Effect of Sn on the microstructural evolution of quasicrystal-reinforced Mg-Zn-Y alloy

The effect of Sn content on the microstructure evolution of the as-cast, as-extruded and as-aged Mg-8Zn-2Y-x Sn alloys were systematically investigated. The results show that addition of Sn not only refines the grains but also promotes the precipitation of quasicrystal I-phase and the for-mation of Sn3Y5. The phase transformations during solidification were also studied in detail. After extrusion, the broken second phase particles (I-phase) are more uniformly and densely dis-tributed in the matrix with Sn addition. Moreover, ultra-fine dynamically recrystallized grains are obtained in extruded Mg-8Zn-2Y-0.5Sn alloy. In addition, high density nano-scale precipitates are uniformly dispersed by aging, and these precipitates are identified to be Mg-Zn particles, I phase and mixture of the beta?1 Mg-Zn precipitates and I-phase.