Abstract
In Al alloys, intermetallic particles (IMPs) play an important role in the initiation of pitting corrosion though the process of growing pit is unclear. IMPs in commercial Al alloys are fine and it is difficult to elucidate the mechanism of pitting corrosion by using the alloys. Therefore, in this study, model specimens were fabricated in which coarse IMPs were dispersed, and analysis of pitting corrosion was conducted by using these specimens.Pure Al powders were mixed with Pure Fe or Cu powders and then they were sintered. After sintering, they were hot forged, and heat treated. To analyze the corrosion behavior, open circuit potential was measured in 0.1 M NaCl solution adjusted to pH 6.0.These specimens contained dispersed phases of different colors from the Al matrix phase. In the Cu powders added specimens, the phases were Al2Cu and in the Fe powders added specimens, the phases were Al3Fe. After open circuit potential measurement, in specimens containing Al2Cu, the IMPs turned from grey to black and trench formed around the IMPs. In specimens containing Al3Fe, crystallographic pits occurred.
Published Version
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