• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.164-174
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• 1995

New metallic powder making processes, named "Centrifugal Emulsification Process(CEP)" and "Mixer and Settler(MS)" have been developed to synthesize rapid solidified metallic powders. Through CEP and MS processings, the high temperature metals as well as the low temperature alloys are manufactured. Also, the effects of rapid solidification on the undercooling, solidification rate and crystallization behaviors can be evaluated effectively through the processes. The standard deviations of the synthesized typical Pb-Sn eutectic powders are 1.63 and 1.51 for CEP and MS respectively, and the average size of the MS powders was $18{\mu}m$. The possibility of the customized not only size and shape control but microstructure control was also shown. Both of the new methods can be applied to continuous powder making processes.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.582.2-582.2
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• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1048-1049
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• 2006

Rapidly solidified ribbon-consolidation processing was applied for preparation of high strength bulk Mg-Zn-Gd alloys. Mg alloys have been used in automotive and aerospace industries. Rapid solidification (RS) process is suitable for the development of high strength Mg alloys, because the process realizes grain-refinement, increase in homogeneity, and so on. Recently, several nanocrystalline Mg-Zn-Y alloys with high specific tensile strength and large elongation have been developed by rapidly solidified powder metallurgy (RS P/M) process. Mg-Zn-Y RS P/M alloys are characterized by long period ordered (LPO) structure and sub-micron fine grains. The both additions of rare earth elements and zinc remarkably improved the mechanical properties of RS Mg alloys. Mg-Zn-Gd alloy also forms LPO structure in -Mg matrix coherently, therefore, it is expected that the RS Mg-Zn-Gd alloys have excellent mechanical properties. In this study, we have developed high strength RS Mg-Zn-Gd alloys with LPO structure and nanometer-scale precipitates by RS ribbon-consolidation processing. $Mg_{97}Zn_1Gd_2$ and $Mg_{95.5}Zn_{1.5}Gd_3$ and $Mg_{94}Zn_2Gd_4$ bulk alloys exhibited high tensile yield strength (470 MPa and 525 MPa and 566 MPa) and large elongation (5.5% and 2.8% and 2.4%).

• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.453-458
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• 1988

Al-Si alloy powder produced by the gas atomizer showed fine eutectic structure between ${\alpha}-dendrites$, that was grown by coupled growth, and there remained small amount of ${\alpha}$ in Al - 20 wt% Si alloy. The morphology of Si in the eutectic structure was largely influenced by the recalescence caused by solidification latent heat, and that was thought to be due to decrement of the surface energy of Si. In modified eutectic Si by rapid solidification, fine twin about $0.01\;{\mu}m$ was observed and growth direction of eutectic Si was <112>. This fact implied that the growth mechanism of eutectic Si in rapid solidification was related to TPRE mechanism. Due to rapid solidification Si was soluble in ${\alpha}-phase$ in Al - 12.6wt%Si alloy up to about 3.4wt%, and the solubility of Si in ${\alpha}-phase$ reaches the equilibrium solubility stare after 60min, holding when it was held isothermally at $253-296^{\circ}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.10a
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• pp.31-31
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• 1999

• Journal of Powder Materials
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• v.16 no.6
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• pp.438-441
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• 2009

Mg-Cu composites were successively fabricated using a combination of rapid solidification and extrusion processes. In addition, the microstructural variation of the composite was investigated by performing the extrusion repeatedly. It resulted that the composite formed an uniform and dense structure by the extrusion, and the microstructure became fine as the extrusion conducted repeatedly. The microstructural variation was known to be dependent on the number of extrusion and the area reduction ratio. The tensile strength was also measured as a function of the microstructural variation.

• Proceedings of the Korean Magnestics Society Conference
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• 1995.05a
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• pp.64-65
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• 1995

• Proceedings of the KWS Conference
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• 1993.10a
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• pp.21-24
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• 1993

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1999.04a
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• pp.26-27
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• 1999

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1996.11a
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• pp.12-12
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• 1996