**4. Discussion**

In this study, the symmetrical rod phase was found in the Mg66Zn30Gg4 alloy but not in the other two alloys considered, which indicates that the formation of the phase is related to the content of Gd, i.e., the ratio of Zn to Gd. The di ffraction pattern of the symmetrical rod phase was found to be very complex, probably because it evolved from a lamellar eutectic structure, and its Zn/Gd ratio was observed to be close to the quasicrystal ratio, thus forming a more complex internal structure. Moreover, the increase of thermal stability and microhardness of the phase may also be due to the complex structure of the phase. Because the composition, Zn/Gd ratio, phase transition temperature, and microhardness of the symmetrical rod phase are similar to those of a quasicrystal phase, but its electron di ffraction spot does not show the characteristics of a typical quasicrystal phase, we consider it to be a new kind of complex metallic alloy phase whose composition and properties are close to those of quasicrystals but is not quasicrystalline. The specific spatial structure and related parameters of the phase need to be further studied in the future.
