Abstract
We use the coexisting phases approach to calculate melting phase diagrams of several Fe-C interaction potentials, such as Embedded Atom Method (EAM) potential of Lau et al. [Phys. Rev. Lett. 98 (2007) 215501], EAM potential of Hepburn and Ackland [Phys. Rev. B 78 (2008) 165115], and two flavours of the Analytic Bond Order potential (ABOP) of Henriksson and Nordlund [Phys. Rev. B 79 (2009) 144107]. Melting of both bcc (ferrite) and fcc (austenite) crystals is investigated with C concentrations up to 5 wt%. The results are compared with the experimental data and suggest that the potential of Hepburn and Ackland is the most accurate in reproducing the melting phase diagram of the ferrite, although the austenite cannot be stabilized at any C concentration for this potential. The potential of Lau et al. yields the best qualitative agreement with the real phase diagram in that the ferrite-liquid coexistence at low C concentrations is replaced by the austenite-liquid coexistence at higher C concentrations. However, the crossover C concentration is much larger and the ferrite melting temperature is much higher than in the real Fe-C alloy. The ABOP of Henriksson and Nordlund without the Ziegler-Biersack-Littmark (ZBL) correction correctly predicts the relative stability of ferrite and austenite at melting, but significantly underestimates the solubility of C in the solid phases, while the same potential with the ZBL correction predicts the austenite to be more stable compared to the ferrite at all C concentrations near the melting transition.
Highlights
We use the coexisting phases approach to calculate melting phase diagrams of several Fe-C interaction potentials, such as Embedded Atom Method (EAM) potential of Lau et al [Phys
While we do not expect that a model Fe-C potential will reproduce exactly the phase diagram structure of the real system, it would be desirable to obtain at least a qualitative agreement with the experimental results
We present results of our calculations of the fcc and bcc Fe-C alloy melting phase diagrams for the model potentials discussed in the previous section
Summary
We use the coexisting phases approach to calculate melting phase diagrams of several Fe-C interaction potentials, such as Embedded Atom Method (EAM) potential of Lau et al [Phys. Melting of both bcc (ferrite) and fcc (austenite) crystals is investigated with C concentrations up to 5 wt%. The results are compared with the experimental data and suggest that the potential of Hepburn and Ackland is the most accurate in reproducing the melting phase diagram of the ferrite, the austenite cannot be stabilized at any C concentration for this potential. The potential of Lau et al yields the best qualitative agreement with the real phase diagram in that the ferrite-liquid coexistence at low C concentrations is replaced by the austenite-liquid coexistence at higher C concentrations. The key feature of the diagram at temperatures near melting is the interplay between the bcc phase, known as the δ-iron or δ-ferrite, at low C concentrations and the fcc phase, or γ-iron (austenite), at higher C concentrations[1]. To the best of our knowledge, the present investigation is the first which investigates the interplay between the melting properties of fcc and bcc phases in the Fe-C system
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