A high Zn-containing Al-Zn-Mg-Cu alloy was researched due to excellent overall performances. The hardness, electrical conductivity and mechanical properties were investigated and detailed aging parameters subjected to T6, T79, T74 and T73 were proposed. The matrix precipitates of various aging tempers were investigated by transmission electron microscope (TEM) and high-resolution transmission electron microscope (HREM) techniques and quantitative information of matrix precipitates was extracted from the bright-field TEM images projected along 〈110〉_Al orientation with the aid of an imaging analysis. The fatigue crack propagation (FCP) behaviors subjected to different aging tempers were investigated, the related fracture morphology of the stable expanding regions was analyzed and corresponding fatigue striations were measured to verify the FCP rates. The results showed that with the deepening of aging degree, the matrix precipitates coarsened with an expanding of precipitate size distribution and an enlargement of average precipitate size while the precipitates evolved from GP zones and η' phase to η' phase and η phase. The FCP resistance was improved with the aging degree deepens and the evolution of related tearing ridge, tearing dimple and fatigue striation also proved it. Due to a smaller cyclic plastic zone of the alloy with various tempers compared with the average grain size, the FCP rate was significantly influenced by matrix precipitate characteristics and a theoretical model which directly correlated FCP rate with matrix precipitate characteristics was proposed. From T6 state to T73 state, the enlargement of cuttable GP zones and η' phase, its evolution to η phase and the nucleation, growth and coarsening of η phase were in favor of enhancing the FCP resistance.

由于优异的整体性能，对高含锌量的Al-Zn-Mg-Cu合金进行了研究。研究了其硬度，电导率和机械性能，并提出了受T6，T79，T74和T73影响的详细时效参数。通过透射电子显微镜（TEM）和高分辨率透射电子显微镜（HREM）技术研究了各种时效状态的基体析出物，并从沿＆lt; 110＆gt; _Al投射的明场TEM图像中提取了基体析出物的定量信息。借助影像分析确定方向。研究了不同时效状态下的疲劳裂纹扩展行为，分析了稳定扩展区的相关断裂形态，并测量了相应的疲劳条纹，以验证FCP率。结果表明，随着时效程度的加深，基体析出物粗化，析出物尺寸分布扩大，平均析出物尺寸增大，同时析出物从GP区和η'相向η'相和η相演化。随着老化程度的加深，FCP抵抗力提高，相关的撕裂脊，撕裂凹痕和疲劳条纹的演变也证明了这一点。由于与平均晶粒度相比，不同回火温度的合金的循环塑性区更小，FCP速率受基质析出物特征的显着影响，提出了将FCP速率与基质析出物特征直接相关的理论模型。从T6状态到T73状态，可切割GP区和η'相的扩大，向η相的演化以及η相的形核，生长和粗化有利于增强FCP的抵抗力。