The threshold energy for atom displacement in irradiated copper studied by high-voltage electron microscopy

Abstract

Abstract The dependence of atom displacement on irradiation direction and temperature has been studied in copper at low electron energies in a high-voltage electron microscope. The displacement was monitored by observing the nucleation and growth of interstitial dislocation loops. At 550 K a pronounced dependence of the displacement rate on irradiation direction was found. From this it can be concluded that the threshold energy surface exhibits ring-shaped ranges of minimum threshold energy around the 〈110〉 directions. The angular separation of them ranges from the respective 〈 110〉 directions is about 6° and the angular width about, 4°. The minimum threshold energy increases from 16.5 eV at 10 K to 17.5 CV at 70 K and then decreases continuously to 10.5 eV at 550 K. As the result of a sub-threshold process at suitably oriented stacking faults, displacement occurs already at energies that are about 1 eV lower. The observed dependence of atom displacement on knock-on direction and temperature can be explai...