Reports are available regarding the nm-scale hardening IMCs present in Al-Cu-Li alloys such as Al₂CuLi (T₁), Al₆CuLi₃ (T₂), Al_7.5Cu₄Li (T_B) and Al₃Li (d¢) [1-7], but systematic surveys of IMCs corrosion in the third generation of Al-Cu-Li alloys has not yet been studied thoroughly [8, 9,10-13]. This study provides a comprehensive overview of the electrochemical characteristics of intermetallic compounds (IMCs), particularly nm scale IMCs commonly encountered in 3^rd generation Al-Cu-Li alloys, specifically 2070-T8. The electrochemical measurements were carried out on AA2070-T8 and synthesized model alloys representative of the IMCs in Al-Cu-Li alloys using the electrochemical microcell technique. The effects of environmental variables, including Cl^- concentration and pH, on the corrosion potential, pitting potential, repassivation potential, corrosion rate, and galvanic current of these IMCs were systematically evaluated and are thoroughly discussed. The electrochemical measurement results and statistical analysis on the basis of the current work and a literature survey provide a rich electrochemical database of common IMCs in several groups, including Al-Si-(Cu, Fe, Mn), Al-Cu-(Fe, Mn), Al-Fe-Mn, Al₃X (X=Ni, Ti, Ta, and Zr), Al-Mg-(Cu), Al-Zn, Al-Li-(Cu), and Mg-Zn-Si-(X), and their relative nobility in Al alloys, particularly 2xxx and 7xxx series, and potentially improve an understanding on corrosion thermodynamics and kinetics of the interaction between matrix and IMCs in corrosion mitigation and new materials design.

ACKNOWLEDGEMENTS

This material is based on research sponsored by Office of Naval Research under agreement number N00014-14-2-0002 through a consortium of LIFT. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The work was partially performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and financially supported by LLNL under project 20-SI-004. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the Office of Naval Research or the U.S. Government.

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