Refinement and modification of primary Mg2Si in an Al-20Mg2Si alloy by a combined addition of yttrium and antimony

• Main Authors: Wang, Hui-Yuan, Zhu, Jia-Ning, Li, Jie-Hua, Li, Chao, Zha, Min, Wang, Cheng, Yang, Zhi-Zheng, Jiang, Qi-Chuan
• Format: Article
• Language: English
• ISSN: 1466-8033
• DOI: 10.1039/c7ce01309d

The complex modification of primary Mg 2 Si in an Al-20Mg 2 Si alloy by simultaneous addition of yttrium (Y) and antimony (Sb) was investigated in the present work. It was found that the combined addition of 0.5 wt% Y-Sb had a more significant modifying effect than the single addition of an equivalent amount of Y or Sb. After modification, coarse Mg 2 Si dendrites were changed into fine polyhedra with an average size decreasing from 86 to less than 18 μm. It has been demonstrated that Sb participated in the formation of Mg 3 Sb 2 , which acts as a heterogeneous nucleus of primary Mg 2 Si and hence significantly refines their sizes. Meanwhile, Y could obviously adsorb and poison the preferred growth along the directions of primary Mg 2 Si crystals, and hence not only changed their final morphology to a truncated octahedron but also reduced their sizes. Furthermore, the skeleton-type growth process of the truncated octahedral primary Mg 2 Si in the Al-20Mg 2 Si alloy co-modified by 0.5 wt% Y-Sb was also revealed. Our study provides a new insight into the design of more efficient modifiers by the combined addition of a refiner ( e.g. Sb) and a growth inhibitor ( e.g. Y), which is critical to tailor new light-weight alloys with high strength and toughness. The complex modification of primary Mg 2 Si in an Al-20Mg 2 Si alloy by simultaneous addition of yttrium (Y) and antimony (Sb) was investigated in the present work.