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Vol.50, No.12, 897 ~ 906, 2012
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| Title |
| A Study on Microstructure Formation during Directional Solidification of a Hypoeutectic Al-11.3Si-3.5Cu alloy |
| 서희식 Hee Sik Seo , 구지호 Ji Ho Gu , 박경미 Kyung Mi Park , 이정석 Jeong Seok Lee , 이재현 Je Hyun Lee , 정원섭 Won Sub Chung |
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| Abstract |
| Directional solidification experiments were carried out in a hypoeutectic Al-11.3Si-3.5Cu system to investigate the microstructural evolution with the solidification rate. At a fixed temperature gradient, a dendritic microstructure was observed at a constant speed of more than 25 ㎛s-1, a cellular interface developed at 5 ㎛s-1 and the growth rate of 0.5 ㎛s-1 led to the stability of the planar interface. The results revealed that primary silicon phases formed among cells, even though the studied Al-Si alloy system formed the composition within a hypoeutectic silicon composition. This suggests that the liquid concentration among cells during solidification reached a higher concentration, i.e., the eutectic concentration. It is, however, interesting that primary silicon phases did not form during a dendritic growth of more than 25 ㎛s-1. These experimental observations are explained using the theoretical models on the interface temperatures. |
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| Key Words |
| Al-Si alloy, directional solidification, solidification rate, segregation, dendrite spacing |
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