Comparison of room-temperature stretch formability of the as extruded Mg-Gd alloys with different double-peak pole spacing

This paper focused on the effect of angle a that the basal poles tilted from normal direction (ND) toward the extruded direction (ED) on the formability of as-extruded Mg-2Gd (wt.%) alloy sheets. The studied Mg-2Gd (wt%) alloy sheets with the angle alpha of 23 degrees, 32 degrees and 45 degrees, respectively, were designed. The Erichsen test was carried out at the ambient temperature, in which the microstructure and texture evolution was characterized by the electron backscatter diffraction (EBSD) technique. The results showed that the strain coordination ability of the Mg-2Gd sheet along the thickness direction was enhanced with the increase of angle alpha, giving rise to a higher Index Erichsen (IE) value of 7.5 mm for the alpha of 45 degrees due to a lower gamma-value. This superior high formability is not only closely associated with the lower gamma-value but also with the higher Schmid factors for basal slip (SFbasal) in the large-angle alpha alloy sheets. Furthermore, the twinning induced a more random distribution along the transverse direction (TD) of basal texture in the early stage of the Erichsen test, which cancels out the SF b asa l reduction effect caused by the activation of basal slip. The TDextended twinning texture provided a softer orientation for the TD strain during the Erichsen test, such that excellent formability was achieved in the alloy sheets with a larger angle alpha. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

This study focused on the effect of the angle a on the formability of extruded Mg-2Gd alloy sheets. The results showed that with the increase of angle alpha, the strain coordination ability along the thickness direction was enhanced, leading to a higher Index Erichsen value. This superior formability is attributed to both the lower gamma-value and higher Schmid factors for basal slip in the large-angle alpha alloy sheets.