| Abstrakt: |
This study investigated the effect of Nb-content on the corrosion behavior of the Al7Cr20Fe35-xNi35Mo3Nbx(x= 0, 1 and 2) high-entropy alloys in a Cl−environment. The results indicated that only the face centered cubic phase existed in the Nb0 and Nb1 alloys, while the emergence of Laves phase was observed when Nb-content reached 2 at.%. The Nb0 and Nb1 alloys exhibited pitting corrosion, while the NiAl-rich phase experienced localized preferential corrosion in the Nb2 alloy. The electrochemical results revealed that the corrosion current density of the Nbx(x= 0, 1 and 2) alloys fell within the range of 10−8–10−7A·cm−2, with a pitting corrosion potential exceeding 700 mVSCE. Notably, the Nb1 alloy exhibited the most impressive corrosion resistance, as its corrosion current density (7 × 10−8A·cm−2) was merely half that of 316LN stainless steel. This is attributed to its rapid passivation process, resulting in the development of a protective film characterized by an increased Cr2O3/Al2O3+Cr(OH)3ratio. This study highlighted that the addition of Nb contributed to grain refinement, decreased corrosion current density, and elevated pitting potential, favoring passivation and improving corrosion resistance. However, excessive Nb-content resulted in the emergence of the Laves phase, inducing galvanic corrosion and diminishing resistance to corrosion. |
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