Microstructure and mechanical properties of Mg-4Zn-xGd (x=0, 0.5, 1, 2) alloys

The present work mainly focuses on the effect of minor content of Gd element on the microstructure and mechanical properties of Mg-Zn alloy. The Mg-4Zn-xGd (x=0, 0.5, 1, 2) alloys were fabricated and subjected to extrusion at 280°C with the ratio of 25:1. Results revealed that the addition of Gd could inhibit the dynamic recrystallization (DRX) of Mg-4Zn alloy, and both the size and volume fraction of DRXed grains demonstrated a decreasing tendency as the Gd content increased from 0.5 to 2 wt.%. It is the weakening effect on DRX behavior that lead to the smaller amount of fine precipitate and the stronger texture intensity. As compared with the Mg-4Zn alloy, the yield strength and ultimate tensile strength of Mg-4Zn-xGd alloys were improved obviously by the addition of minor content of Gd, however, at the expense of elongation. Excellent tensile properties with the yield strength of ∼369.8 MPa and ultimate tensile strength of ∼400.3 MPa were obtained when the Gd content was 2 wt.%.