Ion irradiation induced mass transport of Ni in Ni and Fe-20Cr-20Ni

Diffusion coefficients of 63Ni in Ni and Fe-20Cr-20Ni were measured with SIMS after 300 keV Ni+ irradiation at temperatures between 293 and 1000 K with an ion flux of 6.3 x 1012 cm -2s-1. At lower temperatures up to about 600 K a temperature independent diffusion coefficient of about 1.4 x 10-16 cm2 s-1 was observed, which indicates that transport is dominated at these temperatures by athermal recoil mixing. At higher temperatures the diffusion coefficients are temperature dependent. These results are discussed with respect to point defect reactions and diffusion. The activation energies of the thermally activated process of 0.58 eV for Ni and 0.67 eV for Fe-20Cr-20Ni are determined by half the respective vacancy migration enthalpies. The production rate of freely migrating defects is estimated to be about 2.5% of the calculated damage rate per atom in self-ion irradiated nickel. (orig.)