Effect of long period stacking ordered structure on mechanical and damping properties of as-cast Mg-Zn-Y-Zr alloy

The effect of long-period stacking ordered (LPSO) structure on mechanical and damping properties of as-cast Mg-Zn-Y-Zr alloy were investigated. Obtained results indicate that the Mg-x%Zn-2x%Y-0.6%Zr alloys are mainly comprised of α-Mg and LPSO phase. The grain sizes of the Mg-Zn-Y-Zr alloys are obviously refined and the mechanical properties are improved continuously with the formation of LPSO phase, with a maximum value of 222.5 MPa in ultimate tensile strength and 18.9% in elongation. The fracture mechanism of alloys transforms from cleavage fracture to quasi-cleavage fracture with increasing amount of LPSO phase. The damping capacities of Mg-Zn-Y-Zr alloys increase continuously with the increasing LPSO phase and the damping behavior can be explained by the moving model of Shockley partial dislocation. Due to the stacking fault probability, the LPSO phase in the Mg-Zn-Y-Zr alloys could be new damping source to dissipate energy so as to contribute to the improvement of damping capacities.