Effects of alloyed Mn on oxidation behaviour of a Co–Ni–Cr–Fe alloy between 1050 and 1250°C

• Published in: Corrosion science Vol. 104; pp. 236 - 247
• Main Authors: Liu, Longfei, Wu, Shusen, Dong, Yunbo, Lü, Shulin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2016
• Subjects: A. Cobalt; B. SEM; B. XPS; C. Interfaces; C. Oxide coatings; B. SEM; B. XPS; C. Interfaces; A. Cobalt; C. Oxide coatings
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2015.12.016

•Oxidation of a Co-base alloy with 0–2.0wt.% Mn at 1050–1250°C.•Kinetics of Mn-added samples follow two-stage parabolic law.•Oxidation is controlled by Mn ions diffusion.•Mn addition leads to a different oxide layer structure. The effects of Mn content on the oxidation behaviour of a Co-base superalloy with compositions of Co–29Cr–21Ni–23Fe–2.2Nb–1.6Si–xMn (x=0, 0.5, 1, 2) (Co22 alloy for short, wt.%) have been studied. Isothermal oxidation behaviour was investigated, and it showed kinetics of the Mn-containing samples followed a two-stage parabolic law. In the absence of Mn, scales on Co22 alloys consisted mainly of Cr2O3 and SiO2, and small amounts of Fe–Cr, Ni–Cr spinel nodules formed on the surface. When Mn was added, a triple oxide layer could be observed, consisting of Mn–Cr spinel as outer layer, Cr2O3 as middle layer and SiO2 in the innermost layer.