On the Microstructure and Mechanical Properties of Mg-Gd Alloy with Combined Zn and Ca Addition

The effects of combined addition of Zn and Ca to Mg-1Gd alloy (Mg-1Gd-1.5Zn-1Ca wt.%) on its microstructure and mechanical properties were studied. The results showed that the fine and coarse Mg 2 Ca and Ca 2 Mg 6 Zn 3 phase particles were formed in the matrix by the combined additions of Zn and Ca. A drastic refinement of dynamic recrystallized grains was observed in the extruded Mg-1Gd-1.5Zn-1Ca alloy sheet. A remarkable yield strength enhancement and minor ductility decrement have been observed, where strength remarkably increases from 73 to 153 MPa along ED and from 119 to 182 MPa along TD and the ductility decreases from 25.1 to 18.8% along ED and from 13.6 to 9.8% along TD. The SEM and TEM analysis showed that the formed high-density fine Mg 2 Ca and Ca 2 Mg 6 Zn 3 particles and the co-segregations of Ca and Zn in grain boundaries led to the fine structure and the strength enhancement.