中文摘要：

在熔炼过程中以单质形式加入Sb，研究了0～1．8％（质量分数，下同）范围内不同含量的Sb对Mg-3Sn-1-5Al-1Zn-1．2Si合金显微组织和力学性能的影响。结果表明，Sb能与Mg基体优先生成Mg3Sb2相，加入1．0％的Sb对Mg2Si相的汉字状结构变质作用显著，Mg2Si中的Si能与Sn发生取代反应，生成富Sn的Mg2（Si，Sn）。随着Sb的增加，铸态合金和挤压态合金的延伸率逐渐减小，而抗拉强度呈现先增加后降低的趋势，塑性和强度的最佳配合点约为1．0％，Sb含量的增加有利于改善Mg-3Sn-1-5Al-1Zn-1．2Si合金的耐热性能。

英文摘要：

The effects of Sb on microstructure and mechanical properties of Mg-3Sn-1-5Al-1Zn-1.2Si magnesium alloy were studied when Sb was added into melt in the form of pure metal with the range of 0-1.8% （mass fraction, similarly hereinafter）. The results demonstrate that Sb element and Mg matrix preferentially combine to form Mg3Sb2 phases, the addition of 1.0% Sb has a strong modification for Chinese script morphology Mg2Si phases. Sn can replace Si of Mg2Si then form Sn-rich Mg2 （Si,Sn） compound phase, whose physical properties lie between Mg2Si and Mg2Sn. With the increase of Sb content, the elongations of as-cast and extruded alloy decrease, and tensile strengths increase firstly and then decrease, a best combination of strength and plasticity was 1.0% or so. The increase of Sb was beneficial to improve the heat resistance of Mg-3Sn-1-5Al-1Zn-1.2Si alloy.