Electron radiation damage and properties of point defects in molybdenum

Electron radiation damage of molybdenum was performed in a high voltage electron microscope at temperatures up to 6000C. The defects formed by the clustering of point defects are dislocation loops of interstitial type on (111) planes with their Burgers vector perpendicular to the loop plane. The characteristic shape of the loops is induced by the directional flow of interstitial atoms along the gradient of the dilatational strain field of the dislocation loops. The nucleation of loops is found to be impurity sensitive. An analysis of the temperature dependence of the number of loop nuclei gives the activation energy for the release process of interstitial atoms from the impurity traps to be 0.19 eV. The nucleation period and growth nature of interstitial loops are classified with irradiation temperature, and they are well explained in terms of the vacancy mobility. It is confirmed that the lower the irradiation temperature is, the greater the amount of vacancies accumulated in a specimen. (auth.)