Effect of Al-Fe-Si intermetallic compound phases on initiation and propagation of pitting attacks for aluminum 1100

Abstract

It is well known that iron and silicon are major elements in industrial pure aluminum alloy 1100. These elements form Al- Fe-Si ternary intermetallic compounds such as FeAl3,Fe3SiAl12, Fe 3Si2Al9,Fe2Si2Al 9 etc. The corrosion characteristics of the 1100 specimen and the Al-Fe-Si intermetallic compound specimens are experimentally investigated in NaCl and AlCl3 solutions. The electrochemical measurements, SEM surface observation and EPMA analysis reveal that (1) the iron content of the compounds influences the initiation of pitting attacks: the higher content of iron in the compound is, the more easily occurs the initiation of pitting attack, and (2) an existence of the compound in the bottom of the active pitting cavity, whether the iron content of the compound is higher or not, contributes to the further propagation of pitting attack as a cathodic site. © WILEY-VCH Verlag GmbH.