Precipitation of Long-Period Stacking Ordered Structure in Mg–Gd–Zn–Mn Alloy

Precipitation of long-period stacking ordered (LPSO) structure in Mg–15Gd–0.8Zn–0.8Mn (wt%) alloy after solution treatment at 520 °C for 1 000 h has been investigated using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The stacking periodicity of the LPSO phase is lengthened 14-fold along the c-axis and the LPSO phase consists of Gd- and Zn-enriched solute clustering. Detailed HAADF-STEM imaging shows a clear evidence of a co-segregation of Gd and Zn within a LPSO phase. This paper provides a better understanding of the interaction between Gd and Zn, which can, therefore, provide useful guidelines to develop high performance Mg alloys.