Influence of small amounts of Si and Cr on the high temperature oxidation behavior of novel cobalt base superalloys

• Published in: Corrosion science Vol. 184; p. 109388
• Main Authors: Liang, Zhida, Göken, Mathias, Lorenz, Uwe, Neumeier, Steffen, Oehring, Michael, Pyczak, Florian, Stark, Andreas, Wang, Li
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 15.05.2021; Elsevier BV
• Subjects: Aluminum oxide; Chromium; Co-based superalloys; Cobalt base alloys; Heat resistant alloys; High temperature; Oxidation; Oxidation resistance; Silicon; Superalloys; Synchrotron radiation; Thermodynamics and kinetics; Thermodynamics and kinetics; Oxidation; Co-based superalloys; Synchrotron radiation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2021.109388

•The effect of small amounts of Si on oxidation resistance in Co-base superalloys is better than that of Cr.•The formation of a continuous Al2O3 scale can be induced by minor amounts of Si but not Cr.•Alloying Cr or Si can improve the adhesion between oxide layers and metal substrates and inhibit spallation of oxide layers. The effect of small amounts of Si and Cr on the high temperature oxidation of alloys based on Co-9Al-9W was investigated at 900 °C. The results show that the effect of Si additions on oxidation resistance was more pronounced than for Cr additions. An addition of 4 at.% Cr was insufficient to produce a protective layer, while 2 at.% Si led to the formation of a dense, continuous Al2O3 scale. The thermodynamics and kinetics for Al2O3 layer formation were analyzed by combining CALPHAD and Wagnerʼs theory.