Formation of long-period stacking ordered phase only within grains in Mg–Gd–Y–Zn–Zr casting by friction stir processing.

Highlights: [•] Friction stir processing (FSP) was applied to Mg–Gd–Y–Zn–Zr casting. [•] The grain boundary Mg3RE and LPSO phases in the casting dissolved after FSP. [•] Fine grains with LPSO phase distributed only within the grains was achieved. [•] High mechanical properties were obtained in FSP Mg–Gd–Y–Zn–Zr. [ABSTRACT FROM AUTHOR]