Abstract:Improving the extrusion speed of Mg alloys is crucial for expanding their applications. Here we show a novel heavily alloyed Mg-8Al-0.4Zn-0.9Ca-0.2Gd-0.2Mn (AZXVM80100, wt.%) alloy having outstanding extrudability and good mechanical performance. It can be extruded at a die exit speed of 32.4 m/min without any hot cracks. The excellent extrudability is mainly attributed to the dominant presence of Al2Ca, Al2Gd and Al8Mn5 phases with high thermal stability, which did not melt despite the substantial amount of deformation heat generated during the high-speed (32.4 m/min) extrusion, avoidiing hot cracking. Meanwhile, these thermally stable Al2Ca, Al2Gd, and Al8Mn5 phases exerted a remarkable refining effect on the recrystallized grains. Besides, the as-extruded AZXVM80100 alloy displays a fully dynamic recrystallized microstructure. It has a typical basal texture and fine grains with an average grain size of 8.6±1.7 μm. Owing to the significant grain boundary strengthening, the as-extruded AZXVM80100 alloy demonstrates a high tensile yield strength of 257.4±4.1 MPa. Furthermore, the as-extruded AZXVM80100 alloy also exhibits a high elongation of 14.9±0.8%, which is dominantly coordinated by dislocation slip. The newly developed high speed extrudable AZXVM80100 alloy, containing large amounts of cheap elements (Al, Zn, Ca, Mn) and trace amounts of rare earth (Gd), has great potential in manufacturing extrusion profiles because of its good strength-ductility synergy.