Diffusion in the LI_2 Ordered Structure: a Monte Carlo Study

摘要

Diffusion in Li_2 structure is investigated by means of atomistic kinetic Monte Carlo simulations on a rigid lattice. We observe that two diffusion mechanisms resulting from the interactions of vacancies with antisites located on both sublattices allow for the displacement of the minority element and can enhance the diffusivity of the majority element. The respective contributions to the diffusion process of these two mechanisms depend on temperature and on the deviation from the stoichiometric composition. They can explain the minimum of nickel diffusivity experimentally observed around the stoichiometic composition in Ni_3Al and the suspected lower activation energy for gallium than for nickel in Ni_3Ga.