Cold rollability improvement by twinning and twin-slip synergy in an Mg-Zn-Gd alloy with rare earth texture

In this study, the Mg-2.0Zn-0.8Gd (wt%) alloy with rare earth (RE) texture was successfully cold-rolled in a single-pass rolling with 35% reduction without edge cracks. The microstructure and texture evolutions were minutely examined to reveal the deep reason for the higher cold rollability than commercial AZ31 alloy. Several {10-12} extension twins were found to be activated due to the RE texture. The {10-12} extension twinning that occurred in parent grains with orientation tilted toward one side of the transverse direction (TD) could reverse the orientation to another side of TD, i.e., from +TD to -TD or from -TD to +TD, which partially resulted in the stability of RE texture component. Complex twin types, including {10-12}-{10-12} secondary extension twin, {10-11}-{10-12} double twin, and even the coexistence of extension twin with contraction twin or double twin were found. Basal and prismatic slips, were extensively activated during the cold rolling process due to the RE texture and Gd alloying. The synergy effect of various types of twinning and multiple dislocation slip, which postponed the shear banding, was the major cause of the high cold rollability. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study revealed that the RE texture played a crucial role in enhancing the cold rollability of the Mg-2.0Zn-0.8Gd alloy, by activating various twinning and dislocation slip types to delay shear banding and improve the cold rollability of the alloy.