Microstructures and mechanical properties of the Mg–4.5Zn–xGd (x = 0, 2, 3 and 5) alloys

Microstructures and mechanical properties of the peak-aged Mg–4.5Zn–xGd (x = 0, 2, 3 and 5 wt.%) alloys have been investigated. The results showed that grain size increased with increasing Gd. Phase analysis showed that MgZn2 phase was observed in the Mg–4.5Zn alloy. While with Gd additions, Mg3Gd and Mg3Gd2Zn3 phases formed, and the volume fraction of the Mg3Gd2Zn3 phase increased with increasing Gd. Tensile test results indicated that the optimal mechanical properties were obtained in the Mg–4.5Zn–2Gd alloy, and the ultimate tensile strength and yield strength were 215 MPa and 121 MPa, respectively. However, the strength decreased with increasing Gd, which was mainly due to the increasing volume fraction of the Mg3Gd2Zn3 phase.