Microstructure and mechanical properties of a compound reinforced Mg95Y2.5Zn2.5 alloy with long period stacking ordered phase and W phase

The microstructure evolution of Mg100-2xYxZnx (x=2, 2.5, 3, 3.5) alloys was investigated. Results showthat the Mg100-2xYxZnx alloys are composed of α-Mg, long period stacking ordered (LPSO) phase and eutecticstructure phase (W phase), and the Mg95Y2.5Zn2.5 alloy has the best comprehensive mechanical properties.Subsequently, the microstructure evolution of the optimized alloy Mg95Y2.5Zn2.5 during solidification and heattreatment processes was analyzed and discussed by means of OM, SEM, TEM, XRD and DTA. After heattreatment, the lamellar phase 14H-LPSO precipitated in α-Mg and W phase transforms into particle phase (MgYZn2).Due to the compound reinforcement effect of the particle phase and LPSO phase (18R+14H), the mechanicalproperties of the alloy are enhanced. The tensile strength and elongation of the Mg95Y2.5Zn2.5 alloy is improved by9.1% and 31.3% to 215 MPa and 10.5%, respectively, after solid-solution treatment.