Effect of Ca addition on the microstructure and tensile properties of Mg–4.0Zn–2.0Gd alloys

In this paper, the Mg–4.0Zn–2.0Gd alloys with 0%, 0.1%, 0.2%, 0.5% and 1.0 wt% Ca were fabricated. Subsequently, they were extruded at 573 K with the ratio of 16:1. The results indicate that the addition of Ca element has a significant effect on grain size, precipitated phase and the Mg content in W-phase. After extrusion, the grains are refined and the large precipitates in as-cast state are cracked to fine and dispersive particles. All these changes are helpful to the improvement of tensile properties. The Ca content has different effects on the tensile properties of the as-cast and as-extruded alloys, and the reasons are given. Dimples appear on the fracture surface of as-extruded alloys, the size and amount of the dimples increase with increasing Ca content.