对比研究了未变质、锶变质、硼变质、锶和硼复合变质对铸态与T6态Al-6Si-3Cu-0.3Mg合金组织与力学性能的影响；考察了复合变质条件下，锶含量（0.025%，0.050%，0.075%，质量分数）对合金组织与力学性能的影响。结果表明：锶变质、硼变质、锶和硼复合变质均可细化铸态与T6态合金组织，提高其抗拉强度，其中复合变质效果最为显著；与未变质处理合金的相比，复合变质铸态合金的抗拉强度和伸长率分别提高了3.71%和13%，T6态合金的抗拉强度提高了33.6%，但伸长率降低了41.9%；复合变质条件下，随着锶含量的增加，铸态合金中初生α-Al粗化，抗拉强度总体变化不大；T6态合金中共晶硅平均长度随锶含量增加先减小后增大，抗拉强度逐渐升高；锶含量为0.025%，共晶硅尺寸最小，复合变质合金塑性最好。

Effects of strontium modification, boron modification, and compound modification of strontium and boron on microstructure and mechanical properties of as-cast and T6 state Al-6Si-3Cu-0.3Mg alloys were studied. Effects of strontium content (0.025wt%,0.050wt%,0.075wt%) on microstructure and mechanical properties of the alloys after compound modification were also studied. The results show that strontium modification, boron modification, and compound modification of strontium and boron all could refine the structure and improve the tensile strength of as-cast and T6 state alloys, and the effect of compound modification was the most remarkable. The tensile strength and elongation of as-cast alloy increased by 3.71% and 13%, respectively, compared with that of the modified alloy, and the tensile strength of T6 state alloy increased by 33.6%, but the elongation decreased by 41.9%. Under the compound modification condition, the primary α-Al was coarsened in the as-cast alloy with increasing strontium content, and the overall tensile strength did not change much. The average length of eutectic silicon in T6 state alloy decreased first and then increased with the increase of strontium content, and the tensile strength gradually increased. When the strontium content was 0.025wt%, the eutectic silicon size was the smallest, and the compound modified alloy showed the best plasticity.