• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.11a
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• pp.54-54
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• 2004

• 한국전자현미경학회:학술대회논문집
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• 1999.11a
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• pp.45-46
• /
• 1999

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.17-17
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• 1993

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.88-88
• /
• 1999

• Proceedings of the Korean Ceranic Society Conference
• /
• 2002.10a
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• pp.72.2-72
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• 2002

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.27.2-27
• /
• 2003

• Proceedings of the Korean Magnestics Society Conference
• /
• 2000.09a
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• pp.561-562
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• 2000

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.513.2-513.2
• /
• 2006

• Journal of Korea Foundry Society
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• v.15 no.5
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• pp.514-522
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• 1995

The microstructural evolution with isothermal stirring during semi-solid state processing of hypoeutectic Al-6.2wt%Si alloy was studied. Substructure of the individual primary solid particle in the slurry was investigated through transmission electron microscopy(TEM). Formation of subgrain boundaries on the rheocast Al-6.2wt%Si alloy is observed and the misorientation between the grains is shown typically under 2 degrees by analyzing selected area diffraction (SAD) and convergent beam electron diffraction (CBED) patterns. The existence of high angle grain boundaries are also observed in the alloy. Based upon these observations, mechanisms for the primary particles fragmentation are considered. With isothermal stirring, the dislocation density increases, and the evolution of dislocation cell structure takes place, which is interpreted as a process of achieving uniform deformation by dynamic recovery under applied shear stress.

• Journal of Korea Foundry Society
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• v.36 no.5
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• pp.159-166
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• 2016

The microstructural evolution of a cast Ni base superalloy, IN738LC, has been investigated after long term exposure at several temperatures. Most of the fine secondary ${\gamma}^{\prime}$ particles resolved after 2000 hour exposure at $816^{\circ}C$. At higher temperatures of $871^{\circ}C$ and $927^{\circ}C$, secondary ${\gamma}^{\prime}$ resolved after 1000 hours of exposure, and cuboidal primary ${\gamma}^{\prime}$ grew with exposure time. During the thermal exposure, ${\sigma}$ phase formed at all tested temperatures, and ${\eta}$ phase was observed around interdendritic regions due to carbide degeneration. The influence of microstructural evolution during thermal exposure on the mechanical properties has been analyzed. The effects of ${\gamma}^{\prime}$ particle growth are more pronounced on the high temperature creep properties than on the room temperature tensile properties.