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pISSN : 1598-706X / eISSN : 2288-8381


(논문)연구논문

한국주조공학회지 (24권3호 145-152)

The Effects of Sc on the Microstructure of Hypoeutectic Al-Si Alloys

아공정 Al-Si합금 조직에 미치는 Sc의 효과

Myunghan Kim, Jongtae Lee

Chungbuk National University

Abstract

The eutectic Si in Al-8.5wt.%Si alloy was changed from large flake to fine lemellar(or fibrous) shape when the Sc amount in the Al-Si alloy reaches 0.2wt.%. The optimum amount of Sc for the best modification effect was 0.8wt.% and slight decrease of modification effect occurred over this value. The study on the distribution of the modifiers(Sr, Na, and Sc) and the measurement of the surface tension of the Al-8.5wt.%Si alloy melt added with Sr, Na, and Sc modifier, respectively, reveals that Sc modifies the eutectic Si by the decrease of surface tension, while Sr and Na modify the eutectic Si mainly by impurity induced twinning mechanism.

Keywords

Hypoeutectic Al-Si, Sc, Modification, Surface tension, Impurity induced twinning