采用热顶直冷半连续铸造法制备了一种Zn元素含量达9．6％（质量分数）的Al‐Zn‐M g‐Cu系铝合金。利用金相显微镜、透射电镜进行微观组织观察，采用差热分析仪测试相转变温度。测试了硬度、拉伸性能并利用扫描电镜进行断口分析。表明：铸锭的铸态组织细小，晶间共晶相较少，共晶相的熔化温度为473．4℃。铸锭的均匀化工艺为465℃／24h ，经均匀化处理后，晶界变为断续状，晶界相明显回溶。通过挤压法制备合金棒材，系统研究挤压棒材在不同温度下的单级和三级时效硬化曲线。表明在135℃／12h的单级时效制度下，合金挤压棒材的峰值硬度为197．7HBS ，抗拉强度、屈服强度和伸长率分别为727．5，718．0M Pa和9．3％；在120℃／24h＋190℃／5min＋135℃／3h的三级时效制度下，合金挤压棒材的峰值硬度为204．7HBS ，抗拉强度、屈服强度和伸长率分别为764．0，749．0MPa和7．2％。
A kind of Al‐Zn‐Mg‐Cu alloy containing 9 .6% (mass fraction) Zn element was produced by the Hot‐top semi‐continuous DC casting technology .The microstructure of the alloy and the tempera‐ture of phases transformation were investigated by optical microscopy (OM ) ,transmission electron mi‐croscopy(TEM) and differential scanning calorimetry (DSC) respectively .The hardness and tensile properties of the alloy were tested ,and the fracture was studied by scanning electron microscopy (SEM ) .Results show that the as‐cast microstructure of this alloy is fine and has less intergranular eu‐tectic phases ,with the melting temperature of 473 .4℃ .Therefore ,the homogenization heat‐treat‐ment is 465℃/24h . After the homogenization heat‐treatment , the grain boundary of the ingot has turned to be intermittent and the phases have dissolved significantly .Besides ,the systematic experi‐ments were conducted on the T6 and RRA of this alloy after extrusion .The results show that on the condition of 135℃/12h treatment ,the highest hardness is 197 .7HBS ,and the tensile strength ,yield strength ,elongation are 727 .5 ,718 .0M Pa and 9 .3% respectively .On the condition of 120℃/24h+190℃/5min+135℃ /3h treatment ,the highest hardness is 204 .7HBS ,and the tensile strength ,yield strength ,elongation can reach 764 .0 ,749 .0M Pa and 7 .2% respectively .
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