Hot corrosion behavior of Ni–16Cr–xAl based alloys in mixture of Na2SO4−NaCl at 600 °C
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. State Key Laboratory of Porous Metals Materials, Northwest Institute for Nonferrous Metal Research,
Xi’an 710016, China)
2. State Key Laboratory of Porous Metals Materials, Northwest Institute for Nonferrous Metal Research,
Xi’an 710016, China)
Abstract: The hot corrosion behaviors of Ni–16Cr–xAl(x=4.5%, 6.8%, 9.0%, mass fraction) based alloys in Na2SO4–25% NaCl molten salts at 600 °C were investigated. The effects of pre-oxidation and Al content on the resistance to hot corrosion were examined. The hot corrosion resistance of Ni–16Cr–xAl based alloy with Al addition from 4.5% to 9.0% increases with increasing Al content. The alloy with Al content of 9.0% shows the highest hot corrosion resistance among the examined alloys because more β–NiAl phases are obtained to sustain the Al2O3 scale repaired during hot corrosion. Pre-oxidized specimens have a superior hot corrosion resistance compared with the as-cast specimens, due to a protective oxide scale formed after pre-treatment.
Key words: Ni–16Cr–xAl based alloys; pre-oxidation; Na2SO4–25% NaCl mixed salt; hot-corrosion mechanism