Effects of alternating current imposition and alkaline earth elements on modification of primary Mg2Si crystals in hypereutectic Mg-Si alloy
(1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China;
2. Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan)
2. Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan)
Abstract: The effects of alternating current imposition and/or alkaline earth elements on modification of the primary Mg2Si crystals in the hypereutectic Mg-Si alloy were investigated. An alternating current of 60 A with frequency of 1 kHz was applied into the hypereutectic Mg-Si melt which was alloyed with alkaline earth elements or not in the fixed temperature range from 700 to 630 ℃. The results show that the primary Mg2Si crystals could be refined by imposing alternating current or adding alkaline elements. Compared with the samples treated by adding 0.4% Ca or 0.4% Sr, higher modification efficiency could be obtained for the samples treated by imposing alternating current. No further modification efficiency could be obtained for the samples treated by imposing alternating current combined with 0.4% Ca or 0.4% Sr addition.
Key words: Mg-Si alloys; primary Mg2Si crystal; alternating current imposition; alkaline earth elements; refinement