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Y.V. Shan, W. Mayer, E. Kozeschnik:
"Thermodynamics of Carbon Trapping at Dislocations in Martensite";
Poster: Calphad XLIII, Changsha, VR China; 2014-06-02 - 2014-06-06.

With the following work we introduce a model for the description of carbon trapping at dislocations. The interstitial lattice, in which carbon diffuses, is separated into a trap lattice, caused by dislocations, and a trap-free lattice, where carbon can diffuse freely. In equilibrium the ratio between these two lattices is determined by the trapping enthalpy between dislocation and carbon. This allows a new and more general description of the Gibbs energy, which can reproduce the solubility of carbon in relation to the dislocation density. One application of this model is the numerical treatment of the metastable phase martensite using the thermo-kinetic software MatCalc. The thermodynamics of martensite can be well described and are compared to recent experimental results. The model also provides a new fundament for future works on kinetic evolution of carbide precipitates in tempering of martensite.

carbon trapping, dislocations, thermodynamics, martensite