gamma}'-Fe4N\;and\;{\varepsilon}-Fe2-3N$. Case depth increased with increasing the plasma nitriding temperature and time. Surface hardness of nitrided Fe-12Cr-22Mn-X alloys obtained the above value of Hv 1,600 and case depth obtained the above value of $45{\mu}m$ in Fe-12Cr-22Mn-3Co alloy and $60{\mu}m$ in Fe-12Cr-22Mn-1Ti alloy. Wear-resistance increased with increasing plasma nitriding time and showing the higher value in Fe-12Cr-22Mn-1Ti alloy than Fe-12Cr-22Mn-3Co alloy.

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Effects of Ni Addition on the Microstructures and Magnetic Properties of Fe70-xPd30Nix High-Temperature Ferromagnetic Shape Memory Alloys

  • Lin, Chien-Feng;Yang, Jin-Bin
    • Journal of Magnetics
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    • 제17권2호
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    • pp.86-95
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    • 2012
  • This study investigated the effects of adding a third alloying element, Ni, to create $Fe_{70-x}Pd_{30}Ni_x$ (x = 2, 4, 6, 8 at.% Ni) ferromagnetic shape memory alloys (FSMAs). The Ni replaced a portion of the Fe. The $Fe_{70-x}Pd_{30}Ni_x$ alloys were homogenized through hot and cold forging to gain a ~38% reduction in thickness, next they were solution-treated (ST) with annealing recrystallization at $1100^{\circ}C$ for 8 h and quenched in ice brine, and then aged at $500^{\circ}C$ for 100 h. Investigation of the microstructures and magnetostriction indicated that the greater Ni amount in the $Fe_{70-x}Pd_{30}Ni_x$ alloys reduced saturation magnetostriction at room temperature (RT). It was also observed that it was more difficult to generate annealed recrystallization. However, with greater Ni addition into the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys, the $L1_0+L1_m$ twin phase decomposition into stoichiometric $L1_0+L1_m+{\alpha}_{bct}$ structures was suppressed after the $500^{\circ}C$/100 h aging treatment. The result was that the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (${\Delta}{\lambda}{_\parallel}{^s}/{\Delta}H$) after the alloys were aged at $500^{\circ}C$ for 100 h. This magnetic property of the $Fe_{70-x}Pd_{30}Ni_x$ (x = 6, 8 at.% Ni) alloys make it suitable for application in a high temperature (T > $500^{\circ}C$) and high frequency environments.

Fe-Cr-Mn-X계 합금의 감쇠능 및 플라즈마이온질화 특성에 미치는 합금원소의 영향 [I 감쇠능] (The Effect of Alloy Elements on the Damping Capacity and Plasma Ion Nitriding Characteristic of Fe-Cr-Mn-X Alloys [I Damping Capacity])

  • 손동욱;정상훈;김재환;이종문;김익수;강창룡
    • 동력기계공학회지
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    • 제9권1호
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    • pp.70-75
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    • 2005
  • The damping property of Fe-12Cr-22Mn-X alloys has been investigated to develop high damping and high strength alloy. Particularly, the effect of the phase of austenite, alpha and epsilon martensite, which constitute the structure of the alloys Fe-12Cr-22Mn-X alloys, on the damping capacity at room temperature has been investigated. Various fraction of these phases were formed depending on the alloy element and cold work degree. The damping capacity is strongly affected by ${\varepsilon}$ martensite while the other phase, such as ${\alpha}'$ martensite, actually exhibit little effect on damping capacity. In case of Fe-12Cr-22Mn-3Co alloy, the large volume fraction of ${\varepsilon}$ martensite formed at about 30% cold rolling, and in case of Fe-12Cr-22Mn-1Ti alloy, formed at about 20% cold rolling and showed the highest damping capacity. Damping capacity showed higher value in Fe-12Cr-22Mn-1Ti alloy than one in Fe-12Cr-22Mn-3Co alloy.

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On the Use of Elemental Powders to Prepare Fe-50Co Alloys by Powder Injection Moulding

  • Silva, A.;Wendhausen, P.A.P.;Machado, R.;Ristow, W.
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.1185-1186
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    • 2006
  • In order to obtain specific magnetic properties, it is of paramount importance to increase the alloy density of components fabricated by powder metallurgy. An alternative to increase the density of alloys such as Fe-49Co-2V would be the use of elemental Fe and Co instead of the pre-alloyed powder. Trying to give some insight on the industrial application of this strategy, this paper investigates the replacement of more conventional pre-alloyed Fe-49Co-2V powders with elemental Fe and Co. A previous analysis shows that it is possible to achieve higher densities and leads to a noticeable improvement in some important magnetic properties.

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