Abstract The localized corrosion of Li-containing nm hardening precipitates in the 3rd generation of Al-Cu-Li alloys was investigated based on a quasi in situ approach by sequentially exposing the material to NaCl solution and characterizing the structural, chemical, and electrochemical evolution at atomic scale using electron microscopy, spectroscopy, 3D tomography, electrochemical measurements, and DFT calculations. Localized corrosion of Al7.5Cu4Li (TB phase) initiated along {001} family of planes through the dealloying of Al and Li due to a low surface work function. Cu was enriched along the Cu (110) // TB (011) // Al (100) orientations on and around corroded TB precipitates. No strong galvanic interactions were observed at the TB and Al matrix interface due to the formation of a Li-C-O rich passivation layer during electrolyte exposure. Similarities and differences between TB and other common Al-Cu-Li precipitates (Al2CuLi, Al6CuLi3, and Al3Li) with respect to corrosion are discussed. The reported corrosion mechanism can assist in the assessment of the localized corrosion susceptibility of precipitation-hardened Al alloys and assist in the design of new alloys.

中文翻译：

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Al-Cu-Li 合金中纳米级硬化沉淀的局部腐蚀

摘要 基于准原位方法，将材料依次暴露于 NaCl 溶液中，并表征了第三代 Al-Cu-Li 合金中含锂纳米硬化沉淀物的局部腐蚀，并表征了其结构、化学和电化学演化。使用电子显微镜、光谱学、3D 断层扫描、电化学测量和 DFT 计算的原子尺度。由于低表面功函数，Al7.5Cu4Li（TB 相）的局部腐蚀沿 {001} 族面通过 Al 和 Li 的脱合金开始。Cu 沿着 Cu (110) // TB (011) // Al (100) 方向在腐蚀的 TB 沉淀物上和周围富集。由于在电解质暴露期间形成了富含 Li-CO 的钝化层，因此在 TB 和 Al 基体界面未观察到强电相互作用。讨论了 TB 与其他常见的 Al-Cu-Li 沉淀物（Al2CuLi、Al6CuLi3 和 Al3Li）在腐蚀方面的异同。报告的腐蚀机制有助于评估沉淀硬化铝合金的局部腐蚀敏感性，并有助于新合金的设计。