Low-dose neutron irradiation damage in FCC and BCC metals

Abstract

In this paper the progress made by the author and co-workers in transmission electron microscope studies of the irradiation damage structure induced in pure metals (Cu, Mo and α-Fe) and dilute Cu-Ge alloys by low-dose fission neutron irradiation will be reviewed. Neutron doses (>1 MeV) were generally 10 21 − 10 22 n/m 2 and irradiation temperatures were between 80° and 600° C. A common feature of the results in all the systems studied was that frequently the damage showed considerable spatial variation with the development of highly damaged regions around in-grown dislocations. The form of the damage between the dislocations depended sensitively on the metal, irradiation temperature and neutron dose. For example, in copper at elevated temperatures the damage was predominantly vacancy in nature, with a complex interdependence between stacking fault tetrahedra and voids. An extensive parallel study has been undertaken of cascade collapse in different metals as a function of material purity, irradiation temperature, and cascade parameters. The considerable insight these results have given into the neutron damage structures are discussed.