中文摘要：

在熔炼时以单质形式加入Sb元素,研究了不同含量的Sb对Mg-5Sn-2Al-1.5Zn-0.8Si合金显微组织和力学性能的影响。结果表明,Sb能与Mg基体结合生成Mg3Sb2相。加入0.9%（质量分数）的Sb对Mg2Si相的汉字状结构具有强烈变质作用,Mg2Si中的Si能与Sn发生取代作用,生成Mg2（Si,Sn）复合相,该相的物理性能介于Mg2Si与Mg2Sn之间。随着Sb含量的增加,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。挤压态合金的强度和塑性明显优于铸态合金,并且Sb含量的增加有利于改善Mg-5Sn-2Al-1.5Zn-0.8Si合金的耐热性能。

英文摘要：

The effects of stibium element on microscopic structure and mechanical properties of Mg-5Sn-2Al-1.5Zn-0.8Si magnesium alloy were studied when Sb was added into melt in the form of pure metal. The results indicate that Sb element and Mg matrix combine to form Mg3Sb2 phases. The addition of 0.9% Sb has a strong modification for Chinese script morphology of Mg2Si phases. Sn can replace Si of Mg2Si phase to form Mg/（Si,Sn） composite phases, whose physical properties lie between Mg2Si and Mg2Sn. With the increase of Sb content, the elongations of the as-cast alloy and the extruded gradually decrease, while tensile strengths increase firstly and then decrease. Strength and plasticity of the extruded alloy are better than that of the cast alloy, and the increase of Sb content is beneficial to improve the heat resistance of Mg-5Sn-2Al-1.5Zn-0.8Si alloy.