In the present work, the effect of artificial aging on the Cu-Mg co-clustering and mechanical behavior in a pre-strained Al-Cu-Mg alloy are investigated by tensile and fatigue testing, X-ray diffraction (XRD), transmission electron microscope (TEM) and atom probe tomography (APT). Results show that in the pre-strained samples, sample with artificial aging (170 °C/30 min) possesses unchanged strength and higher elongation in comparison with naturally aged sample. This is due to the greater strengthening effect caused by cluster hardening but the weaker strengthening effect caused by strain hardening in 170 °C/30 min sample. The fatigue crack propagation (FCP) resistance of 170 °C/30 min sample is higher than that of naturally aged sample. APT analysis indicates that artificial aging remarkably increases Cu-Mg co-cluster size, which leads to a greater critical shear stress for dislocation motion. This undoubtedly enhances fatigue crack closure effect and FCP resistance. Meanwhile, artificial aging reduces the dislocation density, which enhances FCP resistance as well. Compared to the sample without pre-strain, the pre-strained samples exhibit a higher FCP rate as a high density dislocation favors a detrimental effect on FCP resistance.

在当前工作中，通过拉伸和疲劳试验，X射线衍射（XRD），透射电子研究了人工时效对预应变Al-Cu-Mg合金中Cu-Mg共聚和力学行为的影响。显微镜（TEM）和原子探针断层扫描（APT）。结果表明，在预应变样品中，与自然时效样品相比，经过人工时效（170°C / 30分钟）的样品具有不变的强度和更高的伸长率。这是由于在170°C / 30 min的样品中，由于团簇硬化而产生的强化作用较大，而由于应变硬化而导致的强化作用减弱。170°C / 30分钟的样品的抗疲劳裂纹扩展（FCP）的能力高于自然老化的样品。APT分析表明，人工时效会显着增加Cu-Mg共簇的尺寸，这导致位错运动的临界剪切应力更大。毫无疑问，这增强了疲劳裂纹闭合效果和抗FCP性能。同时，人工时效降低了位错密度，也增强了FCP抵抗力。与没有预应变的样品相比，预应变的样品表现出更高的FCP率，因为高密度位错有利于对FCP抵抗力的有害影响。