对Mg-3Al-0.8Gd合金进行了压缩变形及半固态等温热处理，研究了压缩变形量（10%，15%，20%）、等温温度（530，540，550，560，570 ℃）及保温时间（3，5，10，15 min）对该合金显微组织与硬度的影响，并对比了铸态和热处理态Mg-3Al-0.8Gd合金的拉伸和冲击性能。结果表明：不同条件压缩变形及等温热处理后，Mg-3Al-0.8Gd合金组织均由α-Mg基体和β-Mg₁₇Al₁₂相组成；随着等温温度、保温时间及压缩变形量的增加，合金中的α枝晶逐渐转变为等轴晶，晶粒细化，组织均匀性提高，同时显微硬度增大；压缩变形20%并经550 ℃保温15 min热处理后，Mg-3Al-0.8Gd合金的抗拉强度、断后伸长率、断面收缩率和冲击吸收能量较其铸态合金的分别提高了11.3%，32.6%，3.8%和23.3%。

Compression deformation and semi-solid isothermal heat treatment of Mg-3Al-0.8Gd alloy were carried out. The effects of the compression deformation (10%,15%,20%), isothermal temperature (530,540,550,560,570 ℃) and holding time (3,5,10,15 min) on the microstructure and hardness of the alloy were studied. The tensile and impact properties of as-cast and heat-treated Mg-3Al-0.8Gd alloys were compared. The results show that the microstructures of Mg-3Al-0.8Gd alloy after compression deformation and isothermal heat treatment under different conditions were all composed of α-Mg matrix and β-Mg₁₇Al₁₂ phase. With the increase of compression deformation, isothermal temperature and holding time, the α dendrites were gradually transformed into equiaxed grains, the grains were refined, the structure uniformity was improved, and the microhardness increased. The tensile strength, elongation after fracture, section shrinkage and shock absorption energy of Mg-3Al-0.8Gd alloy with compression deformation of 20% after isothermal treatment at 550 ℃ for 15 min were 11.3%, 32.6%, 3.8% and 23.3% higher than those of the as-cast alloy, respectively.