Kinetics of interstitialcy diffusion in electron-irradiated Cu-Ni alloys

The residual electrical resistivity of an alloy Cu + 58.7 at% Ni has been measured during 3 MeV electron irradiation at temperatures between 120K and 570 K as well as during isothermal annealing up to 570 K. During isothermal irradiation the resistivity decreases due to decomposition of the alloy. For the temperature range 120 to 370 K the observed decomposition kinetics is consistently interpreted by interstitialcy diffusion and a diffusion path of the three-dimensionally-migrating interstitials which is terminated by trapping and recombination reactions. The interstitials trapped during low-temperature irradiation are detrapped during 350 K annealing. The reaction parameters obtained by a fit of the model calculations to the data amount to the same order of magnitude as the parameters found for pure Cu and dilute Cu alloys. For the vacancy capture radius a stronger temperature dependence is found than in copper. By irradiation the equilibrium state of decomposition could be attained down to 400 K. The resistivity of equilibrium increases linearly with increasing temperature between 400 and 770 K. (author)