Corrosion behavior of magnesium alloy AZ91 and its MMC in NaCl solution

W. M. Chan, F. T. Cheng, L. K. Leung, R. J. Horylev, Tai Man Yue

Research output: Journal article publicationConference articleAcademic researchpeer-review

Abstract

The corrosion behaviors of magnesium alloy AZ91C and its Al2O3(short fibre)-reinforced metal matrix composite (MMC) in alkaline solutions (pH 10.5) containing chloride were compared using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS) and immersion tests. Dependence of polarization characteristics (corrosion potential and corrosion current density) on chloride concentration was similar for both materials. The corrosion potential Ecorrdecreased linearly with the logarithm of chloride concentration, while the corrosion current density jcorrincreased rapidly at chloride concentrations larger than 0.1%, with the icorrfor the MMC consistently higher than that for AZ91C, reaching a factor of about 3 in 3.5% sodium chloride solution. EIS data indicated that the protective film on the MMC was inferior to that on the matrix alloy. With stirring and at frequencies higher than 5 Hz, the electrode/electrolyte interface might be described by the simplified Randies model for both materials. Immersion tests showed that the corrosion rate of the MMC, in terms of weight loss, was about 7 times that of the matrix alloy. Thus the present investigation indicated that in alkaline solutions containing chloride ions, the presence of Al2O3short fibres in the alloy did not drastically alter the corrosion behavior, but significantly reduced its corrosion resistance.
Original languageEnglish
JournalNACE - International Corrosion Conference Series
Volume1997-March
Publication statusPublished - 1 Jan 1997
EventCorrosion 1997 - New Orleans, United States
Duration: 9 Mar 199714 Mar 1997

Keywords

  • Al O -reinforced metal matrix composite 2 3
  • Corroison potential
  • Corroison rate
  • Effect of chloride concentration
  • Electrochemical impedance spectroscopy
  • Magnesium alloy
  • Polarization

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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