Abstract High strength Al-Zn-Mg-Cu (7xxx) aluminium alloys obtain the required balance of mechanical and corrosion properties through complex heat treatments developed through empirical experiment. Understanding the influence of these heat treatments on the composition of the strengthening precipitates (η′ and η-phase) is critical to obtain a better mechanistic understanding of their effect. In this work, the composition of strengthening precipitates has been studied at the atomic scale in microstructures of commercially processed AA7010 alloy in the standard overaged temper state. Copper enrichment in the precipitates on over-aging is confirmed for both small (η′) and large (η) particles. It is demonstrated that in addition to entering the precipitates, a copper enriched layer forms at the particle/matrix interface on the broad faces of the precipitate plates. The implications of this structure for the mechanical and environmentally assisted cracking performance of the alloy are discussed.

中文翻译：

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AA7010铝合金η'和η析出物宽面铜偏析的直接观察

摘要 高强度Al-Zn-Mg-Cu (7xxx) 铝合金通过经验实验开发的复杂热处理获得所需的力学和腐蚀性能平衡。了解这些热处理对强化析出物（η' 和 η 相）组成的影响对于更好地了解其效果至关重要。在这项工作中，在标准过时效状态下商业加工的 AA7010 合金的微观结构中，在原子尺度上研究了强化析出物的组成。对于小 (η') 和大 (η) 颗粒，都证实了过时效沉淀物中的铜富集。证明除了进入沉淀物外，在沉淀板宽面上的颗粒/基质界面处形成富铜层。讨论了这种结构对合金的机械和环境辅助开裂性能的影响。