The effects of the extrusion speed on the microstructures,mechanical properties and aging hardening behaviors of Mg—9Gd—3Y—1.5Zn—0.8Zr alloy have been investigated.The microstructure evolution during hot extrusion has also been discussed.The microstructures of the extruded alloys mainly consist of the equiaxed dynamically recrystallized grains and fiber-like long period stacking ordered(LPSO)phase.The increasing extrusion speed results in grain coarsening and the mechanical properties deterioration.Meanwhile,it could also retard the aging hardening response.The extrudability of the investigated alloy is limited.Cracks nucleate and grow up rapidly when the extrusion speed is over 0.3 m/min.It should be closely related to the large amount of LPSO phase and the unique microstructure evolution.The rapidly precipitating fine lamella during extrusion could pin the dislocations and grain boundaries effectively.It could strengthen the alloy but also limit the extrudability of the investigated alloy.
Xuan LiuZhiqiang ZhangWenyi HuQichi LeLei BaoJianzhong Cui
