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Updated: Sep 28, 2026

Potentiodynamic Corrosion Testing
Published on: September 4, 2016
Corrosion Resistant Multi-Principal Ni60Cr15Co15Ti5Al2.5Nb2.5 Alloy: Loss of Passivation (LOP) and Recovery of
Virgilio Pereira Ricci1, Emerson Cortez Gallego Campos1, Victor Hugo Mafra Monfredo Ferreira1
1Department of Materials Engineering (DEMa), Federal University of São Carlos (UFSCar), Rodovia Washington Luís, km 235 SP-310, 13565-905 São Carlos, SP, Brazil.
Abstract:
This study explores the corrosion behavior of a nonequiatomic Ni60Cr15Co15Ti5Al2.5Nb2.5 high-entropy alloy (HEA) subjected to thermal aging. Electrochemical testing in 3.5 wt% NaCl solution revealed that short-term aging (≤1 h) induces a loss of passivation (LOP), marked by a corrosion potential drop to -260 mVSCE and an increase in corrosion current density i corr to 2.7 μA/cm2. In contrast, prolonged aging (≥10 h) promotes a recovery of passivation (ROP), driven by microstructural elemental redistribution. This recovery is evidenced by a positive shift in corrosion potential to -125 mVSCE, a significant reduction in i corr to 7.1 × 10-2 μA/cm2, and an increase in pitting potential (E pit) from +413 mVSCE to +495 mVSCE. Electrochemical impedance spectroscopy (EIS) further confirmed enhanced passivity through a reduction in effective capacitance (from 3.2 to 2.6 μF/cm2) and an increase in polarization resistance (from 960 to 1084 kΩ·cm2). However, excessive aging (>50 h) may trigger a secondary LOP. An optimal aging window (30-50 h) yields a stable and protective passive film.
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