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Batch to batch variations in the oxidation behaviour of alumina forming Fe‐based alloys
Author(s) -
Quadakkers W. J.,
Naumenko D.,
Singheiser L.,
Penkalla H. J.,
Tyagi A. K.,
CzyrskaFilemonowicz A.
Publication year - 2000
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/(sici)1521-4176(200005)51:5<350::aid-maco350>3.0.co;2-7
Subject(s) - alloy , chemistry , oxide , kinetics , metallurgy , volume fraction , atmospheric temperature range , materials science , thermodynamics , quantum mechanics , physics
Two batches of a commercial alumina forming Fe based ODS alloy were studied in respect to their oxidation behaviour in the temperature range 1100–1300°C. In the early stages of exposure the oxidation kinetics of the two materials appeared to be virtually identical, whereas strong differences in oxide growth rate occurred after longer exposure times. Extensive microstructural studies using optical metallography, SEM, TEM and MCs + ‐SIMS showed that these differences are related to a larger volume fraction of Ti(C,N) precipitates in one of the studied batches. The Ti(C,N) precipitates present in this batch were found to become incorporated into the growing oxide scale. Transformation of these particles into Ti‐rich oxides leads to a volume change resulting in microcracking of the scale and subsequent enhanced oxygen access. The results show that the question whether Ti alloying additions are beneficial or detrimental in respect to alumina scale properties strongly depends on the form in which Ti prevails in the alloy.