Microstructure and Mechanical Property of the Large Cross-Sectioned Mg–Gd–Y–Zn–Zr Alloy Produced by Small Extrusion Ratio

Abstract

In this work, the microstructure and mechanical properties of large cross-sectioned Mg–9Gd–3Y–1.2Zn–0.5Zr (VWZ931) samples produced by the small extrusion ratio has been investigated. The as-extruded VWZ931 sample with diameter of ~ 30 mm can exhibit the high yield strength (YS) of 339 MPa, ultimate tensile strength (UTS) of 387 MPa and elongation of 8.2%, respectively. After peak-aged, the YS and UTS of the Mg samples were significantly increased to 435 MPa and 467 MPa. The small extrusion ratio leads to the low fraction of dynamic recrystallized (DRX) grains in VWZ931 sample, and the texture hardening effect can be fully utilized to achieve high strength. The combined effect of precipitation strengthening due to the long-period stacking ordered phases and the \(\beta\)′ phase, grain boundary strengthening due to the fine DRX grains, heterogeneous deformation-induced strengthening caused by bimodal microstructure, can together contribute to the high strength of present Mg alloy. The findings can shed light on designing other large-sized Mg wrought alloys with high mechanical performance.