Effect of Mo and aging temperature on corrosion behavior of (CoCrFeNi)100-xMox high-entropy alloys

The present work investigates the influence of Mo additive and aging temperatures on the microstructure and corrosion behavior in 3.5% NaCl solution. The microstructure of (CoCrFeNi)(100-x)Mo-x(x = 1, 2, 3) alloys aged at 700 degrees C and 900 degrees C comprises single FCC solid solution structure. When the Mo content increases from 1% to 2%, the polarization curves and electrochemical impedance spectroscopy in 3.5% NaCl solution indicate that the corrosion resistance of the alloys gradually increases with increasing aging temperature and Mo content. However, the corrosion resistance of (CoCrFeNi)(97)Mo-3 alloy aged at 900 degrees C decreased suddenly. XPS analysis reveals that the main components of the passive film are Cr2O3 and MoO3, and the intensity of Cr2O3 and MoO3 in the passive film tends to increase with Mo increases from 1% to 2%, which can improve the stability of the passive film. The first-principles calculation was used to understand the effect of on the pitting mechanism of the passive film. (C) 2019 Elsevier B.V. All rights reserved.