Kang Mokuang

Thermodynamics of the iron martensitic transformation and the ms temperature of iron

Based on the methodology put forward by Hsu on the thermodynamics of martensitic transformations of iron-carbon alloys, some aspects of thermodynamics of the iron martensitic transformation have been investigated by employing relatively reasonable experimental data. The Ms temperature of iron is 700 °C, as obtained in this paper. This is in good agreement with major experimental data in the literature. The driving force for the iron martensitic transformation is 438 J/mol, and the yield point of γ-iron at its Ms temperature is 46.3 MPa. Results presented in this paper can play as a modification to Hsu’s methodology.

A regular thermodynamic model for interstitial iron-carbon solutions

Abstract A thermodynamic model for the interstitial iron-carbon solution is proposed. The equilibrious thermodynamics properties of carbon in austenite which is predicted by the present model is in full agreement with the experimental data within the temperature range of 900–1400°C. The model can also give a description to the kinetic behavior of the variation in diffusion coefficient of carbon in austenite with the carbon content at various temperatures. Combined with the quasi-regular treatment of carbon atoms in ferrite, the model can further be used to depict accurately the γ (α + γ) and α (α + γ) phase boundaries in the iron-rich region of the FeC phase diagram. What is more, the expressions of thermodynamic functions in the model are simple and explicit, as compared with KRC, LFG and MD models.