The effects of trace silver (Ag) on the precipitation behavior of strengthening phases and the mechanical properties of Al-Cu alloys have been investigated by performance testing, scanning electron microscopy, and transmission electron microscopy. Ag retarded the aging response of the Al-Cu alloys. The density of the θ′′ and θ′ phases decreased with increasing Ag content in under- and peak-aged alloys, and there was almost no θ′ phase in the 0.12 wt.% Ag alloy in the under-aged state. The θ′ phase morphology was narrower and longer after addition of Ag. Fatigue striations became more obvious and their spacing reduced at the fracture surface of experimental alloys with increasing Ag content, reflecting an improvement in the fatigue life of the alloys. On addition of 0.06 wt.% or 0.12 wt.% Ag, the fatigue life of the Al-Cu alloys was increased by 72.7% and 155.5%, respectively.

中文翻译：

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微量银对铝铜合金强化相的析出行为和力学性能的影响

通过性能测试，扫描电子显微镜和透射电子显微镜研究了痕量银（Ag）对强化相的析出行为和Al-Cu合金力学性能的影响。Ag延缓了Al-Cu合金的时效响应。在欠时效和峰值时效合金中，随着Ag含量的增加，θ'和θ'相的密度减小，而在时效状态下，0.12 wt％的Ag合金中几乎没有θ'相。添加Ag后，θ'相形态变窄且变长。随着Ag含量的增加，疲劳条纹在实验合金的断裂表面变得更加明显，并且间距减小，这反映出合金疲劳寿命的提高。添加0.06重量％或0.12重量％的Ag后，Al-Cu合金的疲劳寿命增加了72岁。