Mechanism of Ductility Enhancement of the Mg-8Gd-4Y-1Nd-0.5Si Alloy by Multi-Directional Forging Process before Extrusion

Noteworthy ductility Mg-8Gd-4Y-1Nd-0.5Si (wt.%) alloy with a strong non-basal texture was developed by 12 passes of multi-directional forging (MDF) combine with extrusion. The slip trace analysis indicated that deformation mechanism after 3 passes of MDF and extrusion were basal , pyramidal and pyramidal slips. The intensity of non-basal texture increased from 5.37 to 8.03 with the MDF passes increased from 3 to 12, which means grain orientation tends to be more consistent and makes the basal slips easy to pass through grain boundaries to accommodate ductility. With more basal slips crossing the grain boundaries, dislocation interaction in grain interior caused stress accumulation, exceeding the critical shear stress (CRSS) of slips with low schmidt factor (SF), and multiple slips appeared. The activation of slip cross grain boundary and multiple slip improved the elongation from 14.7% to 25.6% of MDFs-extruded Mg-8Gd-4Y-1Nd-0.5Si alloy. Graphical abstract