Effect of gadolinium on the deformation and recrystallization behavior of magnesium crystals

Single crystals of pure Mg and Mg-0.8 wt% Gd alloy oriented for non-basal slip were deformed in plane strain compression at room and elevated temperatures to investigate activation of prismatic and pyramidal 〈c+a〉 slip in both materials. Compression along the c-axis of Mg–Gd single crystals revealed no marked improvement in room temperature ductility compared to pure Mg because there was no noticeable increase in 〈c+a〉 slip activity. At room temperature, Mg–Gd single crystals fractured along {112¯4} planes, which was the same fracture habit for pure Mg. Compression perpendicular to the c-axis, where specimens were favorably aligned for prismatic slip, exhibited cooperative extension/compression twinning and no notable increase in prismatic slip activity. Although the addition of Gd did not promote activation of non-basal slip, it had a significant impact on continuous dynamic recrystallization. It is concluded that the improved formability in polycrystalline Mg–Gd alloys must be primarily attributed to a change in recrystallization behavior and its effect on texture, rather than the activation of additional slip modes.