Obtaining gamma '' phase by addition of Mn in Mg-Gd-Y-Zn-Ni-Mn alloy: atomic-scale insights by scanning transmission electron microscopy

摘要

To develop gamma '' phase (hexagonal structure with space group P (6) over bar 2m) containing high strength Mg-Gd alloys at lower cost, Mn instead of Ag was added. The state-of-art scanning transmission electron microscopy was applied to characterise gamma '' in solution-treated and aged Mg-Gd-Y-Zn-Ni-Mn alloys on the atomic scale. gamma '' was not found in the solution-treated state but was captured to precipitate during aging. gamma '' with nonuniform occupations of Gd and Y was observed. Different modes of interaction between gamma '' and beta ' are proposed. The formation of gamma '' promoted by Mn was not accidental, suggesting the possibility to form plenty of gamma ''.