Effect of Gd content on the microstructure, texture and mechanical properties of Mg-xGd-0.5Mn alloys

Abstract

In this work, we investigated the microstructure and the mechanical properties of extruded Mg-xGd-0.5Mn alloys (GMx0) with the variation of Gd content (0, 2, 4, 7 wt.%). For the GM00 alloys with no Gd content, the typical basal fiber texture (BFT) was formed, which led to similar mechanical properties to the pure Mg. However, with the dilute addition of the Gd element, the texture was transformed into ED-split texture, termed Rare Earth (RE)-texture, which improved the ductility significantly. As the Gd content increased, the texture was transformed from RE-texture to the BFT, decreasing the ductility and increasing the stretch yield strength. Furthermore, the electron backscattered diffraction (EBSD)-assisted slip trace analysis method and the Visco-Plastic Self-Consistent (VPSC) model were utilized to uncover the strain coordination mechanism variation. The results indicated that non-basal slip systems, including prismatic slip and the pyramidal slip, were activated more frequently with the increase of Gd content. The Gd addition has more excellent facilitation for the pyramidal slip than the prismatic slip. However, this promotion effect of non-basal slip systems was insufficient to compensate for the overall reduction in ductility owing to the texture change.

Keywords

• Mg-Gd-Mn alloys
• Microstructure
• Texture
• Mechanical properties
• Visco-plastic self-consistent model