한국주조공학회

Sr, added in the hypereutectic Al-Si alloys, is absorbed on the surfaces o f primary Si as well as eutectic Si, and can change the growth mode o f primary Si from non-faceted to faceted mode, as the amount o f Sr increases larger than 0.04 wt.%, even though it cannot affect the grain size o f primary Si, significantly. The EBSD analysis shows that the fraction o f Z3 boundary(twin boundary) increases as the amount o f Sr in the hypereutectic Al-Si alloys increase until the over-modification occurs at 1.6 wt.%Sr and proves that the change in growth mode o f primary Si results from the change o f TPRE growth to IIT growth.

Hypereutectic Al-Si, Growth mode, EBSD analysis, S3 boundary