Study on the planar segregation of solute atoms in Mg-Al-Gd alloy

Abstract Solute segregation plays an important role in forming long-period stacking ordered (LPSO) structure in Mg-M-RE (M: Zn, Ni etc., RE: Y, Gd, etc.) alloys. In this work, the planar segregation in Mg-Al-Gd alloy is characterized by high angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM) and three-dimensional atom probe (3DAP). It is found that the planar segregation can be considered as Guinier-Preston (G.P.) zone, since there is no planar fault or ordered structure within the segregation. The G.P. zone mainly enriches with Gd atoms based on 3DAP data. Furthermore, the segregation behaviour is examined by first-principles calculation.