• Journal of Magnetics
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• v.8 no.1
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• pp.45-49
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• 2003

We present a brief review of recent experimental and theoretical results on new magneto-optical phenomena in magnetic granular metal-insulator alloys with tunnel-type magnetoresistance, focusing on magnetorefractive effect and cubic nonlinear magneto-optics.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.16-16
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• 2002

Granular metal-insulator alloys, consisting of nano-scale magnetic particles in an insulating matrix are of unique consideration for the technological application and fundamental physics. They display a wide variety of unusual both linear and nonlinear electric-transport, optical and magnetooptical properties, especially for compositions close to the percolation threshold. (omitted)

• Journal of the Korean institute of surface engineering
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• v.35 no.4
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• pp.232-240
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• 2002

The composition and the microstructure of the Zn-Cr alloys electroplated in chloride bath with EDTA were studied according to electrolysis conditions. The cathode current efficiency decreased with increasing both Cr/(Cr+Zn) ratio and current density. The Cr content of the alloy deposits increased with Cr/(Cr+Zn) ratio and current density The phase structure of Zn-Cr alloy deposits changed from η-Zn through η-Zn+${\gamma}$'-ZnCr to ${\gamma}$'-ZnCr with increasing Cr content of alloys. The surface morphology of Zn-Cr alloy deposits changed from fine needle shaped crystallites through the mixed structure of needle-shaped and granular one to the colony structure with fine granular crystallites according to the change of phase structure

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.296-296
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• 2003

• Journal of the Korean institute of surface engineering
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• v.48 no.5
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• pp.227-232
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• 2015

Corrosion characteristic of the duplex Al-Mg-Si alloys with low, commercial and high solute contents were studied using an anodic polarization test in 1M NaCl solution at room temperature. Polarization range condition of the experiment were form .0.3V to .1.3V with a 0.2 mV scanning speed. The exchange current density means corrosion rate of the low solute alloy was low as about $16.29{\mu}A/cm^2$, and that of the high solute alloy was high as $84.92{\mu}A/cm^2$. The difference was mainly attributed to the inter-granular precipitates $Mg_2Si$ and Si which could make a galvanic corrosion on the aluminum base. The amount of precipitates was greater in high solute alloy at mainly in grain boundary. While, the extruded alloys had better corrosion resistance than the cast alloy because the silicon precipitates become coarse during the extrusion process.

• Korean Journal of Metals and Materials
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• v.48 no.9
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• pp.798-806
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• 2010

The effects of alloying elements and the cooling condition on the microstructure, tensile properties, and Charpy impact properties of high-strength bainitic steel plates fabricated by a controlled rolling process were investigated in the present study. Eight kinds of steel plates were fabricated by varying C, Cr, and Nb additions under two different cooling rates, and their microstructures and tensile and Charpy impact properties were evaluated. The microstructures present in the steels increased in the order of granular bainite, acicular ferrite, bainitic ferrite, and martensite as the carbon equivalent or cooling rate increased, which resulted in a decrease in the ductility and Charpy absorbed energy. The steels containing a considerable amount of bainitic ferrite or martensite showed very high strengths, together with good ductility and Charpy absorbed energy. In order to achieve the best combination of strength, ductility, and Charpy absorbed energy, granular bainite and acicular ferrite were properly included in the high-strength bainitic steels by controlling the carbon equivalent and cooling rate, while about 50 vol.% of bainitic ferrite or martensite was maintained to maintain the high strength.

• Corrosion Science and Technology
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• v.18 no.1
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• pp.33-38
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• 2019

Alloy 600/182 with excellent mechanical/chemical properties have been utilized for nuclear power plants. Although both alloys are known to have superior corrosion resistance, stress corrosion cracking failure has been an issue in primary water environment of nuclear power plants. Therefore, primary water stress corrosion crack (PWSCC) growth rate tests were conducted to investigate crack growth properties of Alloy 600/182. To investigate PWSCC growth rate, test facilities including water chemistry loop, autoclave, and loading system were constructed. In PWSCC crack growth rate tests, half compact-tension specimens were manufactured. These specimens were then placed inside of the autoclave connected to the loop to provide primary water environment. Tested conditions were set at temperature of $360^{\circ}C$ and pressure of 20MPa. Real time crack growth rates of specimens inside the autoclave were measured by Direct Current potential drop (DCPD) method. To confirm inter-granular (IG) crack as a characteristic of PWSCC, fracture surfaces of tested specimens were observed by SEM. Finally, crack growth rate was derived in a specific stress intensity factor (K) range and similarity with overseas database was identified.

• Journal of Korea Foundry Society
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• v.41 no.5
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• pp.434-444
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• 2021

This study investigated the overall dependence of the tensile properties of Al-Si alloys on the distribution aspect of a eutectic Si particle in terms of defect susceptibility to the effective void area fraction, referring to the sum of pre-existing microvoids and the damage evolution of the Si particle. The network morphology of as-cast Al-xSi (x=2,5,8,11) alloys was modified to a granular type via a T4 treatment, after which a computational topography (CT) analysis and scanning electron microscope (SEM) observations were utilized to evaluate the size and distribution of the microvoids. The CT and SEM analyses indicated that the main cracks grow along local regions that possess the highest porosity level. The local plastic deformation around the microvoids and the distribution aspect of the microvoids induced a practical difference between the iso-volumetric CT measurement and the SEM fractography outcomes. The results demonstrated that the overall dependence of the ultimate tensile strength (UTS) and elongation on the effective void area fraction is more sensitive to the variation of the area fraction of the Si particle in the network morphology than in the granular type; this is due to the sequential damage evolution of the neighboring Si particles in the eutectic Si colony.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.638-643
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• 2008

Biomimetic apatite formation and deposition behaviors of Ti-6Al-7Nb and Ti-6Al-4V plates in simulated body fluids(SBF) under various conditions were examined. In case of regular samples without collagen treatments the weight gain due to apatite precipitation on the surface in Ti-6Al-4V was found to be higher than in Ti-6Al-7Nb. In case of collagen-coated samples, the weight gain in Ti-6Al-4V continued to be higher than in Ti-6Al-7Nb, but the difference between the two became smaller. Both Ti-6Al-7Nb and Ti-6Al-4V samples with collagen coating exhibited an appreciable increase of weight gain, which may be caused by the interaction between collagen and $Ca^{+2}$ ions. The weight gain was found to be not much affected by the addition of collagen to SBF. The ill-defined granular structure in the presence of collagen can be associated with the increasing volume fraction of amorphous calcium phosphate.

• Journal of Magnetics
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• v.18 no.3
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• pp.240-244
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• 2013

The influences of Gallium doping on the magnetic microstructures and corrosion behaviors of Nd-Fe-B-Ti-C alloys are investigated. The cooling rate for obtaining fully amorphous structure is raised, and the glassforming ability is improved by the Ga addition. The High Resolution Transmission Electron Microscopy image shows that the ${\alpha}$-Fe and $Fe_3B$ soft magnetic phases become granular surrounded by the $Nd_2Fe_{14}B$ hard magnetic phase. The rms and $({\Delta}{\varphi})_{rms}$ value of Nd-Fe-B-Ti-C nanocomposite alloy thick ribbons in the typical topographic and magnetic force images detected by Magnetic Force Microscopy(MFM) decreases with 0.5 at% Ga addition. The corrosion resistances of $Nd_9Fe_{73}B_{12.6}C_{1.4}Ti_{4-x}Ga_x$ (x = 0, 0.5, 1) alloys are enhanced by the Ga addition. It can be attributed to the formation of more amorphous phases in the Ga doped samples.