• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.338-345
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• 1999

The objective of this study is to developed the refrigeration vehicle system installed eutectic olu-tion plates which consists of copper tubes carrying the refrigerant between two aluminum plates and the space between the plates filled with eutectic solution. The numerical analysis for the loca-tion of plates to get the uniform low temperature distribution in storage space was carried out and the result showed that the top left-side and right-side walls were the proper places to install plates. For three different concentrations of ethylene glycol solution the temperature distribution of inside space were measured during the day time of summer and the 21% solution was found to be properto sustain the temperature of $5-10^{\circ}C$ for milk transportation. The result showed that the refrigeration truck installed eutectic plates was very efficient to keep the milk fresh during vehicle transportation.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.11.1-11.1
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• 2009

Ternary Al2O3.ZrO2.Y2O3 samples with a eutecticcomposition were prepared by slow cooling. The microstructural evolution wasobserved with X-ray diffraction (XRD), scanning electron microscopy (SEM). TheSEM observation of the ternary samples agreed with the XRD with a completion ofcrystallisation by slow cooling. The target materials commonly have 'cantaloupe skin' microstructures as shown inthe previous studies by Han et al. The nanocomposite may have experienceddifferent cooling rates with two different microstructures, near the surfacehaving experienced optimal conditions for the eutectic reaction during theircooling and thus formed the eutectic microstructure, near the centre havingexperienced a slower cooling rate. The crystallised eutectic ternary Al2O3.ZrO2.Y2O3 system had three different phaseswith a 3Y2O3. 5Al2O3 (yttrium.aluminiumgarnet phase), an alumina phase formed by the eutectic reaction, and a solidsolution of ZrO2 and Y2O3.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.833-841
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• 2021

During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

• 한국주조공학회지
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• 제9권4호
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• pp.311-319
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• 1989

The effects of the alloying elements and cooling rates on the formation of phosphide eutectics of compacted vermicular graphite cast irons containing copper, tin, molybdenum for producing pearlitic matrix, and also containing phosphorus and boron for increasing wear resistance, were investigated. The liquidus phosphide eutectic was found to solidify as a pseudo-binary phosphide eutectic, but with increasing of the cooling rate non-equlibrium phosphide eutectic with needle type carbide could be formed. However, the liquidus phosphide eutectic containing both phosphorus and carbide-forming boron was found to solidify always as a non-equlibrium phosphide eutectic with coarse carbide, independent from the cooling rate. It was also confirmed that the tiny isolated phase observed by SEM was gamma iron solid solution with phosphorus, silicon, molybdenum and the matrix containing these tiny islands was phosphide phase containing manganese and molybdenum. The addition of copper was found to decrease the tendency of forming ledeburitic carbides in the phosphide eutectic.

• 한국주조공학회지
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• 제28권2호
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• pp.69-73
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• 2008

In the present study, microstructural evolution and mechanical properties of Ti-Fe-Sn ultrafine eutectic alloys have been investigated. Ultrafine eutectic microstructure consisting of a mixture of ${\beta}$-Ti solid solution and TiFe intermetallic compound homogeneously formed in $(Ti_{70.5}Fe_{29.5})_{100-x}Sn_x$ alloys with x = 0, 1 and 3. Addition of Sn is effective to modify the eutectic colony into the spherical shape with decreasing the lamellar spacing and colony size. This results in enhancing the macroscopic plasticity up to 3.1% of the Ti-Fe-Sn ultrafine eutectic alloys.

• 한국주조공학회지
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• 제38권1호
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• pp.1-8
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• 2018

In this study, we focused on the correlation between the solidification structure, heat treatment and mechanical properties of the A356 alloy according to the conditions of Sr modification. The microstructural evolution of the eutectic Si and ${\alpha}-Al$ phase in the A356 alloy castings depending on the amount of Sr were investigated during solid solution heat treatment using an optical microscope, a scanning electron microscope and an image analyzer. In addition, tensile tests on the heat treated materials examined the relationship between the microstructure and the fracture surface. The as-cast A356 alloys under 40 ppm Sr showed an undermodified microstructure, but that of the added 60-80 ppm Sr had well modified structure of fine fibrous silicon. After solid solution treatment, the microstructure of the undermodified A356 alloy exhibited a partially spheroidized morphology, but the remainder showed the fragmentation of fibrous shaped silicon. The spheroidization of the eutectic silicon in the modified A356 alloys was completed during heat treatment, which was very effective in increasing the elongation. This is supported by the fracture surface in the tensile test.

• 한국주조공학회지
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• 제34권5호
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• pp.156-161
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• 2014

This study is focused on the effect of $Al_2Ca$ as a modifier on eutectic Si modification of A356 alloy. Microstructural observation was carried out for as-cast, as-solution treated and as-aged samples. Solution treatment and aging were performed for 2, 4, 6 and 10 hrs at $540^{\circ}C$ and $170^{\circ}C$, respectively. Although A356 alloy, which $Al_2Ca$ was added, has no significant difference in as-cast phases with normal A356 alloys, it shows much more modified eutectic Si, grain refinement and improved tensile property both in as-cast and as-heat treated conditions. TGA result shows that $Al_2Ca$ added A356 alloy has a certain improvement in oxidation resistance.

• Corrosion Science and Technology
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• 제20권6호
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• pp.367-372
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• 2021

The effect of carbon addition on the general corrosion behavior of high-chromium cast iron (HCCI) was studied by a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) or electron back-scattered diffraction (EBSD), or electrochemical polarization techniques in 0.1 mol dm^-3 H₂SO₄ + 0.05 mol dm^-3 HCl at room temperature. The addition of 2.1-2.8 wt% carbon to HCCI increased the fraction of eutectic austenite and eutectic carbide phases, while that of HCCI decreased the fraction of the primary austenitic phase. Potentiostatic polarization of the HCCI at -0.35 V_SSCE or 0.0 V_SSCE resulted in preferential general corrosion of the primary austenitic or eutectic austenitic phases, respectively. The decrease in corrosion current density and the shift in noble corrosion potential direction with increasing carbon content in the HCCI indicated that the fraction and the chemical composition of austenitic (primary and eutectic) and carbide phases were strongly related to the general corrosion behavior of the HCCI.

• 열처리공학회지
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• 제31권3호
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• pp.97-103
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• 2018

The objective of this study is to develop the mechanical properties of AlSiCu aluminum alloy by the two-step solution heat treatment. The microstructure of gravity casting specimen represents a typical dendrite structure having a secondary dendrite arm spacing (SDAS) of 40 mm. In addition to the Al matrix, a large amount of coarsen eutectic Si phase, $Al_2Cu$ intermetallic phase, and Fe-rich phases are generated. The eutectic Si phases are fragmented and globularized with solution heat treatment. Also, the $Al_2Cu$ intermetallic phase is resolutionized into the Al matrix. The $2^{nd}$ solution temperature at $525^{\circ}C$ might be a optimum condition for enhancement of mechanical properties of AlSiCu aluminum alloy.

• 한국재료학회지
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• 제23권4호
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• pp.227-232
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• 2013

Al-based alloys have recently attracted considerable interest as structural materials and light weight materials due to their excellent physical and mechanical properties. For the investigation of the potential of Al-based alloys, a surface porous $Al_{88}Cu_6Si_6$ eutectic alloy has been fabricated through a chemical leaching process. The formation and microstructure of the surface porous $Al_{88}Cu_6Si_6$ eutectic alloy have been investigated using X-ray diffraction and scanning electron microscopy. The $Al_{88}Cu_6Si_6$ eutectic alloy is composed of an ${\alpha}$-Al dendrite phase and a single eutectic phase of $Al_2Cu$ and ${\alpha}$-Al. We intended to remove only the ${\alpha}$-Al phase and then the $Al_2Cu$ phase would form a porous structure on the surface with open pores. Both acidic and alkaline aqueous chemical solutions were used with various concentrations to modify the influence on the microstructure and the overall chemical reaction was carried out for 24 hr. A homogeneous open porous structure on the surface was revealed via selective chemical leaching with a $H_2SO_4$ solution. Only the ${\alpha}$-Al phase was successfully leached while the morphology of the $Al_2Cu$ phase was maintained. The pore size was in a range of $1{\sim}5{\mu}m$ and the dealloying depth was nearly $3{\mu}m$. However, under an alkaline NaOH, aqueous solution, an inhomogeneous porous structure on the surface was formed with a 5 wt% NaOH solution and the morphology of the $Al_2Cu$ phase was not preserved. In addition, the sample that was leached by using a 7 wt% NaOH solution crumbled. Al extracted from the Al2Cu phase as ${\alpha}$-Al phase was dealloyed, and increasing concentration of NaOH strongly influenced the morphology of the $Al_2Cu$ phase and sample statement.