Towards understanding micro-galvanic activities in localised corrosion of AA2099 aluminium alloy


Liew Y., Örnek C. , Pan J., Thierry D., Wijesinghe S., Blackwood D. J.

ELECTROCHIMICA ACTA, vol.392, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 392
  • Publication Date: 2021
  • Doi Number: 10.1016/j.electacta.2021.139005
  • Title of Journal : ELECTROCHIMICA ACTA
  • Keywords: AA2099, SKPFM, Relative humidity, Localised corrosion, Atmospheric corrosion, PROBE FORCE MICROSCOPY, AL-LI, INTERMETALLIC PARTICLES, NUMERICAL-SIMULATION, LITHIUM ALLOY, MICROSTRUCTURE, SUSCEPTIBILITY, AL20CU2MN3, EVOLUTION, AEROSPACE

Abstract

The micro-galvanic interactions between Cu-Fe-Mn-Li-containing aluminides and the alloy matrix of aluminium alloy AA2099 during chloride-induced corrosion were investigated in-situ with real-time monitoring of the local contact potential difference (V-CPD) using the scanning Kelvin probe force microscopy (SKPFM) at controlled relative humidities. The aluminides showed noble potentials and were able to ennoble their neighbouring matrix sites when a cluster of aluminides surrounded the matrix. The matrix, hence, adopted a more positive V-CPD, towards that of the aluminides. The anode-to-cathode ratio changed throughout the corrosion exposure and was seen to show a dynamic character. Much higher local V-CPD activities were recorded during the earliest stages of corrosion, when the Al-Li AA2099 surface was first exposed to high humidities, than in later RH cycles; a phenomenon not seen in other aluminium alloys. (C) 2021 Elsevier Ltd. All rights reserved.