Corrosion behaviors of hot-extruded Mg96Y2Zn2 alloy in transverse and longitudinal directions: Guidance for parameters selection

The hot-extruded Mg alloys containing long period stacking ordered (LPSO) phase suffered from the difference of corrosion behavior between transverse and longitudinal sections. To fathom out the mechanism of the difference and improve the overall corrosion resistance, the extruded Mg96Y2Zn2 alloys are prepared through different ram speed. Dynamic recrystallization was achieved in extruded Mg96Y2Zn2 alloys and the LPSO phases were elongated along the extrusion direction (ED). The results indicates that the basal texture can be strengthened by increasing the ram speed, since the volume fraction of dynamically recrystallized (DRXed) grains is reduced. As a result of the extruded Mg96Y2Zn2 alloys did not undergo passivation during corrosion, the decrease in grain size led to an increase in corrosion rate. The peeling off of LPSO strips with larger size caused more serious damage to the alloys. The existence of texture and huge LPSO strips lead to the difference of corrosion properties in the two directions. Therefore, larger DRXed grains with a higher volume fraction and finer scaled LPSO strips are beneficial to the corrosion properties of extruded Mg96Y2Zn2 alloys. Parameters have the same effects as low ram speed are conducive to improve corrosion resistance. (C) 2022 Elsevier B.V. All rights reserved.