Extraordinary Bending Formability of Mg–2.5Nd–0.5Zn–0.5Zr Alloy Sheet Through Pulsed Current

The pulsed current effect on the bending formability and microstructure evolution of the Mg–2.5Nd–0.5Zn–0.5Zr (wt%) alloy sheet was systematically studied at near room temperature (20 ~ 45 ℃). The results showed that the bending ability of the alloy could be significantly improved by the pulsed current. Specifically, compared with the non-electrically-assisted bending, the limiting bending depth (from 5.05 to 14.82 mm) and limiting bending angle(from 57 to 145°) of the alloy were increased by 193.5% and 154.3%, respectively, and the bending yield strength (from 252 to 162 MPa) decreased by 35.7%. When the peak current density was 12.1 A/mm² (EA12), the limiting bending angle reached 145°, and there was no crack on the outer surface of the bending sample. The main reason was that the pulsed current promoted the dislocation movement, which was conducive to the activation of basal slip and non-basal slip to maintain deformation compatibility. The deformation mechanism of electrically-assisted bending samples showed that {10–12} twin dominated in the compression zone, while basal slip dominated in the tension zone. In addition, the effects of peak current density on microstructure, texture evolution and fracture mechanism were analyzed in detail. It provided important theoretical guidance for mastering the bending-forming mechanism of rare-earth magnesium alloys.