| Title |
Casting & Grain Refining Mechanism of Mg-Al Base Alloys by Carbon Addition |
| Authors |
김영환(Young Han Kim); 김낙준(Nack Joon Kim); 유봉선(Bong Sun You); 임창동(Chang Dong Yim); 김영민(Young Mim Kim) |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Mg-Al alloy; grain refinement; carbon addition; heterogeneous nucleation; duplex nucleation |
| 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. |