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研究了3.5％,5％,6.5％,8％和10％(质量分数)Zn含量铸轧Al-Zn-Mg-Cu合金的宏观裂纹和微观组织.结果表明:Zn含量由10％减少至5％时,铸轧条带的宏观裂纹数量明显降低;但当Zn含量由5％减少至3.5％时,裂纹数量减少十分有限.铸轧条带显微组织从表层到中心呈柱状晶向等轴晶的转变.随着Zn含量的增加,铸轧板中心低熔点共晶相偏聚带变宽,粗大非平衡共晶相数量增多,偏析加重.在高Zn含量(10％)的铸轧条带组织中有明显的孔洞存在.“,”The microstructure and macroscopic cracks of five twin-roll casted Al-Zn-Mg-Cu alloys strips with various Zn contents(3.5wt％,5wt％,6.5wt％,8wt％,and 10wt％)were investigated.The results show that the macroscopic cracks of strips decrease in numbers as the Zn content decreases from 10wt％to 5wt％,while this decrease is inhibited as the Zn content continuously decreases from 5wt％to 3.5wt％.The microstructure shows a transition from columnar crystals to equiaxed crystals along the surface to the center of the cast strip.The center segregation band of the cast strips becomes wider and the non-equilibrium coarse eutectic phases increase in amount as the Zn content increases in these Al-Zn-Mg-Cu strips.Unsolidified liquid phases and holes appear in the microstructure of strips with 10wt％Zn.