Combined effects of source hardening and activation of new slip systems on simultaneous enhancement of strength and ductility in fine-grained Mg-3Gd alloy

Yield point phenomenon often occurs in fine-grained and ultrafine-grained fcc and bcc metals, which causes a sharp increase in yield stress by source hardening but a rapid decrease in ductility due to the limited work hardening capacity. Here we report that an occurrence of yield point phenomenon in a fine-grained Mg-3Gd alloy can increase the yield stress to a level that facilities the activation of <c+a> type dislocations and their interactions with <a> type dislocations. As a result, not only the yield stress but also the tensile ductility are improved that suggests a new strategy overcoming the conventional strength-ductility trade-off.