An effective twin‐roll casting path omitting solution treatment to achieve high‐performance Mg sheets via Sc addition

Abstract A long‐time solution treatment is indispensable to eliminate the centerline segregation of twin‐roll casting (TRC) magnesium (Mg) alloys, which greatly limits the preparation efficiency of Mg sheets. In this work, we find that the addition of 0.2 wt% Sc to Mg–1Zn–0.2Ca–0.2Mn (wt%) alloy can effectively inhibit the centerline macro‐segregation of TRC and refine the microstructure. This optimization allows the omission of solution treatment prior to final rolling. After the hot‐rolling and annealing process, we surprisingly find that the non‐solution‐treated sample (~ 225 MPa) even exhibits a ~ 24 MPa higher yield strength than that of the solution‐treated counterpart (~ 201 MPa), while maintaining a similar ductility (~ 20%). The increased yield strength of the non‐solution‐treated sample results from a high density of nanoscale MgZn 2 phases that precipitated during the hot rolling and annealing process, which are absent in the solution‐treated counterpart. This phenomenon is ascribed to the residual dislocations and twins retained by the TRC process, providing nucleation sites and accelerating diffusion for the precipitation of MgZn 2 phase. Our work presents an approach for short‐process production of high‐performance Mg alloy sheets.