Corrosion behavior of AlCoCrFeNi2.1 high entropy alloy in a simulated oilfield produced fluid environment compared to 2205 duplex stainless steel
Ting Mao, Songlin Chen, Lan Tang, Lin Mo, Yang Wang, Jing Yan
Abstract
In this study, we investigated the corrosion resistance and passive film characteristics of AlCoCrFeNi2.1 high entropy alloy (HEA) and 2205 duplex stainless steel (DSS) when exposed to a simulated oilfield produced fluid. Our findings reveal that AlCoCrFeNi2.1 HEA exhibits a nobler self-corrosion potential (-340 mVSHE) and a lower self-corrosion current density (3.6 μA/cm2), in comparison to 2205 DSS, exhibiting better overall corrosion resistance, albeit with a narrower stable passivation interval. Long-term immersion tests establish that AlCoCrFeNi2.1 HEA primarily experiences overall corrosion, while 2205 DSS mainly undergoes localized corrosion, notably characterized by pitting corrosion. The predominant elements in the passive film on AlCoCrFeNi2.1 HEA are Al (13.4 at.%), supplemented by varying amounts of Fe (2.4 at.%), Cr (4.8 at.%), Ni (2.2 at.%), and Co (1.3 at.%). In contrast, the passive film formed on 2205 DSS consists solely of Fe (7.9 at.%) and Cr (5.0 at.%). The absence of the corrosion-resistant elements Mo and Ni in the passive film of 2205 DSS may account for its inadequate corrosion resistance.