Oxidation of Iron-Molybdenum and Nickel-Molybdenum Alloys

Abstract

Binary alloys of iron and molybdenum (up to 12.5 atomic % Mo) and nickel and molybdenum (up to 19.7 at. % Mo) do not exhibit "catastrophic oxidation" up to 1000~ either in stationary or in flowing atmospheres. In both systems, MoO2 and iron molybdate or nickel molybdate are formed in addition to iron oxides or nickel oxide. Molybdenum significantly decreases the oxidation rate of iron by preventing forma-tion of the cation deficient FeO normally formed on iron above 570~ The oxidatiml rate of nickel, however, is affected only to a small extent. Up to 3 at. % molybdenum the rate is slightly increased by the formation of additional vacancies in the nickel oxide, while beyond 12 at. % the oxidation rate is again decreased owing to the densification of the MoO: subseale.