Synergistically improved strength and ductility of dual-phase Mg-Li-Zn-Y alloy via phase regulation

• Optimizing the extrusion ratio effectively regulates the phase evolution • EBSD characterization was employed to analyze the grain evolution behavior in dual-phase Mg-Li alloys. • The needle-like nanoscale MgLiZn phase demonstrates superior strengthening effect. The dual-phase Mg-8Li-6Zn-2Y alloy was prepared by traditional hot extrusion with the extrusion ratios of 16 and 25, and the influence of extrusion ratio was investigated by microstructure and properties analysis. The results show that the second phases of Mg-8Li-6Zn-2Y alloys with different states include Mg-Li-Zn, Mg 24 Y 5, and Mg 3 Zn 3 Y 2 phases. After hot extrusion, the size and shape of the phase are changed. The eutectic W phase (Mg 3 Zn 3 Y 2 ) is broken into fine particles, and some nano MgLiZn phases precipitate in the matrix phase. With the increase of extrusion ratio, the precipitated nanophase changes from a spherical MgLiZn phase to a needle-like MgLi 2 Zn phase. Meanwhile, both the grains of α-Mg and β-Li phase gradually refine, and more dislocations are introduced. Under the synergistic effect of fine-grain strengthening, dislocation strengthening and second phase strengthening, the Mg-8Li-6Zn-2Y alloy extruded at a ratio of 25 exhibits the best comprehensive properties with a yield strength of 232 MPa and an elongation of 28 %.