The activity of N in α-Fe is derived from the solubility at fairly low temperature (580°C) in the Fe–N diagram. The interaction coefficients between Fe and N, Fe and C, and C and N are obtained and the phase boundaries of single-phase ɛ- and γ′-fields are subsequently calculated. The calculated results show that the γ′ -region of the Naumann and Langenscheid Fe–C–N ternary phase diagram is correct, but the ɛ-region requires revision. The calculations suggest that recent experimental data on the ɛ-phase appear reasonable. Calculations taking graphite to be a standard state confirm this conclusion.
MST/385
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References
1.
NAUMANNF. K. and LANGENSCHEIDG. A.: Arch. Eisen-hiittenwes., 1965, 36, 677-682 (BISIT 4583).
2.
RAGHAVANV.: Trans. Indian Inst. Met.,1984, 37, (4), 293.
3.
WELLSA. and BELLT.: Heat Treat. Met.,1983, 10, 39.
4.
ELLIOTTJ. F., M. GLEISER, and v. RAMARKRISHNA: in ‘Thermochemistry for steelmaking’, (ed. ElliottJ. F. and GleiserM., 405; 1963, London, Addison-Wesley.
5.
DARKENL. S. and GURRYR. W.: in ‘Physical chemistry of metals’, 379; 1953, New York, McGraw-Hill.
6.
REEDT. B.: ‘Free energy of formation of binary compounds’, 26; 1971, Cambridge, Mass., MIT Press.
7.
DEW-HUGHESD. and KAUFMANL.: Calphad, 1979, 3, 175–203.
8.
KAUFMANL.: Calphad, 1978, 2, 295–318.
9.
ZUYAOXU(T. Y. HSU): in ‘Thermodynamics of metallic materials’, 254; 1981, Beijing, Science Press.
10.
MINGYUEFAN and YINGZHANG: in ‘Elements of optimization technology’, 164; 1982, Beijing, Qeng Hua University Press.
