Gibbs energies of formation of chromium carbides
- Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Chemical Group
- Indian Inst. of Science, Bangalore (India). Dept. of Metallurgy
Hyperstoichiometric mixed carbides of plutonium and uranium have been under development as fuel for fast breeder reactors. The fuel is normally in the form of pellets enclosed in AISI 316 stainless steel cladding tubes. Depending upon the difference in carbon potential, transport of carbon between the fuel and clad can occur at points of contact. The flux of carbon may affect the stability and distribution of chromium carbide precipitates, which control the chemical and physical properties of stainless steel. Accurate data on Gibbs energies of formation of chromium carbides are useful for analyzing the morphological stability of the carbide precipitates in a carbon chemical potential gradient. In this paper, the carbon potentials corresponding to the two-phase mixtures Cr + Cr{sub 23}C{sub 6}, Cr{sub 23}C{sub 6} + Cr{sub 7}C{sub 3}, and Cr{sub 7}C{sub 3} + Cr{sub 3}C{sub 2} in the binary system Cr-C were measured in the temperature range 973 to 1,173 K by using the methane-hydrogen gas equilibration technique. Special precautions were taken to prevent oxidation of the samples and to minimize thermal segregation in the gas phase. The standard Gibbs energies of formation of Cr{sub 23}C{sub 6}, Cr{sub 7}C{sub 3}, and Cr{sub 3}C{sub 2} were derived from the measured carbon potentials. These values are compared with those reported in the literature. The Gibbs energies obtained in this study agree well with those obtained from solid-state cells incorporating CaF{sub 2} and ThO{sub 2}(Y{sub 2}O{sub 3}) as solid electrolytes and sealed capsule isopiestic measurements reported in the literature.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 282241
- Journal Information:
- Metallurgical Transactions, A, Journal Name: Metallurgical Transactions, A Journal Issue: 7 Vol. 27; ISSN MTTABN; ISSN 0360-2133
- Country of Publication:
- United States
- Language:
- English
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