Effects of Cu on Mechanical and Corrosion Properties of Mg-8Al-3Li Alloy

In order to design soluble magnesium alloys for shale gas exploitation, Mg-Al-Li-Cu alloys with different compositions were prepared by vacuum induction melting-argon protection method, and the extrusion ratio wass 16∶1 at 350 ℃.Using X-ray diffractometer, optical microscope and scanning electron microscope, the influence of Cu content on structure,mechanical and corrosion properties of the alloy was studied. The results show that Mg-8Al-3Li-x Cu alloy is mainly composed of α-Mg, Mg₁₇Al₁₂, and MgAlCu phases, and with the increase of Cu content, the amount of MgAlCu phase increases, and the amount of(α-Mg +Mg₁₇Al₁₂) eutectic decreases. Both the(α-Mg +Mg₁₇Al₁₂) eutectic and MgAlCu phase have a certain strengthening and corrosion promotion effect, and the effect of MgAlCu phase is relatively more obvious. When Cu content is about 2wt%, the alloy corrosion rate is fastest, the tensile strength（326 MPa） is highest, and the elongation is greater than 10%, that is, the overall performance is best.