Magnesium alloys are concerned for its mechanical properties and high damping performance. The influence of Mn toward the internal organization morphology of long-period stacking ordered (LPSO) second phase and the consistent damping performance in Mg-4.9Zn-8.9Y-xMn have been studies in this work. It has shown that the addition of Mn tends to diffuse to the LPSO interface and causes the LPSO phase to expand in the arc direction. The circular structure of LPSO can optimize the damping property of the alloy better than the structure with strong orientation, especially at the strain of 10−3 and 250 °C. With more additions of Mn, damping would have a reduction due to the dispersed fine LPSO phases and α-Mn particles. When the Mn content is higher than 1.02%, the grain is refined, and mechanical properties have been significantly improved. Mg-4.9%Zn-8.9%Y-1.33%Mn shows the best mechanical property.

The damping and mechanical properties of extruded Mg-ZnX-Y1.33X (X = 1, 2, 3 at%) alloys were investigated in this experiment. The results shown that the alloy was mainly composed by long-period stacking ordered (LPSO) phase and magnesium(Mg) matrix. With the increase of Zinc(Zn) and Yttrium(Y) content, the grains had a certain refinement, the LPSO content was significantly increased, accompanied by a small amount of rare Y-enriched particles. After extrusion, the second phase of the alloys were broken into small pieces. The tensile strength(UTS) and yield strength(YS) of the alloy increased significantly, but the elongation decreased with the increase of LPSO phase. Mg-4.9Zn-8.9Y shown the best mechanical properties, with the tensile strength of 415 MPa, yield strength of 325MPpa, and elongation of 6.5%. Research on alloy damping performance shown that as the content of LPSO increases, the damping performance of as-cast alloys increased, and there is no obvious change after extrusion. It was due to a large number of dislocations entangled with work hardening, which greatly reduced the dislocation damping in magnesium alloys.

Mg alloys with fine mechanical properties and high damping capacities are essential in engineering applications. In this work, Mg–Zn–Y based alloys with lamellar long period stacking ordered (LPSO) phases were obtained by different processes. The results show that a more lamellar second phase can be obtained in the samples with more solid solution atoms. The density of the lamellar LPSO phase has an obvious effect on the damping of the magnesium alloy. The compact LPSO phase is not conducive to dislocation damping, but sparse lamellar phases can improve the damping capacity without significantly reducing the mechanical properties. The Mg95.3Zn2Y2.7 alloy with lamellar LPSO phases and ~100 μm grain size exhibited a fine damping property of 0.110 at ε = 10–3.

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