Effects of different amounts of AlCa2 addition on the microstructure and mechanical properties of Mg-Gd-Zn alloy

In this work, the microstructure and mechanical properties of Mg96.5Gd2.5Zn1 alloys containing different contents AlCa2 (0, 0.1 and 0.5 wt%) have been investigated. The results show that a small amount of AlCa2 addition promotes the formation of 18R-LPSO structure while inhibites that of (Mg, Zn)3Gd eutectic structure in as-cast alloys. With 0.5 wt% AlCa2 addition, the eutectic structure have been almost entirely transformed into 18R-LPSO structure in the as-cast state, and the as-extruded alloy exhibits the optimal combined mechanical properties with the ultimate tensile strength of 360 MPa and the elongation of 7.1% due to the grain refinement of α-Mg matrix phase and the delamination and bending deformation of abundant 18R-LPSO strips along the extrusion direction.