Passivation and potential fluctuation of Mg alloy AZ31B in alkaline environments

Shengxi Li, Ana C. Bacco, Nick Birbilis, Hongbo Cong

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18 Citations (Scopus)

Abstract

The passivation and corrosion behaviors of Mg alloy AZ31B were investigated in chloride-free NaOH solutions with pH range from 10 to 14. The results indicate that various phases behave differently at different pH levels. Al-Mn intermetallics serve as strong cathode at pH ≤ 11, but dissolve at pH ≥ 13. Ambient oxygen is responsible for the potential rise at pH ≥ 13 and subsequent significant potential oscillation (>1 V) is attributed to the passive film breakdown at the intergranular boundaries in the oxide film. Optimal passivation is achieved at pH 12 with thin uniform passive film formed across the surface.

Original languageEnglish
Pages (from-to)596-610
Number of pages15
JournalCorrosion Science
Volume112
DOIs
Publication statusPublished - 1 Nov 2016

Keywords

  • A: Magnesium
  • B: Polarization
  • C: Alkaline corrosion
  • C: Oxygen reduction
  • C: Passive films
  • C: Pitting corrosion

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