Achieving extraordinary thermal stability of fine-grained structure in a dilute magnesium alloy

IMPACT STATEMENT By achieving extraordinary fine-grain thermal stability under high-temperature solid-solution treatment, appreciable bake-hardenability along with fine-grained structure are obtained simultaneously to ensure the development of dilute Mg alloys with high strength. High-temperature solid-solution is indispensable for bake-hardenable dilute Mg alloys, which generally induces grain coarsening. Herein, we report extraordinary thermal stability in a bake-hardenable dilute Mg-1.61Zn-0.57Mn-0.54Ca-0.46Al (wt. %, ZMXA2110) alloy, maintaining fine-grained structure at 450 degrees C. The thermal stability is stemmed from the Zener pinning effect of dense fine (similar to 15.0 nm) core-shell beta-Mn particles and co-segregation of Zn and Ca at grain boundaries. The fine-grained (similar to 3.2 mu m) dilute alloy exhibits high room-temperature formability in solid-solution condition with an Index Erichsen value of similar to 6.0 mm, and impressive yield strength of similar to 293 MPa with an evident increment of similar to 60 MPa by bake-hardening treatment.