Electron Radiation Induced Diffusion of Point Defects in Metals

Effects of electron radiation on the displacement of point defects in metals are evaluated with various conceivable models. The collision cross-section to transfer the energy required for the displacement is calculated. The effect of large energy recoil is taken into consideration. Synergestic effect with the thermal vibration is estimated to be small. Electron energy dependence is evaluated to find the maximum effect by the medium energy electrons. The effect is in general larger for heavier elements and also larger for the point defects with smaller migration activation energy when compared within the same kind of point defects. The number of jumps of both vacancies and interstitial atoms under normal operating conditions of an electron microscope is in the order of 1∼10 jumps/sec. The influence of the effect on the already published results on point defect natures derived from electron irradiation experiments by high voltage electron microscopy is discussed.