• Korean Journal of Materials Research
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• v.8 no.10
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• pp.898-904
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• 1998

Ni-W alloys containing 10 to 50wt% W were prepared by electrodeposition. Tungsten content in the alloy increased with current density. X-ray diffraction analysis revealed that the alloy was crystalline phase when deposited at current densities lower than 50mA/${cm}^2$. Their crystal structure transformed to amorphous at higher current densities. In terms of tungsten content, the crystal -+ amorphous transition occurred at 40-46wt% which was identified by the 3 fold increase in the width of a diffraction peak. The lattice parameter of crystalline phase increased with W upto 40wt% which is higher than the solubility limit of W (about 30wt%) in Ni. Therefore, the alloys are considered to be Ni solid solution supersaturated with W. The amorphous Ni-W alloys were recrystallized by annealing them at temperatures over $400^{\circ}C$. This was evidenced by the appearance a strong [ 11 11 annealing texture. The supersaturated W was precipitated during the annealing at over $800^{\circ}C$. The current-density dependence of W content and crystallinity was utilized to produce alternating layers of crystalline (30wt% W) and amorphous (50wt%) phases which may exhibit unique mechanical and corrosion properties.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.319-325
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• 1994

Permalloy films were deposited by an RF magnetron sputtering method using several different targets which had been cold-rolled and annealed at various temperatures to give different microstructure and texture. The grain refinement occurs at high temperature annealing due to recrystallization and subsequently the initial (110) target texture transforms to the random texture. The coercive forces of thin films fabricated using targets which are not recrystallized are below 0.2 Oe in the AI pressure range of 1~5 mTorr and the lowest coercive force achieved is 0.07 Oe. The low value of coercive force, 0.25 Oe, is only obtained at the sputtering conditions of 400 W and 1 mTorr, and 300 W and 5 mTorr when recrystallized targets are used. The internal stress changes from compressive to tensile as the Ar pressure increases, the stress-free being at 5 mTorr. The changes of coercive force and permeability can be well interpreted by the differences from the composition and the internal stress.

• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.103-108
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• 2002

We investigated magnetoresistance(MR) and exchange bias properties by annealing in top and bosom type spin valves (SV) with nano-oxide layers (NOL). In top SVs with NOL, MR ratio of 9.2% is obtained after postdeposition annealing at 250$\^{C}$. In bottom SVs with NOL, MR ratio of 10.1 % is obtained after postdeposition annealing at 250$\^{C}$. Therefore, specular reflection of the NOL in bottom SVs is higher than that of the NOL in top SVs. Exchange biasing of bottom SVs with NOL is 28% higher than that of bottom SVs without NOL after annealing. This enhancement of exchange biasing is thought to be due to the reduced magnetic moment of the pinned layer with NOL and enhanced (111) FeMn texture.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.1-5
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• 2004

Long length of Bi-2223/Ag superconducting wives were fabricated by stacking and drawing process with advanced heat-treatment schedules. Intermediate annealing was carried out to increase the homogeneity and uniformity of the superconducting filaments embedded in the silver matrix. Phase modification from tetragonal to orthorhombic Bi-2212 by pre heat treatment(PHT) was executed to improve the texture and phase transformation of Bi-2223. Drawing stress was measured to predict the sausaging and stress limit. Rolling Parameters such as thickness. width and winding tension were investigated to roll the tape with uniformity. 1 km length of Bi-2223/Ag superconducting wires were fabricated without any breakage. Critical current (Je) of 270 m length of superconducting tapes was measured over than $70 A/cm^2$ continuously after final sintering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.917-920
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• 2001

Effects of addition of manganese and final reduction on segregation behavior of sulfur and final mangetic induction during final annealing have been investigated in the 300 ppm sulfur-contained 3% silicon-iron alloy strips with or without manganese. At the same concentration of sulfur, lower final reduction is favorable for final Goss texture. This is because the probability that the initial Goss grains survive under the highly segregated sulfur atmosphere and grow selectively within the segregated sulfur-free time range becomes higher. In the case of 3% silicon-iron with manganese, much lower magnetic induction was obtained, although the weak final reduction of 30% is given to the alloy, comparative to the 40%. This is because MnS particles acted as an reducer in the primary grain size.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.365-373
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• 2004

The sheet formability of single AA5182 sheets and sandwich sheets comprising of AA5182/polypropylene/AA5182 (AA/PP/AA) was studied. Rolling without lubrication and subsequent recrystallization annealing led to the formation of favorable ｛111｝//ND fiber textures in AA5182 sheets, which provided a higher plastic strain ratio of $R_m=1.5$. $R_m$ value of 1.58 was obtained in the AA/PP/Ah sandwich sheet sample. Furthermore, a proper combination of the sample direction of the upper and lower skin sheet gave rise to an optimization of the sheet formability of the sandwich sheets.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.228-230
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• 2004

Samples of the aluminum alloy 3103 sheets were repeatedly deformed by ECAR up to twelve passes. Shear textures developed after the first passage of ECAR. However, the intensity of shear texture components decreased with increasing number of ECAR passages. Observations by TEM and EBSD revealed that the degree of misorientations within the deformed grains increased with increasing number of ECAR passes. Changes in textures and microstructures were hardly observed during recrystallization anneal. Upon subsequent annealing, the samples deformed by a large number of ECAR passes displayed a continuous grain growth. A higher deformation by ECAR resulted in a slower softening, which reflects the stability of ultra-fine grains against the grain growth.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.06a
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• pp.64-65
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• 2004

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.63-66
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• 2003

1 km length of Bi-2223/Ag superconducting wires were fabricated by stacking, drawing process with advanced heat-treatment schedules. Intermediate annealing was carried out to increase the homogeneity and uniformity of the superconducting filaments embedded in the silver matrix. Phase modification from tetragonal to orthorhombic Bi-2212 by pre heat treatment(PHT) was executed to improve the texture and phase transformation of Bi-2223. Drawing stress was measured to Predict the sausaging and stress limit, Rolling parameters such as thickness, width and winding tension were investigated to roll the tape with uniformity. Critical current of 1 km length of superconducting tapes was measured about 50 A continuously after final sintering.

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.85-91
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• 1998

고주파 마그네톤 스퍼터법을 이용하여 ZnO 박막 증착시, 증착 조건, 증착 후 표면스퍼터 및 열처리 분위기에 따른 ZnO 박막의 표면조직과 전기적 특성을 분석하였다. ZnO 박막의 면저항은 500℃에서 행한 증착후 열처리의 분위기에 따라 수 GΩ/ㅁ에서 수 KΩ/ㅁ까지 변하였다. 이들 박막의 전하운반자 농도는 1015∼1018/㎤이었으며, 이동도는 10∼40㎠Vsec이었다. 특정한 스퍼터 조직에서 박막의 표면을 스퍼터할 경우 박막 표면적이 증가하였으며, 이러한 박막의 분위기 열처리에 민감한 반응을 보였다. 증착한 박막과 증착후 열처리한 박막의 화학조성 비교를 통하여, 박막의 원자결함 유형 및 전기적 특성을 미치는 이들의 영향에 관한 고찰을 하였다.