Effect of Al content on the high-temperature oxidation of Co-20Cr-(5, 10)Al oxide dispersion strengthened superalloys. (April 2017)

• Record Type: Journal Article
• Authors: Yu, Hao; Ukai, Shigeharu; Hayashi, Shigenari; Oono, Naoko
• Is Part Of: Corrosion science. Volume 118(2017)
• Page Start: 49
• Page End: 59
• Publication Date: 2017-04
• Subjects: A. Cobalt -- A. Alumina -- B. SEM -- C. Oxidation; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2017.01.015
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Effect of Al on the oxidation of Co-based ODS alloys was studied at 900 °C/1000 °C. 5Al (wt%) addition forms a duplex scale of CoCr2 O4 /Cr2 O3 and internal Al2 O3 . Alumina-forming Co-based ODS alloy was developed with 10Al (wt%). θ/α-Alumina transformation results in a smaller mass gain at 1000 °C than 900 °C. Abstract: The high-temperature oxidation of Co-based oxide dispersion strengthened (ODS) Co-20Cr-(5, 10) Al-2.4Hf-1.5Y2 O3 (wt%) superalloys was investigated at 900 °C and 1000 °C. The 10Al (wt%) superalloys possess better oxidation resistance with the formation of alumina scale than the 5Al (wt%) with a duplex scale of CoCr2 O4 /Cr2 O3 and internal Al2 O3 . The alumina on the 10Al superalloy is composed of θ- and α-alumina at 900 °C but dominated by α-alumina at 1000 °C. The lower weight gain of 10Al superalloys at 1000 °C than at 900 °C was associated with different growth mechanisms of the Al2 O3 scales.