Localized corrosion at nm-scale hardening precipitates in Al-Cu-Li alloys

Yakun Zhu, Jonathan D. Poplawsky, Sirui Li, Raymond R. Unocic, Leslie G. Bland, Christopher D. Taylor, Jenifer S. Locke, Emmanuelle A. Marquis, Gerald S. Frankel

Research output: Contribution to journalArticlepeer-review

56 Scopus citations

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.

Original languageEnglish
Pages (from-to)204-213
Number of pages10
JournalActa Materialia
Volume189
DOIs
StatePublished - May 1 2020

Funding

This work is partially based on research sponsored by Office of Naval Research under agreement #N00014-14–2–0002 through a consortium of LIFT. Dr. Ken Smith at UTRC, Prof. John Allison and Dr. Kai Sun at the University of Michigan are acknowledged for helpful discussions throughout the entire work. APT and part of the STEM imaging were conducted at the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Lab, which is a U.S. DOE Office of Science User Facility. DFT calculations were performed on the Ohio Supercomputer Center (OSC). Part of this work were supported by UT -Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The support of the Michigan Center for Materials Characterization at the University of Michigan for microscopy work was acknowledged. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. 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 U.S. Government. This work is partially based on research sponsored by Office of Naval Research under agreement #N00014-14–2–0002 through a consortium of LIFT. Dr. Ken Smith at UTRC, Prof. John Allison and Dr. Kai Sun at the University of Michigan are acknowledged for helpful discussions throughout the entire work. APT and part of the STEM imaging were conducted at the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Lab, which is a U.S. DOE Office of Science User Facility. DFT calculations were performed on the Ohio Supercomputer Center (OSC). Part of this work were supported by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). The support of the Michigan Center for Materials Characterization at the University of Michigan for microscopy work was acknowledged. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. 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 U.S. Government.

Keywords

  • Al-Cu-Li hardening precipitate
  • Atomic/nm-resolution analysis
  • Electrochemical methods
  • Localized corrosion
  • Passivation

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