Growth of defect clusters in thin nickel foils during electron irradiation (I)

Thin nickel foils were irradiated with 650 keV electrons in a Hitachi high-voltage electron microscope at temperatures between 20 and 650 °C. The formation of interstitial dislocation loops was observed during irradiation in the temperature range from 20 to about 540 °C. In an intermediate temperature region from above 200 to 420 °C vacancy-type defect clusters were also found. Vacancy dislocation loops did only grow on the compression side of an edge dislocation. The growth of interstitial dislocation loops at elevated temperatures is interpreted under the following assumptions: (i) The point defect concentrations are mainly determined by mutual annihilation and diffusion to the foil surfaces, and (ii) the interaction of a dislocation with an interstitial is stronger than that with a vacancy.