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A. Jacob, M. Talik, J. Lopez, B. Kuhn, E. Povoden-Karadeniz, E. Kozeschnik:
"Thermodynamic and kinetic modeling of Laves phase containing systems for the development of high Cr ferritic steels";
Talk: CALPHADXLIV, Japan; 2016-05-29 - 2016-06-03.

Prediction of materials properties by employing computational thermodynamics assists optimisation and acceleration of materials processing and extension of service life. Prediction of the microstructure evolution is based on thermodynamic and kinetic multicomponent databases coupled with kinetic models of phase transformations [1].
In high-Cr ferritic stainless steel, precipitation of Laves phase is important for high creep strength [2,3]. However, its thermodynamic description, being a pre-requisite of predictions on its time- and temperature dependent evolution, is not complete: a comprehensive literature survey has shown that many of the sub-systems containing Laves phase have not yet been described via the Calphad method, and thus existing databases cannot be used for simulations of Crofer 22H stainless ferritic steel [3,4]. In this study, thermodynamic optimizations of (Cr,Fe,Si)2(Nb,W) Laves phase containing systems were performed [4,5]. Published modelling results were inserted in multicomponent steel database ME-Fe [6], leading to a strong improvement of the predicted phase stability in Crofer 22H. The extended thermodynamic database was then used for prediction of precipitation kinetics of model alloys during different technological heat treatments, and the results were compared with experimental data.

[1] E. Kozeschnik et al., Mater. Sci. Eng. A. 385 (2004) 157-165.
[2] J. Quadakkers et al., Crofer 22H, Patent number: PCT/DE2007/000166, WO2007093148-A1; DE102006007598-A1 (2006).
[3] B. Kuhn et al., Material Science Engineering A. 594 (2014) 372-380.
[4] C. Schmetterer et al., Journal of Phase Equilibria Diffusion 35 (2014) 434-444.
[5] A. Jacob et al., Calphad, 50 (2015) 92-104.
[6] http://matcalc.tuwien.ac.at/

Calphad, thermodynamics, Laves phase, Steel