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Influence of Cooling Rate and Alloy Composition on The Microstructural Evolution of Al-Ag Eutectic System  

Sohn, Sung-Woo (Center for Noncrystalline Materials, Department of Metallurgical Engineering, Yonsei University)
Park, Jin-Man (Center for Noncrystalline Materials, Department of Metallurgical Engineering, Yonsei University, Institute for Complex Materials, IFW-Dresden, Institute for Complex Materials)
Kim, Tae-Eung (Center for Noncrystalline Materials, Department of Metallurgical Engineering, Yonsei University)
Lim, Ka-Ram (Center for Noncrystalline Materials, Department of Metallurgical Engineering, Yonsei University)
Kim, Won-Tae (Division of Applied Science, Cheongju University)
Kim, Do-Hyang (Center for Noncrystalline Materials, Department of Metallurgical Engineering, Yonsei University)
Publication Information
Journal of Korea Foundry Society / v.29, no.2, 2009 , pp. 64-69 More about this Journal
Abstract
In the present study the effect of cooling rate during solidification on the microstructural characteristics of Al-xAg (x = 31, 33, 35 at.%) in-situ binary eutectic composites has been investigated. To provide a wide range of cooling rate three different casting techniques, i.e. conventional casting, injection casting, and melt spinning have been used. The observed microstructure is very much dependent on the cooling rate. The fcc ${\alpha}$-Al and hcp $Ag_2Al$ phases exhibits an orientation of (111)Al//(0001)$Ag_2Al$, [1-10]Al//[11- 20]$Ag_2Al$. The microstructure of the melt-spun samples contains Widmanstatten structure resulting from solid-state transformation and nano scale two-phase structure resulting from solid-state phase separation. The microstructure of injection-cast samples contains eutectic structure and solid state phase-separated structure. On the other hand, conventional-cast samples exhibit a microstructure consisted of plate-type eutectic structure.
Keywords
Al-$Ag_2Al$ eutectic; Eutectic alloy; In-situ eutectic composite; Phase transformation.;
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