Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 55: Topical Session Growth Kinetics V
MM 55.5: Vortrag
Donnerstag, 25. März 2010, 15:00–15:15, H4
Trapping effects on the critical nucleus size in nucleation a growth processes, kinetic Monte Carlo simulations — •Zoltan Balogh1,2, Zoltan Erdelyi2, and Dezso L Beke2 — 1Westfälische Wilhelms Universität-Münster, Institut für Materialphysik, Münster, Germany — 2University of Debrecen, Department of Solid State Physics, Debrecen, Hungary
The critical nucleus size - above which a nucleus will grow and below dissolve - is calculated in a binary alloy during diffusion controlled phase separation using kinetic Monte Carlo simulations. In the calculations the differences in atomic mobilities are often neglected, however the difference of diffusion coefficients in a binary alloys can be as high as 4-8 orders of magnitude in technically important materials (like Si-Ge, Fe-Cr or Ni-Cu).
If the atomic jumps are slower in the A-rich nucleus than in the embedding B-rich matrix, the nucleus will trap the approaching A atoms to its surface. It has not enough time to reject them - despite this process would be favored thermodynamically - before new A atoms arrive. Thus the kinetic and thermodynamical critical size would be different for the nucleus. With reasonable trapping effect the former can be even an order of magnitude smaller than the latter.