Difusión de Ni en volumen de Zr y aleaciones de Zr-Nb

Abstract

Tesis para optar al título de Magister en Ciencia y Tecnología de Materiales

In this work, Ni diffusion coefficients in alpha-Zr and betha-Zr were experimentally measured by conventional siffusion techniques. In the betha phase a linear Arrhenius plot was obtained for the first time, with the following diffusion parameters: frequency factor Do=(2,8 ± 0,6) x 10 supra-6 m2/s and activation energy Q = (121 ± 9) kJ/mol. Comparison of these results with those of Ni in both Zr-20wt percent Nb and pure ß-Nb, allowed us to describe the influence of Nb addition in ß-Zr-matrix in Ni diffusivity: the higher amount of Nb, the lower diffusion coefficient and the higher activation energy of the process. An equation was obtained describing such variation with parameters based on the differenct Q and D(sub)o. It was demonstrated that a similar relation can be applied to Co, and the same could be obtained for Fe. For the alpha phase measurements, single crystals were grown and oriented, six diffusion pairs were prepared, the diffusion annealings performed and two coefficients corresponding to the highest temperature were measured.