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J. Svoboda, Y.V. Shan, E. Kozeschnik, F.D. Fischer:
"Determination of depths of traps for interstitials from thermodynamic data: a new view on carbon trapping and diffusion";
Modelling and Simulation in Materials Science and Engineering, 21 (2013), 6; 065012 - 065026.

Traps, such as dislocation cores, foreign atoms, surfaces of nano-precipitates, etc, can significantly influence the kinetics of diffusion of interstitial atoms in a crystal lattice. Trapping is reflected in the chemical diffusion coefficient, whose value can be up to several orders of magnitude lower than the corresponding diffusion coefficient in a trap-free system. If we consider trapping only at dilute foreign atoms, we may assume only one sort of traps in the system, the depth of which is characterized by Delta E (trapping enthalpy) given by the decrease in energy due to trapping of one mole of interstitials. In this paper, a rigorous thermodynamically based concept is offered to extract the value of trapping enthalpy Delta E from chemical potentials of interstitial atoms which are, for instance, available in the form of CALPHAD-type thermodynamic databases. Exemplarily, the values of Delta E for C-trapping at Cr impurities are evaluated. For comparison, trapping enthalpies of C at various typical alloying elements in steel are also extracted and compared with literature values. The chemical diffusion coefficient of C in an Fe-Cr-C system at 500 degrees C is calculated for different mole fractions of C and Cr atoms. The influence of traps on diffusion becomes evident from this analysis.

Fe-Ni alloys; alpha-iron; computer-simulation; solid-solutions; vacancy; hydrogen; atoms; bcc; dislocations; deformation

http://dx.doi.org/10.1088/0965-0393/21/6/065012