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

TL;DR

This study investigates the planar segregation of Gd atoms in Mg-Al-Gd alloys, revealing no planar faults and a periodic distribution resembling LPSO structures, with segregation mainly enriched in Gd, supported by experimental and computational analysis.

Contribution

It provides detailed characterization of Gd segregation in Mg-Al-Gd alloys using advanced microscopy and atom probe techniques, combined with first-principles calculations, revealing new insights into segregation behavior.

Findings

Segregation mainly enriches Gd atoms.

No planar faults accompany segregation.

Segregation distribution resembles LPSO periodicity.

Abstract

Solute segregation plays an important role in formation of long-period stacking ordered (LPSO) structure in Mg-M-RE (M: Zn, Ni etc., RE: Y, Gd, etc.) alloy systems. 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 there is no planar fault accompanying the segregation, and the spatial distribution of segregation may resemble the periodicity of LPSO structure. The segregation is further quantified by 3DAP, and it mainly enriches with Gd atoms. The segregation behaviour is rationalized by First-Principles calculation.