Grain refinement of Mg-Al alloys inoculated by MgAl2O4 powder

作者：Liao, Hengbin; Zhan, Meiyan; Li, Chengbo; Ma, Zhiqiang; Du, Jun^*

来源：Journal of Magnesium and Alloys, 2021, 9(4): 1211-1219.

DOI：10.1016/j.jma.2020.04.010

• Grain refinement
• Inoculation
• Heterogeneous nucleation
• Mg-Al alloys
• MgAl2O4

As a potent nucleating substrate for alpha-Mg grain, MgAl2O4 powder was used to inoculate the Mg-Al melt in this study. The effects of MgAl2O4 amount, holding time and Al content on the grain size and grain refining ratio of the inoculated Mg-Al alloys are systematically investigated. The results show that the minimum grain size of Mg-3Al alloy is achieved by adding 2 wt.% MgAl2O4 powder and this alloy exhibits higher grain refining ratio than Mg-5Al and Mg-8Al alloys. The crystallographic misfit calculation indicates the well-matching and possible orientation relationships (ORs) between alpha-Mg and MgAl2O4. Among these predicted ORs, [10-10](alpha-Mg)//[110](MgAl2O4) in (0002)(alpha-Mg)//(1-13)(MgAl2O4) possesses the smallest misfit, i.e., 2.34% (f(r)). Both results of the experiment and crystallographic calculation demonstrate that the grain refinement of Mg-Al alloys is attributed to the MgAl2O4 particles acting as the heterogeneous nucleation substrates for a-Mg grains.