熔炼制备了单独添加锰、铬以及复合添加锰铬的Al-Mg-Si-Cu系铝合金铸锭，并依次进行560 ℃×10 h均匀化退火处理、热挤压成形和T6处理（535 ℃×75 min水淬+175 ℃×10 h时效），研究了锰和铬的添加对合金显微组织与拉伸性能的影响。结果表明：在均匀化退火过程中，锰或铬会置换Al-Fe-Si相中的部分铁原子，促进杆状β-Al₉Fe₂Si₂相向颗粒状α-Al₈Fe₂Si相转变，从而在组织中形成α-Al₈（FeMn）₂Si，α-Al₈（FeCr）₂Si或α-Al₈（FeMnCr）₂Si相；T6处理后，与单独添加铬的相比，单独添加锰后试验合金晶内针状β″相较少，晶界附近的亚微米级相数量较多；与未添加锰铬的相比，单独添加锰、铬或复合添加锰铬后试验合金的强度和伸长率提高，拉伸断裂形式均为韧性断裂，且复合添加质量分数0.10%锰和质量分数0.15%铬时的拉伸性能最优。

Al-Mg-Si-Cu aluminum alloy ingots with separate addition of Mn, Cr and composite addition of Mn and Cr were prepared by smelting, and then subjected to homogenizing annealing at 560 ℃ for 10 h, hot extrusion forming and T6 treatment (holding at 535 ℃ for 75 min and water quenching+aging at 175 ℃ for 10 h), in sequence. The effects of Mn and Cr additions on microstructure and tensile properties of the alloy were studied. The results show that during homogenizing annealing, Mn or Cr displaced some iron atoms in Al-Fe-Si phase and promoted transformation of rod-like β-Al₉Fe₂Si₂ phase to granular α-Al₈Fe₂Si phase, resulting in the formation of α-Al₈(FeMn)₂Si, α-Al₈(FeCr)₂Si or α-Al₈(FeMnCr)₂Si phase in structure. After T6 treatment, compared with the alloy added of Cr, the alloy with addition of Mn had less acicular β" phases in grains and more sub-micron phases near grain boundaries. Compared with those without addition of Mn and Cr, the strength and elongation of the alloy with separate addition of Mn, Cr and composite addition of Mn and Cr were improved; the tensile fracture modes were all ductile. After composite addition of 0.10wt% Mn and 0.15wt% Cr, the tensile properties were the best.