Effects of Zn on the microstructures and mechanical properties of Mg-3Sm-0.5Gd-xZn-0.5Zr (x = 0, 0.3 and 0.6) alloy

The effect of Zinc (Zn) additions (0, 0.3, and 0.6 wt.%) on the microstructure and mechanical properties of Mg-3Sm-0.5Gd-0.5Zr (wt.%) alloy has been investigated by optical microscopy, scanning electron microscope, X-ray diffraction and transmission electron microscopy. The peak-aged Mg-3Sm-0.5Gd-0.3Zn-0.5Zr alloy exhibits an good ultimate strength, of above 270 MPa. The plate precipitates β′ are formed on the prismatic plane of the matrix in peak-aged state, which contributes to the strengthening of the alloy. The peak-aged Mg-3Sm-0.5Gd-0.6Zn-0.5Zr alloy precipitates basal plane phase γ, which has a bad effect on the mechanical property.