Accumulation of point defects and their complexes in irradiated metals as studied by the use of positron annihilation spectroscopy – a brief review

During the last few years positron annihilation spectroscopy (PAS) has gained increasing recognition as a useful tool in studies of the accumulation of point defects and their complexes in irradiated metals. The technique is sensitive to both the size (in the range from monovacancies up to cavities containing 50–100 vacancies) and the density of vacancy clusters. In order to illustrate the potential of the PAS technique, we present a brief review of results obtained in our laboratory. One series of data show the distinct difference in microstructure between neutron irradiated bcc iron and fcc copper as a function of both irradiation and post-irradiation annealing temperature. Another set of results show the presence of sub-nanometre voids whose size and density increase with dose in neutron irradiated iron. The results show that PAS can be an important experimental tool for the validation of modelling of radiation produced microstructures.