High strength Mg-9Al serial alloy processed by slow extrusion

The AZ91-0.5Ca alloy was extruded at 250 degrees C with slow extrusion speed (0.03, 0.3, 3 mm/s) in the current study. The results showed that both the volume fraction and average grain size of DRXed grains increased with the increase of extrusion speed. Furthermore, numerous fine Mg17Al12 phase were observed in the DRXed regions of the extruded alloys, the amount of which decreased by increasing extrusion speed. The decrease of extrusion speed led to the improvement of yield strength and ultimate tensile strength, however, at the expense of elongation. As the extrusion speed decreased to 0.03 mm/s, the yield strength, ultimate tensile strength and elongation of present alloy were similar to 347.8 MPa, similar to 402.2 MPa and similar to 9.1%, respectively, which were superior to the present commercial Mg-Al serial alloys. Detailed reasons are given and analyzed.