Anomalous ductility-strength synergy occurred after cold rolling in a high Gd content Mg alloy

Abstract

During cold rolling in magnesium (Mg) alloys, there will always be serious ductility deterioration, which greatly restricts the application of this processing method. In this work, ductility-strength synergy occurred after cold rolling was carried out on a 〈0001〉 fiber textured Mg-17.5Gd-Zr alloy (wt.%). The ductility-strength synergy can be mainly attributed to texture randomization, microstructure refinement, and easier basal slip transfer condition in the twinned grains. Firstly, the activation of multiple twinning behaviors, i.e., {10−12}, {10−11}, and {11−21} twinning, and related twin-twin interaction restrict the formation of strong basal texture and facilitate the texture randomization. Secondly, profuse high-angle grain boundaries form through dislocation-twin interaction, twin-twin interaction, and dislocation interaction, which promote microstructure refinement. Thirdly, the basal slip transfer becomes easier in the twinned grains owing to the activation of multiple twinning behaviors and their impingements. Activation of {11−21} twinning and 〈c + a〉 dislocations and the 〈0001〉 fiber texture which is favorable for multiple twinning activating during cold rolling are considered to be the key roles for microstructure and texture optimization.