The influence of Fe on the Zr self-diffusion: An ab-initio assessment

R.C. PASIANOT, V.P. RAMUNNI, R.PÉREZ Y M. WEISSMANN

La Florida - EUA

Conferencia; The Fourth International Conference on Multiscale Materials Modeling; 2008

As is well known the diffusion in hcp-Zr does not follow the accepted common behavior for metals, namelyi) Arrhenius law is not obeyed.ii) Some 3d transition elements, Fe, Co, and Ni among them, are ultra fast diffusers, with diffusivities exceeding in about 9 orders of magnitude the one for Zr self-diffusion.iii) Small amounts, sucha as some few tens ppm, of the above elements seem to be responsible for a remarkable enhancement of self and substitutional diffusion. Particularly Fe because of its unavoidable presence in commercial Zr samples. In the rpesent work we apply the ab-initio electronic structure code Siesta, coupled with a recently developed transition state finding technique, the MONOMER, in an effort  to assess the equilibrium and barrier, structure and energy, of some point defects in the vecinity of the Fe impurity. The results are discussed in the light of experimental measurements and available semiempirical models.