In-situ microstructural observation of radiation damage in nickel produced by energetic heavy particles

Microstructural changes during 300 and 400 keV Ar+ irradiation in pure nickel between 300 and 773 K have been observed in-situ in an electron microscope. Some of the observations are recorded on a video tape. Various phenomena characteristic of cascade damage have been observed. Clustering of point defects is influenced strongly by the presence of point defects sinks: surfaces, pre-existing dislocations, loops and cavities. Wedge-shaped specimens are utilized to sort out the complex behavior of microstructural evolution. Of great interest is the fact that under certain conditions, metastable defect clusters with a very short lifetime are formed during irradiation at 773 K. The implication of these observations to fusion neutron damage modeling is discussed. (orig.)