Effect of Al content on the high-temperature oxidation of Co-20Cr-(5,10)Al oxide dispersion strengthened superalloys

The high-temperature oxidation of Co-based oxide dispersion strengthened (ODS) Co-20Cr-(5, 10) Al-2.4Hf-1.5Y(2)O(3) (wt%) superalloys was investigated at 900 C-omicron and 1000 C-omicron. The 10Al (wt%) superalloys possess better oxidation resistance with the formation of alumina scale than the 5Al (wt%) with a duplex scale of CoCr2O4/Cr2O3 and internal Al2O3. The alumina on the 10Al superalloy is composed of theta- and alpha-alumina at 900 C-omicron but dominated by alpha-alumina at 1000 C-omicron. The lower weight gain of 10Al superalloys at 1000 C-omicron than at 900 C-omicron was associated with different growth mechanisms of the Al2O3 scales. (C) 2017 Elsevier Ltd. All rights reserved.