ISSN:
1573-4889
Keywords:
oxidation
;
carbide dispersion
;
iron-base alloys
;
decarburization
;
thermodynamic stability
;
oxidation resistance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The oxidation behavior of Fe-5M-C alloys (where M is Si, Ti, V, Nb, Ta, Cr, W, or Ni, and C is 0, 0.1, 0.4, 0.8 or 1.2 wt.%) has been studied in the temperature range of 600–850°C in one atmospheric pressure of oxygen. Except for Si-containing alloys, all the alloys exhibited a parabolic rate law during oxidation, and the oxidation rate increased with increasing carbon content. The deviations from the above generalization can be explained on the basis of either phase composition of the alloy matrix at the oxidation temperature or carbon losses incurred during oxidation. Alloys rich in carbide phases have much lower oxidation rates than alloys containing solid-solution phases. This has been attributed to the decrease in mobility of carbon in iron-base alloys in the presence of a carbide-formin addition. The disruption of the oxide scales, which is the result of decarburization, also influences the oxidation behavior of iron-base alloys. At the 1.2% C level, the parabolic rate constant, Kp, follows the order: $$Fe - 5Cr 〉 Fe 〉 Fe - 5Ni 〉 Fe - 5Ti 〉 Fe - 5Ta 〉 Fe - 5Nb 〉 Fe - 5V 〉 Fe - 5W$$ The order is approximately similar to the increasing free energy sequence for the oxidation of carbides to oxides in Fe-5M-C alloys.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00657060
Permalink
