Ordered Phases

The ordered phases BCC_B2 and FCC_L12 are described with a two sub-lattice model using a single Gibbs energy curve which enables order/disorder transformations to be modeled as described by [2001Dup].

In TCS Steel and Fe-alloys Database (TCFE) (version TCFE10 and newer), the disordered part of BCC_B2 and FCC_L12 (A2_BCC and A1_FCC, respectively) are identical to the ordinary BCC_A2 and FCC_A1, but only 1 J/mole of formula unit less stable. This way the ordered phases BCC_B2 and FCC_L12 are split from the disordered BCC_A2 and FCC_A1, and the second order phase transitions are automatically displayed by a narrow first order transition.

Fe-Si

Fe-Si phase diagram.

Figure 1: Fe-Si phase diagram.

Al-Fe-Ni

Isothermal section of Al-Fe-Ni phase diagram at 1173 K .

Figure 2: Isothermal section of Al-Fe-Ni phase diagram at 1173 K. Experimental data from [1984Hao; 1994Jia; 2005Hum; 2008Chu].

References

[1984Hao] S. M. Hao, T. Takayama, K. Ishida, and T. Nishizawa, Miscibility gap in Fe-Ni-Al and Fe-Ni-Al-Co systems, Metall. Trans. A, vol. 15, no. 10, pp. 1819–1828 (1984).

[1994Jia] C. C. Jia, K. Ishida, and T. Nishizawa, Partition of alloying elements between γ (A1), γ′ (L12), and β (B2) phases in Ni-Al base systems, Metall. Mater. Trans. A, vol. 25, no. 3, pp. 473–485 (1994).

[2001Dup] N. Dupin and B. Sundman, A thermodynamic database for Ni-base superalloys, Scand. J. Metall., vol. 30, no. 3, pp. 184–192 (2001).

[2005Him] Y. Himuro, Y. Tanaka, I. Ohnuma, R. Kainuma, and K. Ishida, Phase equilibria and γ′-L12 phase stability in the Ni-rich portion of Ni–Fe–Si and Ni–Fe–Al systems, Intermetallics, vol. 13, no. 6, pp. 620–630 (2005).

[2008Chu] I. Chumak, K. W. Richter, and H. Ipser, Isothermal Sections in the (Fe, Ni)-Rich Part of the Fe-Ni-Al Phase Diagram, J. Phase Equilibria Diffus., vol. 29, no. 4, pp. 300–304 (2008).