Synergistic improvement in mechanical properties of Mg–Zn–Y alloys with Mille–Feuille structure by prestrain introduction and grain refinement

In this study, we attempted to enhance the mechanical properties of the Mille–Feuille (MF)-type Mg–0.4Zn–1.0Y (at.%) alloy prepared by a conventional casting technique. Previous studies have shown that extruded MF-type Mg–0.4Zn–1.0Y (at.%) alloys prepared by rapid solidification exhibit high cluster-arranged nanoplate (CANaP) dispersion, resulting in numerous kinks and demonstrating excellent yield strength with moderate ductility. In contrast, the extruded MF-type Mg–0.4Zn–1.0Y (at.%) alloy produced by casting exhibits low CANaP dispersion, resulting in reduced kink deformation and significantly inferior mechanical properties. CANaPs form owing to the enrichment of L1 2 clusters (Zn 6 Y 8 ) on stacking faults. Therefore, introducing strain before aging treatment is expected to promote CANaP formation. The extruded MF-type Mg–0.4Zn–1.0Y (at.%) alloy with 10% precompression exhibited an approximately 1.7 times increase in the dispersion of CANaPs, increasing kink boundary dispersion. As a result, the extruded MF-type Mg–0.4Zn–1.0Y (at.%) alloy subjected to 10% precompression exhibited a yield strength of 359 MPa and an elongation of 6%. The extruded MF-type Mg–0.4Zn–1.0Y–0.1Zr (at.%) alloy subjected to 10% precompression exhibited a yield strength of 388 MPa and an elongation of 7.2%, demonstrating mechanical properties comparable to those of MF-type alloys produced by rapid solidification. • Precompression before aging treatment helped promote the formation of CANaPs. • The extruded Mg–Zn–Y alloy with 10% precompression exhibited a yield strength of 359 MPa. • With Zr addition, area fraction of high-KAM-region in α-Mg grains increased after precompression. • The extruded Mg–Zn–Y–Zr alloy with precompression exhibited a yield strength of 388 MPa.