• Journal of Magnetics
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• v.11 no.4
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• pp.182-188
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• 2006

The search for high-density recording materials has been one of most active and vigorous field in the field of magnetism. $FePt-L1_{0}$ nanoparticle has emerged as a potential candidate because of its high anisotropy. In this paper, we provide an overview of recent work at Argonne National Laboratory that contributes to the ongoing dialogue concerning the relation between structure and properties of the FePt nanoparticle system. In particular we discuss the ability to control structure and properties via dosing with Cr. Cr-dosed FePt films were grown via molecular beam epitaxy and annealed at $550^{\circ}C$ in an ultrahigh vacuum chamber, and were studied with the surface magneto-optic Kerr effect (SMOKE), scanning electron microscopy (SEM) and x-ray magnetic circular dichroism (XMCD). We found that small dosage of Cr helps to generate $L1_{0}$ phase FePt magnetic nanoparticles with small size, defined shape and regular spatial distribution on MgO (001) substrate. The nanostructures are ferromagnetic with high magnetic coercivity (${\sim}0.9T$) and magnetic easy axis in the desired out-of-plane orientation. We also show that controlling the lateral region where nanostructures exist is possible via artificial patterning with Cr.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.350-356
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• 2009

Perovskite codoped with chromium and iron have been studied. Samples with $YAl_{0.96}(Cr_{0.04-x}Fe_x)O_3$(x=0.01, 0.02, 0.03, 0.04) were prepared by solid state reaction at $1450^{\circ}C$ for 6 h and were characterized by XRD, FT-IR, Raman spectroscopy, SEM and UV-vis spectrophotometer. The color of the synthesized pigments were from red to dark brown(in bulk). Up to 0.02 mole $Fe_2O_3$ for substituting $Cr_2O_3$ development of color in lime-glaze gives good red color but as increasing amount of $Fe_2O_3$ and decreasing $Cr_2O_3$ proportionally produce from brownish red to brown. Increasing $Fe_2O_3$ amount lead to weaken crystal field relatively due to have smaller ionic radius than $Cr_2O_3$ ionic one. The UV-vis peaks were shifted to lower wavelength.

• 한국해양학회지
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• v.18 no.1
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• pp.49-54
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• 1983

sediments were collected from 23 ststions in Jinhae Bay and Cd, Cr, Cu, Fe, Ni, Mn, Pb and Zn were determined by atomic absorption spectrohotometry. The concentrations of Cd, Cr, Cu, Pb and Zn in the sediments decreased gradusally with increasing distance from the gead of Masan Bay, indicating pollutant transport from industrial and municipal wastewaters. But the levels of Co, Fe, Ni and Mn showed no difference througout the bay. analysis of correlation coefficients showed that Cd, Cr, Cu, Pb and Zn in the sediments were [losely associated to one another, whereas co, Fe and Ni were so associated.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.962-963
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• 2006

The precipitation behaviors of ${\gamma}"(Ni_3Nb)$ in four Ni-base alloys were investigated. The four alloys were forged Ni20Cr20Fe5Nb alloy, mechanically alloyed Ni20Cr20Fe5Nb alloy, IN 718 alloy and ECAPed(equal channel angular pressing) IN 718 alloy. Aging treatment was employed at either $600^{\circ}C$ or $720^{\circ}C$ for 20 hrs. The TEM observation and hardness test were performed to identify the formation of ${\gamma}"$. The precipitation of ${\gamma}"$ was noticed after aging at $600^{\circ}C$ for 20 hrs in the mechanically alloyed Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy, while it was observed after aging at $720^{\circ}C$ for 20 hrs in the forged Ni20Cr20Fe5Nb alloy and IN 718 alloy before ECAP. The lower aging temperature for ${\gamma}"$ precipitation in the mechanically alloyed Ni20Cr20Fe5Nb alloy and ECAPed IN 718 alloy than in the forged Ni20Cr20Fe5Nb alloy and IN 718 alloy before ECAP appeared to be due to the severe plastic deformation which occurred during mechanical alloying or ECAP.

• Journal of the Korean Magnetics Society
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• v.8 no.3
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• pp.125-130
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• 1998

13Cr-1.5Nb-Fe alloy powder was fabricated by water atomization method, and ring-shape specimen of this composition was fabricated by oil press, and then sintered in the vacuum furnace. Powder shape, size distribution, composition (C, N, O, S) analysis and saturation magnetization of as-prepared 13Cr-1.5Nb-Fe alloy powder were investigated. Ac permeability and power loss was measured after forming and sintering process. Saturation magnetization and contents of oxygen of the alloy powder is160 emu/g and about 6000 ppm, respectively. 50 % volume fraction indicate particle size of 70$\mu$m. The ac permeability of sintered specimen increases with increasing sintering temperature and forming pressure. The power loss is 107 W/cc at sintering temperature of 1200 $^{\circ}C$, 12 ton/$\textrm{cm}^2$ forming pressure, and 20 KHz. It is the lowest among the prepared specimen.

• Journal of Korea Foundry Society
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• v.19 no.5
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• pp.410-418
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• 1999

To overcome the undesirable deformation, peeling off and geometrical restrictions which were mainly caused by differences in thermal expansion coefficients during the cladding of aluminum strip and stainless strip, new processing method based on vacuum die casting is designed and implemented in fabricating Fe-17wt%Cr steel (stainless steel). To increase cast-bonding ability, the surface of Fe-17wt%Cr steel is electrochemical etched to have optimum pit size (above 0.2 mm) and pit density (above 30%). The implementation of vacuum die casting by using surface treated stainless steel (Fe-17wt%Cr Steel) produces good trial products having acceptable cast-bonding ability. The enabling conditions for cast-bonding are pouring temperature $690^{\circ}C$, filling speed 30 m/sec and casting pressure $800\;kg/cm^2$. The microscopic observation of cast-bonded Al/Fe-17wt%Cr steel does not show any evidence of intermetallic compounds. The bonding strength of trial products is $150-400\;kg/cm^2$ and this is stronger than conventionally cladded metal having $30-70\;kg/cm^2$.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.153-160
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• 2011

The AISI 216L stainless steel with a composition of Fe-16Cr-6Ni-6Mn-1.7Mo (wt.%) was oxidized at $700{\sim}900^{\circ}C$ in air for 100 h. At $700^{\circ}C$, a thin $Mn_{1.5}Cr_{1.5}O_4$ oxide layer with a thickness of $0.4{\mu}m$ formed. At $800^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $FeCr_2O_4$ oxide layer with a total thickness of $30{\mu}m$ formed. The non-adherent scale formed at $800^{\circ}C$ was susceptible to cracking. At $900^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $Mn_{1.5}Cr_{1.5}O_4$ oxide layer formed, whose total thickness was $10{\sim}15{\mu}m$. The scales formed at $900^{\circ}C$ were non-adherent and susceptible to cracking. 216 L stainless steel oxidized faster than 316 L stainless steel, owing to the increment of the Mn content and the decrement of Ni content.

• Journal of Powder Materials
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• v.29 no.2
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• pp.132-151
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• 2022

The CoCrFeMnNi high-entropy alloy (HEA), which is the most widely known HEA with a single face-centered cubic structure, has attracted significant academic attention over the past decade owing to its outstanding multifunctional performance. Recent studies have suggested that CoCrFeMnNi-type HEAs exhibit excellent printability for selective laser melting (SLM) under a wide range of process conditions. Moreover, it has been suggested that SLM can not only provide great topological freedom of design but also exhibit excellent mechanical properties by overcoming the strength-ductility trade-off via producing a hierarchical heterogeneous microstructure. In this regard, the SLM-processed CoCrFeMnNi HEA has been extensively studied to comprehensively understand the mechanisms of microstructural evolution and resulting changes in mechanical properties. In this review, recent studies on CoCrFeMnNi-type HEAs produced using SLM are discussed with respect to process-induced microstructural evolution and the relationship between hierarchical heterogeneous microstructure and mechanical properties.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.639-644
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• 2007

Spinel pigments, developing black color in high temperature glazes at oxidation or reduction atmosphere, without CoO because of its high price were synthesized by solid solution method. Ten mixed compositions consisted of NiO, MnO, $Fe_2O_3 and $Mn_2O_3$ were fired at $1250^{\circ}C$ for 1h. The resulting pigments were characterized by using XRD, FT-IR, SEM and UV-vis spectrometer. Structure of the pigments are spinel and particles' shape are spherical or cubic. Glazed tiles containing 5 wt% pigments were fired at $1260^{\circ}C$ and $1240^{\circ}C$ in reduction atmosphere. Color in glazes were analyzed by UV-vis spectrometer. Colors of NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole% in lime glaze showed black in oxidation, in reduction NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0125 mole% and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.55{\cdot}Mn_2O_3$ 0.0125 mole% showed black. In case of lime-barium glaze, NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.975 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black color in oxidation and NiO 0.875 MnO $0.125{\cdot}Fe_2O_3$ $0.3875{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.1125 mole%, NiO 0.925 MnO $0.075{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% and NiO 0.725 MnO $0.275{\cdot}Fe_2O_3$ $0.4375{\cdot}Cr_2O_3$ $0.50{\cdot}Mn_2O_3$ 0.0625 mole% showed black one in reduction.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.361-368
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• 2012

Fe-(10, 20, 30, 40) wt%Cr alloys were corroded in $Na_2SO_4$ salts ($m.p.=884^{\circ}C$) at $800{\sim}900^{\circ}C$ for 3-300 hrs. Their corrosion resistance increased with an increase in Cr content owing to the formation of slowly growing $Cr_2O_3$. During corrosion, $Na_2SO_4$ dissociated and reacted with the alloys to form $Cr_2O_3$ and $Fe_2O_3$. Since $Fe_2O_3$ dissolved fast into the salts, most of the scales consisted primarily of $Cr_2O_3$. Inside the scale, a small amount of sulfides also existed. The oxidation, dissolution and detachment of the formed scales occurred significantly.