The mechanical properties of Mg-Gd-

The mechanical properties of Mg-Gd-Y ternary alloys could be further improved by the addition of Zn [9]. The addition of Zn will lead to the formation of long-period stacking ordered (LPSO) phase during solidification or heat treatment process [10]. This phase has an excellent strength [11] and high elastic modulus [12], thus its formation would be beneficial for strength improvement [9,13,14]. Based on the morphology difference, this phase can be classified into two types: one is the micro-scale block-shaped LPSO phase precipitated at the α-Mg grain boundary and the other is nano-scale thin plate-shaped LPSO phase formed inside the grain [15,16]. Both the block-shaped LPSO phase and thin LPSO phase can strongly influence the dynamic recrystallization behavior during the thermo-mechanical processes[17–20]. The block-shaped LPSO phase can enhance the nucleation of dynamically recrystallized grains via the particle-stimulated nucleation mechanism [17–19], while the thin plate-shaped LPSO phase distributed inside the α-Mg grains hampers the dynamic recrystallization behavior by hindering the migration of grain boundaries [20]. In addition, β phase, (Mg5(Gd, Y)), not only promotes the particle-stimulated nucleation, but also improves the continuous dynamic recrystallization by promoting the grain subdivision. Hence β phase can assist dynamic recrystallization through particle-stimulated nucleation and hinder grain growth by grain boundary pinning [21]. With the combined precipitation strengthening (LPSO and β phase) and the grain boundary strengthening enhanced by these phases, Mg alloys with LPSO usually have remarkable mechanical properties [9–12,22].