The microstructure and mechanical properties of as-extruded Ca-containing Mg–6Zn–3La alloys

Effects of Ca additions (0, 0.3 and 0.5 wt%) on the microstructure and mechanical properties of the as-extruded Mg–6Zn–3La alloys are investigated by OM, XRD, SEM, TEM and tensile testing. With the addition of Ca, a small number of Ca atoms is dissolved in Mg–Zn–La phase, fine Ca₂Mg₆Zn₃ particles with diameter of 50–150 nm are also found in the Ca-containing Mg–6Zn–3La alloys. These precipitates can inhibit growth of the dynamic recrystallization grains during extrusion, which play an important role on the improvement of yield strength. The ultimate tensile strength, yield strength and elongation of the as-extruded Mg–6Zn–3La–0.5Ca alloy are 357 MPa, 345 MPa and 13%, respectively. Compared with the Ca-free alloy, the ultimate tensile strength, yield strength and elongation are improved by about 37%, 53% and 24% respectively. (paper)