采用普通压铸和真空压铸工艺制备了铁和镁含量不同的铝硅合金, 并对它们进行固溶和时效热处理, 研究了铁、镁含量对普通压铸合金组织和拉伸性能的影响, 以及热处理对真空压铸合金拉伸性能及断口形貌的影响。结果表明：当铝硅合金中镁的质量分数为0.55%时, 铁的质量分数不能超过0.60%, 否则过量的铁易生成针片状Al9Fe2Si2相, 该相会恶化合金的拉伸性能; 镁元素的添加能使针片状Al9Fe2Si2相转变为Al8Mg3FeSi6相, 在一定程度上消除铁元素的有害影响, 提高合金的拉伸性能; 辅以真空条件可使压铸合金的抗拉强度提高12%, 热处理可使真空压铸合金的抗拉强度提高26.17%。

Al-Si alloys with different contents of Fe and Mg were prepared by conventional and vacuume die casting processes, and then solid solution and aging heat treatment of the alloys were completed. The effects of Fe and Mn contents on microstructure and tensile properties of coventional die-casted alloys, and heat treatment on tensile properties and fracture of vacuume die-casted alloys were studied. The results show that when mass fraction of Mg in Al-Si alloys was 0.55%, mass fraction of Fe must not exceed 0.60%, otherwise flaky Al9Fe2Si2 phase would generate easily because of excess Fe content, this phase was bad to mechanical properties of the alloys. Adding Mg could make flaky Al9Fe2Si2 phase turned to Al8Mg3FeSi6 phase, which could remove harmful effects of Fe to some extent and improve tensile properties of the alloys. Tensile strength of the die-casted alloys increased by 12% under vacuume die-casting condition, and heat treatment could make the tensile strength of vacuum die-casted alloys increase by 26.17%.