Significant improvement in mechanical properties of Mg-Zn-La alloy by minor Ca addition

The microstructure and mechanical properties of a Mg-Zn-La alloy with and without Ca were investigated in the present study. Results indicated that small addition of Ca in Mg-Zn-La alloy induced the formation of Ca2Mg6Zn3 phase distributing at grain boundaries in the as-cast state and promoted dynamic precipitation in the as-extruded state. The existence of fine precipitates postponed dynamic recrystallization and refined dynamically recrystallized (DRXed) grains for Ca containing alloy. However, small addition of Ca did not affect the texture of the as-extruded Mg-Zn-La alloy obviously. The yield strength was increased by 70% after minor Ca addition from 141 MPa of the as-extruded Mg-Zn-La alloy to 241 MPa of the as-extruded Mg-Zn-La-Ca alloy. The significant increase of strength was mainly ascribed to refined microstructure and dynamic precipitates.