Electrochemical behavior and compositions of passive films formed on the constituent phases of duplex stainless steel without coupling

The electrochemical behavior and compositions of passive films formed on the constituent phases (alpha-phase, gamma-phase) of 2205 duplex stainless steel (DSS) without coupling in neutral 3.5% NaCl solution were investigated, utilizing single-phase samples prepared by selective dissolution. The results demonstrate that, compared to alpha-phase, Fe species in passive film of alpha-phase are more stable due to the higher content of Mo within alpha-phase. The superior stability of Cr (III) species in the passive layer of gamma-phase may result from the higher content of Ni in gamma-phase, which leads to the higher content of Cr, Cr/Fe ratio, and better passivity of passive layer. The beneficial effect of coupling of two phases on the passive behavior of 2205 DSS is also found. (C) 2015 Elsevier B.V. All rights reserved.