Dislocation Vibration as a Possible Cure for High Temperature Void Formation in Metals under Fast Neutron Irradiation

Abstract

EXTENSIVE void formation occurs in metals subjected to fast neutron irradiation in the temperature range of 0.3 Tm to 0.5 Tm where Tm is the melting temperature of the metal1–4. This phenomenon is a serious problem in reactor technology. In conditions of fast neutron irradiation large numbers of lattice vacancies and interstitial atoms are produced in equal amounts. Dislocation lines and voids (pre-existing ones or newly nucleated ones) act as sinks to these point defects. If a void is just as efficient a sink for an interstitial atom as for a lattice vacancy and if a dislocation line also is just as efficient a sink for each of these types of defect there can be no tendency for a void to grow2–4. Equal numbers of vacancies and interstitials will be destroyed in a void as well as at dislocation lines. But dislocation lines are probably a more efficient sink for interstitials than for vacancies. Thus more interstitials are destroyed at dislocation lines than are vacancies. The excess vacancies are destroyed at voids, causing them to grow. This very plausible explanation has been presented in the literature to account for growth of voids (see refs. 2–4 and the references cited there).