ISSN 2594-5327
49º Congresso anual — Vol. 49, Num. 1 (1994)
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The oxidation of two Fe-Nb alloys containing 15 and 30 wt.% Nb has been studied at 800°C both under 1 atm of pure O₂ and in an H₂–CO₂ mixture providing an oxygen pressure of 10⁻²⁰ atm, below the dissociation pressure of iron oxide. The samples of both alloys corroded under the low oxygen pressure show only a region of internal oxidation composed of a mixture of alpha iron and niobium oxides (NbO₂ and Nb₂O₅) and the double oxide FeNbO₄, which formed from the Fe₂Nb phase. At high oxygen pressures the two alloys formed an outer scale containing an outermost layer of pure iron oxides followed by an inner layer containing a mixture of the double oxide with iron oxides, but did not undergo any internal oxidation of Nb. Moreover, no layer of Nb-depleted alloy was formed at the interface between the unaffected alloy and the region of internal oxidation both at low and at high oxygen pressures. The corrosion mechanism is examined with special reference to the effect of the low solubility of niobium in iron and to the relation between the microstructure of the alloys and of the scales.
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Fe-Nb alloys, high temperature, oxidation, corrosion, microstructure
Como citar
Rebello, M. Castro; Rizzo, F.C.; Lopes, M.F. Silva; Niu, Y.; Gesmundo, F..
THE OXIDATION OF TWO Fe-Nb ALLOYS AT 800°C UNDER 10⁻²⁰ AND 1 ATM OXYGEN,
p. 5082-5097.
In: 49º Congresso anual,
Rio de Janeiro, Brasil,
1994.
ISSN: 2594-5327, DOI 10.5151/2594-5327-49v11-79-94
