Abstract
The atomic structural evolution of the precipitated phase and the metastable pitting corrosion behavior of AlxCoCrFeNi alloys were investigated. With the increase of Al content, the (Cr, Fe)-rich phase in AlxCoCrFeNi alloys changed from FCC (A1 phase) to BCC (A2 phase) structure, and their shapes changed from strip to sphere, but the increase of the (Al, Ni)-rich phase (B2 phase) deteriorated their corrosion resistance. Al0.25CoCrFeNi alloy is single phase FCC structure, while Al0.75CoCrFeNi alloy is FCC + B2 structure, and Al1.0CoCrFeNi and Al1.5CoCrFeNi alloy are A2 + B2 structures. The Al1.5CoCrFeNi alloy had the worst corrosion resistance with the weak potential difference between the precipitated phases. Although the element segregation (nano-B2 phase) and the large potential difference at the interphase boundary were regarded as a factor of galvanic corrosion, the passive film played a key role in the corrosion resistance of AlxCoCrFeNi alloys.
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