Tracer diffusion, ordering kinetics and surface reordering in FCC structures – Stochastic Kinetic Mean-Field method vs. Kinetic Monte Carlo

Simulation of ordering and atomic migration in ordered alloys was always the subject of Monte Carlo simulations. Usually, such methods need a lot of computation time. In the present paper, the advantages and disadvantages of an alternative method are discussed.

In our presentation, the tracer diffusion and chemical ordering processes in two FCC binary systems mimicking Ni3Al and FePt are simulated by means of the Kinetic Mean Field (KMF) method. The systems simulated within the present work were modelled with fixed nn pair-interaction parameters fitted to their equilibrium properties and also fixed saddle-point energy whose value might in turn be fitted to the parameters of diffusion and ordering kinetics [1-2]. Modelling of Ni- and Al-tracer diffusion in Ni3Al yielded higher diffusivity in Ni. The simulated “order-order” relaxations in Ni3Al showed either one, or two-time scales depending on whether the “direct exchange” or vacancy mechanism for atomic migration was implemented. Modelling of the discontinuous process of the surface-induced re-orientation of the Fe and Pt monatomic planes in FePt was made by the Stochastic variant of the KMF (SKMF) [3].

[1] Oramus, P., Kozubski, R., Pierron-Bohnes, V., Cadeville, M. C., & Pfeiler, W. (2001). Monte Carlo computer simulation of order-order kinetics in the L12-ordered Ni3Al binary system. Physical Review B, 63(17), 174109.

[2] Kozłowski, M., Kozubski, R., Goyhenex, C., Pierron-Bohnes, V., Rennhofer, M., & Malinov, S. (2009). Atomic ordering in nano-layered FePt. Intermetallics, 17(11), 907-913

[3] Erdélyi, Z., Pasichnyy, M., Bezpalchuk, V., Tomán, J. J., Gajdics, B., & Gusak, A. M. (2016). Stochastic kinetic mean field model. Computer Physics Communications, 204, 31-37