Radiation-enhanced diffusion due to interstitials and dynamic crowdions

It is shown from measurements of the radiation damage rate in copper and in gold that dynamic crowdions cause spontaneous annihilation of radiation-produced vacancies and interstitials during irradiation so that the initial production rate of interstitials and vacancies is decreased by orders of magnitude with respect to the initial damage rate. The number of replacement collision sequences is N = 40 000 in pure materials decreasing to N = 15 if under- or over-sized atoms are added. It is shown that dynamic crowdions cause tracer-diffusion and inter-diffusion, e.g. of silver in nickel and of nickel in silver, and that they are able to destroy order very effectively. Three-dimensionally migrating radiation-produced point defects cause micro-structural changes above the temperature range above which they are sufficiently mobile, e.g. above 125 °C in nickel and above -16 °C in copper. There is no three-dimensionally migrating defect below these respective temperatures in nickel and copper contributing to diffusion.