研究固溶态和挤压态Mg?xLi?3Al?2Zn?0.5Y(x=4,8,12,质量分数,％)合金的显微组织和腐蚀行为.结果表明,当锂含量从4％增加到12％,合金基体由α-Mg单相转变为α-Mg+β-Li双相,再转变为β-Li单相.Mg?4Li?3Al?2Zn?0.5Y和Mg?12Li?3Al?2Zn?0.5Y合金具有晶间腐蚀和点蚀的混合腐蚀特征,前者与沿晶界析出的AlLi相有关,后者与第二相与基体之间的高电位差有关.挤压态合金的耐蚀性优于固溶态合金.挤压态Mg?8Li?3Al?2Zn?0.5Y合金具有最低腐蚀速率(P W=(0.63±0.26)mm/a),主要归因于该合金的第二相分布更均匀、通过牺牲β-Li相形成的保护性α-Mg相和相对完整的更均匀分布的氧化膜.“,”The microstructure and corrosion behavior of the as-homogenized and as-extruded Mg?xLi?3Al?2Zn?0.5Y alloys (x=4, 8, 12, wt.％) were studied. The results show that as the Li content increases from 4％ to 12％, the matrix transfers from single α-Mg phase, (α-Mg+β-Li) dual phase to single β-Li phase. A mixed corrosion feature of intergranular corrosion and pitting corrosion occurs in the Mg?4Li?3Al?2Zn?0.5Y and Mg?12Li?3Al?2Zn?0.5Y alloys. The former is related to the precipitated AlLi phase along the grain boundaries, and the latter is related to the high potential difference between the second phase and the matrix. The corrosion resistance of the as-extruded alloys is better than that of the as-homogenized alloys. The superior corrosion resistance of the as-extruded Mg?8Li?3Al? 2Zn?0.5Y alloy with the lowest corrosion rate (P W=(0.63±0.26) mm/a) is attributed to the more uniform distribution of second phases, the protective α-Mg phase via sacrificing the β-Li phase and the relatively integrated oxide film.