Hot corrosion behavior and mechanism of cryo-rolled MP159 superalloy with long rod-like γ′ phase

Abstract

The hot corrosion behavior and corrosion mechanism of cryo-rolled MP159 superalloy in a salt mixture of 75 % Na2SO4 + 25 % NaCl (wt %) at 800 °C were investigated by using XRD, SEM, HRTEM and first-principles calculations. Many of long rod-like γ′ phases with stacking faults and deformation nano-twins can be generated during hot corrosion, which promotes the outward diffusion of Cr element. Moreover, a high content of Nb element in the long rod-like γ′ phase can increase the activity of Cr element, which is conducive to the formation of a denser Cr2O3 film by the selective oxidation of Cr element, and results in a better hot corrosion resistance.