Effect of Sm on Microstructures and Mechanical Properties of Mg-10Gd-0.5Zr Alloy

Mg-10Gd-0.5Zr alloys with 1wt%similar to 5wt% Sm addition were prepared by a melting and casting method. The effect of Sm on microstructures and mechanical properties were investigated by tensile tests, SEM and XRD. The results show that the Mg41Sm5 phase is found because of Sm addition, and Sm promotes the precipitation of Mg5Gd. After solution-aging treatment, the coarsening eutectic structures at grain boundary are dissolved and the precipitation disperses homogeneously. The finer grain size is observed when the content of Sm comes to 3wt%. Some of Mg5Gd phase become short rod-like when Sm addition is 5wt%. At the same experimental temperature, the strength of tested alloys increases at first and then decreases, and the peak strength appears when the content of Sm is 3wt%. For the same alloy, with increasing of test temperature, the strength increases at first and then decreases too. When the Sm content is 0 similar to 1wt%, the temperature of tensile strength peak is 200 degrees C while when Sm content is 3wt%similar to 5wt% the temperature is 250 degrees C. There is an abnormal temperature effect in tensile tests; the Sm addition reinforces the effect and increases the temperature of tensile strength peak.