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Vol.45, No.8, 465 ~ 473, 2007
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| Title |
| Casting & Grain Refining Mechanism of Mg-Al Base Alloys by Carbon Addition |
| 김영환 Young Han Kim , 김낙준 Nack Joon Kim , 유봉선 Bong Sun You , 임창동 Chang Dong Yim , 김영민 Young Mim Kim |
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| Abstract |
| This study is aimed at investigating the grain refining mechanism of Mg-Al base alloys by carbon addition. In AZ91 alloys, the morphology of Al-Mn particles were modified from rod to globular-type by inoculating C2Cl6 to AZ91 alloy melt. These particles were identified as Al8(Mn,Fe)5 phase and formed in the melt before the formation of α-Mg, resulting in grain refinement by heterogeneous nucleation. However, no grain refinement was found in Mn-free Mg-Al binary alloys with an addition of C2Cl6, because most of Al carbides and Al-Fe compounds existed in eutectic region, indicating that they are not effective nucleants for Mg grains. Therefore, Al8(Mn, Fe)5 is considered as the most effective nucleant in Mg-Al base alloys. In this study, it is suggested that the grain refinement in Mg-Al base alloys is achieved by the sequences that Al carbides formed by carbon addition are surrounded by Al8(Mn,Fe)5, which in turn are surrounded by α-Mg. |
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| Key Words |
| Mg-Al alloy, grain refinement, carbon addition, heterogeneous nucleation, duplex nucleation |
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